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Old 12th January 2006, 01:41 PM   #11
rozak is offline rozak  Israel
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How much is in db the amount of interstage feedback?
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You have only lockal feedback. Gain=R10/R1.
R9, C1 for min. DC ofset.

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In your proposal I must use, according to my schematic, the "INPUT B", is that right?
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Right.

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Is it possible to implemet the two "INPUT A", linking this to collectors of Q23 and Q27 on your schematic?
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No, if you need low Zout

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I have got Micro Cap evaluation. Will your schematic work on it?
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No.

For input A:
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Old 12th January 2006, 04:13 PM   #12
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Thank you very much!

According to your knowlege, is there another possibility (maybe easier) to implement the stage?

What do I1 and I2 mean on the schematic?
When you write on transistors "BC550BP/ZTX", what do you mean? Could you be more precise?


Is possible not to use C1 and R9?

Thank you in advance, regards!
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Old 12th January 2006, 06:23 PM   #13
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Quote:
Originally posted by andythefirst
Here is the schematic...
Thanks.

Ok. Reason I was asking is I was thinking of recommending using a step-up transformer and attenuator to be used at the input of your buffer which would eliminate the need for a preamp if your source(s) were capable of driving a 1.5k load. But with the balanced input of your buffer, that rather complicates things a bit.

se
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Old 12th January 2006, 08:38 PM   #14
grataku is offline grataku  United States
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If you want to keep with Aloia spirit of the GY50 why not use the Aikido with 12ax7.
See tubecad.com for several examples of power amp using aikido as the VAS stage.

on a separater point, something I never quite "got" about the italian Bart "T" follower stage is the motivation behind the rail to rai emitter resistors in the predriver-driver as opposed to the original Locanthi T with common emitter resistor. Can anyone explain?
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Old 12th January 2006, 10:28 PM   #15
rozak is offline rozak  Israel
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What do I1 and I2 mean on the schematic?
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Constant Current Sourse.

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When you write on transistors "BC550BP/ZTX", what do you mean? Could you be more precise?
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This transistor is from my simulation library.
You can use any small signal transistors.

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Is possible not to use C1 and R9?
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You must for this topology at least.

Don't take my schematics us is-it is just theorytical proposition for
starting real project.
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Old 13th January 2006, 08:06 AM   #16
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To grataku.
Thank you for your reply.

Yes, you are right, ECC88 or 12AXT ar OK, but I would like, as I wrote, to try in the pre stage:

- NO Vacuum Tubes
- NO Coupling Capacitors

Any ideas?

Regards.
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Old 13th January 2006, 10:37 AM   #17
zinsula is offline zinsula  Switzerland
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Ciao Andyprimo

Only BJT, you exclude also J-Fet's, that is?

Ciao, Tino
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Old 13th January 2006, 03:30 PM   #18
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Hi and thank you.

I think BJT, especially when you need to use 2 complementary, as in this case to have an OCL, are better with less problems. And it's easier, I think, to have a very low impedence with only 2 BJT.

But a good J-fet OCL non feedback stage can also be considered!

Any ideas?

Regards, A.
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Old 15th January 2006, 10:36 AM   #19
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I beg you pardon,
but I ask help to have a little schematic with named components for the purpose I need

I join one schematic I found here but in another thread, but It has two problems:

- The swing is not sufficient. I need 30 volt at very low THD. The problem is also because the power supply cannot be higher with the BJT and Jfet in use;

- Is not Output Capacitor Less. Maybe using two transistor in push pull...?

Any help, ideas?
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Old 18th January 2006, 08:29 AM   #20
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Sorry,
my last attempt... then I'll give up.

is there anybody can help?

Thank you in advance, regards, A.
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