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Mystery has an end, in this case, enough is enough

108.213.216.95
Posted on November 16, 2014 at 21:26:35
GSH
 Identify this:




I once promised to not post/share this, but since who I promised this to has broken countless promises to me, I have less than zero apologies to whoever is foolish enough to complain. We will know who's behind this by the absence of comments, unless playing fair suddenly occurs to them.

I know exactly what this is. I will tell you if you can't guess correctly.
But first, it would be in the spirit of constructive criticism to present this to a panel of DIY enthusiasts and hear whatever your opinion may be.
Not just what is it, but with what quality is this built, inviting whatever improvements you see as possible or necessary.

 

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RE: Mystery has an end, in this case, enough is enough, posted on November 17, 2014 at 00:13:40
tube wrangler
Manufacturer

Posts: 2484
Location: USA
Joined: January 29, 2007
Interesting. This is an old one for sure. Probably I built it in the middle '90's.

I took this picture many years ago-- I recognize my old carpet (underneath it).

I didn't give these pictures out, but I took two of them along to Room 2020, my old demo room at Denver's RMAF show.

I think someone must have swiped this one! I had them there so I could show a visitor an underchassis, should he ask, without having to remove the bottom cover of one of the show amps that were playing (which were several years newer than this old picture).

I therefore could teach or lecture from the picture, and could comment on what had improved in the newer Models that was not in the old picture.

I don't know who you are, GSH and I certainly made you no promises, so I think you owe this forum your full name right here and now: I think you should do that... so that I may understand.

New models of this amp are different, but the currents, voltages and tube types are the same. Layout, parts and wiring have changed much over the years in the search for better performance.

Something like this post had to happen someday, it's kind of like a nice, plump peach hanging there on its tree, all ripe and ready to be picked by someone.

Since I don't know your name, only "GSH", and you don't know me at all-- you could have called me, and I would have let you post this honestly, as it's very old and not current.. After all, someone did steal my picture!
(Heck!-- I wonder who that was)!

No matter. Have at it guys. Make as many comments/ideas as you want. You may also ask me questions-- feel free to do so.

I will come on the forum occasionally and have a look at what you say and ask, and see if I have an answer for you. I won't do that every day, but I'll follow-up when I can.

This is open to every one on this forum, but I do require that it be done with respect, honesty and courtesy to everyone concerned.

---Dennis---









 

Gracious response. nt., posted on November 17, 2014 at 00:21:12
RC Daniel
Audiophile

Posts: 1922
Location: Brisbane
Joined: November 3, 2002
 .
"In the beginner's mind there are many possibilities, in the expert's mind there are few." Shunryo Suzuki

 

RE: Mystery has an end, in this case, enough is enough, posted on November 17, 2014 at 01:35:53
GTCharlie
Audiophile

Posts: 983
Location: Philippines
Joined: December 9, 2004
 those yellow cylinders are obviously polyprops. hovland? but the one tacked on to the side is certainly not hovland.

the red ones are? wondercaps?

the black plumps looks like something covered with shrinkable tube. maybe some kind of a ferrite?

 

RE: Mystery has an end, in this case, enough is enough, posted on November 17, 2014 at 02:24:36
LinuxGuru
Audiophile

Posts: 582
Location: European Union
Joined: November 11, 2008
 > I know exactly what this is. I will tell you if you can't
> guess correctly.


At first I thought this is DrLowMu creature.

Typical amateur build, definitely not the worst one.
Nothing worth 5-digit price tag however.

> inviting whatever improvements you see as possible or necessary.

Trash can.

 

RE: Mystery has an end, in this case, enough is enough, posted on November 17, 2014 at 05:57:47
Al Noakes
 Please do not bait Dennis , you'll scare him away . I'm definitely not one of Dennis' creepy-cheerleaders like those other two clowns but he seems to be a really decent bloke and a bit of a character . Regardless of how you view his engineering input on this forum , I think he's a major personality around here :)

Al

 

RE: Mystery has an end, in this case, enough is enough, posted on November 17, 2014 at 06:17:22
RPMac
Audiophile

Posts: 377
Location: So. Mississippi
Joined: January 3, 2005
 How does it sound?

 

How does it sound?, posted on November 17, 2014 at 07:16:57
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 At an RMAF around 2008 I had the good fortune to listen, alone with Dennis, to the then-current version of this amp playing some of his favorite music. It was this experience that really turned my head towards SET, although it took a lot research before i got up a good head of steam in that direction.

I now own 3 SET amps and have owned two others. I admit to having one that is a 300B type, a tube i love to hear with my LS3/5As.

 

I like this one., posted on November 17, 2014 at 07:30:07
Tre'
Industry Professional

Posts: 17304
Location: So. Cal.
Joined: February 9, 2002



It has a much cleaner layout.

It's too bad both have deficient power supply filters (unstable even at idle) and driver stages that can't fully drive the output tube's Miller capacitance (output impedance too high, delivery current too low, designer admits amp start to roll highs at 15kHz because of this) along with output tube cathodes that are far from fully bypassed leaving the -3db point at about 20Hz instead of the normally accepted 5Hz (to little total capacitance).

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Oddity, posted on November 17, 2014 at 07:33:14
Awe-d-o-file
Dealer

Posts: 21037
Location: 50 miles west of DC
Joined: January 10, 2004
 "Dennis" who has the M classification meaning he is a manufacturer is the only one I've ever seen that doesn't mention his company name/website. Dennis Had, Fraker? Anyway this is an odd thread and someone is on the offensive and someone will be on the defensive. It will be interesting to see how this plays out as they say. I feel out of the loop which is fine. I'm no regular here. It would be nice to have at least a modicum of facts though.

ET
ET

"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936

 

RE: Mystery has an end, in this case, enough is enough, posted on November 17, 2014 at 07:40:49
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 Yo Dennis and Forum Members,

A number of years ago, Dennis sent me three shots of an early Serious Stereo 2A3 amp ( we had been friends for two decades at that point ), so I could see / study his execution as I built a DC 2A3 amp for myself.

On the Forum, maybe 6-7 years ago, I made email friends with a audiophile batchelor in California named Grant S. Handley, an interesting guy. When Grant wanted to build a DC 2A3 amp, I tried to assist him, as best as I knew back then ( this was early in my Dennis Fraker amp experience, and there were gaps in my understanding ).

With certain errors on my part, Grant and I made up a parts list, and, ON A TOTALLY CONFIDENTIAL BASIS THAT GRANT UNDERSTOOD, I sent him that photo.

Unknowns would not steal a photo from Dennis in his RMAF demo room.

I gave the photo to Grant, with one provision - he always kept it to himself.

Grant is capable, intelligent, and he tried to design an amp with a parts layout that would have as little wire lengths in it as possible. I liked it from what I saw, unheard. He did a very "fresh" approach to layout, and posted it on line, this Forum, under his moniker " Satan Patiently " Look it up !!

The problem was, Grant didn't apply the budget to select the best parts, and he SERIOUSLY had gaps in his amps' execution. A botch job. Missing were at least half of the film bypass caps in various key places. He wouldn't or couldn't spend the money on them, and I didn't know enough to correct him then.

A second area of total goof-up was in his use of wire. I told him that silver needed to be used from the RCA Jack to the driver's grid pin, and between the direct couple, and that he needed to use a heavy AC cord, like 10 AWG. I asked him to wire the B+ runs, and grounds with multiple TCSS, ( something I did at that time as a budget alternative to Siltech which I can't afford ), the "big stuff " in the amp's underside picture.

GSH took it upon himself to take the cheap ( ACME wire, sourced from Lowes Hardware stores, which I gave him for AC cord wire ) and wire the amp's B+ and Ground runs with that, a wire I told him was for AC cord use only !!!

