Channel switching on D-style amp without relays etc?

[titser_marco]

Hi!

Is it possible to have a footswitchable D-style amp without a relay, and using a standard DPDT style footswitch? I can only imagine a solution where I would need a special four wire cable (and plug) to make this happen but I was wondering if there was a way to do this using only a stereo cable going into a box with a DPDT footswitch.

Another idea I have is to just have an SPDT switch where the middle lug is connected to the PI input, while lug 1 is connected to the clean preamp out, and lug 23 is connected to the OD preamp out. To make this happen, that will mean that the clean preamp out is permanently connected to the OD preamp in. I'm worried that this might cause some loading and I am trying to avoid any signal loss and degradation with this system.

Any ideas? Would be great if you guys can send over a schem. Thanks!

Thanks!

[sluckey]

You're talking about running the guitar signal out to a footswitch and back, probably 20 or 30 feet total length. That will be susceptible to noise and line loss. Probably not a good idea.

[Garthhog]

You'd have to build it like an active effects loop... buffer on the way out, amplify on the way in, shield the HE!! out of the cable. Because of the buffer/amplifier, your channel switching scheme would color your sound, and there would be an fairly obvious difference in sound when using the foot switch versus panel switch. DC relays work great as long as the control voltage is clean.

[titser_marco]

I see. So I guess I'd really have to use a 4-wire shielded cable and a 4-pin plug then. Thanks!

[vibratoking]

Sure, you could use a BJT or FET control it with the switch. But sending the signal out and back is more than just a bad idea.

[guitarmike2107]

Relays would be much easier than dealing with the issues of taking the signal out to a footswitch.

You will need a fancy switching socket or a switch on the panel to select footswitch operation, normal or lead modes too.... for when the footswitch fails or you forget it....

[titser_marco]

Sure, you could use a BJT or FET control it with the switch. But sending the signal out and back is more than just a bad idea.

Ah now this may be something my limited skills can do!

[titser_marco]

I just realized that a relay-based system isn't such a bad idea after all/ The biggest deterrent was that based on the schematics, I saw that there was a separate power supply powering the relay. I was thinking of powering this relay with a 9v battery outside the amp and using that footswitch to house the battery. So essentially, the only thing that goes in and out of the cable from the amp to the footswitch is the 9v from the battery that powers the relay. Do you think this can work? If so, what are the specs of the DPDT relay needed for this? Thanks!

[Bob Simpson]

there used to be a site called skipzcircuits that made a pre-built fet switch board that drew a tiny amount of juice from the heater circuit.
His stuff used to be well thought of on TGP and a couple of marshall boards.
You might try a search for him...

Bob

[johnnyreece]

there used to be a site called skipzcircuits that made a pre-built fet switch board that drew a tiny amount of juice from the heater circuit.
His stuff used to be well thought of on TGP and a couple of marshall boards.
You might try a search for him...

Bob

+1 for Skip. I hope all is going well for him. I see the site is down...I bought something from him less than a year ago, I think...

[xtian]

Dave's relay boards are awesome:

http://www.colossalamps.com/boards.html

[M Fowler]

+2 for Dave's boards Colossal Amplification

http://www.colossalamps.com/boards.html

[Bob Simpson]

I agree on Dave's boards.
I've had 3 relay boards working happily for a while now.

I thought OP wanted to do it without relays.

The FET switches didn't need separate power supplies & were therefore cheaper and easier.

If we are back to relays & power supplies, Doug Hoffman's stuff looks
pretty good, as well, although I've not used them yet...

Bob