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long tailed pair - need more gain
long tailed pair - need more gain
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Old 9th April 2021, 04:28 AM   #61
directdriver is offline directdriver  United States
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Quote:
Originally Posted by TonyTecson View Post
would increasing the open loop gain in a williamson help? like instead of 12au7's the 6072's are used instead...
Like the Altec 1520T?
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Old 9th April 2021, 04:42 AM   #62
TonyTecson is offline TonyTecson  Philippines
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Originally Posted by directdriver View Post
Like the Altec 1520T?
i am not a fan of too many stages in an amp....
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Old 9th April 2021, 10:24 AM   #63
directdriver is offline directdriver  United States
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Originally Posted by TonyTecson View Post
i am not a fan of too many stages in an amp....
It is still a Williamson circuit, if you minus the cathode follower stage. You asked if the 12AU7 can be replaced with a 12AY7 and the Altec 1520T gives an example that can be done, not suggesting you to copy the circuit.

I understand the purist standpoint of aversion to multi-stage circuits. I don't see a problem if two stages are direct coupled, which I treat it as a single unit as one stage is dependent on the other for bias. Personally, I'm not a purist. I like colorations as long as noise is not added. By the way, the Altec 1520T is great sounding amp that is transparent and accurate.

Last edited by directdriver; 9th April 2021 at 10:30 AM.
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Old 9th April 2021, 10:36 AM   #64
TonyTecson is offline TonyTecson  Philippines
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the reason for my aversion is you end up with too many coupling caps...

but i can surmise that the grid are happier being driven by the cathode instead of the plate side where impedance are higher...

today there are other ways to do such things...

my theory is if the open loop of the williamson is higher by using the 12ay7 instead of the 12au7, then open loop will be higher and so addition of global feedback gives better margines....that is what i am interested in...

Last edited by TonyTecson; 9th April 2021 at 10:41 AM.
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