Anyone using values other than a 100pf capacitor and 3.3M resistor?
TM
FET: alternative values
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UltraHookedOnPhonix
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Re: FET: alternative values
I did a stand-alone FET circuit where I used a rotary switch to switch the input impedance. More info here:ToneMerc wrote:Anyone using values other than a 100pf capacitor and 3.3M resistor?
TM
https://tubeamparchive.com/viewtopic.ph ... hlight=fet
Lowering the 3.3M resistor can tame the significant treble increase to a more flat frequency response. Believe it or not, a 68K input resistor will provide that for you and anything over 100K will get progressively brighter than the bypassed signal.
Re: FET: alternative values
You mean 3.3M/100pF or 1M/100pF? Cause the 1M/100pF filter is the tone shaping at the beginning of the circuit.
Re: FET: alternative values
My reference was to the 3.3M and 100pf, while leaving everything else the same.
TM
TM
Last edited by ToneMerc on Sun Oct 31, 2010 5:19 pm, edited 1 time in total.
Re: FET: alternative values
Which schematic for the FET input is the acknowledged correct one?
Is it this #124 1988 one?
Is it this #124 1988 one?
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Tom
Don't let that smoke out!
Don't let that smoke out!
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David Root
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Re: FET: alternative values
That's the one I've always seen.
However, instead of 8K2 and 8K2 I had to use 22K below the 150K entrance, and 2K5 off the FET in order to get about 10V/20V in my 100W #124, and also in my '70s ODS 50W.
However, instead of 8K2 and 8K2 I had to use 22K below the 150K entrance, and 2K5 off the FET in order to get about 10V/20V in my 100W #124, and also in my '70s ODS 50W.
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David Root
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Re: FET: alternative values
Double post.