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Don't rule out using a higher quality relay. I have a Fender Prosonic on my bench right now that uses relays for overdrive and reverb foot-switching. One of Bruce Zinky's mods (if you have one of the production units) is to replace the relays with better, lower current relay. He suggests an NEC ED2-5NJ available from Mouser. Apparently Fender cheaped out on a few things when if left the Custom Shop. Go figure

Joe G

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That snubber will mainly help reduce switching clicks and pops, rather than reducing hum or rectifier buzz. Stephen's done some further tests last night and concluded that we really need to install a separate low voltage transformer to completely eliminate hum.

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Maybe I'll try a "powered" footswitch. Drive the amp's relay from a 9v battery in the pedal itself or off of the effects power supply on people's boards.
Throw a sexy, bright "Yes, I'm in overdrive" LED on there... whoa baby

Joe G

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The footswitch is coming, You guys are great

I've read similar things about relays. There are relays designed for audio applications that do a better job of isolating the coil than generic jobs. More expensive too I'm sure.

Has anyone consider a MOSFET switching rig or an opto-switch? I know Mojo has pre-built boards for those. A little more exotic & pricey than we'd want maybe, but if it works...

With that said, I'm not a fan of opto-switchers. I don't like that audible delay you get with "soft-switching". It's the one thing I detest about modern Mesa multi-channel heads (well, that & the price tags!).

Going with a separate board incorporating a small PCB mounted transformer (1.375"x1.125" x .930") & rectification/filtering. The board will be mounted vertically on the end of the chassis on stand-offs.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

That's not a bad idea..... I may try that as well....... or a gutted "one spot" type pedal PS running off the mains might be isolated enough.....

For a DIY, you can just add a jack to the back for a regulated wall wart.

I like the 9V in the pedal too but you have to consider the way the foot switch overrides the front switch. Look at the footswitch schematic. You'd need three leads down that cable to the amp.

Of course you could simplify that to do whatever you wanted.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

You're right Stephen, you would be then limited to "footswitch only" operation if you wire it like the schematic. You would have to be clever and careful about how you implement it.
On the plus side, you could probably get away with something like a shielded Ethernet cable from the footswitch to the amp (maybe not even shielded). Those are common and cheap enough, they have twisted pairs, cheap connectors, room for expansion if you had anything else to switch, etc. etc. Just thinking out loud...

Joe G

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Good idea. Custom Footswitch.

Plus - for a totally connected amp with Internet Access!! LOL

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I can always count on an engineer to come in and re-complicate things

Joe G

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Hey you give a guy a Cat 5 plug, he expects IP Access!

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

If you have 9V in the footswitch, there's no reason you can't then have a little *simple* electronics inside the footswitch to operate an LED, as well as provide a switch contact via the cable to the amp. It would only take a couple of transistors and a small relay.

Having said all that, I'm fairly well known on various BBSs for my preference to control an amp's tone with the guitar volume and pick attack. Basically, you can leave this amp with the Overdrive permanently engaged, and just control it from the guitar end. It's a very responsive amp.

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Not to go OT, but has anyone ever used a cat 5 cable for a guitar cable? I've got like 200 ft of this stuff around and I still can't get over how expensive guitar cables are.

I don't think CAT5 is sheilded (the stuff I have in my place isn't at least). That might be an issue for an instrument cable.

I have used it on longer runs for jury-rigged temporary line-level audio connections with OK results (like getting my expensive gear hidden for parties). I've also tried it for composite video & it was too noisy for even passable results. I do admit I'm a bit of a snob for this stuff though, so YMMV.

Ever tried the switching that is used in Dumbles? I always thought their switching design was pretty good. They use a DIN 5 pin but with the Triwatt you could get away with a common 3 pin XLR.

That extra transformer seems like a good idea. I have a few of those that are 12V at 100mA, flat packs. They are quite small, seems like there will be lots of room.

Both are good choices. With the XLR you could use standard mic cables, with the DIN you could use off-the-shelf MIDI cables. Both would be very heavy duty for the road, etc. The problem is someone may plug in a mic or MIDI device to either the footswitch or the back of the amp. Labeling would be key, or use odd styles like a 4 pin XLR. Great ideas though I hate using phone jacks for anything except phones and computers.

Joe G

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I purposely didn't use an XLR on my Jimmy Page for that exact reason. It probably wouldn't hurt anything if a sound guy plugged a cable into the board to it, but why take the chance...

Jimmy's used an XLR for the footswitch. I used a 1/4".....


I am still brainstorming using pedalboard power to work the relay and doing away with the pot mounted switch altogether.

Actually plugging 5, 6, 12 or 24 volts of relay power into a mic input on the board could prove to be unpleasant

Joe G

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I think it's still a good idea to have the pot-mounted switch, so that you can engage or disengage the Overdrive stage without needing to have the footswitch pedal plugged in all the time. In the amps that have the footswitch option this switch only carries DC, and not signal, and simply turns the relay ON or OFF. When the footswitch gets plugged into the jack at the back of the amp, then the pot-mounted switch gets bypassed and the external switch takes control.

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