Valve EQ workings

[Roland Rock]

Both of my amps (Streamliner and all valve 100w) have valve-based EQ. No problems there, as they both sound great.

I don't normally fiddle with EQ much, but recently started playing around to get the best tone for various songs when recording. I was surprised at how much twiddling one eq knob could have an effect on the others. For example, totally cutting the treble seems to have a diminishing effect on the bass eq.
I could get a suitable tone easily enough, but it's more by trial and error, rather than a logical method.

So, is there a science behind what happens with valve EQ? Which one affects the other and how? If I knew this, I'd be able to know what I was doing, rather than twiddling and hoping for the best.

[LukeFRC]

it's the design of tone stack rather than the fact it's valves i think

[Graham]

This thread came up the other day in relation to the Streamliner EQ - might be of some help

http://www.talkbass.com/forum/f15/genz-streamliner-600-900-tone-control-primer-813663/

[Mr. Foxen]

http://www.duncanamps.com/tsc/index.html

This tool gives you an eq curve, you can tweak the values to match your amp if you can find a schematic.

[Prime_BASS]

Yeah it's biased on the fender tone stack of yester year. The bass and treble at 'flat' are boosted and the mids are scooped.

They also interact a fair amount as they have a wide Q.
Flat on the streamliner is the treble and bass cut a fair some and the mids boosted. I never really got on with the controls myself, and haven't on any similar designed controls, I.e the OTB.

[paul_5]

That Fender tone stack crops up in a lot of places, most recently a derivative can be found on the LH series amps from Hartke.