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Revisiting an old friend

170.225.12.33
Posted on October 20, 2009 at 07:31:51
SteveBrown
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Posts: 1523
Location: Tulsa!
Joined: November 14, 2002
 Thought I'd post some new experiences with an old friend. It was about 10 years ago that I decided to test the waters of SET amps. I had just finished my first big project: restoring a Dynaco ST-70, and while I loved the sounds I was getting, I was enticed by the call of "better". With that in mind, I ran across the now famous article by Herb Reichert where he details the design of his 300B amp called "Flesh & Blood" (link below).
At the time, being just out of grad school and starting a new relationship (now married 9 years), I was broke. So the prospect of selecting all the parts he had used (like Tango transformers and 800vct, 500ma power transformers) was way out of the realm of possibilities. So in fact, it ended up not being HIS amp, but rather mine due to the compromises I made.
As many have noted over the years, this is an amp that performs best when built according to the original plan. Had I built it exactly as designed I'd likly be happier with it, and by now divorced. However, it did whet my interest to go further down the SE road. Recently, having spent lots of time and effort on some super PP amps (like Allen's PP-1C), I decided that maybe I should revisit that old 300b (long since recycled into other projects). So I set off to make a "less compromised Flesh & Blood" (The LCFB).
It is a work in progress. I have my OPTs on order from MQ (FS-030's), and in the mean time, using James. My power transformers are not 800vct at 500ma, but they are 760vct at 200+ma. I didn't use the AN silver coupling caps called for, but I may give them a try. Using a mix now of Russian teflon and Kimber.
One criticism of this amp is too much gain in a 2 stage 6SN7 front end, and another complaint is that a 6SN7 can't possibly drive a 300b. The first point is well taken. But as designed, it calls for a volume pot on the front end, and that can knock the gain down if you're using an active pre, which I am. The other down side of the high gain is that it really calls for a clean layout and careful grounding or you'll be dealing with lots of hum chasing. As for the 'SN7 not driving a 300b, I think that's more a matter of personal preference. I've certianly used single stages (e.g. 417a, 6n6p, etc with CCS, with R load, with choke load, etc). I've also used BIG drivers like an EL34 preceeded by a 'SN7. Bottom line, it has it's own charm and if you've not tried it, you might want to.
Charm is probably a good way to describe the sonic results. I'm glad I'm on this path again, at least for now. This amp has great dynamics and like most SETs really nice soundstage. Musical textures are outstanding, without being too warm or tuby. I like it. I find myself relaxing more while I listen, not eager to jump up and put on a different tune. The "jump factor" is very high. Bass is tighter than I remember, not bloated at all.
So the bottom line is, I'm very happy that I met back up with my old friend from 10 years ago. I'm a much better builder now, maybe that helped this time around. If you've ever considered building this design, please do yourself a favor and give it a try. I think you'll be charmed as well.

RE: Revisiting an old friend, posted on October 21, 2009 at 20:07:58
SteveBrown
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Posts: 1523
Location: Tulsa!
Joined: November 14, 2002
 Eliminated the first gain stage tonight. Works fine with my 6N6P linestage. Better focus of the soundstage, otherwise not much difference. It's a keeper. At least for now. So far I've made a slight change in the bias on the 2nd stage to account for lower B+, and to operate the 6SN7 a bit more conservatively. Also changed from a hum pot + 1k cathode R on the 300b to dual 150ohm R, joining at parallel 1.5k Mills 12w resistors, bypassed by 100uf Blackgates. Each change make a bit of an improvment, so it is a fun journey.

RE: Revisiting an old friend, posted on October 20, 2009 at 23:00:31
Caucasian Blackplate
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 I like this schematic quite a bit, and I agree about its minor shortcomings.

Tre is correct, with a strong linestage, you could drive the second stage and probably get full output.

If I had to build something like this, I would use a dual triode with one half being close to half a 6SN7 or 12AT7, and the other half being a low Rp, high current triode. Something like a 6FY7, 6EW7, 6DN7, etc. etc.

Those FS-030's will be awesome!

