Favorite Promethium/HM-2 mods?

[dot matrix madness]

What are your favorite modifications to the Promethium/HM-2 ? Please let me know:
Numbering of parts referring to the schematic of the Promethium:
1. bypass D4 and D5 (switch). Instead of Germanium ones I've seen BAT46 in the Aion Gravition
2. remove D1, D2, D3 (1N4148) (switch)
3. replace D2 by 1N4001 (switch)
4. introduce symmetrical clipping by adding another diode in the same direction as D2 (switch)
5. change D6 and D7 (1N4148) to red LEDs (switch)
6. increase C11 (1nF) to 10nF or more
7. split middle and high gyrators (add separate 10kA poti)
8. increase R18 (220k) to 330k
9. increase C2 (47nF) to 1µF
10. reduce C10 (1µF) to 33nF
11. modify center frequencies of the gyrators. See this calculator

 

[Nostradoomus]

Replace all the pots with reaistors so everything is on 10 all the time.

 

[zeropluszero]

I built a GCI NEW HM-2 recently.... preferred my stock standard promethium fwiw

 

[maertz13]

R7 and R13 - 10k and 220k

 

[jcpst]

Replace all the pots with reaistors so everything is on 10 all the time.

This thing doesn’t really need knobs. If I build another one, I would have OUTPUT, and a toggle switch that goes between min and max GAIN. BASS and TREBLE on max.

Max GAIN gets you to chainsaw, min GAIN is a nice dirty boost.

 

[ftumch]

R7 and R13 - 10k and 220k

Looks like that does something dramatic to the gain structure?

 

[Nostradoomus]

This thing doesn’t really need knobs. If I build another one, I would have OUTPUT, and a toggle switch that goes between min and max GAIN. BASS and TREBLE on max.

Max GAIN gets you to chainsaw, min GAIN is a nice dirty boost.

I will admit I would also put a toggle in to take the highs from 10 to around 7-8, (just under the chainsaw peak), it’s a great boost where you don’t want the chainsaw grind. The lows being at 10 are what brings the joy.

 

[zeropluszero]

I love my hm2 but detest treble dimmed.

 

[Nostradoomus]

I love my hm2 but detest treble dimmed.

dimmed or dimed? There is a distinct difference

 

[zeropluszero]

Well I don't know what a dime is either

 

[jwin615]

Well I don't know what a dime is either

Bout half a gram these days.
Full gram back in the day.

 

[zeropluszero]

Also can't help you there haha

 

[maertz13]

Looks like that does something dramatic to the gain structure?

reduces the gain of the boost section from "way too much" screaming death mode to a more reasonable distortion pedal. very similar to the Orman DS-1 mod.

 

[Feral Feline]

Bout half a gram these days.
Full gram back in the day.

So the dime has dimmed...



Actually don't have anything to offer other than a question, aimed at @Nostradoomus and @jcpst ...


Q: If you were to incorporate the highs switch with the Hi-LO GAIN Sw, one switch to rule it all, would you back off the highs for high-gain mode or for the low-gain mode?



BTW, zeropluszero, you still haven't answered the question — do you detest the treble-knob turned down, or treble knob turned up?

 

[neiltheseal]

I built a GCI NEW HM-2 recently.... preferred my stock standard promethium fwiw

How did you go with the blend control? I built this and found it useless because the clean side was too quiet.

 

[zeropluszero]

I run my Promethium with high about 3oclock, low about 4.

I just sold the GCI, I recall it didn't sound right with the blend less than full, but also didn't try it with my bass. I assume it was added for bass players as an add-on that probably no bass player ever asked for.

 

[jcpst]

Q: If you were to incorporate the highs switch with the Hi-LO GAIN Sw, one switch to rule it all, would you back off the highs for high-gain mode or for the low-gain mode?

I wouldn’t on either mode. If I had to do one, it would be the low-gain mode. If I roll off any highs in high gain mode, then I can’t justify painting a chainsaw on the enclosure.