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In Reply to: RE: Looking for simple fully balanced 6BQ5 schematic posted by rage on January 19, 2022 at 09:08:53
is to start with an amp that is fairly linear to begin with. What this means in a nutshell is that amp should be good enough that the only reason to use feedback is to reduce gain.
Otherwise you'll get into trouble with the feedback causing the amp to be brighter and harsher.
Follow Ups:
Most Negative FBK schemes impose a time-delayed signal
onto and mixed-in with the input signal that is going thru
the amplifier.What this means in sonic terms is what you hear--
the mixing-in with and the "mushing" (for want of a
better word) of your music being dumped into a blender
of sorts. You get a MESS-- sonically. Whether this is
harsher, brighter, or less defined and coherent, and maybe
milder and less offensive, but not at all the real music,
can depend on where and how it is applied.While I have built several kinds of SE amps, and love
them, most of my earlier days experience was with push-pulls.Since I operated, and serviced many a movie theatre,
I soon learned to trash the existing amps, and replace
them with Hi-Fi gear. These were nearly all of the brands
and types that people on this forum play with to this day.They all had loop-Negative FBK. I have never found any
P/P Neg-FBK amp that wasn't drastically improved by simple
unhooking the FBK loop. NOT ONE SINGLE CASE--EVER.Feedback schemes can correct for some things in a music
system-- I admit. What FBK schemes cannot do is playback
music or events in a convincing manner.-Dennis-
Edits: 01/22/22
Most Negative FBK schemes impose a time-delayed signal
onto and mixed-in with the input signal that is going thru
the amplifier.
This statement is false and I know it well since I used to think the same thing and it died a hard painful death.
What's really happening is there is phase shift in the amplifier since all amplifiers are a form of filter and therefore obey filter theory. They also obey control theory which is something not understood very well by audio people but is very well understood elsewhere in the industry!
Put another way, if it looks on the 'scope like the output is delayed compared to the input, that's the result of phase shift. You are correct that this messes with the amp if the shifted signal is fed back into the amp.
But that in many ways is the tip of the iceberg. In a very related fashion, if there is phase shift present anywhere near the audio band, the simple fact is that the circuit simply does not have the gain bandwidth product to support the feedback. And since feedback causes bifurcation of the incoming audio, it generates higher ordered harmonic and inharmonic (intermodulation) distortions, which the ear perceives as 'harsh and bright'.
To get away from that, you need in excess of 35dB so the circuit can clean up its mess. The problem is with most tube circuits this sort of thing simply isn't possible. The old Futterman OTL was supposed to have 60dB which it does at 100Hz, but its feedback is considerably lower at 10KHz!
Consequently, if you are going to use feedback in a tube amp, the best way you can be effective with it is to use it to reduce excess gain and nothing else.
These days most loudspeakers are 'voltage driven' meaning that the amp has to behave as a voltage source to drive the speaker correctly. So there are a lot of tube designs that have feedback that is there for that purpose. But in those cases and a lot of solid state amps that really isn't the way to do it since the application of the feedback will be audible as increased brightness.
This should be set in stone.
Filter theory clearly states:
- Phase response is not delay.
- Group delay is proportional to the phase response derivative w.r.t. frequency of phase response.
- Phase response is the Hilbert transform of the amplitude response.
Most people do not know, even most audio designers, I would say ALL audio designers based on what I read here...
The only way to avoid this and to decouple amplitude response and group delay is going digital with non 'minimum phase' filter networks but that is another story.
Omnes feriunt, ultima necat.
Good analysis. However, one only needs
to get played-back music to behave like
the original venue/recording, and he
has, whether he knows it or not-- satisfied
your statement.
-Dennis-
-
"Phase response is the Hilbert transform of amplitude response" has consequences.
As negative feedback flattens and widens amplitude frequency response by reducing gain it improves in band phase linearity (id est group delay flatness).
But nobody cares...
Omnes feriunt, ultima necat.