RE: Revisiting an old friend, posted on October 20, 2009 at 19:56:52
mbhcid
Audiophile

Posts: 115
Location: east coast
Joined: August 8, 2006
 I have a pair of AN copper Hi-B C-core transformers and MQ QS-025 (silver primary and secondary) transformers for sale. email me if interested.

RE: Revisiting an old friend, posted on October 20, 2009 at 13:21:55
Tre'
Industry Professional

Posts: 4846
Joined: February 9, 2002
 There is nothing stopping you from just losing the first stage.

With an active preamp, you don't need it and it is not doing you any favors.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Losing the First Stage, posted on October 21, 2009 at 07:13:49
AstroSonic
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Location: SE Pennsylvania
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 Losing the first stage is likely good advice if one is using a store-bought preamp or similar DIY design. You basically need enough total gain to drive the output stage. If you are building both the power amp and preamp, you can choose to put all the voltage gain stages in the preamp and use a 2-stage power amp, or put one of the stages from the preamp into the power amp (which is then a 3-stage design). The total parts count and number of gain stages is the same either way. OTOH, if you buy a commercial preamp you will likely end up with excess gain, if the power amp is a 3-stage design. A person could just build all of the gain required on one chassis, eliminating a cable run.

It seems to me that this really boils down to a choice between the use of high mu tubes (like the 12ax7) in the preamp and power amp (including the driver - not so feasible with a 300B output), or the use of more linear low mu tubes. Which sounds better: decreasing the number of gain stages (by using high mu tubes), or the use of more linear low mu tubes (with an additional stage or two)? Is the sonic gain from using very linear low mu tubes (76, 6J5, 6sn7, etc.) overwhelmed (lost) due to colorations from the additional required parts? Is there a clear-cut answer or is this just a matter of taste?

Regards,

Bob

RE: Losing the First Stage, posted on October 21, 2009 at 11:21:22
Tre'
Industry Professional

Posts: 4846
Joined: February 9, 2002
 "Which sounds better: decreasing the number of gain stages (by using high mu tubes), or the use of more linear low mu tubes (with an additional stage or two)?"

What is the efficiency of your speakers?

I run my CD player and phono pre output directly into my 2 stage 300b amp. I have plenty of gain.

I use one triode of a 5687 (7119 right now) as the driver. The driver is CCS loaded and I have a grid choke so I am getting the full gain (17 for the 5687 and 24 for the 7119) from the driver tube.

I may not be able to drive the 300b to full power but I don't need to.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
RE: Losing the First Stage, posted on October 21, 2009 at 17:06:19
AstroSonic
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"What is the efficiency of your speakers?"

More to the point: how much power do you need to achieve the desired spls at the listening seat?


"I run my CD player and phono pre output directly into my 2 stage 300b amp. I have plenty of gain."

And

"I use one triode of a 5687 (7119 right now) as the driver. The driver is CCS loaded and I have a grid choke so I am getting the full gain (17 for the 5687 and 24 for the 7119) from the driver tube."

You have gain stages in the phono preamp and in the CD player. Again, this boils down to : "Which sounds better: decreasing the number of gain stages (by using high mu tubes, or heaven forbid, ICs), or the use of more linear low mu tubes (with an additional stage or two)?" We really need to be thinking about the total amplification chain and not just what's mounted on the power amp chassis.


"I may not be able to drive the 300b to full power but I don't need to."

I am glad that you are satisfied with your amplification. Obviously, many people would also be satisfied with it, but many others would not. One of the great aspects of DIY is that you can build to suit your needs.

Bob
RE: Losing the First Stage, posted on October 21, 2009 at 18:18:54
Tre'
Industry Professional

Posts: 4846
Joined: February 9, 2002
 "More to the point: how much power do you need to achieve the desired spls at the listening seat?"

Exactly!

"You have gain stages in the phono preamp and in the CD player"

Well, the gain of the phono pre is designed to keep up with the gain of the CD player.

The gain of the CD player is out of my hands as I didn't design or build it.

What I am really try to say, most systems have more gain than they need. Most volume knobs never get past 11:00.

If a person can eliminate a gain stage, that's a good thing.

You will lose the gain that you don't need and the noise and distortion of that stage.

