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In Reply to: RE: Penny wise posted by drlowmu on December 13, 2014 at 06:23:14
Jeff,
"How long you gonna live and use this piece?"
I wish I knew.
"Don't you deserve hearing whats really good?"
Yes I do.
Since this would be my first amp, something tells me to breadboard it with the cheapest parts possible, just as a learning excercise. OTOH I don't want to pay for it twice, and build it twice. Quite the conundrum.
There are two little bits of old SET lore that stick in my mind, and I would like your opinion on them. They may be obsolete, or just plain wrong.
One is, Use motor run caps in the C1 position.
The second on is, Don't use caps of all the same type in one amplifier. Mix it up at least a little.
What do you think?
This lore makes me want to run a PIOs in C1, and DC Link everywhere else, or PIOs everywhere and a DC Link in the UP spot.
Thanks,
Jamie
Big speakers and little amps blew my mind!
Follow Ups:
Jamie,
Breadboarding will only tell you if it works and not the final sound quality you can expect so IMO do it in a chassis. Hammond chassis are quite cheap and easy to work with.
You'll end up with a reasonable amp, however, be prepared to build another as you will learn so much and want so much more that you wil be compelled to do it all over again with upgraded components, wiring and layout.
That's the fun of DIY. So, skip the breadboard and you'll have something to be proud of.
Re. Caps, never did like motor runs and there is so much more out there (Wima, Clarity cap) and yes, I like mixing it up a bit too.
Had the Ultrapath and the DC45 I have now is so much better.
Cheers
Smart
"Had the Ultrapath and the DC45 I have now is so much better."They are not mutuality exclusive.
You can Ultrapath your DC45 amp but to do it right you will need a much cleaner PS.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 12/14/14
'So, skip the breadboard and you'll have something to be proud of'
Poor advice . Always breadboard ! It's the best way to get the layout right and get a feel for the sound before committing . This applies especially with relation to placement of iron . Amps built directly into a chassis are fine if it's a proven design but a lot more risky if it's a ground-up DIY effort . I rarely get past the breadboard stage , currently I have six completed amps in various stages of development on pieces of wood . If I built every design I came up with into a chassis , I'd be bankrupt and have even less space for amps than I do at present :)
Al
Thanks Al and Smart.
I think it's going to be cigar boxes for me. Four boxes with two PS, and two main amps.
Do you think it's worth the trouble to line the inside of the wood box with aluminum foil?
Jamie
Big speakers and little amps blew my mind!
Think about this !!
You could get chassis for FREE from the local USPS.
They offer a variety of sizes, called " Flat Rate Shipping Boxes ".
Free !!! The only thing better is if they paid you to take them home.
Jeff Medwin :-)
What do I think..... you ask me??Well, several things. The amp you wanna build has deal-breaker flaws. I'll tell you what they are, before you build it, as it is obvious to me.
The driver stage is too low in its mu, and as such, the amp will only come alive when pushed hard, which gets tiring to hear over time. Its gotta "come alive" at low listening levels. ( That takes a mu of 100 driver for a 2A3 or 45 DC two stage amp. Mu of 70 driver is the bare minimum for a lively presentation, and an octal based tube - like a 6SL7 - is second best. )
The second thing I know is that I would NEVER EVER be able to live with over 100 Ohm inductors, feeding a DHT Final. I have A-Bed this since 1982. The second amp building rule my audio mentor, Robert W. Fulton gave me in 1982 was that the chokes to the finals in a 2A3 amp " a direct access to the music tube " have to be " 20 Ohms or less." Of course, he was correct, and I use 7-10 Ohms DCRs in 2014.
So, Mr. Steady, all these other questions you ask me become somewhat superfluous to me.
I will answer you this.
(1) I will never build a breadbaord.
(2) Its a NEW BALL game with these new capacitors, old wive's tales no longer apply.
A SE amp needs to be built as a finished product. Layout and parts selection are of extreme importance. Your DIY amp reflects your "woo", " chi " or life force, as Herbie Reichert used to say. Resolder a part a second time, and its never better than the first time you soldered it. Wire runs, lengths, types, solder type, everything is important in a simple SE DC 2A3 amp.
You would be better off buying a used FI "X" amp, or a Moth, in my opinion. That FI amp is much like a 1947 Robin-Lipman amp. It has the right gain structure, and it is listenable.
Photo is the (re)start of a new DC 2A3 stereo amp I am doing for myself for ALTEC A7-800s, as of today, a work in progress. Separate L1, L2, and 2A3 Ef XFR shown mounted for each channel. NO friggin' breadboard here, no clip leads, etc.
Jeff Medwin
Edits: 12/13/14 12/13/14
"What do I think..... you ask me??"
I think the metal work is very good. I wish you would keep a photolog of your build, and then post it to youtube or something.
I take your point on high gain vs low gain. It is a very complex subject given everybody has a different gain and power requirement for their speakers. For my horn system I find 1/2 of a 6SN7 is not enough, and 1/2 of a 12AT7 is too much. I would like to find a happy medium between the two. The low gain tube you have to turn up to the 12 o'clock position, and then it is about to run out of headroom. The high gain tube gives a hair trigger volume control. With a phonostage the 9:oo position is very loud, with the same at 10:00 for a CD player. At least you can play it loud, and still have plenty of headroom. This is all with incomplete information, as my active crossover just died, and I was not able to switch in the low gain amp into long term system. I have had to put back in a passive crossover, so everything is different, and comparisons are a stretch. But this has been my experience with low gain amps in the past.
I am considering all DC Link caps.
The BB amp is simple enough to make me want to try to build it. I think I will.
I don't expect for Paul to put his best design out there for free. Neither do I expect it from you or DF.
