OD drive and level pot values

[Tdale]

I see 100K pots for the level and drive pots on all schematics I can remember having seen.

But if I remember correctly, dogears said that the level (OD master) should be 1M...with some resistor/trim pot before it...

Am I wrong?

I'm trying to make a schematic and layout for a "basic Dumble"...meaning a Dumble with no tweaks, but with the values that most of you think are the best. I'm going through lots of old posts to find all the values....but it's not easy. There are several opinions obviously, but if anyone would be interested in making a list of plate resistor, cathode resistor, cathode bypass cap, coupling cap values etc. for each tube, I'd be happy to post the schematics and layouts when it's done..



Tommy

[sgp]

Hi Tommy,
The 1M is used if you are doing the HRM post OD tone stack with seperate masters for clean and od, Look at the 1997 skyliner schematic in the files section.
sgp

[Tdale]

I see...thanks.

By the way, if I use clean master and OD master, but no HRM, the OD master should still be 100K, right?

Tommy

[sgp]

Yup, with the 150K feeding the OD Master.

[mlp-mx6]

OK, what values and tapers would you use if you have a switchable HRM?

Gary? Dog?

[sgp]

My take is that you have two 1MA Masters.
The NonHRM feeds a 150K and a 100Ktrim to ground with the wiper feeding the 1M OD master (or I think Dogears mentioned two 50K resistors in series acting like the mid point of the 100K trim) Feeding into the 1M OD master. This preserves the impedance that the stage is driving at 250K.
The HRM circuit feeds a 100K resistor into the 1M OD master.
Did I get that right?
Gary? Dog?