About three years later, I "discovered" by A-Bing, that I was WRONG to have an inch of that ACME wire in ANY AC cord, it was "shredded and ultra-strident sounding" as an AC cord. ( I now use Fulton FMI Brown 10 AWG as my AC cord. Very quiet, love it .)

Well folks, poor GSH had :

(1) the amp wired with this shredded / strident sounding wire, and

(2) he had HUGE HOLES in the amp's response, due to his cheapo half baked bypassing, which takes LOTSA $$$$ to do right !!!

So Grant was sitting with a botch job, and I did not know what to do for him long distance, to fix his execution. He got frustrated with me I suppose, although we have remained neutral to each other, and without my knowledge, on his own , sent the botched amp to Tre Perry for "evaluation ".

For the life of me, I have no idea what Grant means when he writes above I have " broken promises" to him, as a justification to post this photo, given in total confidence to him. If I did break a promise, tell me about that, and I am sorry for that !! But we all know, two wrongs don't make a right.

These are the facts as well as I can say them. It is up to others to judge GSH / Satin Patiently AND ME, for ever releasing the photo on a confidential basis.

The most interesting thing of all is , that GSH has never been to a RMAF show, or Montana, to HEAR Dennis' amps, and they somewhat THINK the botched job that GSH executed is what Dennis' sounds like!!!!!! Not so at all, thats not the truth,...... one can hear the truth easily.

This fallacy has been going-on, with this Forum, for maybe five years now.

So the facts remain : (1) they never heard a a Serious Stereo amp, neither of the people, and how well it plays and (2) Dennis has taken the basic amp to a new and even higher performing level with his latest implementations, same circuit, better implementation, the best possible !!

Dennis, I apologize sincerely, but I am hoping we will have a new opportunity to discuss audio up here, by those seriously looking to improve performance, with this recent turn of events.

Grant, I think you need a wife or close friend, to bounce things off of, before you act!

Sincerely,

Jeff Medwin

 

RE: Mystery has an end, in this case, enough is enough, posted on November 17, 2014 at 07:42:23
Tre'
Industry Professional

Posts: 17304
Location: So. Cal.
Joined: February 9, 2002
 "You may also ask me questions-- feel free to do so."

OK.

What is the total capacitance value for the cathode bypass cap for the output tube?

What is the output impedance of the driver stage?

What is the idle current of the driver stage?

What is the inductance of the first choke in the power supply filter?

What is the DCR of the HT secondary winding of the power transformer?

What is the capacitance value of the first cap in the power supply filter?

What is the impedance of the primary winding of the output transformer?

Answer those questions first and then I will have more questions.

Thanks Dennis.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Oddity, posted on November 17, 2014 at 07:47:43
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 See my post above, I try to explain this as much and as well as I can.

Always remember this ....."None on those on offense have ever HEARD amp made by Dennis Fraker"!!

There is NO substitute for direct listening experience.

Jeff Medwin

 

RE: Oddity, posted on November 17, 2014 at 07:48:59
Al Noakes
 'It would be nice to have at least a modicum of facts though.'

Facts hardly come into it . To stay sane , just take those posts at face value and sit back and watch the creepy cheerleaders make fools of themselves :)

Al

 

RE: Oddity, posted on November 17, 2014 at 07:52:11
Awe-d-o-file
Dealer

Posts: 21037
Location: 50 miles west of DC
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 Excellent, thanks for the post AND responding to me. Man gather data, good, what he do with data more important........


ET
ET

"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936

 

RE: Oddity, posted on November 17, 2014 at 07:55:53
Awe-d-o-file
Dealer

Posts: 21037
Location: 50 miles west of DC
Joined: January 10, 2004
 As someone who is quite cynical at times and knows what humans are capable of your schooling of me on that issue is understood. In the end the thread is eye opening in some ways and "see I told ya so" in others which is to say "face value" can be quite distorted in cyberspace. I hope that makes a little sense anyway, thanks for the reply.



ET
ET

"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936

 

You are so lucky..., posted on November 17, 2014 at 09:36:17
DeKay
 I still have that carpet.

 

RE: stancor chokes ..., posted on November 17, 2014 at 10:18:25
deathtube 667
 The Stancor 10 ohm 1500V chokes - I think DF wrote that he used 2 identical chokes in the LCLC filter to finals.

Not exactly sure what the values of those chokes are, but I recall that Triad C40-X were a recommended replacement.

 

RE: I like this one... me too, posted on November 17, 2014 at 10:29:29
deathtube 667
 I recall this amp and thinking the layout was fantastic.

It honestly does look a bit cleaner/neater that the SS 2A3 amp, agreed.

Did GSH/SP also have a schematic to go by along with the layout photo when he sent it to you or did you reverse engineer it?

 

RE: Mystery has an end, in this case, enough is enough, posted on November 17, 2014 at 10:48:48
GSH
 "Something like this post had to happen someday, it's kind of like a nice, plump peach hanging there on its tree, all ripe and ready to be picked by someone."

I'm glad you see the justification in this.

"I don't know who you are, GSH and I certainly made you no promises, so I think you owe this forum your full name right here and now"

I don't owe anybody anything, yet I will have to point out the obvious (again). JM addresses me by name in almost every response to a post I make, including right here in this thread. How this escapes your attention, I don't know. This kind of apparent senility also appears in the long thread/debate below where numerous misunderstandings are formed.
My moniker is just my initials, my first name is already staring you in the face, my given middle name is Stuart, and my family name is Handley.
Feel better now ? Has this changed anything? Do you remember receiving my call(s) during the process of my building the amp that now has the underside photo posted in this same thread? Do you see why now after such pontificating about superior untouchable build quality, that this must be finally addressed? For the benefit of all, including you?

From what I understand, the, your, amp in the photo is about 6-7 years old, which is when I made a horribly failed attempt to build something similar, which JM refers to all the time. So no folks, this is NOT from the 90's, it's from about 2007.

I find it bazaar, that a "manufacturer" of an expensive "high end" product
which intentionally and consistently surrounds itself with mystery, and inferences that this can't be duplicated by mere mortals, would even bother to tease the DIY crowd, on a public forum, with countless declarations that most of which, are opinions or subjective assessments with explanations that mock physics. To each his own, fine. But to be surprised at all about what this may cause in response, is blind.
And no, it's not offense, it's defense. Just review your remarks in the long thread below, especially the one I responded to, (and that you then DID NOT respond to) and ask yourself if you asked for this or not. You were given a chance right then and there, to lay some cards on the table.

"but I do require that it be done with respect, honesty and courtesy"

You got it, and ignored it.

So now, since the social etiquette issues have been addressed, hopefully to your satisfaction, may we discuss the quality and reasons for the product in the photo, with whatever improvements you've made and why?
You have now stated a willingness to do so, are you ready?

JM has stated he has "moved on" and improved upon the 0.035H/50uf/0.035H/50uf power supply we see in BOTH photos in this thread. Have you?
If yes, then what? And why? Did you use a PSUD sim to "perfect it" ?

We can all see the multiple bypass caps, tell us, what's changed and why?

Are you using a small cap across (in parallel) with the choke(s) ?
If yes, is this how you are compensating for the loss of highs no doubt produced by the driver's inadequacies? If no, how then? Or is this addressed in your current design? Or does it even need to be, based on your concept of "high fidelity", which is...?

What about those RF chokes, still using those? Even on the 7B4's AC filaments?

I notice the soldering iron burn on one of the yellow rectifier wires nearly or actually exposing raw HV. Have the soldering skills improved on this $5000 product beyond what we see here?

Thanks in advance for your respectful, honest and courteous response.