Good post. Thanks!I realize that if everything else in an amp is designed
to be able to support a FBK scheme, then the total result can
be both clean and coherent.McIntosh designed the MI-200 Industrial gold mining shaker-table
amp. (For shaking out gold dust in mining operations by driving
a shaker table with a transducer, driven by the MI-200, that
driven by an audio signal generator.The amp, which was rated at 200W continuous, but could easily
put out 450 watts, sported a P/P pair of 8005 directly-heated
triodes. The B+ supply was 1000 volts, the rectifiers were 4 5U4GB
in a full-wave bridge. There was another power supply, using (2)
5Y3's in a full-wave Center-Tap arrangement. Each monoblock had 4
separate chassis. One was a meter panel.The output triode pair was driven by a stage similar to (2) Kt-88s.
That was driven by the usual "MAC" lineup, using things like 12BH7,
12AU7, 12AX7, etc. I usually removed one of these stages.If modded right this was a great high-fidelity amp. It had 4
different input windings on the primary side of the output
transformer, each connected to a various amplifier stage.This amp is mentioned because negative feedbacks generated were
brought back into phase/and time alignment by building the output
transformer primary with different time-delays and phase
relationships designed to compensate for, and make coherent--
signals that were time delayed from one stage's FBK compared
to the timing of another stage. All was summed-up in the output
trans with its time/phase-compensated windings.This accomplishes what you are talking about-- making a FBK
scheme actually work musically.This amplifier, once cleaned up and prepped, sounds EXACTLY like
one of my triode SE amps. EXACTLY. These old MAC's were built
BEFORE all the "MAC" tube gear that people collect, and are vastly
superior to all of them. This could be called
"multi-stage unity coupling"-- if you please.This is what it takes to make a P/P Neg. FBK amp actually work
musically. And it was designed for Mining Gold.So, I agree with you. But we don't need any of that today.
Just run a tube where it operates at the right temperature,
uses no feedback, and just listen to it.If the power supply, the build and the parts are good enough,
it's not going to have any competition musically.-Dennis-
Edits: 01/24/22 01/24/22 01/24/22
So, I agree with you. But we don't need any of that today.
Just run a tube where it operates at the right temperature,
uses no feedback, and just listen to it.
If the power supply, the build and the parts are good enough,
it's not going to have any competition musically.
I've had a few SETs; 300b, 2A3 and finally 45. I built up a 45-based PP amp to compare to the SET and it seemed better in every way. That one had no feedback.
The second project was to make a pentode based PP amp the same power as the 2A3 amp. That one was also UL but owing to the ease of driving the tubes only needed a 12AT7 wired as a differential amp (with CCS). Even with that there was too much gain as an integrated amp (not just a power amp) so I ran some feedback to reduce the gain. I've yet to hear an SET that can keep up with it. There seems to be something said for lower powered amps in general. But much depends on execution; in the case of that latter amp I wanted something that was also compact but built to a higher standard of parts and material quality.
Makes sense, Ralph. One thing I have
neglected to mention is output transformer
windings.A lot is said and done about proper output
transformer ratios-- what load a tube, operating
under a given set of conditions "wants to see".This is done to minimize THD and IM distortions,
theoretically.Things that never seem to get mentioned are of
far more importance: Power supply speed and impedance,
the size wire that is used on the output transformer
primary. This is a huge factor when it comes to
getting dynamic details delivered on-time.The impedance on the primary is expected to reflect
a certain value to the tube(s) driving it, but nobody
even mentions the EFFICIENCY of the transformer wire
that is used.
(Fine wire with many turns is a good way to lose energy
transients).I think most of us would agree that a 1200 ohm
primary in one transformer, and a 2500 ohm primary
in a similar model, where only the primary is different--
how many of us understand that all else being equal, the
1200 ohm model will outperform the 2500 ohm model.