So I guess a person could redesign their CD player and phono pre. Or lose a stage in the power amp or line stage preamp (or both).

I think the last two are easier.

I could be wrong about this, but I don't think I am.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Losing the First Stage, posted on October 22, 2009 at 07:42:27
AstroSonic
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Posts: 814
Location: SE Pennsylvania
Joined: January 25, 2003
 Agreed that many systems have excess gain and could probably stand to eliminate a gain stage. Many commercial preamps do provide excess gain to allow for differences in source output and power amp gain. If we are DIYing, that compromise (and flexibility) may not be necessary.

Once we have a feel for how much gain is needed, the question becomes "do we obtain that gain using as few gain stages as possible (by using high gain/moderately linear devices) or do we build with maximally linear/low gain devices and end up with one more stage".

The discussions of this topic almost always focus on the number of gain stages mounted on the power amp chassis and ignore everything 'upstream'. Obviously, a power amplifier with 2 stages on the chassis (i.e., a so-called '2 stage' power amp) will not always produce better sound than one with 3 or more stages unless we start with substantial excess gain. Any 'count' of gain stages must include all of them, not just those on the power amp chassis.

The synergy possible with certain combinations of active elements, passive components and topologies is also surely important. It seems to me that too many things come into play to assert categorically that fewer gain stages will always be superior. The fact that so many people seem eager to jump on the 'fewer is better' bandwagon suggests that there is widespread experience supporting it. Yet most such posts offer only assertions and not described experiences or experiments/tests.

Regards,

Bob

RE: Losing the First Stage, posted on October 23, 2009 at 07:35:52
TubeDriver
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Posts: 65
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 I have no problems with gain running an autoformer pre to a two stage 300B amp (half 6SN7 - 300B with a low Rp load of the 6SN7 ie 15k ohms). Most systems have WAY to much gain. I do use ~100db efficient horns and currently run a low gain, single stage 1626 preamp.

RE: Losing the First Stage, posted on October 21, 2009 at 07:46:03
SteveBrown
Audiophile

Posts: 1523
Location: Tulsa!
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 Bob, you asked if there is a clear cut answer. I'm thinking no, it's kind of a system thing along with personal taste. Kind of like making Meatloaf is more of a concept than a recipie, I think this becomes the same kind of thing. You might like onions in yours, but maybe I don't. It's still meatloaf when you pull it out of the oven.

RE: Revisiting an old friend, posted on October 20, 2009 at 15:30:09
SteveBrown
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Posts: 1523
Location: Tulsa!
Joined: November 14, 2002
 I'm sure you're right. I'll probably play with it in the comming weeks (while I wait for the MQ iron). I'm already plotting what I think is a better 2nd stage operating point, given my lower B+ and a desire to not melt down my nice 6SN7's... As is, the 2nd stage is Vp=275 and I=15ma. I'm thinking 270v at 12ma will be a bit better.

RE: Revisiting an old friend, posted on October 20, 2009 at 16:14:56
Tre'
Industry Professional

Posts: 4846
Joined: February 9, 2002
 That pretty hot.

225 at 10ma sounds good to me.

You could try a 5687. That tube has a low plate resistance and can really drive.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Yeah, but..., posted on October 20, 2009 at 16:38:58
SteveBrown
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Posts: 1523
Location: Tulsa!
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 You're missing the whole octal enchantment thing. I'm using GTBs and I'm still more than 20% under Pd (I think).

RE: Yeah, but..., posted on October 20, 2009 at 17:08:41
Tre'
Industry Professional

Posts: 4846
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 I love my octals but the 5687 really sounds good driving DHTs.

BTW a good grid choke for that 300b will take it to the next level.
And load that 6sn7 (or 5687) with a CCS. Sounds like I'm trying to re-design your amp. Sorry.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
5687 vs 6SN7, posted on October 20, 2009 at 17:46:55
GTCharlie
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 the 5687 has lower Rp, and higher I. Which makes for a more dynamic drive IMHO

RE: 5687 vs 6SN7, posted on October 23, 2009 at 09:48:36
jmwaite
Audiophile

Posts: 45
Location: mid-atlantic
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 How about a 6900?