Regards,

Grant Stuart Handley







 

RE: I like this one... me too, posted on November 17, 2014 at 10:53:35
Tre'
Industry Professional

Posts: 17304
Location: So. Cal.
Joined: February 9, 2002
 My wife took that photo while I had the amps at my place.

I studied the circuit and drew the schematic that I then poster here years ago.

GSH didn't send them to me. I picked them up and returned them when I was done.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Me too..., posted on November 17, 2014 at 10:54:57
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 DT667,

I loved its looks also,

but The OP and the builder hate its sound......

foolishly THINK its representaive of a Dennis Fraker build, and have ass/u/me/d that for five plus years. It gets awfully old, the non-truth.

At the end of the day, how it sounds, and the amp not breaking, is what counts !!

Jeff Medwin

 

RE: I like this one... me too, posted on November 17, 2014 at 10:56:34
GSH
 No, it was primarily JM who coached me through this build, although I did speak to DF several times in the process also. No schematic, it's a very simple amp.

Admittedly, I didn't (couldn't afford) to buy and install multiple exotic bypass caps, so I did some, not all recommended by the two builders aforementioned. I honestly thought (at the time) that this would make little difference, and that the main "selling points" were the low DCR PS, and the use of a driver that I normally would Not have chosen for obvious reasons. I figured, hell, maybe I'm missing something, it's easy enough to build, why not try it and see. So I did the best I could.

 

RE: I like this one... me too, posted on November 17, 2014 at 10:57:51
Geary Lyons
Audiophile

Posts: 231
Location: Lincoln, California
Joined: April 10, 2007
 Really?! Imagine that! An under chassis layout looks "a bit cleaner/neater that the SS 2A3 amp" when there are half as many components in what appears to be a similar space? Go figger!

I don't have a dog in this hunt, but some of the "con comments" appear to be "piling on" with little firing of the synapses involved.

Getting the layout/wiring done correctly is vital. Building my Bottlehead Paramours really drove this lesson home! Not much real estate on a 6"x10" chassis! The more components the more complex. What is it, specifically, about the SS 2A3 layout/wiring appears deficient?

Cheers,
Geary

 

RE: stancor chokes ..., posted on November 17, 2014 at 11:02:24
Tre'
Industry Professional

Posts: 17304
Location: So. Cal.
Joined: February 9, 2002
 The Triad choke is 320mH.

I just wanted to know for sure what the inductance of the Stancore is.

Knowing the DCR of the power transformer secondary, the DCR of the choke and it's inductance and the uf value of the first cap (along with other factors that I already know) will allow me to sim the supply to a high degree of accuracy.

I already know that the results are bad, very bad. But the more accurate the input data the more accurate the sim.

Thanks

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

BTW this isn't about my amp torn apart years ago, posted on November 17, 2014 at 11:18:16
GSH
 It's about a relative comparison between DF's amp and anybody else's.
In response to, well, isn't it obvious?
My old non-existent attempt, is/was just one guy's version.

DF talks about honesty, a quality I revere as well.

But it's taken what we can now SEE to provoke a new level of it, no doubt.
I'd guess most of you who've been following the "topic" (LOL) would not have expected what we now can SEE. What you may have expected, I don't know, but the wondering is over now, which is HONEST, finally.

 

RE: How does it sound?, posted on November 17, 2014 at 12:00:37
RPMac
Audiophile

Posts: 377
Location: So. Mississippi
Joined: January 3, 2005
 Thank you for your answer.
I also have 3 SET amps by Bottlehead, but the point that I was trying to make was...isn't that the only question that matters?

 

It depends on your religion, apparently. , posted on November 17, 2014 at 12:39:56
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 It was so long ago that i can't compare the Serious Stereo 2A3 amp to the one i own from memory. But, at the time, it was, as i stated, a revelation of a new sonic world for me.

 

So is this a 2007 SS Amp?, posted on November 17, 2014 at 12:51:23
gusser
Audiophile

Posts: 3649
Location: So. California
Joined: September 6, 2006
 Is this a picture of a production SS amp from 2007?

IMO, it looks OK from a build point of view. Nothing special but then it's just a simple 2 stage amp.

 

Two dishonesties here ....., posted on November 17, 2014 at 13:11:49
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 DISHONEST ONE :

Me sending you the picture to help you in your build, seven years ago, with the clear understanding of confidentiality between us.

DISHONEST TWO :

You posting this photo.

Its hypocrisy see YOU use the word "HONEST", in caps, in your above post Grant !!!

You say "It's about a relative comparison between DF's amp and anybody else's.". Baloney, you people have been invited to A-B sessions, and shows, and declined.

A meaningful comparison requires one thing, listening.

Jeff Medwin



 

Not really...., posted on November 17, 2014 at 13:18:40
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 Its a picture of one of Dennis' Serious Stereo amps I sent Grant in about 2007.

We are not sure how old the amp is, and Dennis is looking at the carpeting to guess.

We see DynamiCaps a plenty, when did they come out ??

Date of manufacture doesn't matter much, how it SOUNDS to a serious listener is what matters.

Jeff

 

Stop beating around the bush!, posted on November 17, 2014 at 13:28:07
gusser
Audiophile

Posts: 3649
Location: So. California
Joined: September 6, 2006
 Ok so it is a Serious Stereo amp. So he is using different component manufactures today. Perhaps a few things are moved around as well.

But it's still the basic 1930 vintage design built in a garage workshop or the kitchen table.

Sure it may sound fantastic to some people. Why not just leave it at that.

Just stop sprinkling pixy dust on it. We all now know what's inside and frankly it's nothing unexpected.

 

RE: Stop beating around the bush!, posted on November 17, 2014 at 13:59:22
airairy
Audiophile

Posts: 43
Joined: July 19, 2008
 What was the original cost of that amplifier is more interesting as those “commercial” amplifiers are not cheap

 

RE: Me too..., posted on November 17, 2014 at 14:04:09
GSH
 "foolishly THINK its representaive of a Dennis Fraker build, and have ass/u/me/d that for five plus years. It gets awfully old, the non-truth."

This is getting closer to the Real question. Thanks Jeff.

Question: How likely, and to what degree will 2 amps built with the same circuit, nearly identical operating points (coached, remember), many parts exactly the same on advise, sound different from each other?

We know what Jeff thinks, which is, there's no comparison.

Of course the "foolishly" built amp has nothing to do with advisors /proponents of it, there couldn't any foolishness there, right?

What has been claimed many times is that my choice of wire(s) is the prime cause of the "no comparison" status. So tell me, now that y'all
can see them both, how likely is this true? Examine the actual amount
of wire on either example. BTW, I did use solid silver wire from plate to grid, and stranded silver on the OPT, which has a partial silver secondary as well. My large gauge copper less than 6" long ground bus, has been named as a huge problem. It's the white wire in the pic posted by Tre. It goes from the center tap of the LOWER DCR PT (than the Hammond in the other amp) to a point near the input. In DF's build the stock red/yellow CT wire of the Hammond is present and connects to the "very special" silver wire under one of the two wires with the blue heat shrink. This is what Jeff is talking about. No guessing anymore.

Next is the obvious absence of multiple bypass caps, but I did at least get a decent one of the correct value, as coached, a Dynamicap, and bypassed it with another 0.01uf Dynamicap too. According to Jeff, I FOOLISHLY assumed there couldn't be a BIG difference. What do you think?

Next, it has been stated by both JM and DF that "a Dennis Fraker build"
is something so special that us morons just can't get it. Now that you can SEE what's been talked about, you can make up your own mind.

The 3 main reasons that are claimed to be the difference between junk and gold, are now here for inspection.


 

RE: Two dishonesties here ....., posted on November 17, 2014 at 14:13:02
GSH
 Yes Jeff, hypocrisy is part of life, our job is to minimize it.