It's getting close to the time of; fish or cut bait. If you want to amend the BB Proof amp to use the driver tube you want with the DCR you want, then you have my permission. It only has to stay a Half Stick Monkey DC 2a3. You are free to set your own voltage budget. You may then offer this amended schematic as an alternative. Otherwise, you may want to whet the filet knife.
Thank you for your recent contributions to the BB Proof amp.
Jamie
Big speakers and little amps blew my mind!
Jamie, the correct gain structure for any modern amp, regardless of whether push/pull or single-ended, regardless of whether 2, 3, or 4-stages-- the correct gain structure for all of these amps is now 18-20 DB of amplification.
More or less than this ideal figure will result in an inferior amplifier if you intend to work with today's line-level music sources.
The gain structure of a 2-stage S.E., using D.C. coupling, driven by a triode with an amp-factor of 100, driven into a 2A3 or 45, falls within this ideal 18-to-20 DB range. Changing the amp's overall gain structure to use the amp as a volume control is wrong.
You'll notice, I didn't mention speakers. You're using Hi-Eff. ones, right? That's fine. But what if you used say-- a speaker of 89 db/watt?
The SAME amplifier gain structure would apply-- 18-20 db range.. You would simply go to a high power solid state amplifier (500 watts or more--preferably 1000 watts) with the same 18-20 db amplification range, and match up the speaker to the amp as usual. The high power amp will deliver the extra CURRENT needed to drive the low-Eff. speaker.
The overall gain structure of the system remains the same as in the low-powered tube amp example..
Correcting for gain structure in an amplifier, once it is in the right range is a no-no, correct system setup is a yes-yes..
ANY of these correctly assembled audio systems will find the volume control located at the ideal "1 1/2-to- 2 1/2 o'clock" position when listening at normal levels.
---Dennis---
"The gain structure of a 2-stage S.E., using D.C. coupling, driven by a triode with an amp-factor of 100, driven into a 2A3 or 45, falls within this ideal 18-to-20 DB range."How do you figure that?
Your driver stage has a gain of about 54 (that's about 35db) and then you have to add the gain of the output stage. You're not even following your own rules!
Or are you including the loss through the output transformer?
Even so, 18db gain would give 8 volts out for 1 volt in and 8 volts across 8 ohms is 8 watts. Your amp does not give 8 watts for 1 volt in.
Your amp gives 1 watt out for .33 volts in. That's a total amplifier gain of about 9.5 db.
".. the correct gain structure for all of these amps is now 18-20 DB of amplification."
The correct gain structure is the gain needed to get the listener's speakers up to the SPL, at the listening position, required by the listener.
Where do you get that 18-20db is somehow the only correct gain?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 12/14/14 12/14/14
It is the correct amplifier gain for today's source components.See "Get Better Sound"-- from an experienced guy in Cummings, Georgia. The book is readily available, and explains it for you-- just Google it.
Since I'm not running "8 watts"-- that's an irrelevant supposition, and an irrelevant power level in my own personal system as well.
The voltage multiplier effect of an amp partially determines HOW it responds to signal input, we're not considering power levels here..
You're considering running an amplifier at, or near full output. While those examples are interesting, I don't ever run an output stage anywhere near full output under any condition, for any reason whatsoever..
I also consider any amp that clips it's output stage before driver stage clipping limits the output stage (conventional amps)-- is a serious design mistake in many, many ways. It's always been a Commercial gimmick used to extract maximum advertised power (and minimum microdynamics) out of tube output stages, which DON'T LIKE that kind of operation, and don't last very long doing it.
I'm interested in what the DRIVER-- and the whole amp as an extension-- SOUNDS LIKE, and BEHAVES LIKE-- at tackling music's leading edges, and at separating musical events while they're all playing at once-- especially at low speaker volumes, and again at very high speaker volume. I expect those two conditions to be as nearly identical as I can get them at any power levels that a given audio system will experience...
The gain structure of an amplifier should stay essentially the same until it runs out of power. Any measurements or mental considerations after that point are.... pointless.
---Dennis---
Edits: 12/14/14
Dennis,
I pulled out my copy of "Get Better Sound" by Jim Smith. I haven't been able to find the part on gain structure yet. No index, and many of the chapters don't have proper names, just Tip 37.
I'll keep looking.
Have a Merry Christmas if we don't hear from you until then.
Jamie
Big speakers and little amps blew my mind!
My amplifier that will output 2 watts into 8 ohms with 2 volts input has a gain of 6db.Your amplifier that will output 1 watt into 8 ohms with .33 volts input has a gain of 19db.
An amplifier that will output 500 watts into 8 ohms with 1 volt input has a gain of 36db.
An amplifier that will output 1000 watts into 8 ohms with 1 volt input has a gain of 39db.
So you are completely wrong when you said "The SAME amplifier gain structure would apply-- 18-20 db range.. You would simply go to a high power solid state amplifier (500 watts or more--preferably 1000 watts) with the same 18-20 db amplification range, and match up the speaker to the amp as usual."
If the listener were to get a higher powered amplifier (with the same gain structure) for his lower sensitivity speakers he would not be able to drive that amplifier with the same source voltage. He would need more source voltage but clearly that's not how it works.
The higher powered amplifiers have higher gain so the user will get the higher power to the speakers with the same source voltage but you don't seem to understand that.
I get tired of following you around trying to clean up the messes you make with the misinformation you post but as long as you continue to make false statements I guess I will have to continue to try to clean it up.
Have a nice day Dennis.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 12/16/14 12/16/14
Hi TRE.Merry Christmas to you and yours if I don't get back on here before that.
I decided to do a little Christmas shopping/dreaming, visit a few amps that I like to listen to-- see how their gain structures turned out.
Here's a sweet little 100-watter that I thought a lot of at RMAF-- DarTZeel NHB-108 model one-- Looks like it has 100 watts @ 8 ohms, 26 db gain.