RE: 5687 vs 6SN7, posted on October 23, 2009 at 13:10:48
FenderLover
Audiophile

Posts: 3309
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Contributor
  Since: May 17, 2009
 I believe that the 6900 is a ruggedized version of the 5687. Electrically, should be closer to the 5687 than the 6SN7. I haven't seen an NOS in years. I used to have some Bendix and Tung-sols. Last 6900 went into an overdrive effects pedal stomper. I remember the tube being very quiet and insanely over-built. Could have originally been designed for missile use. Anyhow, gave the pedal as nice smooth onset of overdrive. Lending a more Bluesy tone to an originally cold sounding amp (in this case a Fender Bandmaster).

RE: Yeah, but..., posted on October 20, 2009 at 17:42:08
Wojciech
Audiophile

Posts: 45
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 I had my story with F&B too.I also used 760ct transformer with 250mA capability and nice heavy 16 oHm chokes , all cerafine/Black Gate caps , AN copper PIO/s (they were manufactured by Jensen at that time) Mix of Tantalum and AB resistors.First OPT's were custom Hong Kong jobs ("you will have the best OPts in Town or maybe even in the state -sir" )not very impressive sounding although perfect technically (according to my friend who measured them ). I managed to borrow MQ FS030 too. Better bass and soundstage ,liquid sounding. Than I've got a pair of AN Quest for repair ,update.Just the standard version with metal film resistors and mix of standard caps ,(some xicons ,rubicons cheapies etc)They literary "wiped the floor" and walked over my F&B exotica. My conclusion was, either you use original Tango transformer or it's not F&B. And ,yes I tried grid , plate chokes too and was relieved when I've got them out the circuit. Good luck with your project ( and marriage too;)

PS. MQ FS030 trans came from a clone of Audio Note 300B kit with silver PIO's ,BG's , Tants and all exotica-the owner never really liked that amp.
I think that the builder of that amp thought that MQ trans will be improvement over Audio Note transformer.
RE: Yeah, but..., posted on October 20, 2009 at 18:12:56
SteveBrown
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Posts: 1523
Location: Tulsa!
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 The Quest is very similar to the JE Labs - two stages, one direct coupled to the second. Much more B+ filtering than the F&B, bigger 300b cathode bypass, and of course, AN transformers. I wish it were easier to get AN transformers in the US, and I already have a deposit on the FS-030, so that's probably a done deal (hate to wait for the 3 months It's likely to take, however). Having a weekend ahead without much to do, I might build up the Quest and see how she does.

Historical Note..., posted on October 20, 2009 at 19:19:05
drlowmu
Manufacturer

Posts: 4649
Location: East of Kansas City
Joined: January 10, 2005
 Hi Steve:

The choke Herbie used in the "Flesh and Blood" was a direct result of me alone, personally "baptizing" Herbie (and maybe J.C.) into the low DCR religion, 'way 'way back then. (middle 1980s, pre-internet, hand written letters and phone calls.)

This choke was manufactured by ESPEY Manufacturing Company, and was 3 HY at 24 Ohms DCR as I recall, close to the "20 Ohms or less" that my audio mentor, Mr. Bob Fulton, told me about.

For unknown reasons, that particular ESPEY choke always sounded marvelous to me, my favorite back then, and I got Herbie Reichert to order some. This was back "in the day" when Fair Radio had TONS of surplus "iron", for pennies on the dollar, and I experimented extensively with most of their iron, listening to all the available power supply iron, size and weight NO object!!

To my surprise, and delight, I eventually recognized a photo of "my choke favorite" in Sound Practices magazine, when Joe Roberts published Reichert's "Flesh and Blood" article. Notice, Herbie used a 500 mA. power trannie for each monoblock. He got that right also. Not 250 mA., but 500 mA.

It is now 2009, and today I use lovely sub-8.2 Ohm DCR chokes at 3/4 of a HY, and 900 mA. power trannies, all having SE-friendly (good sounding) wire lead outs, so some real incremental audio progress has been made. Dual rectifiers also!!

