EHX Black figer input impedance modification

[alblupo]

Hi,
this is the first thread I start on this forum.
Just looking for suggestions. I have got a Black Fingher, the tube version some times ago to be used in my guitar effect chain
I have to admit I was not aware of the incredibly low input impedance (about 4 kohm according both schematics and measurements

As long as I do not want to ad a buffer (even if the temptation of making some tube cathode fllower buffers is very high... or just a BJT  one  ) my idea was to simply swap and put there a 1M log pot. I am not a tube design expert, but I have to say I cannot see any drawback,
Do you have any suggestion? Do you think it could be done?
Thanks for the help

Alberto

[amz-fx]

Alberto,

Make pre-gain pot = 500k
Change the 2k2 from the pot to ground to 510k, or 470k if that's all you have.

regards, Jack

[alblupo]

Thanks.
I was thinking to go for such a solution...

[PRR]

I would wonder if the "2.2K" is an error, and the real value is 100K to 1 Meg.

[alblupo]

I can check again, but I measured 2.1k... that would be 2.2k...
Anyhow I would like to have the usual 1M... so 100 would be anyhow to low for a guitar effect.

[Scruffie]

According to the factory schematic it should be 100k.

[alblupo]

Yes, I think it is 100k the pot and 2.2k the resistor. I will check when disassembling to make the 1M mod...