Boulder amps turn me on-- here's the model 1050-- 500 watts @ 8 ohms, 26 db gain. Then, Boulder has the model 1060, that one is 300 watts @ 8 ohms, the same 26 db gain........ OK....
There's Nelson Pass (Labs). The XS 150 is 150 watts @ 8 ohms, 26 db gain. The XS 300-- 300 watts @ 8 ohms is still 26 db gain.
Bryston has the 2.5BSST2-- 135 watts @ 8 ohms. You can choose 23 or 29 db gain-- dealer's choice. Bryston's 14BSST-PRO has 600 watts @ 8 ohms. Again, 23 or 29 db. You choose....
Spectral's DMA-360 and 400 have 300 watts and 350 watts respectively @ 8 ohms, they say 1.5 volts in, and output is "nominal". I suspect they don't get into DB Wars.....
McIntosh weighs in at 600 watts @ 8 ohms with their MC601. It has dynamic headroom of 1.8 db. That's it. Want to argue.... I don't think they would be interested....
MBL says nothing on this subject, neither does AYON-- that I could find. Their big one sounded good driving the big SONY speakers at RMAF.
We all have different reasons for the gain structures in our amps. With me, it's the idea of having a source component that puts out 3 to 7 volts drive right into a passive attenuator into an amp that has 18-20 DB gain structure.
The "Get Better Sound" guy also likes that range-- maybe thinks it's the best. I agree and neither of us coached the other.. We're not trying to run high power amps into high-eff. speakers, or trying to match-up to older gain structure preamps, although the really great ones will work quite well into a 18 db gain amplifier, we just love lively dynamics and great detailing, low interconnect losses---- playing all the musical instruments intact. And simpler amps too!
Merry Christmas, and my best to you.
---Dennis---
.
Edits: 12/16/14 12/16/14 12/16/14
I also love lively dynamics but gain structure does not affect dynamics unless you're fighting a high amplifier noise floor.
"Bryston's 14BSST-PRO has 600 watts @ 8 ohms. Again, 23 or 29 db"
600 watts [RMS] into 8 ohms is 69 volts [RMS] across the 8 ohms speaker.
If this amp has a gain of 23 the input would have to be 4 volts [RMS] for it to make 600 watts.
Side note, if I needed 600 watts I would have to have a active line stage preamp. My CD player only outputs 2 volts at a digital zero (in other words, it only outputs 2 volts when the digital signal is peaked). If I needed 600 watts, the amplifier would have to produce those 600 watts with only 2 volts input because I will not add a active line stage preamp just like neither of us will add a third stage to our power amps.
"DarTZeel NHB-108 model one-- Looks like it has 100 watts @ 8 ohms, 26 db gain"
At a gain of 26 this amp requires only 1.4 volts [RMS] input to make 100 watts.
None of the amplifiers you listed follow your rule and nothing about the gain of an amplifier will affect the dynamics so I still don't understand what you rule is about.
"With me, it's the idea of having a source component that puts out 3 to 7 volts drive right into a passive attenuator into an amp that has 18-20 DB gain structure."
What source component output 7 volts? Active line stage preamps? You do understand that it doesn't matter if the extra stage is in the preamp or the power amp. An extra stage is an extra stage and I thought you were against that?
I run my CD player (2 volts RMS at max) and my phono preamp (perhaps a tiny bit hotter) into an AVC and, with very little gain in my amplifier, I can play my system louder than I ever want to.
I would think the same would be true for you with the very sensitive speakers that you have.
I have no idea what you do with all the gain (19db) your power amplifiers have. I can only guess that you keep your passive VC preamp turned way down.
6db vs. 19db....that would be more than 6 clicks on my AVC switch. I usually run my volume switch at 8 clicks (16db) down from wide open.
With your amp I would have to run the AVC switch 14 clicks (28db) down from wide open. And that would be the difference, not a difference in dynamics.
The bottom line, there is no rule.
If a listener's source outputs enough signal voltage to drive his amplifier to the wattage that is needed for his speakers to reach the SPL at the listening position that he desires, then that's the right gain structure for that listener.
And none of this has anything to do with dynamics.
Merry Christmas!
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
One more time, then-- Hey! It's Christmas!
-None of the amplifiers listed follow your rule- TRUE! They have their own priorities and reasons-- mine work better.
-What source component outputs 7 volts?- The LYNX L-22 computer sound card puts out 3.5/3.5 or 7 volts balanced. Most Blu-Ray players output in this range also. This is absolutely ideal for a passive volume control/attenuator. Blu_Ray movies are now the best sound the consumer can easily buy.
-I can only guess that you have your passive VC preamp turned way down-- It normally runs at 1 to 1:30 O'clock.
-none of this has anything to do with dynamics- Oh, but it does, and the difference is large. You're dealing primarily with the S/N (signal-to-noise-ratio) of the interconnects used in the system.. Any wire has a "perfect" power range where it performs best. Put too much energy into it, and it balks, put too little in and it becomes a poor conductor at that signal level.
This does depend on what interconnects are used, how good RCA jacks are, etc., but in general, the boutique wire makers have this pretty well ball-parked for their intended uses.
If you build your own cables & interconnects, (I sometimes do, and sometimes I buy them-- depends), then you'll want to take a look into that.
---Dennis---
The LYNX L-22 computer sound card balanced output is pro +4.
That's a different conversation.
BTW I didn't know your passive VC was balanced in and out?
I know, as a fact, that your power amp does not have a balanced input. So why would you be using the balanced output of your sound card?
The blu-ray players I looked up have 2 volts outputs but there is no standard, no rule.
"We've found some BD players output at 2Vrms when presented a 0dBFS signal while other outputs are at 1Vrms."
You said,
"You're dealing primarily with the S/N (signal-to-noise-ratio) of the interconnects used in the system.. Any wire has a "perfect" power range where it performs best. Put too much energy into it, and it balks, put too little in and it becomes a poor conductor at that signal level."
