Channel switching – opto isolator?

[Buddha's Guitar Tech]

I need to take the next step and build a two-channel amp.

I see Soldano use VTL5C1 optocouplers – four of them. They're not exactly cheap.

Any suggestions for fast, silent switching methods?

CMOS any use?

[Stevem]

Mojotone has a couple of nice ways to go and so does London amps !

[bal704]

If you're just looking for just a basic channel switcher, the weber channel switcher is nice. It's quiet, reliable and cheap.

You can buy one pre-built if you want, and just install it where you have space.

[Buddha's Guitar Tech]

Dang. Out of stock.

[roberto]

Why not relays?

[Buddha's Guitar Tech]

It's been a few years, but I could never get relays to act silently.
High-gain setup.

[bal704]

I'm not sure what the actual difference is between the high power and low power. The HP might work, as it looks the same as the HP. Might be as simple as a different relay, as the rest of the circuitry looks the same. Relays are readily available.

These are really easy to build yourself if your so inclined, as there's only a relay and 4 parts. That's what I do.

[Colossal]

It's been a few years, but I could never get relays to act silently.
High-gain setup.

Out of curiosity, did you have a "switch pop" resistor such as 2M2 to 4M7 or more on either side of the relay?

[Buddha's Guitar Tech]

I may have done. I remember (hazily) trying all sorts of things. Perhaps the relays I used were simply not very good.

Voodoo Labs use "gold contact" relays... Whatever. But even in a high-gain setting, they're silent.

[Buddha's Guitar Tech]

Oh I should also say, those VTL5C1 optos... I discovered cheaper makes.

The main idea is to select signals to shunt to ground. But if I can use a silent relay then I don't mind signal passing through it.

[bal704]

I've used this circuit in a variety of applications, including swtiching between a clean and hi-gain channel. I've never had any popping noises in any application with this circuit.

[Smokebreak]

Relays work just fine and are quiet if installed properly. Check out Colossal's boards, who posted in this thread. He is being humble but he makes great relay boards http://www.colossalamps.com/boards.html

[roberto]

Relay are dead quiet. Look at Engl amps!
I've noticed that a slight lower power supply makes them work even better bump-wise.

[JMFahey]

Checked just in case I remembered wrong: at less then $7 each Vactrols are not expensive, at least compared to the other options, and are guaranteed not to pop.

That said, buy a relay or two and try them , I guess you are breadboarding your new design before comitting to something definitive, so you can try different options.

For testing I contact cement (might use dual side sticky tape if the amp stays unmolested on my bench) the relays upside down (legs up) inside the chassis or even to a free area in a board and experiment.
Remember, as suggested by colossal, to drain any static both sides of the contacts and of course, the proper anti kick diode in parallel with the coil.

Of course getting the suggested boards will make your life easier

FWIW Vactrols are very hard to find and impossibly expensive here in Argentina so I make my own out of 5 mm LDRs , 5mm high efficiency Red Leds and a little 1/4" heat shrink tubing.
Work like a charm for peanuts.

Can make 50 or more an hour while watching TV

[Buddha's Guitar Tech]

Thanks everyone!