Blackface Tremolo Issue

[Bombacaototal]

This is a bit of an odd one. I built a Deluxe Reverb clone which is currently on loan to a friend (who lives in a different city). After lockdown I hope to take it back.

Everything in the amp works fine except for a weird issue with the tremolo. For the tremolo circuit I used a 50K Intensity SPST pot to be able to disconnect it entirely from the circuit. Whenever the tremolo circuit is disconnected via SPST, there is an audible intermitent ticking sound, which responds to the speed pot. With the Tremolo in the circuit (ie NOT disconnected via SPST)the ticking is not existent.

With the tremolo disconnected via SPST when unplugging the footswitch (which is a stereo fender one: with one side the reverb and the other the tremolo) there is no ticking at all, and the amp becomes bigger and responds much better.

The ticking with the tremolo disconnected via SPST and the footswitch plugged only starts when the amp has been ON for a fair bit of time (circa 10 minutes). Bypassing the tonestacks and reverb circut make no difference.

Tried different footswitches with the same results

Any ideas of what may be happening here? It would be easier if I had it on my table but just wanted to have an idea of what to tackle once I meet this amp again.

[sluckey]

Unplugging the footswitch will kill the oscillator and eliminate the ticking. With the footswitch plugged in, just kill the oscillator with the footswitch to eliminate the ticking.

That switch on the INT pot is a popular mod to give a gain boost. While it does kill the tremolo it does not kill the oscillator. Thus the ticking. I don't see this as an issue because when you have the boost engaged you obviously can't have any tremolo, so just eliminate the ticking with the footswitch.

Might be a good candidate for a Trem-O-Nator?

[Bombacaototal]

Unplugging the footswitch will kill the oscillator and eliminate the ticking. With the footswitch plugged in, just kill the oscillator with the footswitch to eliminate the ticking.

That switch on the INT pot is a popular mod to give a gain boost. While it does kill the tremolo it does not kill the oscillator. Thus the ticking. I don't see this as an issue because when you have the boost engaged you obviously can't have any tremolo, so just eliminate the ticking with the footswitch.

Might be a good candidate for a Trem-O-Nator?

Sluckey, your insights on the tremolo circuits are great always! Many thanks for the help. I didn’t realise that removing the Footswitch would kill the oscillator and having the footswitch connected and the tremolo effect engaged even with the spst cutting it from the circuit would still impact the output to the PI.

Makes sense, that the cure would be to either not use the footswitch as there is no point given the tremolo is disconnected, or if the footswitch is plugged to kill the ocilator via the switch

Trem-o-nator is a much better solution for sure!

[Bombacaototal]

Sluckey, your suggestion works great!

One other thing my friend noticed is that, on the configuration with the tremolo in the circuit (with the spst on), and the footswitch connected, and the effect active, whenever he turns the speed to maximum, whenever he gets to the end of the pot there is an audible pop sound.

[sluckey]

Is it a single pop? Does the trem continue to work after the pop? My first suspect is the pot. I would deoxit and/or replace it.

[Bombacaototal]

Is it a single pop? Does the trem continue to work after the pop? My first suspect is the pot. I would deoxit and/or replace it.

It is just one pop every time it reaches maximum. So if you turn to max it pops then going back till 12 o’clock and going to max again it pops again and so forth

Obviously with the footswitch disconnected there is no issue

I will ask him to test if trem continues after the pop and will advise

[Bombacaototal]

The older Deluxe reverb amps have the 100k resistor to ground right after the 3M speed (like I did) and the newer reissue amps seem to have moved the 100k before the 3M speed pot and having the pot going to ground.

Would this make any difference relating to the reported issue?

[Paul G.]

Not related to the SPST (or maybe it is), the cure for ticking tremelo is 1) lead dress, moving the wires to the intensity control may lessen or eliminate the ticking. If that doesn't help a .01uf or .022uf cap across the 10M resistor will eliminate the ticking. I've read that a .01uf between one leg of the lamp and photoresistor will also work although I've not tried that.

[Phil_S]

I believe this could be your problem and there is a nice picture of how to deal with it, near the top of the page.
http://www.timeelect.com/jbl-twin.htm

[Bombacaototal]

Thank you Phil and Paul, but I do not have the usual blackface ticking problem.

Whenever the tremolo is IN the circuit everything works fine as it should. As Sluckey mentioned the issue only occurs when the oscillator is active and the tremolo is disconnected from the amps circuit, which seems to be a “design” problem due to the added flexibility of increasing the amp gain by disconnecting the tremolo.

My only issue now is the pop on the speed at maximum setting which I am trying to sort.