Blending parallel triodes

[guitarmike2107]

I just made that up last night, at the extremes of the mix pot its grounding the signal from one of the two triodes, is that not fully isolated from each other? Or am I missing something?

edit: BTW I would still use the dual volume too ,this circuit changes the loading each triode sees, it was just an idea

[tubeswell]

FWIW I attempted to map the Thevinin circuits to compare the AC load on both types of circuit here under various settings, i.e.:

one pot @ max - other @ zero
one pot @ max, other @ 50%
one pot @ 50% - other @ max
etc

If I've done this correctly, it should illustrate that the two separate vol pots circuit has less AC load under these 'comparative' scenarios than the single vol pot and balance pot circuit (Edited version now replaces incorrect 1st version - which had a mistake in the top RH circuit, also another scenario added for parallel pots @ both maximum).

[guitarmike2107]

FWIW I attempted to map the Thevinin circuits to compare the AC load on both types of circuit here under various settings, i.e.:

one pot @ max - other @ zero
one pot @ max, other @ 50%
one pot @ 50% - other @ max
etc

If I've done this correctly, it should illustrate that the two separate vol pots circuit has less AC load under these 'comparative' scenarios than the single vol pot and balance pot circuit (but I'll take corrections on that if I'm wrong).

Thanks that’s helpful, I am a Mech Engineer, thinking about Db and ac circuits generally sends my brain into overdrive

So the first set shows that the mixer circuit set to use only one triode is -3db less compared to the same setting with separate volume controls, that’s probably enough of a reason not to use it then.

I take it that Gary was referring to the effect that one input triode has on the other. You can see how the two volume controls would give greater isolation between the two triodes at all settings.

Sorry this is probably really basic stuff for the EE's around here.

[mooreamps]

Sorry this is probably really basic stuff for the EE's around here.

You'd be surprised.... :|

-g

[exclamationmark]

I've always wondered about setting up some weird pre-amp designs where you'd split the signal and make the two halves of the circuit treat the signal completely differently and sum them back again. Don't think I have the money or the patience to actually do it though.

[guitarmike2107]

I've always wondered about setting up some weird pre-amp designs where you'd split the signal and make the two halves of the circuit treat the signal completely differently and sum them back again. Don't think I have the money or the patience to actually do it though.

someone has done this with a distortion pedal, was or Cornell maybe? splitting the bass and treble frequencies so that the harmonics dont cause dissonance or something along those lines

[Steve Conner]

I can think of two. The Trace Elliot SMX compressor pedal that compressed the lows and highs separately (I've got one, it works pretty well) and the Hex Distortion patch available on the old Roland guitar synths, which had a separate distortion circuit for each string. This apparently sounded amazing, but it only worked with Roland's own synth pickup.

It was also a commonly used trick in broadcast processors to make FM radio stations louder. The signal would get split into 6 or 8 frequency bands, each one would get the crap clipped out of it, and then the resulting mess filtered again and reassembled.

[mooreamps]

I've always wondered about setting up some weird pre-amp designs where you'd split the signal and make the two halves of the circuit treat the signal completely differently and sum them back again. Don't think I have the money or the patience to actually do it though.

I'm doing that right now, in my jazz amp.. two preamp channels feeding both sides of the P/I.. Similar to a Matchless layout I once saw.... Thus you can have either preamp channel on-line, or go to Preamp Mixed Mode, and blend the both of them....

-g

[exclamationmark]

I can think of two. The Trace Elliot SMX compressor pedal that compressed the lows and highs separately (I've got one, it works pretty well) and the Hex Distortion patch available on the old Roland guitar synths, which had a separate distortion circuit for each string. This apparently sounded amazing, but it only worked with Roland's own synth pickup.

It was also a commonly used trick in broadcast processors to make FM radio stations louder. The signal would get split into 6 or 8 frequency bands, each one would get the crap clipped out of it, and then the resulting mess filtered again and reassembled.

Actually I remember something similar occurring with the new roland synths, where because each string was processed separately it wouldn't have inter-modulation distortion so you could play weird ass chords without them sounding dissonant on high gain. I also recall trying a pedal that used a DSP to achieve the same thing without the split pickups, but it sounded totally strange (different?) when you played a power chord.