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Skorpio 11th April 2006 10:44 AM

Single stage amplifier
 
I am building a amplifier:

Unity gain 15W class A symetrical triple emitter follower output stage.

For voltage gain my first thoughts were a tube circuit, but now I have thought at the possiblity for at mos-fet og j-fet driver/gain stage.

This would be something like a zen with output buffer and according to Nelson Pass' definitions a single stage amplifier :)

Is a bride of zen able of a +/-15-20V voltage sving without too much distorsion? Or should I look for at scaled down zen? Perhaps the new zen-9?

EDIT: There will be ac-coupling between driver and buffer stage and no NFB!

Nelson Pass 11th April 2006 06:06 PM

It is arguable that a triple darlington is three stages, each
amplifying the current and driving the next stage. If the
technical community wants to call a darlington a single-stage,
then I have lots more single-stage amplifiers than I thought.

:cool:

jacco vermeulen 11th April 2006 06:54 PM

But just think, you could have a half-stage amplifier.

mos57 11th April 2006 09:14 PM

From Some years i have realized a single stage power amplifier that can deliver 50 watt/8 ohm or more. This stage have voltage gain so allows to drive it with with a cd player also (however low impedance is necessary). It acceipt balanced and unbalanced inputs and can switch from single ended to push-pull operation.
Also it permit class A or A/B operation of course. No capacitors in signal wire, no FB. I have tried to buy SIT transistors (especially the Tokin TKS45F323/322/320, TKS15R52, TKS17R52, 2SK180 for the best performance, but as we know it is very difficult. Now, thanks this forum i am in listing to buy the Lovoltech JFet and then to try with its. (my scheme is patent pending). I search a collaboration to engineering this product also for commercial use.
There is one?

Francesco

Nelson Pass 11th April 2006 10:35 PM

I think you could make a middle-class income from such a thing.

:cool:

mos57 13th April 2006 11:36 AM

single stage amplifier
 
Hi Mr. Pass.
At this time i have built 3 different power version of this amplifier:
8 W, 30 W, 50 W.
I have compared it with tubes amplifiers as:
leak TL 10 Point one (upgraded version)
Audio Tekne IT 2
DY-2 stages S-E amp (first stage 6463, output AD1 plus input (30k:50k) and interstage (30k:30k) transformes. Out tranny (all are made by Bartolucci) is 5k:16. First stage bias grid is obtained from battery. HV power from CLC filter and tube rectifier (Telefunken 1064 mesh). All filaments are in DC. Next days i will replace the 6463 with 6H30.
I also have compared my amp with solid states as:
Audio labor 8000
Classe Audio DR3 VHC (50 W class A)
Accuphase A50 V (50 W class A)
Spectral (i dont remember the model, perhaps DM 100)
Phatos Twin Tower
others.

I will canned evaluate the weak point of my amp and then improved it.

Now my last version sounds refined as near as the AD1 amp, tell me the friends, but it have other advantages such more dinamic, better bass etc

Do you think that i must insist on this project and offer a commercial version of this amp?
Can i make? (i dont have many money to spent)
Tell me an advice.

Best regards from Francesco.

Nelson Pass 13th April 2006 05:20 PM

I can't advise you as to whether this is what you want to do
with your life.

PMA 13th April 2006 05:39 PM

Quote:

Originally posted by Nelson Pass
If the
technical community wants to call a darlington a single-stage,
then I have lots more single-stage amplifiers than I thought.

:cool:

Does it make any difference how it is called?

Bricolo 13th April 2006 05:49 PM

Quote:

Originally posted by Nelson Pass
It is arguable that a triple darlington is three stages, each
amplifying the current and driving the next stage. If the
technical community wants to call a darlington a single-stage,
then I have lots more single-stage amplifiers than I thought.

:cool:


some people don't even consider that a follower is an amplifying stage (voltage or current follower, so a cascode (folded or not) would be a 1 stage)

so, this amp would be a zero-stage amplifier :D

mos57 13th April 2006 08:47 PM

some people don't even consider that a follower is an amplifying stage (voltage or current follower, so a cascode (folded or not) would be a 1 stage)


Many people consider the cascode a single stage (so the SRPP and the MU-follower) because the devices are in series and the current is the same.
However a triple followers must be consider as 3 stages.

Francesco.


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