But there's no dishonesty here, just what you perceive as such.
Or a form of honesty that's perhaps not the tastiest.

I never said there couldn't be a difference, the question is to what tangible degree? The black and white extremities you claim are exaggerations, among others.


 

Look at the grounding!, posted on November 17, 2014 at 14:14:37
gusser
Audiophile

Posts: 3649
Location: So. California
Joined: September 6, 2006
 I love the way he routes the AC power ground, and the b+ filter ground, the yellow wires, right back through the input circuit and tube! Those have to be the two nosiest wire in any amp. Why not run them around the back side where there is far less change causing of EMI.

Poor engineering practice in my book.

Ahh, but wait. Dennis did claim in a past post that a little amount of hum is good. Something along the lines that it per-energizes the speaker so it can respond faster. This must be how he gets just the right amount of hum into the signal path.

 

never mind that, I can ignore almost anything for good sound... does it sound good?..., posted on November 17, 2014 at 14:57:21
Cleantimestream
Audiophile

Posts: 7551
Location: Kentucky
Joined: June 30, 2005
 {I must admit, is VERY hard to ignore the vulgar cosmetics of a Hogan amp}

The proof of the pudding is in the tasting, while I understand the questioning of outlandish statements made by DF and JM, what really matters is how does it sound?



The Mind has No Firewall~ U.S. Army War College.

 

RE: Look at the grounding!, posted on November 17, 2014 at 15:13:28
Tre'
Industry Professional

Posts: 17304
Location: So. Cal.
Joined: February 9, 2002
 "Ahh, but wait. Dennis did claim in a past post that a little amount of hum is good. Something along the lines that it per-energizes the speaker so it can respond faster. This must be how he gets just the right amount of hum into the signal path."

There's no arguing with Dennis.

No matter what you say (or how technically right you are) he will come up with some crazy idea to makes him right and you (and all of the audio electronic knowledge of mankind that precedes him) wrong.

It's pointless to argue with crazy people.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Stop beating around the bush!, posted on November 17, 2014 at 15:23:08
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since: September 9, 2000
 $15k or something like that.

 

RE: never mind that, I can ignore almost anything for good sound... does it sound good?..., posted on November 17, 2014 at 15:28:35
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since: September 9, 2000
 Sometimes, its like saying, I don't care what goes in my food, all that matters is what it taste like. Nobody has criticized the sound. From what I have picked up, is that there are basic engineering flaws that no one in the right mind would ignore. Maybe the amps would sound even better......

 

The emperor has no clothes, posted on November 17, 2014 at 15:35:59
GEO
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  Since: September 9, 2000
 Cover yourself up Lo Mu

 

RE: How does it sound?, posted on November 17, 2014 at 15:46:09
GEO
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  Since: September 9, 2000
 All that matters is what it sounds like....all that matters is what it taste like. Some things YOU would not do if YOU were COOKING food and some things YOU would not do if YOU were BUILDING an amp....

 

RE: Mystery has an end, in this case, enough is enough, posted on November 17, 2014 at 16:25:01
GEO
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  Since: September 9, 2000
 Move on Jeff. Jonestown is reachable by plane.

 

Peddling long pork is a stretch, tunneling sideways to obtain natural gas for fuel ..., posted on November 17, 2014 at 16:56:05
Cleantimestream
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Posts: 7551
Location: Kentucky
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 is now passe'; even if I do not agree with trashing our water supply in the process. The issue concerns can one HEAR the substandard power supply save through an oscilloscope? Can you? Have you? I have no use for conjecture.
The Mind has No Firewall~ U.S. Army War College.

 

RE: Peddling long pork is a stretch, tunneling sideways to obtain natural gas for fuel ..., posted on November 17, 2014 at 17:08:14
GEO
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  Since: September 9, 2000
 Have you tasted human in a stew? Have you? Would you eat more if you tasted it and liked it?

 

RE: Peddling long pork is a stretch, tunneling sideways to obtain natural gas for fuel ..., posted on November 17, 2014 at 17:48:01
Cleantimestream
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Posts: 7551
Location: Kentucky
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 It does taste good. I believe the reports that it does so. I am now answering you on a moral plane and the answer is no. I will never eat human flesh. There is no degradation of character involved through listening to music, unlike cannabilism. You are comparing apples to oranges when one involves moral precedent. A twisted tautology that makes as much sense as 'in order to be free we must all become slaves'.
The Mind has No Firewall~ U.S. Army War College.

 

RE: Peddling long pork is a stretch, tunneling sideways to obtain natural gas for fuel ..., posted on November 17, 2014 at 18:19:07
GEO
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Posts: 4749
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  Since: September 9, 2000
 This debate is about more than "it sounds good to my ears". You ever hear a John Hogan amp? They sound good but most people would not build an amp like that. Do you want something accurate or something that is pleasing to your ear? Two different things. In some cultures, cannibalism is not taboo. Someone may argue that it is a degradation of character to misrepresent engineering?

 

RE: Not really...., posted on November 17, 2014 at 18:33:18
cpotl
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Posts: 1002
Location: Texas
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 Well it's clear now why there was always so much coyness and secrecy about the internals of those amplifiers. And now we can see what the "three-dimensional wiring" means in practice. I suppose birds' nests are three-dimensional also.

I don't mean to be harsh; it looks pretty much like the kind of things I put together also. But then, I don't try to sell mine for serious money...

Chris

 

Absolute Sound and All That Jazz, posted on November 17, 2014 at 18:41:47
Mr_Steady
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Posts: 2042
Location: North Florida
Joined: August 19, 2014
 GSH,

"What has been claimed many times is that my choice of wire(s) is the prime cause of the "no comparison" status. So tell me, now that y'all
can see them both, how likely is this true? Examine the actual amount
of wire on either example. BTW, I did use solid silver wire from plate to grid, and stranded silver on the OPT, which has a partial silver secondary as well. My large gauge copper less than 6" long ground bus, has been named as a huge problem. It's the white wire in the pic posted by Tre. It goes from the center tap of the LOWER DCR PT (than the Hammond in the other amp) to a point near the input. In DF's build the stock red/yellow CT wire of the Hammond is present and connects to the "very special" silver wire under one of the two wires with the blue heat shrink. This is what Jeff is talking about. No guessing anymore."

Grant, if you maxxed out this amp with all the parts and paid retail, how much do you think it would cost? Give it enough thought to come up with a good honest number.

Thanks,

Jamie

Big speakers and little amps blew my mind!

 

Birds Nest Wiring, posted on November 17, 2014 at 18:55:10
Mr_Steady
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Posts: 2042
Location: North Florida
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 Chris,

It's funny you used this phrase,and I think you meant to.

"I suppose birds' nests are three-dimensional also."

Because I was thinking about "Birds-Nest" wiring today. But then I wasn't so sure this amp was an attempt at birds-nest wiring.

Jamie

Big speakers and little amps blew my mind!

 

RE: Peddling long pork is a stretch, tunneling sideways to obtain natural gas for fuel ..., posted on November 17, 2014 at 19:11:06
Cleantimestream
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Posts: 7551
Location: Kentucky
Joined: June 30, 2005



I have both, I have many amps built, by me and together with a close friend.

I have a push/pull 45 for deadly accuracy.

I have a modified George Wright for euphonic smoothness.

I can build to suit the music or my whim.

Here is one build, there are many other in form... usually, but not always following function.
The Mind has No Firewall~ U.S. Army War College.

 

RE: Peddling long pork is a stretch, tunneling sideways to obtain natural gas for fuel ..., posted on November 17, 2014 at 19:22:09
Mr_Steady
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Posts: 2042
Location: North Florida
Joined: August 19, 2014
 CS,

You posted a PP amp on the SET forum? I would take either one of the SET amps pictured on this thread. Hell, I give up.

