Bride of Son of Zen? big Familie ...
same as BZLS balanced Zen linstage
http://www.passdiy.com/legacy.htm
same as BZLS balanced Zen linstage
http://www.passdiy.com/legacy.htm
Hugh, I'm glad that you can see Charles' point. At very high levels, all class A amps are going to generate their worst distortion. Only extremely high feedback can suppress this. This is why I use global feedback. I have to meet THX specs. This is important for Parasound, and our dealers.
I personally think that zero global feedback is usually best, all else being equal. I noticed that the 'Stereophile' graphs use 20dB/division. This is because the fundamental is not nulled. I generally use 10db/division in my measurements. It changes the 'compression' of the graph. I also somewhat suspicious of the residual higher order distortion present in the test signal. Even the 'exceptions' in the higher order distortion could be cancellation of the residual distortion by the amp. I can't be sure.
I personally think that zero global feedback is usually best, all else being equal. I noticed that the 'Stereophile' graphs use 20dB/division. This is because the fundamental is not nulled. I generally use 10db/division in my measurements. It changes the 'compression' of the graph. I also somewhat suspicious of the residual higher order distortion present in the test signal. Even the 'exceptions' in the higher order distortion could be cancellation of the residual distortion by the amp. I can't be sure.
I think there are two camps here. There are the "3D soundstage, revealling every detail" people and there are the "does this thing play music" people. I think both are very hard to achieve; the latter is rarer in my experience. The former are typically correlated with low or no feedback and the latter with high feedback.
My goal is to achieve both simultaneously. When I hear a live performance it has both in spades. Still plenty for us to do.
Yep.
traderbam said:
Thanks for the post. I agree with you completely here. (Actually, I edited out the part I disagreed with!
) But your last point is very serious, in my opinion.And that's why I really appreciate new ways of thinking and new ideas. There are dozens of companies that just take the same old circuit and simply try to fine tune it a little bit, or use higher quality parts. But I don't think that's going to get us to where we need to go.
That's why I really enjoy new ideas and new ways of thinking. The Wingate amp in the other thread was refreshingly creative, especially considering that it was designed nearly 20 years old. Nelson Pass has consistently come up with new ideas, and so has John Curl. Sometimes the new ideas work well, and sometimes they get abandoned. But I think that coming up with new ideas is how we are going to make real progress in audio, and not by re-refining some ancient circuit to the Nth degree.
The same is true for me with loudspeakers (I used to design those for Avalon). If I read another review of a 6-1/2" two-way speaker with a 1" dome tweeter crossed over at 3 kHz, I think I'll cry. We must have no less than 17,000 designs like that now. Does the designer of the 17,001st of these speakers really think his is going to be significantly better than all of those that came before? Or will it take some new way of thinking to achieve a better result?
It has been my experience that the circuits that are most 'revealing' lack something in the imaging department. Conversely, the ones cursed for not being 'revealing' enough (e.g. tubes) often have spectacular imaging.
So just what the hell is imaging, anyway? My gut assumption would be that it's low level detail preserved in the recording. If so, you would think that the revealing circuits would indeed image better. As best I can tell, the revealing, "accurate," circuits have a build-up of higher order distortion products that add--what do you want to call it...sheen?--to things like fingers on guitar strings. Some people call this resolution. For my part, I've never played a guitar that sounds that way, nor have I heard anyone else play one that sounds like that. It seems to be an artifact of the recording/reproduction process.
So do tubes actually have better resolving power? Is that why they frequently image better than their solid state cousins?
Ugh. If anyone wants to argue that one, do it somewhere else.
But could the common conception of 'resolution' simply be residual nasties left behind by high feedback (irrespective of gain device)?
Grey
So just what the hell is imaging, anyway? My gut assumption would be that it's low level detail preserved in the recording. If so, you would think that the revealing circuits would indeed image better. As best I can tell, the revealing, "accurate," circuits have a build-up of higher order distortion products that add--what do you want to call it...sheen?--to things like fingers on guitar strings. Some people call this resolution. For my part, I've never played a guitar that sounds that way, nor have I heard anyone else play one that sounds like that. It seems to be an artifact of the recording/reproduction process.
So do tubes actually have better resolving power? Is that why they frequently image better than their solid state cousins?
Ugh. If anyone wants to argue that one, do it somewhere else.
But could the common conception of 'resolution' simply be residual nasties left behind by high feedback (irrespective of gain device)?
Grey
OK, here's my $0.02....
I think traderbam, Nelson, and Grey are *all* correct!
To me the distinction that traderbam was making was really more about the "sound" people versus the "music" people. For example, everything that Hugh described above was concerned (at least directly) with sound and not music. So perhaps traderbam's specific "sound" characteristics were not exactly correct, but the overall concept is valid.