That is-- with all else equal.Vacuum tubes are great conductors when they're built
right, and when they're at the correct operating
temperature. Most of us assume that we can place
most anything the tube can handle on the grid, and
the tube will respond efficiently. What the same
argument doesn't state is that the other elements
in that tube are also very forgiving, and will
faithfully reproduce music if not abused in some way.This allows the builder of high fidelity systems a
great deal of space/freedom in which to design-- as
opposed to someone who is asked to produce a given
amount of power, a given frequency response, and a
given set of distortion numbers.Designers of vacuum tube systems designed to drive
high-efficiency, primarily voltage-driven transducers
don't have to obey all those rules. Instead, their
objective should be to get maximum reliability and
maximum sense of reality when listening to the effort.Ralph, you're great as always-- I enjoy your posts and
also enjoy building things that deliver performance in
ways that are a requirement of years of audio experience,
and not a setup destined to satisfy only certain tastes
or certain kinds of music.A good amp should deliver it all, keep individual acoustic
lines that are all playing at once-- both as single spaces
occurring in time-- and at the same time-- a coherent part
of a whole performance-- all of it coherent as a whole--
but with all of its parts reproduced equally well, and equally
in their own individual spaces-- detailed perfectly, regardless
of what else is being played in the overall performance.Then, there are dynamics. Nearly all amps compress
something. I'm not talking about running out of power
here-- I'm talking about the amp running out of time-
spaces, where individual events occurring in an entire,
ongoing performance get added into each other and some
left out-- because the amp can't accommodate all of those
individual time capsules at once, reproduce all of them
at once as a whole, yet keep EACH one separately
identifiable in the mix-- an individual time space for
every kind of dynamic.Usually large, high-power amps with separate power
supplies for various stages (like the 1950's "MAC"
MI-200 monoblock) can get a lot of this right, which
is why I once found a stash of them in an old movie-
theatre (Theatre-Chain owner)-- their retired equipment
area. They were using a 200 plus watt Hard-Rock Gold-Mine
shaker-table transducer amplifier to drive 3 watt Altec
speakers.I bought them all-- 19 of them. Why were they doing this?
Was it power, headroom, frequency response, linearity,
or was it something else? Sure enough, it was the only
amp that "MAC" ever built that could make the timing events
in music play back like it had been recorded.Of course, the amps had to have some help for me to like them.
Better caps, better wiring, better phase-inverter, one less stage,
provision for balanced input if wanted, etc, without compromise
(without using capacitors or an input transformer)-- Definitely items
I don't like.It wasn't power. It wasn't linearity or frequency response.
It wasn't THD, and it wasn't IM ratings.It was the ability to separate musical dynamics, yet play
all of them at once as a coherent whole.Later, I learned that I could build a totally reliable
amp that would do the same thing even better- only a watt or
two, and no vacuum-tube maintenance needed. The humble SE
with a very careful build. Why? Because it's not Push/Pull.It has only one active device per stage. This means that
the other of the circuit can't fill-in errors of omission!
The thing has to really work-- like Gangbusters!-Dennis-
Edits: 01/24/22
With PROPER speakers, you could make a case. I can't imagine any problems with using some high sensitivity speakers....Maybe something from the Klipsh Heritage line?I doubt any single digit amp could make my panels work well enough for a normal space.......
but I'm certainly willing to LISTEN. Me? Since It's been DECADES since the family Zenith which was the LAST tubes for me? I'd like to start with something with enough power for a familiar speaker....
Maybe one of the VTA amps. They start with a PP EL34 updat of the dynamo ST70, up the ante with ST120 using KT88 or even KT120 while the M125 uses QUADS of the same @125 per mono......
the last SHOULD work well with my Panels and let me warm up the soldering iron for a couple days...
Too much is never enough
Edits: 01/24/22
DF, you are trying to communicate with people who are not on the "RMAF level" or really know how to compete against other "world class" audio products manufacturers like yourself.
You have tried to help them time and time again.
The light bulb never goes on and probably never will.
DT667
excellent trolling here DT.
non linear biasing...lol
Gotta understand, Dude! One has to think it through
first:It's a Direct-Coupled amp because that's the best sound
that money can buy. That means some considerations:
(A) Main B+ power supply must supply
higher voltage in order to get proper cathode
and grid voltages on the output tube, and to
deliver proper operating voltages for the driver stage.(B) The higher the main B+ is, the more output tube
plate current you can run because your driver plate
can run higher, and this is also the output tube grid.
Higher grid voltage here means more output tube plate current.The best sounding bypass capacitors-- which include
the excellent Dynamicaps, have voltage ratings of
somewhere near 410 volts D.C. Would you like those running
at-- say-- 500-to-550 volts? No? How about a higher voltage
bypass capacitor that sounds like !#@$@$# compared to
Dynamicaps or Mundorf Silver-Oils? Afraid not.......How about rectifiers? 5U4GB's even with choke-input much
prefer Power supply voltages that are under 475 VDC. Want
a higher-voltage rectifier than the 5U4GB? Hint: in order
to sound GREAT, Directly-Heated is far superior. Solid-State?