Jamie

Big speakers and little amps blew my mind!

 

RE: Peddling long pork is a stretch, tunneling sideways to obtain natural gas for fuel ..., posted on November 17, 2014 at 19:25:20
GEO
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Posts: 4749
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Contributor
  Since: September 9, 2000
 Was that built by a guy out upper n. west. It looks familiar.

One of mine.







Former amp





 

RE: Absolute Sound and All That Jazz, posted on November 17, 2014 at 19:57:13
GSH
 Funny, I was thinking about just that this afternoon after learning that I was wrong about the $5K each situation, it's actually $15K/pair which is $7500 each.

I figured the parts for a PAIR even with EML 2A3s would be somewhere between $3300 and $3800, with a $600 allowance for capacitors EACH. Could be less at OEM pricing and quantity discounts. Since I don't know exactly what caps are used, it's a blurry zone, but $600 is generous, could be less, could be a little more (exchange rates shipping etc..)

Here's my ballpark math:

2 x Hammond PT 350
2 x MQ OPT 400
2 x EML 2A3 630
4 x chokes (those) 100
6 sockets, fuses, switch, jacks, hdware 200 (could be more or Less)
2 x chassis 400 (steel powder coated) seems high
2 Filament trans 60
2 x 5U4GB + 2 x 7B4 50
pile o caps 1200 crazy but probably is
thermistor, RF chokes, "special wire" 150 ? Seems high
Misc + shipping taxes what? 200

Total $3740/2 = $1870 each

I believe it could be done for $100's less depending on a variety of things, not that I'd bother. Even if I believed in this concept, there
are various areas where quality could be improved for LESS $. I understand that in a new manufacturing world you need to be able to source all the parts, usually meaning "in current production". But considering the low numbers of these produced, it could be done with some
superior grade surplus stuff, in limited quantities, of course.
They don't make 7B4's anymore, but there's 1000's of them out there NOS for peanuts. Same with 5U4's. JJ 2A3's would save $100'S too.

Hours go into a build like this, drilling, installing and then soldering.
But if you've done it before even once, and it's just a repeat, then it's MUCH faster. Most of the time in one off DIY builds is decision making!


 

RE: Peddling long pork is a stretch, tunneling sideways to obtain natural gas for fuel ..., posted on November 17, 2014 at 20:26:25
Cleantimestream
Audiophile

Posts: 7551
Location: Kentucky
Joined: June 30, 2005
 No, that one was built by Will and I both...that one in the photo is a one off, many too many special attributes unlike what Will sells. Am working out of town at present so am unable to show my builds that do not include Will... they use solid maple wood frame/hi- carbon stainless 9 gauge via plasma cutter. I'm not against overkill... if it is done in moderation.
The Mind has No Firewall~ U.S. Army War College.

 

definitions, posted on November 17, 2014 at 20:42:07
Jim Dowdy
Manufacturer

Posts: 1518
Location: Atlanta, GA
Joined: July 22, 2000
 If an R(k) has a parallel cap connected from cathode to ground, it is fully bypassed.

The amount of capacitance may be inadequate for full range performance, but that is a different issue.

 

RE: definitions, posted on November 17, 2014 at 21:31:41
Tre'
Industry Professional

Posts: 17304
Location: So. Cal.
Joined: February 9, 2002
 "The amount of capacitance may be inadequate for full range performance......"

Yes, that is what I meant.

When a cathode is bypassed to the point that the lowest frequency of interest is unaffected by the filter (amplitude and phase), I call that fully bypassed.

When the cathode is bypassed but the -3db point is higher than a decade below the lowest frequency of interest, I call that partially bypassed.

A fully bypassed cathode will prevent local current feedback from occurring down to the lowest frequency of interest.

A partially bypassed cathode will allow local current feedback to occur below a certain frequency depending on the value of the cap but not above that frequency.

This will give less gain in the lower frequencies and increase the plate resistance of the tube at those lower frequencies thus changing the damping factor of the amplifier if it's an output tube.

My use of the terms, fully bypassed and partially bypassed, can be found all over the internet. Rightly or wrongly.

BTW It is not the cathode resistor alone that is being bypassed but the cathode resistor in parallel with the cathode impedance, r.

The value of the impedance of the cathode of the tube is (the plate resistance + the plate load) / (the mu + 1)

That number is in parallel with the value of the cathode resistor to give us r.

r is what is what we are attempting to bypass.

This can make a huge difference. In the case of Dennis' amp it's not his 5k ohm cathode resistor that needs to be bypassed but that 5k ohm resistor in parallel with the 634 ohm cathode impedance. So 563 ohms is what needs to be bypassed.

56uf would get him 5Hz with 50Hz phase and amplitude correct.

141uf would get him 2Hz with 20Hz phase and amplitude correct.

Understand that I'm just talking about the effects of this filter, not the amplifier as a whole.

I believe Dennis uses 15uf and that will not fully bypass (by anyone's definition) 563 ohms.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Stop beating around the bush!, posted on November 17, 2014 at 22:57:51
airairy
Audiophile

Posts: 43
Joined: July 19, 2008
 OMG
why a DIY SET amp like that have this price tag?

 

Actually 1990s, posted on November 17, 2014 at 23:41:03
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 From the Sound Practices era, which was the American Renaissance for SET, followed by the Baroque.

 

RE: Peddling long pork is a stretch, tunneling sideways to obtain natural gas for fuel ..., posted on November 18, 2014 at 04:58:26
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since: September 9, 2000
 OK. I thought that looked liked a Vincent amp. I have not heard them. I have followed your posts in the pasts. I was using an extreme example because I am sure you not only care about what your amps sound like and I would be surprised that you would chose to do things that make no sense to basic engineering principles Not discovering something untried, but rather doing things that have been proven to be wrong. I would be surprised if you did not care that a car idles twice as fast as necessary, even although it drives nice? Most of these arguments have been about outlandish and made up claims. Look at Dennis' post about how mesh tubes work..... gibberish. Another gem, he said most amps don't sound good after you purchase them because nobody uses the shake test to match tubes like he does. You can't go by how they test. You have to shake them and find the ones that sound the same when you shake them. They have different resonant frequencies based on how the internal rattle around inside. Find the two that sounds the same.

 

RE: Absolute Sound and All That Jazz, posted on November 18, 2014 at 05:00:36
LinuxGuru
Audiophile

Posts: 582
Location: European Union
Joined: November 11, 2008
 > I figured the parts for a PAIR even with EML 2A3s would be
> somewhere between $3300 and $3800

Hi, GSH,

You can be on budget if you build 4P1L based SET with filament bias and no cathode bypass capacitor whatsoever.

Look at the links below. Andy Jevans is professional musician, and Ale Moglia - really skilled engineer, so you can trust them. Its a matter of your personal taste if you like such amp or not, but at least you won't have to replicate and waste time and effort on flawed amateur design.

http://www.diyaudio.com/forums/tubes-valves/183329-one-more-4p1l-se-25.html

http://www.bartola.co.uk/valves/tag/4p1l-pse/

 

RE: Mystery has an end, in this case, enough is enough, posted on November 18, 2014 at 05:05:24
deathtube 667
 In ancient Rome, the custom was to fall on a sword regarding matters of honorable conduct.

Absent swords, toxic kool aid will suffice.

Hail Ceasar!

 

RE: Absolute Sound and All That Jazz, posted on November 18, 2014 at 07:42:28
GSH
 Hi LG,

I like Andy's amp design, never heard it, I've made similar before with other tubes. I haven't tried filament bias yet, but perhaps will sometime.