Jeff Medwin
RE: Historical Note..., posted on October 20, 2009 at 19:43:56
Tre'
Industry Professional

Posts: 4846
Joined: February 9, 2002
 "The choke Herbie used in the "Flesh and Blood" was a direct result of me alone, "

I don't believe a word of it. But even if it were true, why tell us. Do you need your ego stroked that desperately?

One minute, you want to associate yourself with this design? It's a three stage. You hate three stage designs.

Jeff, you're a piece of work. You're like a politician saying whatever he thinks sounds good in the moment.

You have no personal integrity. You're like a cartoon character or maybe Forrest Gump. Did you really do it all? Do you really know it all?

I have hear other people say good things about you, but I don't see it.

Please go back to counting all those paralleled grid stop resistors to get "just the right" value and leave us all in peace.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
RE: Historical Note..., posted on October 21, 2009 at 08:33:37
drlowmu
Manufacturer

Posts: 4649
Location: East of Kansas City
Joined: January 10, 2005
 Dude,

I am sure Herbie and or maybe even JC Morrison will recall the turn of events!! Check it out!

I am a past Member of the Kansas City Board of Trade. I owned a seat on the Exchange, 1984-1988. This means I was background checked thoroughly, before being allowed to purchase said seat. That means I was approved, to make LARGE financial commitments in the pits, with other Members, on my word. I never had any problems - working in that capacity.

That you do not fully understand high end audio is understandable to me, but when you publicaly attack my personal integrity, or my intentions, you are barking up the wrong tree.

Jeff Medwin

Say what you will, posted on October 21, 2009 at 08:16:43
rickmcinnis@dogwoodfabrics.com
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 but at least he doesn't have a TV set between his speakers.

Talk about a loss of credibility.

Believe what you will. Personally, I could imagine Reichert being friends with Jeff more than you, Radiotron Boy! Reichert believes in experimenting and listening to what happens.

Why tell us your tired tirade YET again?

Your stump speech? But, I forgot, YOU are not a politician.

It gets so confusing. Good thing you know what is right, Philosopher King.
Actually he DID have a TV set between his speakers..., posted on November 2, 2009 at 09:16:42
Ivan303
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Posts: 15825
Location: San Francisco
Joined: February 26, 2001

In the Serious Stereo Room at RMAF 2009.


RE: Say what you will, posted on October 21, 2009 at 11:12:57
Tre'
Industry Professional

Posts: 4846
Joined: February 9, 2002
 How and why is this about me?

I'm not the one making claims of "New audio reality".

Do you think the difference between 200 ohms and 200.02 ohms can be heard in a grid stop resistor?

I first heard of Jeff here on the Asylum. He was making these claims at that time. He has made many other far out claims since but has never shown any proof. He just makes claims while stating that anyone not following his instructions is an idiot and listens to lo-fi.

That's a nice way to make friends and influence people. Don't you think?

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
RE: Say what you will, posted on October 21, 2009 at 15:42:31
drlowmu
Manufacturer

Posts: 4649
Location: East of Kansas City
Joined: January 10, 2005
 Tre',

I am sorry if the grid stopper evaluations I did permanently "short circuited" you.

In that 1986 labratory style amp of mine, P-P-P 6B4Gs, with separate supplies, and active double regulation of each stage, and all filaments regulated, it was a range of 114.95 Ohms to about 114.98 Ohms that sounded best balanced and most focussed and to me.

I imagine that is too much for you to imagine, but that was exactly how I heard it - way back then !! :-)

Your comments on a 7B4 not being able to drive a 2A3 in a Direct Couple, is theoretical ONLY, and 100% at odds with what I like and hear in Dennis' Serious Stereo 2A3 amps. Why can they sound as good as they do?? You have not a clue son.

Maybe, just maybe, you don't really know - what you THINK you know.

I believe that is the case, simply from hearing the Serious Stereo 2A3 DC amp at the last four RMAFs. Of course, you have never heard it, 'your problem kiddo, not mine !! Cheers.

Jeff Medwin

That's not what Dennis said, posted on October 21, 2009 at 20:38:17
Tre'
Industry Professional

Posts: 4846
Joined: February 9, 2002
 Dennis himself said that his amp starts to roll at 15kHz using whatever new production 2a3 he uses. (The new production 2a3 Dennis uses has lower Miller capacitance than the old ones)

He said they start to roll at 9.3kHz if you use an RCA NOS 2a3.

