Radio-signal-proofing a Tone Machine clone?

[jrmy]

Hey hey hey - so, I recently had a Tone Machine clone built by a forumite. It sounds awesome, but when I brought it to record last night I got MASSIVE radio signal bleed-through. I was able to reduce it a bit by turning down the gain, and I think we got it controlled to the point that the recordings will be fine, but I'd rather not have the bleed-through at all if possible.

Does anyone here know if Tone Machine circuits are especially radio-receiver-ish? I remember my old green Russian Muff used to get that way, but never worked out a way to fix it. My bandmate suggested lining the inside of the enclosure with copper. Has anyone tried this? Would it work?

[eatyourguitar]

lol @ lining the inside with copper. thats for guitars that are made of wood. you enclosure is metal so no worries. the first thing to try is use all shielded cable. I get mine from small bear but you can cut up any shielded guitar cable. if its a crappy cable, test the resistance of the shield to make sure its not breaking down into dust. rewire the pedal and put it all together to test. don't test the pedal with the back plate off. also, extra drill holes with nothing there should be avoided. since you will never make it radio proof, you just want to minimize the drill holes and use metal jacks to ketch even more RFI. then the remaining RFI needs a place to go. so in the case of shielded wire, it goes into the shield and not your board. you can also modify the circuit with high frequency filtering. there is no reason to amplify something in the Mhz range so just filter it out. use an RC filter calculator on the internet. or look at how to run a cap parallel to your feedback resistor on the opamp.

[Chankgeez]

I have a Prescription Electronics Experience which is based on the Tone Machine. When the Tone and Sustain knobs are cranked I pick up RFI. I asked the builder about it and he said that it's normal. I think it's just the nature of that circuit. IDK? So, I back those controls off until they're just shy of picking up RFI. Are there particular settings that you're getting more RFI than others? Would it be possible to just avoid those settings?

[John Lyons]

Try a 1k resistor in series with the input with a 470p cap to ground.
The input to the circuit would connect to the junction of the two.
This is a small low pass filter which should knock out any radio freqs.

[jrmy]

Thanks all - I have zero clue about electronics (hence the copper lining idea), so this is all a great help. I'll see about getting someone to try the 1k resistor idea first, since it seems like the easiest possible fix. If that doesn't do the trick, I'll try others.

Chankgeez, pretty much all settings are picking up noticeable RFI, though when I'm playing it's not a problem... but when notes die out or are sustained it can be. So... let's hope the 1k resistor idea works!

[eatyourguitar]

Try a 1k resistor in series with the input with a 470p cap to ground.
The input to the circuit would connect to the junction of the two.
This is a small low pass filter which should knock out any radio freqs.

great advice. he has done the RC filter for you right there. you can wire it directly on the input jack point to point. very easy to do. only $0.04 in parts! report back your results

[John Lyons]

BUT, if you do it at the input jack you are affecting the whole pedal, bypass and all.
Better to tack the cap from the board input to ground and then break the connection from
board IN an put a 1k resistor in line, then to the board.

[jrmy]

Innaresting. I'm gonna have to print this thread out when I take the pedal into the shop...

[Chankgeez]

Yeah, hopefully these modifications suggested by eatyourguitar and John Lyons will fix the problem.

I have other pedals that pick up RFI at certain settings, but it's usually only within a fairly small range. Picking up RFI at all settings is no fun. If you're set on a Tone Machine and these fixes don't work for you, just get a different Tone Machine clone. There's no shortage of 'em and one or another is bound to get along better with your equipment.

[eatyourguitar]

BUT, if you do it at the input jack you are affecting the whole pedal

I totally forgot that you might not want it on the bypass. nice. it also made me think of something else. if you filter it at the input jack you still have 2 inches of cable to pickup RFI after the filter. therefor making the filter useless. so maybe do it at the footswitch if you have shielded cable or do it at the board if you dont.

[Fuzz_Pi]

This makes me WANT a tone machine.

[Chankgeez]

Dudes, check this out:

http://www.fmogearshop.com/store/product.php?productid=553&cat=3&page=1

[eatyourguitar]

at first glance, I thought it was a polymoog resonator. makes anything sound like strings and it has identical controls.
[youtube]http://www.youtube.com/watch?v=_XUiJi5153Y[/youtube]

[jrmy]

Whoa.

That appeals to every single part of me.

Pricetag aside, DO WANT!

[Chankgeez]

Sometimes the prices on FMO are astronomically ridiculous. Sometimes not.

I don't think that Emmons String Machine is too overpriced. Especially considering that it looks like it's in good shape and you never see those things for sale. Definitely an impractical collector's piece, but a really sweet one at that. What can you do? It'd be awesome to play around with that. Crazy, just crazy.