Eliminating perceived volume drop on an optical tremolo

[HeavyFog]

Any ideas on what i can do to eliminate this? I'm in the process of putting together and testing a valvecaster/tremolo combo and the volume drop with the trem engaged is way to high for practical use. The trem is located right after the tone control and before the volume and its set up like this:



I'm using a 50ka pot and a roughly 1M-15K LDR in this arrangement with a 3mm clear blue led connected the the lfo from rick holt's vintage vibe (can't post the schematic because of photobucket deleting it).

The trem sounds fantastic and choppy like i was expecting but even with the valvecaster's volume and gain on full it still can hardly get above bypass volume with the trem engaged. During the led pulse cycle the led stays on much longer than it stays off so even though the volume is returning to full levels, the time it stays there is so low that i'm getting that nasty loss of volume. With that in mind perhaps there could be a way to balance out the cycle in the led so it stays off for longer each cycle? Adding an external boost to make up for the loss is the last thing i want to do since there's already way to much going on with this pedal and i hardly have any space in it left, but its something i could pull off if i absolutely had to. I'm alss in this way too far (and i like the sound way too much) to switch it to the standard vibracster trem.  Any help?

(unfortunatly i can't post pictures because i accidentally killed my phone and with it my schematic for the build)

[PRR]

[blackieNYC]

  that up there should help.
I think you might have to have a means of boost engaged with the trem. Is the trem kicked in with another stompswitch?  Can one pole of that switch add (or remove) a trimpot that levels off the gain?

[PRR]

Passive trem is always a volume drop. It won't reach 90% at peak of trem and averages half of that, a significant loss.

However his unstated resistor (and tone stack) against the 50K pot is more loss. And not essential, because Depth can be done by dimmering the LED.

[HeavyFog]

Whoops should have mentioned the resistor. I let it out if the final build. I'm just using the diagram since its the best one i could find quickly. That and i can't post my schematic until i make up a new one. The tone control is also stock for a valvecaster. As for the depth control it works fine and the only problem i'm having is the volume drop

The trem does have its own switch so if i needed to i could add in a boost if i had to.

[PRR]

> depth control it works fine

But "the led stays on much longer than it stays off". The Depth should modulate the LED, not the audio.

[HeavyFog]

I think i might have enough spare parts to put together an lpb1 on the output after the trem. I might just try adding the depth before the led as well to see if that works any better.

[R.G.]

Tremolo can be done three basic ways: tremolo down, tremolo up and down, and tremolo down.

You have a tremolo down. This means that the uneffected.signal has some volume level and all tremolo volume changes are toward a lower level.Even if the circuit does not lower the peak level below the non-effect level, the overall perceived sound level is lower. With all volume changes down from a maximum level, the perceived volume goes down with increases in tremolo depth.

Tremolo up is done with all volume excursions being upwards from zero level, and has even worse perceived volume problems than tremolo down, as the average perceived volume level steadily increases as tremolo depth increases. This quirk means that almost no tremolos are pure tremolo up.

The real winner is tremolo up and down. Its volume changes with tremolo are ideally both to higher and lower volumes around the nominal no-tremolo level. The overall perceived sound level doesn't change, it only gets wobbled, which is more pleasing to most people. But it takes a more sophisticated - and complicated - design to get this. As a result, simple, cheap tremolos are usually tremolo down, and the better fancier ones are tremolo up and down.

It is theoretically possible to make a tremolo down or up into a pseudo-trem up and down. Doing this requires you to adjust the average "middle" level in a compensating way to keep the perceived average level about the same for listeners. In practice, this is more complicated than designing an up/down tremolo in the first place.

I really like the Thomas Organ Vox amps' tremolo circuit's sound. It's done by buffering the dry level, doing a tremolo on an inverted version of the dry signal and amplifying it, then adding it back to the buffered dry signal. The inverted, tremolo'd signal level can be up to twice the dry signal level, so when it's added to the dry signal it can have tremolo up and down. It can be a very deep tremolo.

[Kipper4]

Which has me thinking








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