AUDIOTECH1 said:
I don't bother myself with the questions of why do Zen amps sound good-they simply do. (Especially Zv9) Build one and you'll hear.
I have one question: Did anyone do distortion measurements of F2 and ZV9 without feedback (and without Aleph CCS)?
F2 is a good transconductance amp, however "feedbackless Zv9" should make for even a better one. (both on paper and listening)
Thanks,
Vix
Hi
In the F4 thread Nelson answered that he uses an F3 as a stock amp, not as a current amp, as I thought. I decided to jump to this thread. It seems more appropriate. I didn't want to go far OT on F4 thread.
Nelson, thank you very much for a reply. I was expecting the opposite answer though. Can't say I am not surprised. Didn't you like F3 as a current amp? Was it showing signs of instability, or was it just a matter of taste?
On one hand, one could say that "F1 and F2 are current amps, if you like them, build 'em." F3 is a a voltage amp with low distortion. On the other hand, F3 as a current amp shouldn't have any more distortion than an F1 or F2, plus it will have that Jfet sound.
What will happen if there is a minimal (3 db) of feedback? (vs no feedback at all) I guess that it should behave as a voltage amp with highish output impedance. I am considering this as an alternative to the "no feedback" solution.
Thanks,
Vix
p.s. Happy Easter!
In the F4 thread Nelson answered that he uses an F3 as a stock amp, not as a current amp, as I thought. I decided to jump to this thread. It seems more appropriate. I didn't want to go far OT on F4 thread.
Nelson, thank you very much for a reply. I was expecting the opposite answer though. Can't say I am not surprised. Didn't you like F3 as a current amp? Was it showing signs of instability, or was it just a matter of taste?
On one hand, one could say that "F1 and F2 are current amps, if you like them, build 'em." F3 is a a voltage amp with low distortion. On the other hand, F3 as a current amp shouldn't have any more distortion than an F1 or F2, plus it will have that Jfet sound.
What will happen if there is a minimal (3 db) of feedback? (vs no feedback at all) I guess that it should behave as a voltage amp with highish output impedance. I am considering this as an alternative to the "no feedback" solution.
Thanks,
Vix
p.s. Happy Easter!
Vix said:
Vix said:
So many questions this morning. Of course the F2 has no
feedback already, so the documentation on it answers one
question. Different versions of what became the F3 are shown
in ZV8 and then ZV9, including versions with no feedback and
minimal feedback, and there are distortion curves giving some
examples of those.
In my business I have learned to concentrate on one story at
a time, otherwise people get confused and the point is lost.
The F1 and F2 were current sources, one balanced, the other
single-ended. The F3 is a power JFET. You make make very many
permutations of combinations these techniques, but I leave that
to you for the most part. At present I want to spend more time
on core ideas.
Hi!
I just cut the feedback resistors on my ZEN V9, (and disconnected the Aleph CS). I connected load resistors across the output.
Interesting thing happens: As I try various values of output resistors, sound quality changes. I don't know how to describe it. While trying different values, there seem to be some which "just sound right". At the moment, it is loaded with 7.5 Ohm (2x15 ohms in parallel). It seems to work best for me. I guess it is a matter of adjusting the output impedance, hence damping, bringing it to a "correct" amount.
Speakers are Visaton B200.
Happy listening,
Vix
I just cut the feedback resistors on my ZEN V9, (and disconnected the Aleph CS). I connected load resistors across the output.
Interesting thing happens: As I try various values of output resistors, sound quality changes. I don't know how to describe it. While trying different values, there seem to be some which "just sound right". At the moment, it is loaded with 7.5 Ohm (2x15 ohms in parallel). It seems to work best for me. I guess it is a matter of adjusting the output impedance, hence damping, bringing it to a "correct" amount.
Speakers are Visaton B200.
Happy listening,
Vix
Vix said:
I have pretty much the same standing at my livingroom floor, but developed a little further and based on a ZV1 that got a cascoded JFET and very little local negative feedback, no global negative feedback. I for some reason don't like the aleph current source, so I have used the current source from the ZV1 and used the cascode and the cascode modulation is close to what is seen in ZV9. I have upped the bias to 4A and the rail voltage is upped to 44V.....anturally it only survives due to some pretty massive heatsinking. Oh and I have substituted IRFP240 for IRFP044.
I use the amp for powering my Abbey clones.
Magura
Zen Mod said:
heavy heatsinking ........when you build..........?
nah................
Well, in this case it's heavy heatsinking....even in my book! I tell you it's a pair of serious heatsinks. The same amount of heatsinking per channel as Steenoe is using per channel for his AX-100 monoblocks
....and they run HOT!