 

Not a clue ......., posted on November 18, 2014 at 12:12:10
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 Exaggerations in your mind, but not in fact. Why ?? Because you don't know any better, and never took the time ( and money) to properly bypass an amp, and HEAR what each cap and each value does !!

I certainly have. Its costly to do, and very effective !!

You never heard it and you don't get-it Grant !! Your post comes from an inexperienced perspective, and sadly, you don't even realize that !!

Jeff Medwin

 

Couple points to make for now ........, posted on November 18, 2014 at 12:32:11
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 (1) Almost all who have piled on and posted negative or demeaning comments in this thread so far, NEVER HEARD THIS AMP, but Frihed89 has been to an audio show to actually hear this amp.

I suggest ALL read Frihed89's honest entries in the body of this thread.

Also, look up "lakerfan" posts on this Forum, who claims to have owned over 50 or 60 SET amps. Lakerfan only will listen to a Larry D. Moore Squared Ten amp and his Serious Stereo 2A3 amp....wonder why ?? Because they both excel, both are superior.

If "lakerfan's" comments interest you, also read Smart845 over in the UK's comments on the DC Type 45 amp we did together last year, based on Dennis' build principles. Unlike Grant, Barry spent the money to do it correctly with (a) wire and (b) film bypass capacitors....a whole lot of money !!! Read his review of his amp. I am waiting on Al and Andy to visit Barry and his rig !! :-)

(2) Contrary to what has been written by someone in this post, the innovative supply in a Serious Stereo amp is certainly not deficient at all, but rather, it is just the opposite - the BEST POSSIBLE supply to get the most out of a DHT DC amplifier.

It sounds like the music, and NOT like the time constants of high DCR chokes and over-filtering of the Finals. A conventional tube supply, by the book, for the last 100 years, is screwed up, always playing back music "out-of-time-" ..... ( in the AMP's time, and not in the time of the music. )

Hell, in 1982, the FIRST thing Bob Fulton told me about building a DHT amp was that all chokes have to be 20 Ohms or less in DCR. We use 10 Ohm stuff, or lower, now.

People who have HEARD the more innovative "modern" type of supply, when well executed, ( and I bet FEW of this thread's negative posters have come to a show and heard it ) ....immediately understand the difference.

At the end of the day, the two most important things are (1) how does the amp sound and (2) is it reliable and able to maintain its high performance over a long time.

Personally, no one "I" know, does better tube amps than Dennis Fraker, YMMV, fine with me !!

Jeff Medwin

 

What's new Jeff?, posted on November 18, 2014 at 12:55:52
GSH
 Yawn... Oh yah right, spending money, that's all it takes!
It's as if that's a choice we all have available, regardless of circumstance, and by "choosing" not to, we are actively/consciously saying, "I'm not interested in accurate sound", makes Jeff's kind of sense, at least he's consistent. Good job, especially on that careful wording to avoid you know what...must be tough sometimes.

 

RE: Not a clue ......., posted on November 18, 2014 at 12:59:09
GSH
 On the contrary Jeff, I'm well aware that I'm missing out on something.
What, is the question, and you've already answered that to YOUR satisfaction, and I'm happy for you, seriously.

 

Cheap is cheap !!!, posted on November 18, 2014 at 13:06:00
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 .

 

RE: Couple points to make for now ........, posted on November 18, 2014 at 13:18:53
gusser
Audiophile

Posts: 3649
Location: So. California
Joined: September 6, 2006
 We all know the LSES sounds different. It's been explained why by several people here over the years. If you like the sound it produces, then enjoy it. But a good portion of the industry does feel that a power supply should not be used as a tone control or dynamics enhancer.

As for the wire, you aren't going to convince anyone with a competent electronics background that the use of silver hookup wire versus doorbell wire in the Serious Stereo amp will have any difference in audible performance. That's simply not possible under our laws of physics and no I don't need to try it. And furthermore I don't see much silver wire under that amp either. Seems the stock transformer leads are good enough for Dennis too.

If we want to discuss silver output transformer windings, then I agree there is possibly something to hear.

But we all now know the SS 2A3 amp is just another polished turd, which you have spent years polishing here. It a basic 2A3 amp anyone can easily duplicate. There is no magic under the hood.

 

You are crude ...... typical GEO. nt, posted on November 18, 2014 at 13:24:50
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 ignorant too.

 

RE: Couple points to make for now ........, posted on November 18, 2014 at 13:33:44
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 Beautiful name-calling post from a grown up, supposedly mature Eletronics Engineer, graduate, I think of Lehigh University Remedial College.

Lets call him Clark Kent, because he must be able to see through the wire insulation, to see what is inside. Not that wire matters, that he has already shot himself in the foot via his post, for all to see. I am just posting so he doesn't come to his senses and delete it !!!

Maybe I understated my case about most of them. My two points, made above, remain intact, because its the truth !!

Jeff Medwin

 

Agree, posted on November 18, 2014 at 13:57:05
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 An SET is the ultimate amp for playback on sensitive speakers, no doubt.

Of course, that is why we build SETs !!! Joe Roberts has influenced a lot of this I'd suggest !!! Hi Joe !! Got some Emilar / Showco EH-500s with adaptors for my 802Ds last month .

Jeff Medwin

 

RE: Me too..., posted on November 18, 2014 at 14:24:36
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 I don't have time to go point for point here. What you need to learn is one INCH of bad wire, in the wrong place, can easily ruin the musical experience !!!

I screwed myself for three years and three amp builds with using that ACME ( ? ) wire as an AC cord ONLY only, it sounds harsh and hashy, ugh.

How do you think I felt when I learned how bad that wire was ?? I had to eat humble pie, built three amps using it, never heard their potential, but I learned from my error.

You wanna dust your errors off into the corner and forget it or excuse it.... minimize it - HA !!

An INCH Grant, an INCH.

That is the truth.

Jeff Medwin

 

RE: Absolute Sound and All That Jazz, posted on November 18, 2014 at 14:52:29
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 You are asking the wrong person. Grant and his mind set produced a NON-high-performance amp from a proven design.

I just went on line and looked up the caps, got all but one value covered.

You have to realize that all caps play narrow band in energy release ( my words...not bad Dowdylama ?? ) and so, ONLY the best caps are any good at all, and none of them are good enough, and it takes multiples to cover the audio spectrum.

Missing a value, the bypassing caps would seem to run from $97.00 a position ( minimum quality ) to $131 a position, NOT counting the main FILM cap.

There are about six positions I would currently bypass in a monoblock. That means, per monoblock, $485 to $665 for bypassing each monoblock, PLUS the main film caps.

If you do stereo, take $665 times two, or $1310 dollars as bypassing costs. An audio amp usually sells for four times parts cost, so we are up to $5,240 a pair, just to cover the bypassing caps ONLY, which I guarantee you from my listening experiements, are necessary for high performance.

You can always "dreck" stuff, Grant did, I sometimes do. But you are FOOLING yourself on caps, and in audio, unless you compare the cheap ones from Russia - surplus military, to the best made today, you won't really KNOW what you have. It takes money, AND a good system, to make such evaluations. None of the caps are perfect, and only the very best are usable, and THEY play narrow band energy-relase-wise, so, it takes MultiCaps or multiple caps to get it right. Dennis KNOWS all of that very well, Grant didn't understand !!!

Jeff Medwin





 

Tom Hagen to Pentangelli, posted on November 18, 2014 at 14:58:10
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since: September 9, 2000
 Tom Hagen gave that very Talk to Frank Pentangelli is Godfather II

 

like a loudness button, posted on November 18, 2014 at 15:51:06
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since: September 9, 2000
 many an amp was sold in audio salon's by pushing a loudness button an an amp in the 70s & 80s.