S/N (signal-to-noise-ratio) of the interconnects used in the system? Really Dennis?
Too much and the wire heats up and the DCR goes up and it becomes a poor conductor.
I guess you can call that "balks" if you want to but 2 volts or 7 volts or 20 volts into the input impedance of the power amp is not enough current to heat up the wire. So once again you are wrong Dennis.
As for "too little in and it becomes a poor conductor", that is just so ridicules I won't even offer a retort.
These things are all just more of your made up stuff Dennis with no basis in reality.
You can have an opinion but when you state your opinion as fact, without showing technical proof, then you and I will have a problem.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
"Oh, but it does, and the difference is large. You're dealing primarily with the S/N (signal-to-noise-ratio) of the interconnects used in the system.. Any wire has a "perfect" power range where it performs best. Put too much energy into it, and it balks, put too little in and it becomes a poor conductor at that signal level."How does a passive wire have a signal to noise ratio spec?
You remind me of a "computer tech" years ago who told me I can't make RS232 cables with 22awg wire because "the thicker wire soaks up too much data".
P.S. To the more technical here: Lets not get caught up with all the RF theory that would support the computer tech's theory with high speed data transmission! This was 9600 baud at less than 50 feet! As with audio signals, data signals at that rate and equivalent frequency are not sensitive to these parameters.
And FWEIW, CAT6 cable is 23ga where as CAT5 is 24ga due to the RF issues.
Edits: 12/17/14
The Bryston owner's manual says that with the 29dB setting, 1 volt in produces 100 watts into 8 ohms and with the 23dB setting you need 2 volts in to get 100 watts into 8 ohms. see the link, it's on the last page. They don't indicate the voltage required for 600 watt output.
"They don't indicate the voltage required for 600 watt output. "But they do. The gain of the amplifier is either 23db or 29db and that tells us what we need to know.
Using the 29db setting 1 volt input gives 28 volts across 8 ohms at the output. That's 100 watts.
At the 23db setting 2 volts input gives 28 volts at the output.
At the 23db setting it will take 4.8 volts input to get 69 volts out. 69 volts across 8 ohms is 600 watts.
At the 29db setting it would take 2.4 volts input to get 69 volts output.
Kirchoff's law, power = current times voltage and the online calculator linked below.
What bothered me is that Dennis stated,
"Jamie, the CORRECT gain structure for any modern amp, regardless of whether push/pull or single-ended, regardless of whether 2, 3, or 4-stages-- the CORRECT gain structure for all of these amps is NOW 18-20 DB of amplification.
More or less than this IDEAL FIGURE will result in an INFERIOR amplifier if you intend to work with today's line-level music sources.
The gain structure of a 2-stage S.E., using D.C. coupling, driven by a triode with an amp-factor of 100, driven into a 2A3 or 45, falls within THIS IDEAL 18-to-20 DB range. Changing the amp's overall gain structure to use the amp as a volume control is WRONG."
as if this is some kind of axiom or universal truth.
He later softened that to "We all have different reasons for the gain structures in our amps. With me, it's the idea of having a source component that puts out 3 to 7 volts drive right into a passive attenuator into an amp that has 18-20 DB gain structure."
So I guess he was over-stating his point the first time and realized it.
The bottom line, there is no rule and Dennis knows it.
Dennis just wants his preferences to be seen as the only proper way of doing things.
I think Dennis is a bit of a megalomaniac.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 12/17/14
I agree that there's no rule, that's obvious.What you don't understand is the huge performance gains that result when you idealize any set of parameters-- taking each item, and in turn, idealizing it while considering and idealizing all the other factors that are present and interact with each other.
I do that routinely, you are degrading the attention required and the science involved. Apparently just because you don't like it, or wish to attack the messenger..
Name-calling does nothing to improve the performance of equipment. .
Whether there are rules for the things I describe or not, is---- completely irrelevant to our discussion.
What is relevant and obvious to me is that if ANY amplifier, at ANY power output level is operating in the 18-20 db gain structure range, if all other factors are made whole for that gain structure, and if the system is set up to accommodate an amplifier that has that gain structure, the performance of that system will not need any explanation from me or from you-- it's improved performance will be very obvious.
This factor has proven to me to be so great an improvement in ANY system, that I now try to use amplifiers that have that gain structure exclusively-- when I can-- where the requirements are for the best possible performance that one can get from that audio system.
One can build ANY wattage amplifier to the 18-20 db gain structure if he so chooses to do so, and successfully set up an audio system to use that structure to sonic advantage.
We all have to live with things that we can buy-- including amplifiers and source components. What I described is an ideal-- one of many factors involved in getting THE BEST performance. I didn't say you couldn't use something else.
You can use anything you want-- just don't attack every improvement that comes along because it doesn't match up with your preconceived ideas and only the science and herd-mentality notions that YOU know.
ALL Science and ALL rules were-- at one time-- unproven. They were somebody's UNPROVEN ideas that later were proven by superior performance, not by agreement among engineers and scientists at that time.
What you THINK you know CHANGES with time. It ALWAYS changes. You can learn how to use something superior, or you can half-heartedly "try" it, and fail, and then conclude that it is "bogus".
The problem with your approach is what do you do when IT WORKS for others and is, therefore, NOT bogus?
You have two choices: (1) You can THINK and see how and why it works, or (2) you can denounce both the idea and its messenger.
I think that History makes it obvious which approach really gets results.
---Dennis---
Edits: 12/18/14 12/18/14
"One can build ANY wattage amplifier to the 18-20 db gain structure if he so chooses to do so, and successfully set up an audio system to use that structure to sonic advantage."So if a person has a situation where 1000 watts on peaks are needed and he uses an amplifier with 19db of gain, where will he get the 10 volts of input signal needed for that amplifier to produce 1000 watts?
