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Old 26th June 2003, 01:12 PM   #11
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Quote:
Originally posted by Bricolo


are you slowly telling us that "less is more" is false?
Even Nelson's complicated designs are extremely simple, compared to other amps. What is the problem with inserting a cascode or active current source, if it makes the performance of a simple circuit better?
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Old 26th June 2003, 09:09 PM   #12
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Quote:
Originally posted by Nelson Pass

some will find a smaller gain chip like the 610 more accurate on the top and certainly faster, but may lack other characteristics at the lower frequencies.

Yes , I find this way , turn into bi-amplification and
choose pratically for 2 Zen V2 , one of which is cascoded for the high frequencies speaker .
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Old 27th June 2003, 07:42 AM   #13
ergo is offline ergo  Estonia
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I'm now in process of thinking all this through in my head....

It seems that IRFP044 is a transistor choise hard to beat here. Most of the other choises seem to have much lower gm and thus lower open loop gain.... but unfortunately this is not available near Estonia (don't you guys just hate such situations)

The 2V on gain transitor seemed a bit low at first but after studing the datasheet I can see why Nelson suggests it. The characteristic is indeed very linear around 2V.

***

Now some questions.

Nelson and stefanobilliani, have you tried also cascoding the current source and if so, was this helpful?

What would be the things to consider with circuitry providing bias for cascode transistors. I have never before cascoded high current stages and there might be some additional problems to consider.

Ergo
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Old 27th June 2003, 10:07 AM   #14
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Quote:
Originally posted by ergo
have you tried also cascoding the current source and if so, was this helpful?

Ergo
Inserting a transistor between the +V and the current source ,----is this a right understanding of your question?----is the same at the use of a source follower-voltage regulator , but ZV4 is already featured for this .

Quote:
Originally posted by ergo
What would be the things to consider with circuitry providing bias for cascode transistors.
Ergo
There are not too much things to consider I think...;
Just decrease the resistor value in the active portion of the current source if a small chip like IRF610 is used as a gain device( R16 from ZV4)
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Old 27th June 2003, 08:53 PM   #15
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I have not seen significant improvement cascoding the current
source, but this depends on the nature of the current drive
and/or feedback on the current source circuit.

Regarding the simplicity issue, I regard this as a nice quiding
philosophy, but in reality these projects are exploratory in
nature, and we will wander around the landscape as we please.

If I were to publish the most absolutely simple amplifier I can
come up with and call it a day, what would we do next for
entertainment?

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Old 27th June 2003, 08:57 PM   #16
Stefano is offline Stefano  Italy
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we would play music and enjoy, master
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Old 29th June 2003, 06:53 PM   #17
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Good answer.
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Old 29th June 2003, 08:11 PM   #18
moe29 is offline moe29  United States
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how could you get any more simplier than the SOZ?

m.
/ is very interested to see what's in the landsape next! : )
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Old 9th July 2003, 01:20 AM   #19
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Would this be a correct implementation of cascode for the input and output stages?
Attached Images
File Type: jpg zen4 cascode.jpg (44.8 KB, 329 views)
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Old 9th July 2003, 06:19 AM   #20
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For the input , read this post from Zen lightement thread:http://www.diyaudio.com/forums/showt...457#post182457 .


For the output , it lacks a resistor between V+ and the Zener.

I use 7.5v zener

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