 

Now That's What I Call "High-End", posted on November 18, 2014 at 16:58:00
Mr_Steady
Audiophile

Posts: 2042
Location: North Florida
Joined: August 19, 2014
 GEO,

A tip of the hat to you sir.

Wow, having to discuss audio Absolute Sound style for years on end must be a drag. Even more so for you.

He does seem to get fed regular. I'm not surprised when he shows up at dinnertime.

For myself, I'm going to ignore the ad copy, and respond to the meaningful, and treat them both like they are somebody's grandfather, even when they are abrasive and curmudgeonly.

Jamie

Big speakers and little amps blew my mind!

 

Go Jeff go ! set it straight for us, we need to be told, posted on November 18, 2014 at 17:16:01
GSH
 Damage control at its finest, or at least the Loudest, Horray! Horray!

Tenacity means you're right, have you noticed? Of course you have.

Hmmmm... You know Jeff, you might be able to program your computer or get some "app" that automatically fires your opinion, multiple times, in opposition to anyone's post that disagrees with your views. Thus silencing the opposing view by sheer repetition and redundancy. We have this (or the attempt) already, but it must be time consuming, and hey, you've got better things to do, than spank morons around who will never "get it". Or can't afford to "get it".

 

words have meaning, posted on November 18, 2014 at 18:37:12
Jim Dowdy
Manufacturer

Posts: 1518
Location: Atlanta, GA
Joined: July 22, 2000
 I am not attempting to be argumentative, but it does not matter what may or may not have become common usage on the internet; the words in use here have a very clear meaning.

Any cap (of any size) that is parallel to a given R(k) and connected to the cathode at one end and the ground at the other end comprises a fully bypassed R(k).

The effective bandwidth of such an setup is an entirely different matter; I would suggest calling it 'inadequately bypassed for full-range operation' (or something similar).

 

That's fine., posted on November 18, 2014 at 19:29:22
Tre'
Industry Professional

Posts: 17304
Location: So. Cal.
Joined: February 9, 2002
 The cathode on Dennis' output tube is inadequately bypassed for full-range operation.

Is there a true meaning of "partially bypassed? Or is that just a made up term?

I think I heard that "vape" just became a real word.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

partially bypassed R(k), posted on November 18, 2014 at 19:48:36
Jim Dowdy
Manufacturer

Posts: 1518
Location: Atlanta, GA
Joined: July 22, 2000
 A partially bypassed R(k) is one in which some portion of the R(k) has a bypass cap and some portion of it does not.

To use a specific example (one that I am listening to as I type this): the cathode of the 5744WB submini has an R(k) totaling 627R - 600 ohms is bypassed by a 125 uf cap, and 27 ohms is left unbypassed.

While I agree that the unbypassed portion complicates design considerations...the combination of degenerative feedback, and what I theorize is some isolation from the cap sounds a lot better than simply bypassing the entire R(k).

Experiment, and let us know what you think.

 

RE: partially bypassed R(k), posted on November 18, 2014 at 20:07:10
Tre'
Industry Professional

Posts: 17304
Location: So. Cal.
Joined: February 9, 2002
 "...an R(k) totaling 627R - 600 ohms is bypassed by a 125 uf cap, and 27 ohms is left unbypassed. "

Oh, I see.

Thanks.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: partially bypassed R(k), posted on November 18, 2014 at 20:23:07
GSH
 A lot of the old school split load phase inverters seem to use this method, remember? It even shows up in some guitar amps.

I think there's 2 "partially bypassed" versions.

one is less than full bandwidth, but across the entire Rk

the other is across part of the Rk accommodating whatever bandwidth,
with whatever amount of FB.

 

RE: partially bypassed R(k), posted on November 18, 2014 at 21:44:26
tube wrangler
Manufacturer

Posts: 2484
Location: USA
Joined: January 29, 2007
Tre, Jim's idea is worth investigating.

I have been known to calculate the cathode bypass cap value by considering it separate from the tube cathode-- calculate it looking only at the cathode resistor-- just to have a look at THAT value independently.

I was defining "fully bypassed" as you were-- use the total tube cathode and resistor values to calculate the value you need for a certain low HZ point-- I don't use that much capacitance, but Jim has the DEFINITION right.

Mentally, it makes no difference how you view the definition as long as you understand what you're affecting, but if-- for instance-- I used your 56uf value-- as calculated in your earlier example's total cathode resistor value, a cap that large would badly affect the stage's H.F. response, not to mention that obtaining a high-quality cap of that value is also a problem. Of course, there's always Duelund....

Some cathodes are not bypassed at all, and the stage operates clean.

Adding cathode bypassing is an art. One should proceed cautiously, starting at the value calculated without the tube, slowly increasing the cap's value until you start killing the amp's best qualities-- definition, transparency, speed, etc.. While doing this I have my calculated cap value that I got from ignoring the tube cathode itself-- handy just for reference.

Too little bypassing will be evident as you know from your own experience.

Even a tiny bit too much capacitance will severely stifle the amp-- it will effectively muzzle it's best qualities, and it will sound like everybody else's amplifiers-- not bad, correct-- but not outstanding, not truly inspiring.

It's a process that requires the utmost care if you expect your amp to play with the Spectral DMA200S.

---Dennis---



 

I still want my free wire, posted on November 18, 2014 at 23:20:12
GSH
 why shouldn't I ?

 

shakespeare, posted on November 19, 2014 at 02:15:45
smart845
Audiophile

Posts: 668
Location: East london
Joined: May 24, 2000
 To B or not to B..that is the question:
Whether 'tis nobler in the mind to suffer
The slings and arrows of outrageous fortune
Or to take arms against a sea of troubles
And by opposing end them. To die, to sleep--
No more--and by a sleep to say we end
The heartache, and the thousand natural shocks
That flesh is heir to. 'Tis a consummation
Devoutly to be wished. To die, to sleep--
To sleep--perchance to dream: ay, there's the rub,
For in that sleep of death what dreams may come.

To B or not to B, that is the question . Bypass multiple times, YES

Let's put these factious exchanges to bed so we may sleep to dream about better music.

 

RE: Look at the grounding! 60 cycle hum ..., posted on November 19, 2014 at 04:14:37
deathtube 667
 Those amps were designed to drive movie theatre speakers.

The 60 cycle hum would annoy audience members into making frequent trips to the snack bar, thus driving up profit $$$ margins.

Brilliant concept and engineering, IMO.


 

RE: Me too..., posted on November 19, 2014 at 05:32:47
cpotl
Audiophile

Posts: 1002
Location: Texas
Joined: December 6, 2009
 "What you need to learn is one INCH of bad wire, in the wrong place, can easily ruin the musical experience !!! "

Just imagine how many inches of "bad" wire must have been used in the entire chain of amplification and processing between the microphones in the recording studio and the output from the home CD player or record deck. Not to mention quite a few coupling capacitors that most certainly will not have been "boutique" varieties. And power supplies built using unmutilated transformers. And huge amounts of negative feedback along the path too.

How can you seriously imagine after all those stages of unspeakable degradations to the signal that one inch of wire carrying low-level signals in the home audio amplifier is going to make a critical difference?

Chris

 

RE: partially bypassed R(k), posted on November 19, 2014 at 08:16:55
Tre'
Industry Professional

Posts: 17304
Location: So. Cal.
Joined: February 9, 2002
 "I have been known to calculate the cathode bypass cap value by considering it separate from the tube cathode-- calculate it looking only at the cathode resistor-- just to have a look at THAT value independently."

Well gee Dennis, that doesn't make any sense because, like it or not, the cathode impedance IS in parallel with the cathode resistor.

Bypassing just the cathode resistor value will leave you with too small a cap.

"Too little bypassing will be evident as you know from your own experience."

Too little bypassing will increase the plate resistance of the output tube and leave you with less damping factor.