I know of no source components that outputs 10 volts. So now, because of your rule, that person will need an active line stage preamp.
So now it can be said that Dennis clearly states that adding an active line stage preamp is a sonic advantage?
I know you don't believe that.
I think what a person would want is an amplifier with a gain and power rating that gives the power that's needed for the situation using only the output voltage of his source component without the need of additional active stages.
Doesn't that sound like a better rule?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 12/18/14 12/18/14
So Dennis,
If you have uncovered and implemented these new techniques which contradict established electronic theory, why is there no documentation of it past this public hobbyist internet forum?
Why have you not published your findings in a technical journal?
Why are these ground breaking techniques you have been practicing since 1989 (per LowMu) only admired by casual hobbyists who lack formal technical training?
Where is the commercial application of your techniques beyond your own niche product offerings?
To my knowledge you have no patents or copyrights filed so anyone is free to copy your work for commercial gain is they choose.
Why has no one done that?
Philanthropy
"The gain structure of an amplifier should stay essentially the same until it runs out of power."Well, it will. Unless there are variable mu tubes being used.
Using normal tubes, the gain of the circuit will stay the same through it's normal use voltage range.
So again, you try to make this all sound mysterious as if you're the only person who understands.
You create issues that don't exist so that you can be the hero who slays the dragon, the dragon that only exists in your mind.
Gain is gain.
Other than the output level, the response to a musical signal of a high gain stage is no different than the response to a musical signal of a low gain stage.
Your inference that a high gain stage is needed to "properly capture the leading edge" (or whatever the hell you said) is BS.
If I have a low gain drive stage (and the same output stage and the same speakers and the same source) and I want the SPL in the room to be the same as an amp with a high gain driver stage (and the same output stage and the same speakers and the same source) I will have to attenuate the source signal less.
As long as there is enough signal available from the source, attenuating that signal less will not adversely effect the dynamics or the ability of the system to "properly capture the leading edge---blah, blah, blah".
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 12/15/14 12/15/14
"I also consider any amp that clips it's output stage before driver stage clipping limits the output stage (conventional amps)-- is a serious design mistake"
Dennis, your output stage will clip long before your driver stage. Again, you're amp does not follow your own rules.
"The voltage multiplier effect of an amp partially determines HOW it responds to signal input, we're not considering power levels here"
You can't separate the two. The gain of the driver stage determines how much signal the output tube gets for a given input signal. The amount of signal the output tube gets determines how much POWER the speaker gets.
What do you even mean by "The voltage multiplier effect...determines HOW it responds to signal input"?
Well yeah, the more gain between the input jack and the grid of the output tube, the more power to the speaker for a given input level.
It's as simple as that.
"HOW it responds"
What do you mean by that?
You make it sound like it's some kind of mystery or something.
Higher gain means that the amplifier will reach higher output power with less input signal applied. Period.
Your amp will output 1 watt with .33 volts input signal.
My amp will output 2 watts with 2 volts input signal.
The full output of a CD player will clip the crap out of your amp.
The full output of a CD player will not clip my amp.
What's your point?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Thanks Dennis
Big speakers and little amps blew my mind!
"The low gain tube you have to turn up to the 12 o'clock position, and then it is about to run out of headroom."If the driver stage is designed correctly, high gain tube or low gain tube, the dynamics of the music will not be affected.
The dynamics of the music will not be affected until or unless the output tube is driven to clipping.
With a high gain driver tube it's very easy to drive the output tube into clipping but the dynamics of the music signal is not changed unless one of the tube stages are clipping.
If you can play your music at the volume level that you want using a low gain driver tube and you're not clipping the output tube then there are no worries about "running out of headroom".
Let's say you have 1/2 of a 6sn7 driving a 2a3 biased at -45 volts operating in Class A1.
A peak to peak swing of 90 volts from your 6sn7 driver stage will drive the 2a3 just to the brink of clipping.
Designing a 6sn7 stage that will do 90 volts peak to peak is easy and there are no "headroom" issues. All the dynamics in the music signal would be within that 90 volt peak to peak drive signal that is feeding the output tube and as you turn down the volume control all the dynamics of the music signal is still within the peak to peak signal sent to the output tube.
BTW If your volume control is only at the 12 o'clock position then it sound like you have plenty of headroom in terms of input signal.
It actually sounds like you have to much input signal for the gain of the system.
Wouldn't the perfect gain structure of a system be; plugging the output of the signal source (CD player, phono preamp, etc.) directly into the power amp and having the volume in the room right where you want it without any need for attenuation?
BTW When you speak about "run out of headroom" I don't think it's headroom you're hearing. I'm not sure what it might be that you are referring to but it's not about headroom. Not having enough headroom refers to running out of power on peaks.
With my gain structure I can only get 2 watts from my 300b and that would be with the volume control turned all the way up and I never listen that loud. This would be at the highest peak of the music (digital 0db) from CD player. All the dynamics of the music reside at of below that.
If I turn down the volume control (autoformer volume control) by 6db then I get 1/4 the power (1/2 watt) from my 300b but all the dynamics are still present and there's never a problem with headroom as the 300b at my operating condition will do 5.5 watts given enough grid swing voltage.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 12/14/14
First, I had to switch to a passive crossover that I hadn't used in three years, at the same time I put in these amps. To much changed at once to know to much what is going on. I will have to save this subject for later.
I will swap some amps, so I can get a handle on what's going on.
My initial impression is that the low gain amp is fairly loud at 12:00. You can push it to 1 to 1:30, and it still sound good. At 2:00 it goes into distortion. If you permit me a colloquial term, compressed. And not that loud either.
With a 12AT7 your ears would bleed before you ever heard any distortion or compression.