OK-- step-down a notch on music quality. Not for me.I could go on and on, but one can see that a Direct-Coupled
2-stage amp will TELL YOU what the output tube plate current
WILL BE.It is, however, no problem whatsoever. In fact, the resulting
sound quality is quite superior.This doesn't mean that I run plate currents that are too low
to get great sound. Reliability and sound quality must go together.D.C. amps really design themselves. They will TELL YOU what
output tube plate current you will run for a given combination.Fortunately, we have happy marriages of driver tube,
and output tube that offer stellar performance when connected
directly to each other.These combinations are Lucky Finds that we search for-- and
so far, have been able to find!One does have to consider what vacuum tubes are available,
are built right, and are excellent sounding also.-Dennis-
Edits: 01/24/22 01/24/22
"creative use of harmonic distortion to create "realism" in high fidelity audio reproduction."
If that is what Dennis is trying to do then I would agree with you.
Using HD to create a sound that Dennis likes is not anything I'm interested in and never will be.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
The RMAF trade show era is over.
None of DF's critics will have the opportunity to compete with him and ultimately fail.
DT667
Please tell me what you think Dennis' amps will do better than my amps?
Make a happy happy noise that Dennis and a few other people like even though the technical performance is measurably much poorer?
Yeah, that's what I thought.
Go away, pretender.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
"Make a happy happy noise that Dennis and a few other people like even though the technical performance is measurably much poorer?"
The net results are about "realism" in audio that is "perceived" by the listener's ear.
The ears that belong to legendary audiophiles like Herb Reichert.
Those are the guys that know "greatness" when they listen to the SS product line and declare it superior to all in its niche.
DT667
and what you don't seem willing to grasp is that their niche is that of effects boxes, and there are lots more people who want The Real Thing instead of HD-modified dreck.
It would not matter at all if less people preferred The Real Thing; effects boxes like ss/denise builds are second rate UNLESS that is what you want. In that case, it is easy to agree with you that denise builds the best of 'em.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
"and what you don't seem willing to grasp is that their niche is that of effects boxes, and there are lots more people who want The Real Thing instead of HD-modified dreck."
It would not matter at all if less people preferred The Real Thing; effects boxes like ss/denise builds are second rate UNLESS that is what you want. In that case, it is easy to agree with you that denise builds the best of 'em.
cheers,
Douglas
Pak's comments demonstrate a complete lack understanding to the "concepts" DF and the other MLP "master builders" have so generously gifted AA Tube DIY over the last decade plus.
There is no hope for you, Pak.
You have been consigned to a life of "low to mid-fi" outcomes at best.
DT667
"fi" means fidelity. Douglas' point was that Dennis' amps don't do fidelity, they do "fun, fun happy sound" that is not true to the input signal.You can't call that fidelity. It might be very fun to listen to but it's not Hi-Fi. Hi-Fi means a high degree of fidelity to the input signal and Dennis' amps don't do that. They can't do that for obvious reasons.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 01/26/22
"fi" means fidelity. Douglas' point was that Dennis' amps don't do fidelity, they do "fun, fun happy sound" that is not true to the input signal.
You can't call that fidelity. It might be very fun to listen to but it's not Hi-Fi. Hi-Fi means a high degree of fidelity to the input signal and Dennis' amps don't do that. They can't do that for obvious reasons."
Only an "elite" few in our hobby will EVER match the accomplishments of DF and his SS brand. It is for the individual who wants to be at the forefront of this hobby - an "alpha audiophile" or person who gravitates toward "best in class" products.
A "Tube DIY" audio forum filled with "budget builders" will never be able to the fathom the "Tao of Fraker" or Gestalt of JDM", that level of understanding will not happen here.
DT667
You are living in a dream world. What you say about DF and JDM is what they want you to believe but it is not true.
If you want someone you can hold up as "enlightened" about tube audio you should study Lynn Olson, Gary Pimm and Gary Dahl. Those guys are cutting edge.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
"You are living in a dream world."
DF/JDM and the MLP are living the dream.
