Ry Cooder's Borderline Special

[Bombacaototal]

And this is my layout

[10thTx]

I've tried following this thread information about the vactrol tremolo. Looking at Sluckey's Bandmaster example of how it's inserted into the signal chain and noting the comment about the master volume being the insertion point but also the suggestion of a resistor between the tremolo and the insertion point ………………….. I'm not clear what the final insertion point in the signal chain is???

Using this schematic as an example, can you guys show us where the insertion point is, please? Thanks!

With respect, 10thtx

EDIT: reposted schematic after Bombacaototal's response clarifying the insertion point.

[Bombacaototal]

I've tried following this thread information about the vactrol tremolo. Looking at Sluckey's Bandmaster example of how it's inserted into the signal chain and noting the comment about the master volume being the insertion point but also the suggestion of a resistor between the tremolo and the insertion point ………………….. I'm not clear what the final insertion point in the signal chain is???

Using this schematic as an example, can you guys show us where the insertion point is, please? Thanks!

With respect, 10thtx

It is the input lug on the master volume

[10thTx]

It is the input lug on the master volume

I am understanding this to be a correct "illustration" of how you used the insertion point for the tremolo. (Not necessarily your exact amp schematic, but an accurate example of insertion point).

Thanks for the reply! With respect, 10thtx

[Bombacaototal]

I think that sounds great! And such a simple circuit too.

Hi Sluckey, I have spent good time with the tremolo and looking for improving a couple things in regards to the footswich. I use a fender style stereo Jack for the footswich with the reverb on one side and the tremolo on the other, wired like fender blackface, and noticed a couple issues

(i) there is a loud pop if I add or remove the jack with the amp ON. Fender uses a capacitor to ground at the footswich for that but I am not sure it will work well with the valctro

(ii) if I leave the tremolo ON and simply remove the pedal jack, although the tremolo oscillation stops working, the signal of the amp goes through the tremolo LFO circuit and this causes for a change of tone, which is different then if you turn the tremolo off first which would prevent the signal from going to the LFO. For example, as an experiment I put a 12AU7 on the LFO and can clearly hear the amp remains in low gain if I remove the jack without turning the trem off via the footswich first. But if I turn the trem off then remove the jack the gain is not affected. I am wondering if there is anything to be done about this

[sluckey]

Hi Sluckey, I have spent good time with the tremolo and looking for improving a couple things in regards to the footswich. I use a fender style stereo Jack for the footswich with the reverb on one side and the tremolo on the other, wired like fender blackface, and noticed a couple issues

(i) there is a loud pop if I add or remove the jack with the amp ON. Fender uses a capacitor to ground at the footswich for that but I am not sure it will work well with the valctro

I don't recall ever seeing a cap on the trem footswitch. Can you provide a Fender schematic that shows that? Since you are using a stereo jack, are you sure the pop is caused by the trem circuit and not the reverb circuit? Regardless, there seems to be a simple solution. Plug the footswitch in ***BEFORE*** turning the amp on, or if this is a combo amp, just leave the footswitch plugged in all the time.

(ii) if I leave the tremolo ON and simply remove the pedal jack, although the tremolo oscillation stops working, the signal of the amp goes through the tremolo LFO circuit and this causes for a change of tone, which is different then if you turn the tremolo off first which would prevent the signal from going to the LFO. For example, as an experiment I put a 12AU7 on the LFO and can clearly hear the amp remains in low gain if I remove the jack without turning the trem off via the footswich first. But if I turn the trem off then remove the jack the gain is not affected. I am wondering if there is anything to be done about this

I'm not quite sure what you are saying here. The guitar signal never goes through the trem circuit. The vactrol totally isolates the trem circuit from the amp. The LDR part of the vactrol simply puts a shunt resistance from the guitar signal path to ground. This shunt resistance varies at the rate of the tremolo oscillator. The LED part of the vactrol blinks at the rate of the tremolo oscillator and shines on the LDR causing it's resistance to change. When the LED is shines, the LDR resistance is low causing the guitar signal to decrease in volume. When the LED is not shining, the LDR resistance is high and the guitar volume will return to normal volume level. The only way to stop this action is to step on the footswitch to open the contacts, or unplug the footswitch jack. I don't see how there can be any difference in the guitar signal tone or volume whether you turn the trem off by stomping the F/S or unplugging the F/S jack. Either way, the LED stops blinking and the LDR goes to some very high resistance.

[Bombacaototal]

Here is a Fender schematic with 220pF to ground. And yes, I have been doing exactly that, plugging or unplugging it with the amp off. And, no its not the reverb, I tried iwith the trem lead disconnected from the jack and had no issues.

Well, its odd, if I do not turn off via footswitch and simply remove the jack the amp definately sounds different than if I turn off the trem via footswitch. Now, not entirely sure why, but yesterday was exactly that, I found the amp didn't sound the same, mains voltage was in check at 241V (so it was not that). I added the footswitch, had to click the button two times to engage the trem (probably off then on) and then turned off the tremolo via footswitch and boom, the amp sounded like it should.

[sluckey]

if I do not turn off via footswitch and simply remove the jack the amp definately sounds different than if I turn off the trem via footswitch.

I want to believe you but I just can't. Unplugging the F/S does exactly the same thing as opening the F/S contacts.

Never seen that custom schematic before. Won't hurt to put a 220pf on the jack, but I'm skeptical if that will cure the pop. Keep in mind that the Fender F/S actually stops the oscillator but in the Trem-O-Nator, the oscillator continues to run all the time and only the blinky LED is stopped. This insures instant on when you step on the F/S.

[pompeiisneaks]

if I do not turn off via footswitch and simply remove the jack the amp definately sounds different than if I turn off the trem via footswitch.

I want to believe you but I just can't. Unplugging the F/S does exactly the same thing as opening the F/S contacts.

Never seen that custom schematic before. Won't hurt to put a 220pf on the jack, but I'm skeptical if that will cure the pop. Keep in mind that the Fender F/S actually stops the oscillator but in the Trem-O-Nator, the oscillator continues to run all the time and only the blinky LED is stopped. This insures instant on when you step on the F/S.

Just throwing a guess out here, but doesn't the cable from the amp to the footswitch also add some capacitance? I'm not sure it would be significant, but it's still going to have at least a minor tonal impact? No? Especially with two signal paths, the trem and reverb both going through the cable to the switch.

~Phil

[sluckey]

There probably is some capacitance in the cable. Maybe a few picofarads. Do you think that's gonna have much effect?

Now, if his circuit is wired differently than his schematic, that's a different ballgame. Here's his schematic...

[pompeiisneaks]

Oh but that's just the trem side, didn't you say there was a reverb side? Or is the reverb signal path exclusive from the trem path? (not looking at the whole schematic and just guessing, badly ) I do see how the footswitch on the LED side of the LDR would be out of the signal path though.

~Phil

[Bombacaototal]

Thanks for the help. Indeed the trem is wired exactly as per schematic. I will try the 220pF to ground and report back on the pop.

Yeah I'm puzzled as well. I will try the ftswtch disconnect without turning off a few times and double check if I continue hearing the same thing.