Thanks for giving me the excuse to crank the system. The Steely Dan was sounding good loud. Electric guitars sound wicked to me on good horn speakers.
Jamie
Big speakers and little amps blew my mind!
"My initial impression is that the low gain amp is fairly loud at 12:00. You can push it to 1 to 1:30, and it still sound good. At 2:00 it goes into distortion. If you permit me a colloquial term, compressed. And not that loud either.
With a 12AT7 your ears would bleed before you ever heard any distortion or compression."
Then there's something wrong with the operating point of the low gain driver tube while the 12at7 is running properly.
With your speakers you should need much power at all and a low gain driver tube should give you plenty of system gain without distorting.
Can you give me details of each driver stage?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
"Can you give me details of each driver stage?"
Thanks, but some other time. I'm done.
Big speakers and little amps blew my mind!
OK but understand that if the 6sn7 circuit is working correctly then the distortion you hear must be coming from your preamp or source. Not the 6sn7.
A proper 6sn7 driver stage will not distort driving a 2a3 to full power.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
One can argue that any properly designed driver will not distort driving any following stage.
I'm confused by what Mr_Steady is reporting and I'm only trying to say that a 6sn7 stage should drive a 2a3 to full power (which he doesn't need with his speakers) without distorting noticeably.
A 6sn7 with a reasonably high load impedance running 12ma at around 200 volts plate will swing a lot more that 90 volts peak to peak with very little distortion.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Tre'
I searched the web regarding gain structure. Mostly had to do with recording. Found the following in regard to tube based gain stages, but even it was on a guitar gear site;
"Gain structure is the concept of relative amounts of signal or voltage gain from one stage of a chain to another. If you have three devices capable of voltage gain (lets say each can create a gain of 10%), and you need an overall gain of 17%, the gain structure would be how you allocate the gain between the stages. If you set up the first stage to generate a gain of 10%, the second stage to create a gain of 6% and the third to create a gain of 1%, that would be one method of structuring the gain. Alternatively, you could set it up so that the first stage has a gain of 5%, the second has a gain of 5%, and the third has a gain of 7%. You have change the gain structure but not the overall amount of gain.
By definition, one voltage-gain-inducing device by itself cannot have a "gain structure."
Picture this: in an amp with a master volume and a preamp volume you are juggling gain staging. You can set it up so that you have a lot of gain in the early stages (which often causes distortion in the later stages) or you can set it up so that most of your signal gain comes in the later stages, keeping the overall signal less distorted. This would be more akin to "proper" gain staging in the audio (i.e. concerned with fidelity) world.
The short answer to your question (now that i've finished my little semantic rant) is that "mu" = "gain.""
Maybe you have an opinion about the above? Somewhere I picked up that you should get all the gain you could in the early stages.
Do you know any good books or articles regarding the proper gain structure of a series of voltage amplifiers in audio? Maybe with an emphasis on tube amps? A tip here would be greatly appreciated.
Jamie
Big speakers and little amps blew my mind!
"Gain structure is the concept of relative amounts of signal or voltage gain from one stage of a chain to another. If you have three devices capable of voltage gain (lets say each can create a gain of 10%), and you need an overall gain of 17%, the gain structure would be how you allocate the gain between the stages. If you set up the first stage to generate a gain of 10%, the second stage to create a gain of 6% and the third to create a gain of 1%, that would be one method of structuring the gain. Alternatively, you could set it up so that the first stage has a gain of 5%, the second has a gain of 5%, and the third has a gain of 7%. You have change the gain structure but not the overall amount of gain."This is a rather misleading paragraph. The total gain of multiple stages of amplification is equal to the product of the gain factors for each individual stage. If one really wants to express the gain of each stage in percentage terms, as in the paragraph above, then the total gain is not given by adding the percentages together. It becomes a reasonable approximation if the percentages are small (as in the examples above), but even there, the errors are non-trivial. The overall gain in each of the two cases above is closer to 18% than 17%. But the whole example seems rather bizarre; who would seriously build a three-stage amplifier where the stages had gain factors like 1.05, 1.05 and 1.07? (i.e. about 0.4dB, 0.4dB and 0.6dB.)
Of course, if one uses dB rather than talking of multiplicative gain factors then the process of combining the effects of multiple stages is indeed additive, since the dB scale involves taking logarithms. In fact, the paragraph above would make much more sense if one assumed that the writer had intended those numbers to be dB of gain, rather than percentages. An overall gain of 17dB is something worth talking about, whereas the writer's three-stage amplifier achieving a grand total of about 1.4dB of gain is not!
Having said all this, when Tubewrangler uses the term "gain structure" it appears that the word "structure" is superfluous. Since he quotes just a single figure (or range of figures, like 18-20 dB), he appears to mean simply the overall voltage gain of the amplifier. It seems to me the word "structure" would be better omitted in what he is saying.
Chris
Edits: 12/18/14
There's not many well designed amps out there. I keep looking at my stash of 2B6's and wondering how to use these to best advantage. Weird tube that looks like class B even single ended. It's not, but it looks like it. I'd like to have the knowledge to design an amp around these tubes.
I've got a hunch.
Quasimodo.
Have you read this?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Its really NOT about the place your volume control is set, but rather, how the amp plays music overall, its presentation, vivaciousness, at the normal levels you will use.I think it would be rude and crude to come in with amended schematics. Paul Joppa is a highly competent designer and a perfect gentleman. ALL I did was point out to you, two design areas that "I" deemed to be flawed. Lets please leave it at that.
Jeff Medwin
Edits: 12/14/14 12/14/14 12/14/14
"I think it would be rude and crude to come in with amended schematics. "
I don't think it would in the least. I bet Paul wouldn't mind either.
" Paul Joppa is a highly competent designer and a perfect gentleman."
I agree completely. Would you want his blessing?
"ALL I did was point out to you, two design areas that "I" deemed to be flawed. Lets please leave it at that."