They have "inspired a shared vision" and galvanized a new generation of SE tube amp builders from all parts of the globe.
From cutting edge design and construction "concepts" never before seen or heard in SE tube audio per JDM, to dominating listening rooms in the trade show era and beyond, these men are the true innovators in the hobby.
Why critics waste so much energy trying to tear down "icons" of our great hobby is not understandable but more than likely a product of long-term mental health issues currently unresolved.
DT667
"They have "inspired a shared vision" and galvanized a new generation of SE tube amp builders from all parts of the globe"
That is not true. Most people have never even heard of them.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
"That is not true. Most people have never even heard of them."
You are already aware of JDM's new groundbreaking SE 6005 project.
There are several individuals from AA Tube DIY who have posted trolling comments on that website in an attempt to undermine JDM's efforts but have ultimately failed to do so.
The great minds of the MLP will rise to the top of the SE tube amp world and nothing can stop them or their devoted followers.
DT667
"new groundbreaking"
He's been banned.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
followers are not alpha's. They are followers...and we have seen all too clearly that it is remarkably easy to lead people around by the nose by repeating things often enough and loudly enough.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
followers are not alpha's. They are followers...and we have seen all too clearly that it is remarkably easy to lead people around by the nose by repeating things often enough and loudly enough.
JDM is the "alpha" leading a group of builders under his command.
He is working tirelessly to expand the boundaries of what is possible with SE tube amplifiers.
People who understand "LOW DCR SE tube amplifiers" will be playing attention.
Others, the haters and audio forum trolls, will be left behind.
The choice is yours: a brave new world or status quo.
DT667
"JDM is the "alpha" leading a group of builders under his command."
He's been banned.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
To fall on the sword of conviction is a noble end.Loyal to his mentors and the cause.
May he rest knowing the effort was appreciated.
DT667
Edits: 01/28/22
1/2 of what you write is purposely trolling. You like the needling. Not sure why people engage you as much as they do. You are like bad teeth...-...- if ignored long enough, they are sure to go away.
"1/2 of what you write is purposely trolling. You like the needling. Not sure why people engage you as much as they do. You are like bad teeth...-...- if ignored long enough, they are sure to go away."
DT667 started a thread about AES PT-31 OPT's, not one mention of DF/SS/MLP in the initial post.
GEO seems to want to discuss some of DF's former customers selling their SS products online.
Others contribute pointless off topic comments as well.
Looks like the pot is calling the kettle black in this case.
DT667
This is not that thread. Just saying.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Just pointing out paying customers moving on and taking a bath while doing so, unless Dennis sells them out the back door? Was SS direct to consumer or did Dennis have a dealer network?
Edits: 01/29/22
Serious Stereo has no dealer network.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Thanks.
"Just pointing out paying customers moving on and taking a bath while doing so, unless Dennis sells them out the back door? Was SS direct to consumer or did Dennis have a dealer network?"
You will need to ask DF those questions about SS sales or business practices.
We can see tube amps of various quality for sale at any given time online.
And for a wide variety of reasons.
Nothing unusual about it.
To your earlier point, DT667 does "needle" other forum participants for various reasons. But so do you and many others on AA forums.
The hobby is supposed to be a fun escape from reality and not to be taken too seriously.
If you feel stressed by what you are reading, then don't open the posts or take a break from internet forums and chill out.
DT667
Now that you bring it up, nobody who owns an amp that really is as good as you claim ever sells 'em. I am sorry that we had to point out the flaw in your claims. Have a good day Sir!
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Tell you what, as soon as I see him write something that makes sense, and gives the detailed instructions to build one of his creations, I'll build one to print.If I like it, I will never do anything but encourage others. If I don't, you shall cease posting.
so then, mr. omega... :)
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Edits: 01/27/22
"Tell you what, as soon as I see him write something that makes sense, and gives the detailed instructions to build one of his creations, I'll build one to print."
"If I like it, I will never do anything but encourage others. If I don't, you shall cease posting."
so then, mr. omega... :)
Pak, you would need to connect with JDM before moving forward, if you are sincere about building a SE tube amp under his direction.
There are a lot of custom magnetics used in his new SE 6005 project and that might not be available to you.
Good luck moving ahead, sir.
