Adding a pentode input to a guitar amp

[VMUNIX]

How would you connect this:

To an amp like this:

what i would like is to have both flavors, like triode and pentode (sort of a Champ 5C1 overdrive) independent inputs onto this amp which is already very clean. I have a hole for an extra volume control.

 

[PRR]

Could be as simple as

 

[VMUNIX]

yes that's the easiest way, so easy I didn't even consider until now 🙂 I will try it for sure, how about bypassing the tone-stack altogether connecting the .02 out of the 6sj7 to the wiper of the treble, or even to the concertina .022 ? what would you think if you actually see something like that being done to an amp 😱

 

[jjman]

You can "bypass" much of the tone stack via a 25k+ pot replacing the 6800R. Setting the new Mid Pot at max would be close to bypassing. Or a switch on the 6800R but it will "pop" if thrown when running. Or a switched added 7-20k resistor in line with the 6800R. I've used all those.

 

[PRR]

Pentode-tonestack-triode is already more gain than standard.

Pentode-tonestack-triode is way more gain, a monster.

Pentode-concertina is less gain than standard, hard work.

But I dunno. Any of these may be "your amp". An hour of hot solder may say more than days of bench-racing.

 

[VMUNIX]

Thanks for all the input.

 

[Kay Pirinha]

Could be as simple as

Wouldn't do that. Note the highliy different plate voltages at both input sections. This would give a LAAOOUUD plop when the switch is tripped. Better: Apply each a RC highpass of, say, 0.1 µF/1 Mohms to both plates, right before the switch.


Best regards!

 

[Printer2]

The pentode into a pair of mixing resistors into the second stage would probably give you enough versatility for the amp.

 

[VMUNIX]

The pentode into a pair of mixing resistors into the second stage would probably give you enough versatility for the amp.

I will try that, seems to be another good option.

 

[PRR]

Wouldn't do that. ... LAAOOUUD plop ...

I said it was simple. Won't kill the guitar amp/speaker. May scare the dog.

I want him to try-out the pentode, see if it worth the effort, before complicating. I know many people are trying pentodes. My impression is that just because amp X is cool and amp X has a pentode, doesn't prove much. Pentode is more complicated to set-up clean, and wickedly complicated to set up "tonefully". When/if he gets as far as A/B testing, for-sure he will want a less POP setup.