Ampeg G S-12R tremolo bug

[drewl]

Hey all,
Fliptops has a replacement unit for the tremolo, you guys know of any others that would work?

I'll crack it open, see if the bulb can be replaced.

Tried to see if I could get a Vactrol LDR to work, no dice.

Nice that Fliptops has replacements

[drewl]

Aw dang, think the photo-cell is bad.

After cracking it open, the neon bulb lights and varies in luminance but the cell resistance remains around 2k ohms whether it's dark or light.

[Enzo]

I recently bought a selection of photocells from Jameco. We were going to try to make a replacement for the dual trem opto in my Ampeg B18X. Fortunately FLop Tops came up with more of those optos.

But Jameco has been my traditional source for photocells.

https://www.jameco.com/shop/StoreCat...type=jamecoall


No reason you can't put a new cell in your bug if the light works.

[drewl]

Actually after experimenting with some different Vactrol, a VC9 sounds incredible with a little tweaking.


Thanks.

[drewl]

So while trying to mount the Vactrol vc9 I had broken a leg off.
None of the other vc9's or 4's I had we're working as good so I ordered the Fliptops replacement.

The thing ticks like crazy, worse than any Fender.

Swapping the input leads helped a little.
So did removing the .22 uf cap for the after beat switch.

No other tricks I've tried have helped.

Any ideas?

[Chuck H]

The thing ticks like crazy, worse than any Fender.

Swapping the input leads helped a little.
So did removing the .22 uf cap for the after beat switch.

No other tricks I've tried have helped.

Any ideas?

The trem isn't in the signal chain. So any tick has to be:

1) Transferring through the power supply.

or

2) Riding on a shared ground resistance.

You could try bridging a 100n cap across the filter that feeds the trem oscillator to improve decoupling of higher frequencies. Also, most trems have the footswitch grounded at the chassis in a different place than the rest of the circuit. I don't know that this is always a problem, but a cap to ground from the hot lead of the switch jack solved the problem for me once. I think I used a 220p cap. Not even close to large enough to mess with the oscillator. Then there's grounding. Make sure nothing in the trem circuit is sharing a ground with the preamp or it's filter nodes. Sometimes even if there is chassis distance shared by both ground circuits it can be enough to make an audible click.

HTH

[drewl]

I did try moving the ground with no change.
When you say "add a 100n cap across the filter" you mean the plate supply? Or at the filter cap for that node?

Thanks for the suggestions, I will give them a try tonight.

[Chuck H]

When you say "add a 100n cap across the filter" you mean the plate supply? Or at the filter cap for that node?

I mean the power supply filter cap.