DT667
Hi! Jeff likes the 6005 tube as I do.A 6005 amp isn't practical to sell to
anyone, a good one costs as much to build
as any other SE, but can't power most things.Jeff is different-- he just wants to build
things that I highlight in our discussions.It's been about 4 years since I got him
converted to Altec A7-- 500, or 800 8's.This old movie theatre speaker is a rare
combo of great transducers, and a bass bin
that isn't bass reflex, nor is it MLTL, or
anything else. It's for a movie theatre.Clarity is everything in a movie house.
Bass response, while accentuated by today's
"engineers", is really a cult throwback to
the car-audio of a few years ago, and the sick
druggies who drive them. In that world, bass
response is designed to induce bowel movements, and
nothing else of value.Movie theatres had to have a system where the
viewer got caught up in the action and forgot all
about audio and video. The speaker(s) was designed
to do just that, so a combo of PART bass reflex and PART
free-air woofer-loading was devised by Jim Lansing
for MGM-- MGM hated Western Electric gear with a
vengeance. Jim was hired to get the W.E. JUNK out of
all of their movie theatres. ALTEC was born.Jeff, reluctantly, finally got into Altec speakers
after almost 12 years of me trying to get him to do it.
He was hung-up on Robert Fulton.Of course, you hear clean, clear detail with Altec
speakers. I began designing amps for Jeff, and he
took those ideas to the forums.The 6005 tube, while excellent, is no match for larger
tubes such as the 2A3, but due to closer element-spacing,
it is a thrill to listen to-- it easily does everything
in music.
I have to beat Jeff over the head all the time to get him
to use vacuum tubes which DO NOT have soldered-on pins,
all of which are anti-clean, with only "so-so" detailed
response.The 6005
is, of course, one of the GOOD tubes-- with direct pins
for the tube socket.I know how to build a (3) tube 6005 output stage, and
still keep it clean and coherent. This requires a
balancing act to keep all 3 tubes acting in the same
manner, when we know that no 2 tubes are ever alike--
not in any way, and not by any manufacturer.This means skewed output phases unless you know how
to do it. I talked Jeff into building one, and designed
it over the phone. As usual, Jeff went right to the forums
with it-- before it is even built. He thinks that if do it,
it has to work.Anyhow, it is designed to man-handle the A7-500-8 woofer.
All woofers like current-- the faster it is delivered, the
better. It took me a week to get anybody to understand
that a 3-banger output stage can be made to work sonically.The improvement in the Altec 15" woofer's response will be
huge from the 3 tubes, partly because the output transformer
can be lower impedance primary. The larger the wire size, and
the fewer turns we have, the better. Oh, I know TRE would
be enraged by this-- he knows that THD drops as primary
impedance goes up. He's right, but I don't give a damn--
what I want is fast, clean response. Numbers are just mental
exercise-- I use them, but only when they aren't allowed to
interfere with what I want-- accurate musical expression.So, the Triple 6005 amp is born--
just like MGM, you gotta use and drive properly the right
speaker.-Dennis-
Edits: 01/28/22 01/28/22
Sounds like an interesting project, DF.
Maybe you should be the one to mentor Pak on SE tube amp build?
That is if he is "serious" about building something.
DT667
Only serious about making a bet you'd lose. Proven how and what I build since before you recognized the need to become a fanboy.
Besides, I have never seen any of your bosses say anything good about PSE so why are you holding up that strawman?
Second, the wager requires a set of instructions and a BOM. You will never get that out of low moooo. Not one that won't be disowned when the results are not worth paperwork duty, let alone listening to.
So I dare you to get one... :) I've a Nickel that sez you can't.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Pak,
Until your demeanor improves significantly, the MLP guys will never consult with you on a tube amp project.
Your interest in current MLP projects became another vehicle to project hostility at others including DT667, which is unacceptable.
Is this how you want to move forward in 2022?
Try adopting a more positive attitude.
Good evening, sir.
DT667
LMAO...
let's see, perhaps a review of history.
Some idiot says, 'this is the way to build the best amp'.
An inmate or three applies the instructions, gets a predictably poor result, and gets blamed by The Idiot for not doing it properly.
Sooooo, I am happy to be proven wrong in this hobby. If your way is better, show me...not going to waste any time or $$$$ on something that does not come with good instructions. Or as has been historically proven time and again in this particular approach, instructions that deliberately leave out 'important' pieces.