If you actually do want to leave it at that, but I don't think you will. Just think, the end result could be that everyone has to shut up while you crow. That's quite a prize. You have a little time to think about it.
Jamie
Big speakers and little amps blew my mind!
Hello,
You state
"If you actually do want to leave it at that, but I don't think you will. Just think, the end result could be that everyone has to shut up while you crow. That's quite a prize. You have a little time to think about it."
I really do not know what you mean, or what you are assuming above, or what to say in response.
I don't think ANY of your response ( above ) has much to do with the subject at hand. Are we playing psychological games here? Golly, how dumb of me, and all along, I thought this was the Tube DIY Forum. Oh well.
Jeff Medwin
Hi Jeff.
Over the years I have advocated your right to say what you believe but you need to take a bit of that attitude to heart as well. Not everyone wants your brand of audio joy and even more don't think it's a path they will ever follow. You may think that yours is the only way to DIY bliss but there are so many other ways to get to the destination that don't involve your reverence for personal mentors, audio gurus or other audio/metaphysical methods.
You really need to step back, look at how you are interacting with other inmates and take a deep breath. Pushing your opinions(and that's all they are) on others doesn't make for many converts or on-line friends.
I'm having a hard time lately doing the "I disagree with you, but I'll fight to defend your right to say it" thing, partly because I'm from Canada, where we don't have that in our history and partly because I think you're full of crap.
You sort it out.
Kyle,
I like Canadians generally. YOU may think I am full of crap, which is unfortunate for you, but I don't think that at all.
The things I post about, I have pretty much tried in almost all cases, and I am fairly accurate in what I report. My opinions come from a direct result of me either building the circuit, or, hearing it DIRECTLY in a high quality hi fi systems, which 100% of my detractors seemingly have not done at all !!!
So I have the direct experience, sometimes decades worth, that they don't have.
People who have built stuff with my assistance, are generally speaking very happy campers. There has not been a lot of them that are willing to pay to do it properly, but thats OK with me. Its a hobby for me, not any business.
I agree, interactions have been messy lately. I will remain little changed and consistent. I am not running a popularity contest, its a Forum where we can express our audio ideas.
I will not cow tow to the lowest common denominator. Thanks for your previous support in the past, it was helpful, appreciated.
Jeff Medwin
Hi Jeff.
I'll continue to support you in the same manner I have in the past. It doesn't matter whether I agree. I was thinking of good marketing practices where you don't make the potential buyer feel like a moron or a rube.
I'm not sure which KC you're from but I do know from my limited experience that the folks don't approach things in the same manner. The east version seems more receptive to vague and undefined concepts.
I hope your quest to convert the unwashed in low ohms spirituality goes well.
Hi Kyle,
What am I marketing ?? NOTHING , NADA, ZERO. I am an audio amateur. An enthusiast, like many.
As far as KC is concerned, I have only lived here since 1984 when I bought my seat on the Kansas City Board of Trade. Prior to that, I grew up in New Jersey / Pennsylvania, and spent my after-college years as a stock broker in Beverly Hills, CA. Fun days, often wild.
By the way, Kansas City MAY have presently lay claim to the very best symphony hall in the world - so I have discovered in the past ten days, after attending a concert. Helzberg Hall. It seats 1,600 people, is OVAL shaped, has no prosenium arch, and uses WOOD heavily on the floors, walls. The oval hall is horn-loaded, several stories high from the rear, clamshell like.
Heard four soloists and a 250 piece choir and NOT A SINGLE MIC was used ...all natural, 1,600 in the audience. The Architect was Safdie Associates, Moshe Safdie, originally from Israel, now a CANADIAN, and there is a famous Japanese acoustical firm he worked with.
Experience gained by the Japanese doing L.A's Walt Disney Hall, were applied and IMPROVED upon in Kansas City with Safdie running the build. Its was a $419 million dollar project. Most striking to me, my mentor Mr. Fulton precisely described this hall to me in detail, thirty years ago, as he HATED most concert halls being built back then. Wish he was here to see and hear this masterpiece.
Jeff Medwin
Jeff, relax. Just because you're paranoid doesn't mean that everyone is out to get you.I didn't say you were marketing anything. I was just pointing out a marketing practice that if you want to get an idea across, you shouldn't make the person feel small or less than they should. You should acknowledge their ideas as good with room to expand.
This concept works much better with new converts than belittling ever does.
Got you. Makes sense, now to consciously apply !!!
Jeff Medwin
No, I'm serious, and we will leave everything at that.
Jamie
Big speakers and little amps blew my mind!
In many cases 12:00 on your volume control is pretty good place to be.
"In many cases 12:00 on your volume control is pretty good place to be. "
Yes. Kevin Hayes of VAC and I had a nice long conversation at a show. He said the same thing.
I have to get these low gain amps into a active setup before I can say anything about them really. The low gain high gain thing continues.
Big speakers and little amps blew my mind!
lol I wish he didn't ask you.
I assume Mr. Steady realizes you are being silly most of the time with these ridiculous claims.
Forget the grain of salt, pass the shaker.
How come you aren't pushing the use of black wire anymore?
While I like a good laugh as much as the next guy, your hyperbole comes off as being disrespectful.
New people or folks with English as a second language may actually think your bullshit is real, but then I'm sure you knew that.
I hope all this shilling for the Tube Mangler is profitable for you.
Carry on.
lol I wish he didn't ask you.
Sometimes, the truth is hard to take, you certainly didn't take it well, with the nasty back-handed tone of this letter. But, there is NO getting around the two points I made to Mr. Steady.
I assume Mr. Steady realizes you are being silly most of the time with these ridiculous claims.
You mean claims like " an inch of bad wire "....no I am not being silly, I am straight-up 99 percent of the time. YOU may not be up to snuff to appreciate and understand it, thats OK, you have time to learn.
