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Old 13th March 2012, 06:55 PM   #3371
dvv is offline dvv  Serbia
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Quote:
Originally Posted by a.wayne View Post
It goes into protect driving CLS's and I understand thd increases when you lower the load. When viewing this phenom one can see there is an signature thd vs load vs output .

I will post up some graphs when I'm at my desk ......
Frankly, if it maintains the same output voltage into a load which now requires twice the current to stay the same, I just don't see how can this be done WITHOUT somewhat higher distorion.

How one declares it though can vary vastly. One may say: I'll declare my THD into 4 Ohm loads, and since it's low even so, I won't bother with 8 Ohms specs. Or one may provide specs for both load impedances separately. A matter of personal choice and marketing.
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Old 13th March 2012, 07:05 PM   #3372
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by dvv View Post
This is what I'd like to make for myself
Looks very much latter day HK.

There are many places where dropping in a Fet can cut out a lot of circuitry and/or dramatically improve inherent linearity/bandwidth.

Ciao T

Last edited by ThorstenL; 13th March 2012 at 07:08 PM.
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Old 13th March 2012, 07:06 PM   #3373
dvv is offline dvv  Serbia
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Click the image to open in full size.

I noticed that the picture came off as rather small. Here's a better version.
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Old 13th March 2012, 07:09 PM   #3374
dvv is offline dvv  Serbia
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Quote:
Originally Posted by ThorstenL View Post
Hi,



Looks very much latter day HK.

There re many places where dropping in a Fet can cut out a lot of circuitry and/or dramatically improve inherent linearity/bandwidth.

Ciao T
I have very few FETs available to me. Thus, any suggestions, accompanied with possible sources in Germany, would be most productive.
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Old 13th March 2012, 07:15 PM   #3375
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I hope that you are correct, T. I got the schematic from somewhere, but I don't know where I might have saved it. I would feel happier IF Matti did not take my topology without acknowledgment, because he once took me to task for inadvertently leaving out his Finnish lab from one of my papers, even though I acknowledged him in the paper. (I had included 1 graph that I made there.)
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Old 13th March 2012, 07:16 PM   #3376
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Looks like 'Super Ampzilla' to me, or the way the Ampzilla should have been made.
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Old 13th March 2012, 07:42 PM   #3377
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Dejan,

Quote:
Originally Posted by dvv View Post
I have very few FETs available to me. Thus, any suggestions, accompanied with possible sources in Germany, would be most productive.
With Erno's shop closed German sources may be difficult.

I would suggest 2SK214/2SJ77 or similar as drivers instead of tripple darlington.

2SK370/2SJ108 (or 2SK170/2SJ74) as followers buffering the VAS.

You could more of the J-Fets in the input stage, with a common tail (JC Style) or you could go really RAD with any number of J-Fet buffer schemes, I'd be tempted to look for self-biasing j-Fet/BJT Rush cascodes...

Ciao T
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Old 13th March 2012, 07:48 PM   #3378
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Quote:
Originally Posted by john curl View Post
Looks like 'Super Ampzilla' to me, or the way the Ampzilla should have been made.
I would rather call it OpAmpZilla.

Long time ago I tried symmetrical complementary topologies with multiple complementary output emitter followers, enormous power supply made from 2KV variac toroid, but they did not want to sound better than Tesla Mono-130 tube amp we had in laboratory, it was PITA!
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Old 13th March 2012, 08:13 PM   #3379
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by ThorstenL View Post
Hi,



The room is indeed modest, but I used the speakers and Amp in around 60m^2 as well and they did splendid there as well. The SS Amp does not lack power or control etc., it just sounds for want of a better word "boring" and "uninvolving". It's actually not bad at all, as far as solid state goes.

Speakers are ~90dB/2.83V 3-Way (1st order series crossover, timealigned) with a 270mm Woofer and a pretty much flat 6 Ohm impedance above the bass loading peaks with the Bass minimum at 7 Ohm, what we call a "undemanding load", so even fairly load intolerant SS Amp's have little trouble driving these.

Ciao T
I like the speaker topology , min phase and timed aligned ...

Quote:
Originally Posted by dvv View Post
Frankly, if it maintains the same output voltage into a load which now requires twice the current to stay the same, I just don't see how can this be done WITHOUT somewhat higher distorion.

How one declares it though can vary vastly. One may say: I'll declare my THD into 4 Ohm loads, and since it's low even so, I won't bother with 8 Ohms specs. Or one may provide specs for both load impedances separately. A matter of personal choice and marketing.
Agree there is some manipulation, regardless of how it's manipulated few can show doubling when halfing the load.

Quote:
Originally Posted by ThorstenL View Post
Hi,

Looks very much latter day HK.

There are many places where dropping in a Fet can cut out a lot of circuitry and/or dramatically improve inherent linearity/bandwidth.

Ciao T
Maybe Brad can tell us .....

Last edited by a.wayne; 13th March 2012 at 08:15 PM.
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Old 13th March 2012, 08:47 PM   #3380
bcarso is offline bcarso  United States
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Maybe Brad can tell us .....
I could tell you, but I'd have to kill myself. A swan song
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