Dennis said that this is due to the high output impedance of the 7B4 driver and the Miller capacitance of the output tube.

These numbers are in perfect agreement with theory and my measurements on the bench.

A 50K output impedance driving 77pf of Miller capacitance doesn't cut it.

The problem is not as bad if you use the new production tubes (with their smaller Miller capacitance) but still a problem none the less.

So Dennis has shown that I do know what I think I know.

BTW I'm not you son. Thank God!

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
That's not all there is to it, posted on October 22, 2009 at 00:27:35
drlowmu
Manufacturer

Posts: 4649
Location: East of Kansas City
Joined: January 10, 2005
 Tre',

Your analysis is not complete, and is faulty.

You missed the mark.

Your comments above has little to with the amp's performance in the real world, and what a listener hears.

The amp has a GREAT top end, extended sounding, detailed, about as nice as I have ever heard. Don't tell me this is because I am too old to judge a top end !!

(I actually know the reason and methodology Dennis applies, to get the highs "spot on",.....it is not taken into account in your sophomoric set of calculations, one iota.)

You overlooked something, but the amp's designer certainly did not !!

At RMAF shows, and in Montana, these amps perform.

Jeff Medwin

That's all there is to it, posted on October 22, 2009 at 09:31:43
PakProtector
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Posts: 9949
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 -----Your comments above has little to with the amp's performance in the real world, and what a listener hears.

If the listener can't hear very well at HF, the amp won't present an obvious defficiency. The measurements are what they are, and just because it sounds good to you is only proof of your poor hearing.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
RE: That's not all there is to it, posted on October 22, 2009 at 08:39:35
Tre'
Industry Professional

Posts: 4846
Joined: February 9, 2002
 "Your analysis is not complete, and is faulty. "

My analysis was not meant to be complete but it is not faulty.

My analysis is only about the low pass filter created by the output impedance of the driver tube and the Miller capacitance of the output tube.

There is no getting away from that and Dennis said so himself. "You have to deal with the Miller".

With an output impedance of 50K there will be a loss of highs depending on the Miller capacitance of the output tube.

With the tube Dennis uses that loss starts at 15Khz (according to Dennis).

With a RCA NOS 2a3 that loss starts at 9.3Khz according to Dennis, the theory and my own measurements.

Now, what were you trying to say?

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
RE: That's not all there is to it, posted on October 23, 2009 at 08:16:45
drlowmu
Manufacturer

Posts: 4649
Location: East of Kansas City
Joined: January 10, 2005
 Tre',

1) Your partial "analysis" is certainly incomplete, and misleading.

2) One must judge an amp, in the end, by listening to it over time, in various good systems

3) Dennis amps' highs are pristine, hell - the entire amp performs excellently - in all areas of music!

4) One needs to do 2) above, to understand and totally appreciate it.

------------------------------------------------------------------

So, its not Tre's "incomplete theoretical", but rather, Jeff's "where the rubber actually meets the road" that we two now discuss.

The proof of the pudding is in the eating.

Don't forget, this amp (and Dennis' entire system) earned rave reviews in 2005, and your numerous attempts to discredit are at odds with what the reviewers heard and reported.

You can trust my descriptions, but best of all, simply LISTEN to it at RMAF shows, with different material, for yourself. No more of this incomplete analysis please. That is so sophomoric and far-removed from reality.

"Half truths need not apply". We need to have the truth, the whole truth, and nothing but the truth. It is judged best subjectively by listening.

No more discussions are necessary, just listen to it carefully, Dennis' DC 2A3 amp - the real thing, and not my friend's botched interpretation. Cheers.

Jeff Medwin
RE: That's not all there is to it, posted on October 23, 2009 at 09:04:57
Tre'
Industry Professional

Posts: 4846
Joined: February 9, 2002
 So are you now saying that in spite of the high frequency roll off, caused by the filter that is there and part of reality, that the amplifier sounds good?

That would be completely different than saying that the filter is not there.

Saying that the amplifier still sounds good, in spite of the filter, would be your opinion and there is nothing wrong with you having an opinion.