That those bits are not really important, but are instead built-in, 'you didn't do it right, so of course it sucks; you're a crappy amp builder anyway'...I have zero interest in your game, or its effects-box amps... :)
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
At this moment, it will not be possible for you to create an exact copy of an MLP design team SE tube amplifier circuit for a variety of reasons.
Only a very trusted person within the "inner circle" of the MLP or its contacts can qualify for an internship with the group.
Are you ready to take the next step, Pak?
Are you ready for the MLP-level?
DT667
Looks like a step backwards to me. Several actually. What your magical, mystical, 'mlp' is about has been adequately documented as an effects box. it is obvious they've found their niche of folk who like that sort of thing.
So, I must decline your ever so magnanimous offer. Do let me know when you decide to examine a real amplifier design process...that could not care less about what colour of wire is used, or how many leads you solder onto a cheap choke.
Come on out to MI when it is safe to gather, and examine some real amps in the wild. bring yours to compare... :)
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
"Come on out to MI when it is safe to gather, and examine some real amps in the wild. bring yours to compare... :) "
I actually remember running my first DC 2a3 built under Jeff's guidance and comparing it to a modded Dynaco ST-70 at my place with a SMAC gathering.
I have to admit, the ST-70 was better. At least in the HF region.
I still build effects boxes - but getting out and comparing amps is a good exercise!
"I actually remember running my first DC 2a3 built under Jeff's guidance and comparing it to a modded Dynaco ST-70 at my place with a SMAC gathering."
Pak needs to make the trip to Livingston, MT and hear DF's SS gear in its most perfect setup and listening environment.
That would be the only way to understand what DF is doing.
Anything from another builder under the DF influence, likely has deviated from the original SE 7B4 DC 2A3 design and the end result will not be exactly the same.
DT667
I know that the trip will show me an effects box. You and he have both said it will. repeatedly.
As far as 6005 goes, there is one fine signal amplifier right there. Along with many other small power tubes you have never bothered to explore. 6V6GTA is another. 6CL6, 6DT5 for another. 1.2A of heater current for a tube the size of a 12AX7...effortless comes to mind.
So, happybear, you really need to get out more...really. I'll repeat the invite; would love to have you as an honoured visitor to listen to some amplifiers and speakers.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
"Anything from another builder under the DF influence, likely has deviated from the original SE 7B4 DC 2A3 design and the end result will not be exactly the "
troll on brother!
Even JDM, a man at the side of DF for over a decade at RMAF, failed to replicate the SS 2A3 circuit exactly and moved on to other finals like 45, KT88 and now 6005.
Only DF can build his SE 2A3 circuit correctly.
Any other living human would probably fail to get it right!
DT667
"Any other living human would probably fail to get it right!"
That all depends on your definition of "right".
The design has several obvious flaws. Getting each of the flaws just right to blend together to make the exact type of distortion as Dennis does might be tricky.
On the other hand, fix the driver stage flaw and the power supply flaw and it's not a bad sounding amp.
It's pretty hard to make a SET 2a3 amp sound bad but Dennis can do it.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Awwwww- Shucks, TRE!
Try these: (1) Watch "Ice Road Trucker" on the DEFY
television network.
(2) SolariReport.com.
(3) educate-yourself.org.
-Dennis-
I watch Ice Road Truckers but I'm not sure what that (or the other two links) has to do with audio amplifiers.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Those suggestions provided more proof to the claim you have told us how your amps actually perform.
Effects box, IOW. Thanks.
I hope you have read the completed study on why worm medicine looked promising at first, and might still have a use IFF indeed one has parasites already. IDK, do y'all in Montana run around with untreated parasites these days? Or are you going to ignore the WHY of it, and insist it is useful by itself just because something incomplete said it might be?
I am betting on the latter... :)
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
You neglect the first condition... :) SO far all the evidence I see indicated it is not something he can meet.
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
I don't disagree that NFB causes more problems than is solves but if you didn't triode connect the beam power tubes and the pentodes in the amps that you disconnected the fb then you missed the boat. Without voltage NFB the plate resistance of beam power tubes (and the pentodes) is way too high for the output transformer impedance. But then you never understood much about proper load impedance to start with. You're such a rookie.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I agree that usually-- higher impedance loading
of vacuum tubes delivers less measured distortions of
most kinds, and while I agree that this is true, I
experiment.
