Tremor-Lator for AB763

[2deaf]

Holy Crimson and Clover that's a deep tremolo.

I took the SS tremolo out of one of my amps and put Sluckey's Tremor-Lator in at the position that an AB763 would have it.  It works incredibly well.  No pops, no ticks, immediate on, immediate off.   I selected a VTL5C1 that was middle of the road and got better depth out of it by using a 220K plate resistor.  The thing is so deep that a 50K linear pot might be more appropriate for the intensity control.

 
 

[sluckey]

Thanks for doing that. Do you find it to be smoother sounding than the Fender neon bulb roach? The only issue for me is it requires the footswitch to be plugged in, just like the AB763. Not a big deal, just a personal choice.

[Swampertech]

Hey 2deaf, can I ask you about the 100K attached from the speed wiper to ground? Most of the circuits have seen have a 100K in series with the 3M, with the 3M being a variable R.

[2deaf]

Thanks for doing that. Do you find it to be smoother sounding than the Fender neon bulb roach? The only issue for me is it requires the footswitch to be plugged in, just like the AB763. Not a big deal, just a personal choice.

I'm no aficionado of tremolo by any stretch of the imagination, but that don't mean I ain't got no opinions on the subject.  I have never found the Fender roach tremolo to be usable.  It just sounds like an on-off switch to me.  The Tremor-Lator, on the hand, must be quite usable since I played Crimson and Clover long enough to have the wife come up and ask me if I knew any other tunes.  But yeah, I find the Tremor-Lator to be much smoother than the Fender roach tremolo.

I guess if you use a phone jack for your footswitch, you could use a shorting jack so that the tremolo works with no footswitch plugged in.  I don't have any ideas for a phono jack and a switch to ground right now.   

[2deaf]

Hey 2deaf, can I ask you about the 100K attached from the speed wiper to ground? Most of the circuits have seen have a 100K in series with the 3M, with the 3M being a variable R.

It works just about the same either way.  After I made a little circuit board and started hooking it up, I found that I had neglected to include the 100K on the board.  The speed pot was the last one in the line and there was no convenient point to connect the 100K to its proper ground.  So I mounted the 100K on the pot lugs and ran a wire to ground.

[2deaf]

Here is an idea that turns the tremolo off with a closed switch so that the tremolo is on when no footswitch is plugged in.  The LFO continues to oscillate when the tremolo is off, if that matters.

[PRR]

> 100K attached from the speed wiper to ground? Most of the circuits have seen have a 100K in series with the 3M

They do the same thing, for practical purpose.

[tony321owen]

I have been modifying my old ab763 Bandmaster reverb which includes  trying to improve upon the super weak tremolo. I found sluckeys Tremor-lator schematic and ordered a few Xvive vtl5c1 opto-couplers. Today I made the modification and when I switched it on, there was no trem. I can hear a slight sound of oscillation that comes on when I switch on the footswitch but all that happens when I roll up the intensity knob is that the signal volume is sent to ground which gives me something that works as a master volume..

I have gone through the circuit for errors and have checked voltages, checked resistors, and check caps, but still no trem.. the voltages are different from sluckey examples on his 67 bandmaster build (attached). here are the schematics I went off and a hand drawn layout of the circuit that I copied from my un-working trem circuit in my amp. Anyone notice if maybe I wired the pots wrong or if any errors jump out? Do I need an RA intensity pot? im using a 50kL
I will be very thankful to anyone who can crack this and bring me back to tremolo nirvana. haha

[sluckey]

That 3.2V at the VTL5C1 should be about 1.5v to 1.7v. This indicates the VTL5C1 is bad.

[2deaf]

I have been modifying my old ab763 Bandmaster reverb which includes  trying to improve upon the super weak tremolo. I found sluckeys Tremor-lator schematic and ordered a few Xvive vtl5c1 opto-couplers. Today I made the modification and when I switched it on, there was no trem. I can hear a slight sound of oscillation that comes on when I switch on the footswitch but all that happens when I roll up the intensity knob is that the signal volume is sent to ground which gives me something that works as a master volume..

The voltages noted are what would be expected for a 12AX7 with a 470K plate resistor and a 10K cathode resistor.  Did you take your voltage measurements with the tremolo switch open?

Does the intensity pot act as a master volume with the tremolo switch open or only when the switch is closed?  What about when the tremolo tube is pulled?

It sounds like you started off with a super weak tremolo and you ended up with a super weak tremolo.  Everything you have posted could be explained by the oscillator not oscillating properly.  Have you tried a different 12AX7 for the tremolo tube?  Does your meter have a lot of difficulty deciding what the voltages are when the tremolo is on?

[tony321owen]

thank you guys! Its working now since I switched out the optocoupler but still just a little bit shallow of the depth that I desire. I switched the plate resister from 470k to 220k which helped a lot but theres still a bit more depth i seek. I like my tremolos to be a little bit much with the trem control at 10. right now at ten the depth is at a medium level. any suggestions? I assume i cant keep making the plate resistor smaller, is there another way?

[shooter]

I assume i cant keep making the plate resistor smaller

you can, buyer beware.  math takes out the guessing, kinda 
max plate for an AX7 is 1.2w

most of the reviews I've heard put the trem-mod into swampy range already, might want to verify you have the same volts dc and signal ac that others using it have