Magura
Magura said:
Well, in this case it's heavy heatsinking....even in my book! I tell you it's a pair of serious heatsinks. The same amount of heatsinking per channel as Steenoe is using per channel for his AX-100 monoblocks
....and they run HOT!
Magura
and-just for record..........can you tell me estimated cost of that heatsinking stereo pack?
(I know that I'll not be sole impressed)
Zen Mod said:
oh,boy.........I just can't resist with off topic.....
what you else tried lately,besides B200 ?
Not much. A few years ago I started playing with fullrange speakers, and fell in love with them. I tried various car speakers (pioneer, philips, blaupunkt, and some no-names). Then I had decided to go with something "more serious" and got a chance to buy a pair of Fostex 206. Built an ML TL (M.J. K' project 5). Last december I got a chance to buy Visaton B200, and couldn't resist. Took Fostex out, mounted Visatons and filled the port with foam, so it would act more like sealed box. Despised Visatons at first, they were screaming at me.
At the same time I was having fun with pass amps. Built F2 lite and ZV9. Bride of Zen could no longer satisfy the new Zen variation, so it got retired. A Sovtek 6922 cathode follower took its place.
So, where I am now: I got a transconductance ZV9, Cathode follower as a pre, and Visatons as main speakers. They still scream, although not that much. ( I applied passive EQ network). Geoff H at fullrange forum http://www.diyaudio.com/forums/showthread.php?s=&threadid=99662
did us a favor and designed a PLL circuit to equalize B200's response. Now that I have modified ZV9 into a current amp, I have connected 100 Kohm resistors at the input. If a am not mistaken, this should be its input impedance, that would enable the use of Geoff's PLL circuit, between a pre and ZV9. Didn't have the time to try it today, most probably it will have to wait till the next weekend.
By the way, Fostex-es are still in a box. I don't see a point in connecting them now. They are waiting for a BIB. Way Off Topic: I moved some furniture these days. Now I have enough space for either an OB, or a BIB. The problem is that I want both...
Nelson Pass said:
That's the spirit.
Thanks!
Magura said:I have upped the bias to 4A and the rail voltage is upped to 44V.....anturally it only survives due to some pretty massive heatsinking. Oh and I have substituted IRFP240 for IRFP044.
I use the amp for powering my Abbey clones.
Magura
44 V times 4A..
I'd be afraid to run it that high. Nevertheless, if you manage to cool it, it should be well worth...
Vix said:............................. Now I have enough space for either an OB, or a BIB. The problem is that I want both...
...............
look here, especially at last ones:
http://www.lampizator.eu/SPEAKERS/PROJECTS/Speaker projects.html
and-look at http://www.sonido.hu/eng/home.htm
SFR200...............soon!
Zen Mod said:
why I was in impression that you made them ?
anyway-they look good as that you made them........
btw-where's steen this days......it's sorta quiet without him........
seems that he mention vacation........
The last I heard from him was something about a vacation someplace warm...let's hope it rains where he went
The heatsinks Steenoe has are not made by me, those are just from the supply of heatsinks I bought to get the DIY stuff going here in Denmark a few years ago....the ones you can see in my gallery are made by me. The ones in the gallery are based on the design of the ones Steenoe has. I figured it would be a lot of trouble to do the math for designing a heatsink myself.
http://www.briangt.com/gallery/Heatsinks/PICT0099
Magura
Magura said:
The last I heard from him was something about a vacation someplace warm...let's hope it rains where he went
The heatsinks Steenoe has are not made by me, those are just from the supply of heatsinks I bought to get the DIY stuff going here in Denmark a few years ago....the ones you can see in my gallery are made by me. The ones in the gallery are based on the design of the ones Steenoe has. I figured it would be a lot of trouble to do the math for designing a heatsink myself.
http://www.briangt.com/gallery/Heatsinks/PICT0099
Magura
so -I was right,even if I can't remember that I read somewhere that they are made in your shop ...... I asked not meaning on money primary involved,but cost of your work ........as a illustration of passion involved
hat off to metal guru
Zen Mod said:
so -I was right,even if I can't remember that I read somewhere that they are made in your shop ...... I asked not meaning on money primary involved,but cost of your work ........as a illustration of passion involved
hat off to metal guru
Well, the cost of my work is a very flexible matter....As I have access to pretty much any type of equipment for free, what I'm counting then is time spent. As I recall those heatsinks has like 20 CNC machine hours on them each (at least, probably more) and like 50 or 60 hours to do the design and the finish. There are 12 in total.
Magura
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