I think Grey's observations are spot-on as far as the actual tradeoffs involved in the "sound" side of things and probably more in line with what Nelson was referring to.
I also enjoyed Grey's description of the truthfulness of the "resolution" that many products display. I find the same thing when it comes to the "liquidity" of tubes. I enjoy that sound quality and understand its appeal to people, but I have never heard any real sound (voices or instruments) in real life and thought to myself, "wow, that sounds liquid!" So ultimately I think that the "liquid" aspect of tubes is also a coloration (albeit a *very* pleasant one).
I think traderbam, Nelson, and Grey are *all* correct!
To me the distinction that traderbam was making was really more about the "sound" people versus the "music" people. For example, everything that Hugh described above was concerned (at least directly) with sound and not music. So perhaps traderbam's specific "sound" characteristics were not exactly correct, but the overall concept is valid.
I think Grey's observations are spot-on as far as the actual tradeoffs involved in the "sound" side of things and probably more in line with what Nelson was referring to.
I also enjoyed Grey's description of the truthfulness of the "resolution" that many products display. I find the same thing when it comes to the "liquidity" of tubes. I enjoy that sound quality and understand its appeal to people, but I have never heard any real sound (voices or instruments) in real life and thought to myself, "wow, that sounds liquid!" So ultimately I think that the "liquid" aspect of tubes is also a coloration (albeit a *very* pleasant one).
There's a term used in evolutionary biology: convergence.
The configuration is popular because it makes sense. Twenty years ago, before we started paying as much close attention to off-axis behavior, you could say the same thing, just substituting 8 or 12 inch for the woofer. But 17 cm is a good compromise diameter which can go reasonably low and not beam as much as its bigger forebears. So, it works in its two-way niche. To do better costs more- and you do see more diversity in more expensive designs.
Wups, did I just go off-topic? Sorry.
OK, I'll try to bring this back on track....
The question was raised "what's wrong with a 6-1/2" two-way with a 1" dome tweeter crossed over at 3 kHz?" If all you ever compare this to is other speaker that are similar in design, nothing at all. But if you ever compare it to Quad ESL-57s, or Altec A-7s, or one-way Lowthers, or Dahlquist DQ-10s (remember those?), or Apogee ribbons, or (gasp) live music, the shortcomings are pretty obvious....
Now of course, all of those other speakers have their own shortcomings. But the point is that we can't make any meaningful progress by making small adjustments to the formula of a 6-1/2" two-way with a 1" dome tweeter crossed over at 3 kHz. We need to think outside the box and try to understand what kinds of limitations are imposed by that formula, and what can we do to overcome them.
Going back to amplifiers, substitute:
"the Lin circuit" (as used in Douglas Self's books) for "6-1/2" two-way with a 1" dome tweeter crossed over at 3 kHz"
"push-pull ultralinear tubes" for "Quad ESL-57s"
"push-pull triodes" for "Altec A-7s"
"single-ended triodes" for "one-way Lowthers"
"fully complementary bipolar amps" for "Dahlquist DQ-10s"
"high current class-A solid state" for "Apogee ribbons"
and the same thing applies...
The question was raised "what's wrong with a 6-1/2" two-way with a 1" dome tweeter crossed over at 3 kHz?" If all you ever compare this to is other speaker that are similar in design, nothing at all. But if you ever compare it to Quad ESL-57s, or Altec A-7s, or one-way Lowthers, or Dahlquist DQ-10s (remember those?), or Apogee ribbons, or (gasp) live music, the shortcomings are pretty obvious....
Now of course, all of those other speakers have their own shortcomings. But the point is that we can't make any meaningful progress by making small adjustments to the formula of a 6-1/2" two-way with a 1" dome tweeter crossed over at 3 kHz. We need to think outside the box and try to understand what kinds of limitations are imposed by that formula, and what can we do to overcome them.
Going back to amplifiers, substitute:
"the Lin circuit" (as used in Douglas Self's books) for "6-1/2" two-way with a 1" dome tweeter crossed over at 3 kHz"
"push-pull ultralinear tubes" for "Quad ESL-57s"
"push-pull triodes" for "Altec A-7s"
"single-ended triodes" for "one-way Lowthers"
"fully complementary bipolar amps" for "Dahlquist DQ-10s"
"high current class-A solid state" for "Apogee ribbons"
and the same thing applies...
john curl said:
I am sorry, but I completely disagree. And I do not like generalizing like this. I would say that distortion is only a question of the circuit design. Poorly designed class A amps generate very high distortion at high levels, that is true. And poorly designed class AB or B amps generate cross-over residuals thet are audible regardless high feedback factor. But this is both about poor designs, not any general true.