Or are you still saying that the filter does not exist?

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Serious Stereo 2A3 Frequency Reponse, posted on October 30, 2009 at 11:12:38
TonyB
Audiophile

Posts: 162
Location: Toronto
Joined: October 23, 2000



Here is a quickly measured MLS frequency response of the Serious Stereo 2A3 amp, low power output. dB numbers mean nothing on this graph. I will do accurate calibration of my set up, longer MLS sequence, longer FFT, ... in the future. I am sick right now and have a lot of things to do in the next 2 months. Nothing will be done sooner.

TonyB

RE: That's not all there is to it, posted on October 23, 2009 at 10:14:33
drlowmu
Manufacturer

Posts: 4649
Location: East of Kansas City
Joined: January 10, 2005
 Hi Tre',

I would not quibble with your computations one iota, but I know for a fact that Dennis takes that, and many other design parameters into account, in the build. You computed a small portion, not the whole. In the final result, Dennis gets all the highs he should have, in the amplifier. It is a VERY VERY honest reproducer of music. Delightful to hear.

Jeff Medwin

RE: That's not all there is to it, posted on October 23, 2009 at 14:11:48
PakProtector
Audiophile

Posts: 9949
Joined: May 14, 2002
 So it sounds the way Dennis wants it to, still rolling off the HF; not honest to call it full bandwidth.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
RE: That's not all there is to it, posted on October 23, 2009 at 19:15:50
drlowmu
Manufacturer

Posts: 4649
Location: East of Kansas City
Joined: January 10, 2005
 Douglas,

You are selectively reading my post. I also specifically said this :

" In the final result, Dennis gets all the highs he should have, in the amplifier. It is a VERY VERY honest reproducer of music."

Let those above quoted words of mine sink in some, as it is a vital part of my description, four years worth of my RMAF listening to Dennis' show set ups.

Cheers.

Jeff Medwin

so what?, posted on October 24, 2009 at 05:26:42
PakProtector
Audiophile

Posts: 9949
Joined: May 14, 2002
 Dennis admits the amp rolls off long before 20 kHz. If it was flat to 20 kHz I am sure he would have said so. Your experience listening to such an amp while making the claims you do is just an indictment of your hearing ability. Thanks for clearing that up.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
RE: That's not all there is to it, posted on October 23, 2009 at 11:59:27
Tre'
Industry Professional

Posts: 4846
Joined: February 9, 2002
 So if the highs are being lost in one part of the circuit, is it made up for in another part of the circuit?

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
RE: That's not all there is to it, posted on October 23, 2009 at 12:07:34
drlowmu
Manufacturer

Posts: 4649
Location: East of Kansas City
Joined: January 10, 2005
 Tre',

I really don't know, maybe, you will just have to hear it.

Jeff

RE: That's not all there is to it, posted on October 23, 2009 at 13:00:36
Tre'
Industry Professional

Posts: 4846
Joined: February 9, 2002
 "I really don't know"

Thank you Jeff, that is very honest.

I really do appreciate that honesty.

I mean it, I'm not fooling or trying to mess with you.

All the best, Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
RE: Say what you will, posted on October 21, 2009 at 17:19:03
PakProtector
Audiophile

Posts: 9949
Joined: May 14, 2002
 -----Your comments on a 7B4 not being able to drive a 2A3 in a Direct Couple, is theoretical ONLY

That is a bunch of BS. Per Dennis-es own claims it is not able to deliver a full bandwidth amplifier. If you think it does, that is just an indictment of your hearing ability.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
RE: Say what you will, posted on October 22, 2009 at 00:41:33
drlowmu
Manufacturer

Posts: 4649
Location: East of Kansas City
Joined: January 10, 2005
 Ha,

How can you comment on stuff never heard?? Its like taking art advice from a blind person.

If you think Tre' got it right, you are crazy.

How come you instantly "backed down" when I asked you to tote one of your eLinear amps to RMAF this year, and you offered lame excuses "not this year", .....as though you had usually attended?

Ever attended a RMAF to hear things? Tre' hasn't either. You two are a fine pair, blind art advisors.