Forget the grain of salt, pass the shaker.
How come you aren't pushing the use of black wire anymore?
Its true, that was a bit hard to take, but not using black is NOT "my" original idea, talk to the originators and followers of said practice. Also, if you LOOK in my amp photo, I used black leads off the 2A3 Ef XFRs.
While I like a good laugh as much as the next guy, your hyperbole comes off as being disrespectful.
There is much to disrespect in this world, many things wrong, one of which way be the way you wanna interpret me.
New people or folks with English as a second language may actually think your bullshit is real, but then I'm sure you knew that.
I don't put out any baloney, and since this is a public forum, we need to put some soap in your mouth.
I hope all this shilling for the Tube Mangler is profitable for you.
This is the most uninformed backhanded claim of all. Explain how it could be "profitable" to me? Do you ( and GEO, or others ) THINK I work for Serious Stereo, since I have an "M" designation ??? If so, you are sadly out of touch. I am not his employee, and have never ever been.
My "M" status involves a custom magnetics design service I very ocassionally do as a result of my hobby, whenever myself or a DIY friend needs a special magnetic piece designed. None of my magnetics work has ever been employed in products made by my friend, Dennis. He does his own.
You know, when you first needed audio help up here, you asked very nicely and people, myself included as you know, responded with a good attitude and in nice ways. Now, it seems you want to discredit and attack me. I do not think that is proper on your part. Maybe you need to think about that some, correct yourself, and do the right things henceforth. JEFF
Carry on.
Edits: 12/14/14
Holey smokes,
Are you not the person in Canada with an EE ish background, who was running less efficient Tannoys, and went to Klipsch La Scalas.?? NO, you are not. Come to think of it, you are not that nice guy at all.
That was Maxhifi or something close to that Moniker. My mistake, I had you confused with Max.
In that case, I am so HAPPY to see you building precisely what you are, and not so happy with how you incorrectly perceive things.
Jeff Medwin
You are bringing someone else's name into it, and I hate to think of what would happen in cowboy-land when that occurs. I know what would happen down here.
Please edit your post.
Jamie
Big speakers and little amps blew my mind!
Your moniker of Mr. Steady doesn't seem too appropriate when considered in the light of the posts you've made regarding retribution and consequences for disagreeing with you. ie "cowboys" or "down here" posts.
Regardless of the tone or content of the post you oppose, you shouldn't feel that Florida's "Stand Your Ground" laws apply on line. This is a free thinking and speaking place, approved by the American Constitution and it's amendments. Please treat it and it's posters as such.
Kyle,
JM brought somebody's name into an argument that the named person was not a part of. Where I'm from that's not cool.
And I say it now. It's not cool. I think he should edit his post to remove that persons name.
You may or may have not noticed that Garg0yle deleted one of his posts. I did not ask him to. I think he did it because he thought better of it. I'm sorry JM didn't think better of his.
How do you like GEO's fly covered penis-turd?
Jamie
Big speakers and little amps blew my mind!
If your penis looks like that picture it may be a hindrance to getting a date. It could explain a lot.
Regardless of where you're from, it doesn't matter if you think it's "cool". The idea is that you have a constitution that guarantees a persons right to free speech. If you're not comfortable with that, perhaps you should move to a country where only ideas that are approved can be expressed, maybe North Korea would suit you.
Here, in the free world, we like to think out loud and we want to be able to express those thoughts without fear of retribution from some narrow minded red neck that has another opinion. If you don't like living in the land of the free move to the land of oppression and forced conformity. It might suit you better.
Jeff,
Now things have degenerated down to their usual level. On any thread that I begin I would appreciate it if you and everyone else to use a little decorum. Please.
I approve of how you start your lightning rod threads where you can get your dose. Please continue to take that route. You can feel free to edit or delete your most recent post, and I will delete this one.
Thanks,
Jamie
Big speakers and little amps blew my mind!
"Arguing with a fool proves there are two"
(It does have several meanings)
MS, Jeff gets my goat on a regular basis but why should he change to suit you? He's entitled to say what ever he wants as long as it's not libel or slander.
Just because it's not what you want to hear doesn't mean that you're the forum moderator and neither am I, nor is Jeff. Live with it or cash out.
Thank you Kyle for teaching me about free speech. I didn't know any of that.
Thank goodness freedom of speech and civility and common courtesy are not mutually exclusive. But I see you want to be like the above picture, so I guess that means you can talk about my penis and how much I get laid, which btw is probably a lot more than you, and it's good.
You have the right to be a prick, but should you? Is this place your vent for not being able to say shit to people's faces?
Big speakers and little amps blew my mind!
Well, it seems you know little of free speech or civility so I'm glad to oblige. As for common courtesy, you give the impression that it's a foreign language to you so maybe a brief refresher course could be in order. I'm sure that even in your neck of the backwoods there's a finishing school that could take a recidivist and turn him into a regular citizen.
You crack off about how others don't express themselves in a manner that you approve of - Who cares what you approve of? They can say and think what they like and even if they do, you're not entitled to shoot them. Even in Florida.
I'm not entitled to bitch slap anybody either, but somebody has to see me do it for me to get in trouble for it.
The difference between me and you is; I speak to people on this forum like I would speak to them face to face. That may be out of place here.
You on the other hand speak to people on this forum in a way you would not speak to them face to face. That makes you a pussy, and a bitch.
Big speakers and little amps blew my mind!
On the contrary my little sweety. I'd talk to you or anyone in the same manner I do on-line and I do on a regular basis.
I certainly wouldn't spend as much time in person because I've got a life and my small amount of on-line time is better used in having these types of conversations. It seems that I can think about something completely different, but more important, and still devote the required amount of mental time to properly express my opinions to you. It's not a big deal, anyone could do it.
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