- hopeless fight here 
.
threadjack
I've owned and loved two of the speakers on your list, and also designed, used, and loved a 6-1/2" two-way. Everything in engineering is tradeoffs, whether for cost, max SPL, bass extension, size, or whatever. My Quads were brilliant, but SPL and F3 were weak points. A-7s were dynamic and efficient, but expensive, HUGE, and highly colored. In those respects, a well-designed 6-1/2" two-way trounces both those classics.
Nothing is as good as live music; the Second Law of Thermodynamics is in the way.
/threadjack
Hmmm. Despite being wordy, I did not clearly say what I meant, as Charles has misunderstood.
Musicality is a given in all my designs. That's what I really go for. I spend hours listening to a variety of music genres, and my belief is that if it makes you cry, it's good audio. Get the others right, and there's a good chance you've jagged it.
Since Charles hasn't heard my amp (and likely never will because it's quite conventional!) and I haven't heard his, and indeed, like everyone else here none of us have ever met, then our comments seem to have the impact of a forearm in a bucket of water. (Unless it's an insult, of course, then everyone wants to know!) I guess this brings home that audio design, like most technology and art, is often practised individually.
Each day I walk through a gambling joint to get a good cup of coffee. I look at all the hapless individuals at the machines, and privately thank them for subsidising my excellent cup of coffee in pleasant surroundings, with plenty of space and a small table so I can jot down my circuit designs as I savor each bean....
However, my addiction to this forum, and the coffee, is probably no less significant...
Cheers,
Hugh
Musicality is a given in all my designs. That's what I really go for. I spend hours listening to a variety of music genres, and my belief is that if it makes you cry, it's good audio. Get the others right, and there's a good chance you've jagged it.
Since Charles hasn't heard my amp (and likely never will because it's quite conventional!) and I haven't heard his, and indeed, like everyone else here none of us have ever met, then our comments seem to have the impact of a forearm in a bucket of water. (Unless it's an insult, of course, then everyone wants to know!) I guess this brings home that audio design, like most technology and art, is often practised individually.
Each day I walk through a gambling joint to get a good cup of coffee. I look at all the hapless individuals at the machines, and privately thank them for subsidising my excellent cup of coffee in pleasant surroundings, with plenty of space and a small table so I can jot down my circuit designs as I savor each bean....
However, my addiction to this forum, and the coffee, is probably no less significant...
Cheers,
Hugh
The question is: what do we want ?
A perfectly clean sounding amp that gives us a 1:1 image of what is on the CD.
Or the richness of harmonics etc. adding something that is more pleasant to our ears.
Same in photography:
If I use my digital camera it gives me a very realistic image, all colors as are, everything sharp everywhere.
To my eye it looks disgusting, sterile, hard...
With conventional film and a lens that has not been made for photograpy it looks much nicer.
Some softness is added, different colors, some loss of detail, but everything more smooth.
A perfectly clean sounding amp that gives us a 1:1 image of what is on the CD.
Or the richness of harmonics etc. adding something that is more pleasant to our ears.
Same in photography:
If I use my digital camera it gives me a very realistic image, all colors as are, everything sharp everywhere.
To my eye it looks disgusting, sterile, hard...
With conventional film and a lens that has not been made for photograpy it looks much nicer.
Some softness is added, different colors, some loss of detail, but everything more smooth.
Every once in a while I say something that someone agrees with and it lifts me to be told so.
That's fine too!
I'm not entirely up to date on the market but certainly in the UK the press has made a divide between brands like Naim and those like Krell, Musical Fidelity, Audio Research, Mark Levinson and so on. Naim is known to really "rock", be able to carry a rift, play a tune, maintain engagement in the dynamic/rhythmic content of the music. The others are better known for soundstage, 3D imaging, excruciating detail resolution, depth of field, lack of identifiable electronic "signature", and not least for mass, price and power consumption.
What I would really like to do is come up with an amp that combines both qualities. Just like live music does. I think I know how to do this.
I believe, without any hesitation, that the imaginary "wire with gain" would achieve this. I don't think there is any reason to introduce anything not in the source signal (as Hugh knows). The differences in commercial products are to do with how they tackle the non-linearities in the components, particularly the amplifying devices. The basic Naim approach is to use just a few transistors in the signal chain and apply as much feedback to fix the linearity as possible. The basic Krell approach is to make the components as linear as possible and use as little feedback as possible (when I last looked at a Krell schematic that is - could be out of date here), and this leads to high bias currents, using arrays of output devices, using fully complementary designs and so on. I think Pass Labs follows this approach too.
Neither of these approaches is optimum. Naims don't do the clarity, 3D thing as well as others. Krells don't do the top-tapping, rhythmic engagement as well as others. I've heard both and find myself wanting more in either case. I may be alone here but I believe I can have both.
My dream job would be to be given funding to develop this "complete" amp and then build and market it and fill this gap in the market.
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