6V6 Push Pull, Cathodyne Phase Inverter, 1/2 12ax7 Temolo - bias/voltage swing?

[kevtronic]

I have a 6V6 push pull guitar amp, cathode biased, cathodyne phase inverter with second half of 12ax7 used for tremolo. What I'm wondering is there a ball park bias swing, based on this amp, that any of you go for or would suggest going for?

With the tremolo intensity/depth on 10. Lets say, for ease of number, the amp is biased at 100% with the tremolo off. Would you try for a range of 50% to a 150%, or 75% to 125% or 80% to 120%?

I'm presently diving in a little deeper into the tube tremolo design pool, but for now, I'm wondering if there is a general rule of thumb to adjust the depth to so as not to burn the tubes up?

Between the amp being push pull and the tremolo raising the bias above and below the bias idle point, well, ya

[Enzo]

You are not going to burn the tubes up, that dissipation is only for instants on each peak, followed by an equally lengthy minimum on the other end.

If you apply too much trem, it starts to thump, which sounds awful. The other extreme leaves you with little trem sound.

In other words, make it so it SOUNDS good.

[kevtronic]

You are not going to burn the tubes up, that dissipation is only for instants on each peak, followed by an equally lengthy minimum on the other end.

If you apply too much trem, it starts to thump, which sounds awful. The other extreme leaves you with little trem sound.

In other words, make it so it SOUNDS good.

Thanks for the info Enzo. I found a nice slow range, but of course that slows the faster end of the range too. I'm thinking about adding a two position switch go from a slower range to a faster range. Have you ever done this or know of it being done?

[Enzo]

In almost every eyelet boar Fender I ever worked on, the trem slowest was still way too fast for me, and by the time the speed was half way up, it was a blur. SO I routinely added caps to slow it down so at the low end it was a slow sexy throb, and it still could be turned up too fast for use at the top.

SO I mean really, is the top seed not fast enough for any reasonable use?


HAs anyone done it? I dunno, maybe, it would be utterly simple to do. Do I know either way? No I don;t pay attention to that.

[kevtronic]

Thanks Enzo, I here ya and agree. Just wondering if it can be done, thought it might be cool to have a switch for warp speed range, and of course there's the 'hmmm, I've never done/seen that thing - lol...

Yesterday, because I was wondering and have never done or read about it, I took bias readings with the tremolo intensity at zero and at ten. I did this with different caps to adjust speed and also depth of intensity (lushness I guess). It didn't take real long and seeing the actual differences helped reinforce just how and by how much the bias is affected. My favorite lushness took the bias from about 60% to about 145% with my favorite speed range which was pretty slow over all. I did hit a spot where the tremolo just sounded bad when you dug into the guitar, guess that was reaching the one of the limits you talked about above...

Thanks again, man - I got the answers I needed. Hopefully this short thread will come in handy to someone else later on...