Not to try to prove anything, not to say that I might
be right or wrong.
There is, and has always been with me-- a better
objective, and that is to observe what the result
SOUNDS LIKE.
I always demand conservative operation of all parts.
That's a given. Loading is a variable that I play with
as I see fit. I like to see all the stages in an
amplifier run with minimal loading--high impedances.
BUT-- at the output stage, I prefer heavy loading.
The reason is PHYSICAL and is not according to the
dictates of calculation freaks.
This end-point loading could be described as all wrong--
the output tube delivers more distortions this way.
At this point, I have to inject some logic into this
discussion, and that is-- we don't know what levels
and kinds of distortions are relevant, and which ones
are mere mathematics. I said we don't know. Others
could very well say they DO know, and can easily supply
all kinds of easy to prove examples, according to
electrical laws that we all already know.
I don't break those when it comes to reliability.
I DO, however, do anything else I want if it improves musical
performance-- that is, relegates a recorded performance better.
The "overloading" of the output stage can be envisioned
as a Penstock, carrying water, driving a turbo-generator.
I have built several of these high-pressure Hydro-Electric
systems, which are running today.
Something I did to get the most out of those systems is
that the intake pipe diameter is the largest pipe size used.
As the water proceeds down the mountain, pipe diameter lessens
as pressure increases. At the water turbine, the water output
orifice is suddenly "necked-down" in diameter even further.
This sudden "overload" delivers more power to drive the
turbine, increasing system efficiency.
This is easy to do with an amplifier. Let's say you calculate
that your output transformer should be 2500 ohms, or more.
Try all of your values. Now, connect one that is 1200 ohms.
IF your power supply can handle the current demands, into an efficient
speaker, it will deliver far more realistic-sounding music, with
dynamics that you won't believe. Unwanted distortions won't
occur unless your power supply can't handle it. If it can,
measured distortions will be higher, but actual high-fidelity
listening will be far superior.
Too bad people don't understand this. Laugh all you want,
I have learned to expect it.
Oh, I also tune engines using the same principles. And
they sure do run!
-Dennis-
Well, I have tried some of what you claim to be The Way. Like deciding that a pentode linestage loaded with a 500 Ohm plate load worked well. A quick FFT showed why it was so dramatically different: loads of 2HD. Lots of folk went totally thumbs up over it. Those same folk got a wee bit less enthusiastic after a bit, and went 'holy smoke' when a clean, low output impedance one got plugged in.
You have developed the tone machine into an art denis, of that I have absolutely zero doubt. You are also quite good at selling them. neither of those things fall into a category I'd find valuable.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
DF and the MLP have mastered the "concepts" of transfer efficiency, non-critical inductance LSES L-input PS filters, non-linear biasing, ZERO feedback beam power finals and creative use of harmonic distortion to create "realism" in high fidelity audio reproduction.
These "concepts" are beyond the scope of an EE or bench tech versed in standard tube audio theory and practice.
If we are still alive a decade or two beyond 2022, we might begin to grasp the esoteric knowledge that DF and the MLP designers have presented here and on other audio forums.
But that is perhaps being too hopeful given the overall demeanor of participants on AA Tube DIY.
DT667
Denis has mastered a Marketing Spiel full of words that, in context mean NOTHING.
In several years, we will discover they mean nothing( actually, we already know they mean nothing ). That is not going to change...LOL
It is not that EE's don't 'get it', they know what it is, and want nothing to do with it, regarding it as pointless to build an effects box when faithful reproduction and True listening enjoyment is the goal.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
.
Have Fun and Enjoy the Music
"Still Working the Problem"
Ralph, I have to ask, why use NFB to reduce gain? WHy not just build in less?
Lower output Z, oh yes.
Linearize it, some, but definitely not so critical IME.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Ralph, I have to ask, why use NFB to reduce gain? WHy not just build in less?
Sometimes you can't. For example, in the case of the amplifier of this thread, to get the best performance out of a differential amplifier it is helpful for it to have more gain rather than less.
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