To my way of thinking, 56uf in your output stage is a minimum value. A value that will only "bypass" the cathode to a -3db point of 5Hz meaning there will be some current feedback all the way up to 50Hz, phase shift also.

I'm sure one can get away with cathode bypass cap that are too small in voltage amplifiers, to one extent or another, but output stages are different.

The relationship between the output tube's plate resistance and output transformer's primary impedance is critical and when the cathode bypass cap is too small all hell breaks loose.

You should read a little Lynn Olson on this subject.

(In effect, the performance of the tube is greatly degraded — exactly the same effect as a large drop in emission.)

Dennis, I can't tell you what type of sound you should like but I can tell you that when the cathode bypass cap on the output tube is too small the amplifier will not be right.

Your speakers might "like" the lack of damping and the lower amplitude in the LF caused by degenerative feedback because the bypass cap is too small, but that's a different matter.

BTW If you are worried about the quality of the sound, at the high frequencies, of larger caps you can use a smaller cap value and still have the cathode bypassed all the way down to the lowest frequency of interest by using Jack Elliano's UltraPath technique.

This also helps to "take the power supply" partially "out of the signal path".

This is what I do and I can tell you it's the way to go. If you haven't heard my amps, if you haven't taken the time to come to my house and hear my amps then you are just guessing. Everyone who has not come to my house has never heard it and you don't get-it.

You have never heard my amps, in many venues, as I have, have you??

You are talking unsubstantiated, only guessing, with zero practical experience.

Have YOU ever heard a pair of my amps???

So the facts remain : (1) you never heard a Tre Perry amp, neither of the people, and how well it plays and (2) I have taken the basic amp to a new and even higher performing level with my latest implementations, same circuit, better implementation, the best possible !!

OK, that's enough of that. :-)

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: partially bypassed R(k), posted on November 19, 2014 at 10:33:35
tube wrangler
Manufacturer

Posts: 2484
Location: USA
Joined: January 29, 2007
 I'm delighted that your amp sounds good-- no offense meant.

Damping factor-- I think I got that "perfect". It plays a lot of speakers that it shouldn't, and stays clean and solid right down into some unbelievable lows.

The interesting is that H.F. response is very extended-- enough to place performers right there and fool you. Cymbal clashes, and many other H.F. events sound real, present, and full, and extended.

You're not going to be able to "explain" that, although your attempts are certainly entertaining at the least.

"All Hell breaks loose". HUH? I probably have the most stable amp ever built! NOTHING fazes it! NOT ONE has ever lost a power tube or a rectifier.

Drivers? One could blow a grid out of one by putting a huge voltage spike straight into the input. I tried this a few times on tests. Nothing happened at all, just silence. NOTHING happened. I had to replace the driver to get music!

"MY" speakers? People play these amps on all kinds of things....

"Zero" practical experience? Oh my gosh! Amazing!

Tre, I'd love to hear your amps! In fact, if I make it to RMAF once again, you can bring them in. After hours, we'll hook them up. If they're better than mine, we'll just leave them in (with your permission) and just let the visitors listen to those!


On another subject, scientists at NASA think we've entered a Sun-Spot minimum period, a period of substantial Earth cooling. (Sort of like the old "Maunder Minimum", etc.).

Russian scientists are a bit bolder, some flatly state that we've already entered a new "Ice-Age"-- a 30-50 year one, not a major one--, but one that's going to cut food production way back, and will make your Winter energy bill soar.

If this is true, yours truly-- and perhaps some of you as well-- will be engineering something other than audio amplifiers.

---Dennis---

!

 

RE: Look at the grounding! 60 cycle hum ..., posted on November 19, 2014 at 11:07:47
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since: September 9, 2000
 Also added to the hum to the subliminal images spliced in just to make it doubly sure.

 

Heard the 2013 version at RMAF ....., posted on November 19, 2014 at 12:16:56
drummerwill
Audiophile

Posts: 965
Location: St Louis Mo.
Joined: January 7, 2003

..after building my best DC2A3 amp earlier that year.

I can say the Serious DC2A3 is totally Serious.... so very well done.

While in Denver I got to hear the DF's amp on two occasions, at the RMAF in Dennis's room, he setup with his amp/speaker setup... That was amazing.

Then I got to go to the home of a friend who had Dennis's Amp/speaker setup.... Even more amazing, this setup sounded just as great maybe even a little better .

JMHO...

Willie

 

RE: shakespeare, posted on November 19, 2014 at 12:35:40
Tre'
Industry Professional

Posts: 17304
Location: So. Cal.
Joined: February 9, 2002
 "Bypass multiple times, YES"

I have no argument with that but the total uf value needs to be what science says it needs to be otherwise the FR will be wrong and the damping factor will be lower right where the speaker needs it to be higher.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: partially bypassed R(k), posted on November 19, 2014 at 12:42:50
Tre'
Industry Professional

Posts: 17304
Location: So. Cal.
Joined: February 9, 2002
 "You're not going to be able to "explain" that..."

That's because there is no explaining it. It isn't real, just your imagination.

""Zero" practical experience? Oh my gosh! Amazing!"

That was my attempt at sarcasm. These are the kind of things others say when they no longer have a technical argument.

If you want to hear my amplifiers you will have to come to my house.

""MY" speakers? People play these amps on all kinds of things...."

How many people? Dennis, how many pairs have you sold? 5 maybe?

Be honest.

Tre'


Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: shakespeare, posted on November 19, 2014 at 13:05:14
tube wrangler
Manufacturer

Posts: 2484
Location: USA
Joined: January 29, 2007
This is-- right now, the Golden Age of recorded music playback.

We have never had equipment like we can now buy. An example is Berkeley Audio Design Alpha-Dac2. I have one and I love it. Just 3 years ago, there were far fewer DACs that would really honor music.

This year, Berkeley is getting some good competition. What are they doing about it?

Go to Berkeley Audio Design and look at what they've done now! Read Robert Harley's review of it.

Round three. Music never-- not ever-- had it so good.

---Dennis---

 

Damn, I am salivating ........, posted on November 19, 2014 at 22:47:06
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 Dennis,

You've got good taste !!!

Thanks for bringing this to my attention.

Jeff

 

RE: Stop beating around the bush!, posted on November 19, 2014 at 23:25:03
mach1
Audiophile

Posts: 399
Location: Brisvegas
Joined: April 24, 2005
 Pixie dust, lots of it.

 

Wow!!!, posted on November 19, 2014 at 23:47:21
mach1
Audiophile

Posts: 399
Location: Brisvegas
Joined: April 24, 2005
 Doing a DF on DF!!! - I gotta take my hat off to ya Tre' ....

 

RE: partially bypassed R(k), posted on November 19, 2014 at 23:58:09
mach1
Audiophile

Posts: 399
Location: Brisvegas
Joined: April 24, 2005
 How's about 'partial bypass' and 'sub critical bypass' ?

 

RE: Me too..., posted on November 20, 2014 at 00:58:57
mach1
Audiophile

Posts: 399
Location: Brisvegas
Joined: April 24, 2005
 The perfect excuse to mask poor design 'you had an inch of wire in the wrong place'. It also conveniently negates any possible comeback from the builder.

Face reality Jeff - if an inch of wire can totally make or break an amp, the design is inherently unstable and fundamentaly flawed. Certainly not one a prudent individual would implement or recommend (let alone spend $15k on).

 

And just think...., posted on November 20, 2014 at 01:18:18
mach1
Audiophile

Posts: 399
Location: Brisvegas
Joined: April 24, 2005
 The success of your build would not be critically dependent on the placement of 1" of wire or the use of $1.5ks worth of bypass caps.

Sounds surprisingly like competent engineering to me.

 

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