Jeff Medwin

How Lame..., posted on October 22, 2009 at 09:08:14
PakProtector
Audiophile

Posts: 9949
Joined: May 14, 2002
 -----How come you instantly "backed down" when I asked you to tote one of your eLinear amps to RMAF this year, and you offered lame excuses "not this year", .....as though you had usually attended?


RMAF is a long way away, and I have much better things to do than go and show you up in public. I doubt I'll ever go. However, since you take travel so lightly, let's see you in SE Michigan with one of your amps so that it can be judged by our audio club? ( I am *REALLY* looking forward to seeing you offer some lame excuses as to why you won't show up ).

As to speaking to the frequency response of Dennis-es amps, I am merely taking him at his word as to their response; in truth I suspect their numbers are being padded. They're not full bandwidth, and though you artfully skirt that issue by saying I haven't heard them...they're still rolling off the top, just as the math says they will.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
RE: Say what you will, posted on October 22, 2009 at 08:47:51
Tre'
Industry Professional

Posts: 4846
Joined: February 9, 2002
 Jeff, if you touch a red hot piece of steel you will burn your fingers.

You don't have to try it to know that's what will happen.

With the use math and theory we don't have to "touch the hot steel" to know what will happen.

There is nothing wrong or ambiguous about a reactance chart.

If the output impedance is known and the Miller capacitance that is being driven is known, then we know the out come. I not saying we know the out come of the whole amplifier but we know the out come of the filter created by the driver tube's output impedance and the Miller capacitance of the output tube.

I don't understand why you can't see this simple thing.

"If I have five bananas and Jeff takes away 2 bananas, how many bananas do I have left?"

Just look at a reactance chart and do the math. You are not a child.

Tre'


Have Fun and Enjoy the Music
"Still Working the Problem"
OOOOHH!..OOOOHH!!!!!, posted on October 22, 2009 at 09:10:47
PakProtector
Audiophile

Posts: 9949
Joined: May 14, 2002
 You'd have three banannas, unless it is on Tuesday, and you're playing Fizzbin in Montana...then you'd have a sralk...unless it is dark.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
RE: OOOOHH!..OOOOHH!!!!!, posted on October 22, 2009 at 11:46:34
Ray Moth
Audiophile

Posts: 1962
Location: Jakarta, Indonesia
Joined: November 10, 2003
Contributor
  Since: May 20, 2009
 This is getting silly!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
How many times MUST I TELL YOU NOT TO MOCK THE AFFLICTED ???????????????????????????????????????????????????????

Of course an amp sounds OK if you only listen to sh1t-kickers' music. Hoe-down, anyone?

RE: OOOOHH!..OOOOHH!!!!!, posted on October 23, 2009 at 08:21:31
drlowmu
Manufacturer

Posts: 4649
Location: East of Kansas City
Joined: January 10, 2005
 You tell him Thergit !!!

RE: Yeah, but..., posted on October 20, 2009 at 18:51:47
Wojciech
Audiophile

Posts: 45
Joined: June 23, 2009
 Steve
It was not my intention to steer you out of the project with MQ FS030 transformers.They are one heck of a product! I only think it still won't be
"flesh and blood" amp ;)

RE: Yeah, but..., posted on October 21, 2009 at 06:59:04
SteveBrown
Audiophile

Posts: 1523
Location: Tulsa!
Joined: November 14, 2002
 Thanks for the note. Never having heard the "original", I have nothing to compare to. I have often wondered if Herb is just a good writer, or if the amp was, in fact, all that. Maybe everyone who has chased this design is on a fool's errand. Nevertheless, the outcome even given my LCFB variation, is a long way from unlistenable, I'm rather enjoying it, actually.

RE: Yeah, but..., posted on October 20, 2009 at 18:30:26
Donald North
Manufacturer

Posts: 910
Joined: February 8, 2001
 Have you talked with Brian at Audio Note Kits to see if he has any spare AN transformers available for sale?

Donald North

Now at Parts Connexion, posted on October 21, 2009 at 19:14:37
Frank E
Audiophile

Posts: 643
Joined: May 20, 2000
Contributor
  Since: September 8, 2000
 apparently

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