rocket with tremolo circuit?

[angelodp]

Tony did you ever go for the tremolo in a rocket? I m looking at shoeing it into a current build w/ el34 Rocket reverb.

Ange

[dorrisant]

I made up a board then loaned the amp out for about a year... I have to dig it out and put that in. I need to do a couple other mods, so maybe this weekend. Thanks for the bump, Ange.

Tony

[dorrisant]

There wasn't enough room for my Tremolo board so I figured out a better way to get it in there. Will have to wait for parts to come in though.

Tony

[dorrisant]

Ok, parts in. Got it to work with no problems. This is both sides of the tube in parallel. I forgot to order a stereo jack for the footswitch so I put it on a SPST for now, (under the term strip on the left). My only concern is 420v on the plate. I saw a schem of a twin reverb with 440v on the plate, so I don't think I'll sweat it too much.

Sounds sweet!!! Wish I had room for the pots on the front.

Tony

[pleasantbullet]

Can this be used in an Express, with the unused half of V2?

And does it matter which B+ is tapped?

[hans-jörg]

Hi gents,
I want to implement the above tremolo circuit in my Express clone to give the unused half an appreciation.
Now we dont have here a Rocket stile bias, but a fixed bias and I have my "two 220k" which is in thruth a stereo poti from a Larmar connected via out lug there (at the bias circuit). Can I use this connection too without any problems?
My layout is the origin of TAG.
I ask, because I think there could be a problem with the other biasing, or not?

Best
Hans-Jörg

[hans-jörg]

Hi gents,
I want to implement the above tremolo circuit in my Express clone to give the unused half an appreciation.
Now we dont have here a Rocket stile bias, but a fixed bias and I have my "two 220k" which is in thruth a stereo poti from a Larmar connected via out lug there (at the bias circuit). Can I use this connection too without any problems?
My layout is the origin of TAG.
I ask, because I think there could be a problem with the other biasing, or not?

Best
Hans-Jörg

Hello,

is it such a stupid question?

Or shall I (HAVE TO) wire it up like in the BF Princetone Reverb (the Tremolo part of course).
I never built a Trem in an amp. Therefore ...
But the schematic of the Prince gives me a hint


Best
Hans-Jörg

[martin manning]

You are on the right track. Another Fender circuit that use the same type of tremolo is the 6G16 Vibrolux. There is also the possibility of modulating the cathode voltage of one of the preamp stages.

[hans-jörg]

You are on the right track. Another Fender circuit that use the same type of tremolo is the 6G16 Vibrolux. There is also the possibility of modulating the cathode voltage of one of the preamp stages.

Thank you Martin!
You mean I could wire it at cathode of the 2nd or 3rd stage of the express instad of the Bias point? There is a lot less voltage, or does this don´t mind?
Have to take a look at the schem of Vibrolux.
There are also different qualities of the tremo sound I guess (bias vs. cathode).
Best
Hans-Jörg

[martin manning]

For a preamp stage tremolo you use the oscillator signal to modulate a preamp stage cathode voltage, and note that is really a bias modulation. Stage two is probably a good candidate, and the voltage swing does need to be reduced.

Some info here on various types of tremolo circuits: http://www.lynx.bc.ca/~jc/tremoloCircuits.html

[hans-jörg]

Thanks a lot.

Best
Hans-Jörg

[Teleguy61]

Great thread, but I'd be grateful if someone could explain how it works in a Rocket.
I see that it's an LFO, and in the 6G3 Deluxe, and other apps, it's used with a fixed (adjustable) bias setup.
I can't wrap my head around how it works in the cathode biased amp, with the LFO hooked to a spot that is a ground, obviousloy lifted and grounded through the LFO.
Thanks for any clarification.

[Jackie Treehorn]

Great thread, but I'd be grateful if someone could explain how it works in a Rocket.
I see that it's an LFO, and in the 6G3 Deluxe, and other apps, it's used with a fixed (adjustable) bias setup.
I can't wrap my head around how it works in the cathode biased amp, with the LFO hooked to a spot that is a ground, obviousloy lifted and grounded through the LFO.
Thanks for any clarification.

It's basically the same thing. The slow a/c of the lfo combines with the bias voltage to vary the volume of the amp. In the case of cathode bias, the grid is 0 volts with the cathode at +10. The lfo will make the grid vary +/- the necessary amount to turn off the power tubes to cooking them. Something to be wary of in the rocket, that the bias wiggle tremolo will be tough on tubes. It may be a good idea to increase the cathode bias resistor to 68 ohms or so.

With fixed bias like the express, it's a different starting point, cathode at 0 volts, grid at -30, but you're still sticking that a/c signal on top of the regular bias. At least that's my understanding if it!

[hans-jörg]

Hello,
I tried today the schem of trem from the first post here and it does not work.
I have it in an Express therefor I changed the Deep pot connection to the Princeton Reverb (schem above).
What I found out ist: the footswitch looks like at the wrong place and lifts the ground from the cathode. In this case I have nearly the anodevoltage (390 VDC) there istaed of cathode voltage (2,5 VDC).
Also the 1m from the 0,01/0,01 junction should go to cathode instaed to ground via FS.
This is my experience but I have the fixed bias version (Express). Maybe it works with Cathode bias (Rocket)?

[cbass]

. I tried the 6g3 term on a rocket once.it worked but my other amps (fixed bias)had much better sounding tremolo.preamp wiggle may be the way to go