Fender 68 Vibrolux footswitch

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LucyTheSpud
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Fender 68 Vibrolux footswitch

Post by LucyTheSpud »

Recently went and bought a Boss FS-7 to pair with my Vibrolux as i wanted a switch with LEDs and a detachable cable for pedalboard friendly use.

Its a TRS plug on the amp, and a TRS out on the footswitch, but seems to not be working right.

1) Trem is on when the light is off, off when the light is on. Polarity switch fixes it, BUT makes the reverb do that instead on the other button.

2) Huge amount of noise when i switch the reverb on. Like, bad earth noise.

Cannot find anyone else on the ol' google that has asked the same thing. The TRS cable I have is an old one that SHOULD work fine, but may be the broken piece of the puzzle? Im currently making a dual amp+footswitch+pedal power snake so don't have another TRS to test until that is done, so annoyingly not an option.

Does anyone else use the Boss footswitches with this style of amp? Any one else have issues? Heard of amy issues? Help!

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RectifiedAmps
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Re: Fender 68 Vibrolux footswitch

Post by RectifiedAmps »

This could be due to how the trem and reverb are switched on/off - grounding the trem jack turns the tremolo ON whereas grounding the reverb jack turns the reverb OFF, so the FS-7 would light up when the Trem is off and Reverb on, or vice versa if polarity is reversed. The hum issue for the reverb might be due to poor/no shielding on the TRS cable, or an issue with lead dress inside the footswitch where the reverb circuit is too close to the DC supply. When 'on' the cable to the footswitch is like a giant antenna for the grid of preamp tube V4 - it can be pretty sensitive.

LucyTheSpud
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Re: Fender 68 Vibrolux footswitch

Post by LucyTheSpud »

RectifiedAmps wrote:This could be due to how the trem and reverb are switched on/off - grounding the trem jack turns the tremolo ON whereas grounding the reverb jack turns the reverb OFF, so the FS-7 would light up when the Trem is off and Reverb on, or vice versa if polarity is reversed. The hum issue for the reverb might be due to poor/no shielding on the TRS cable, or an issue with lead dress inside the footswitch where the reverb circuit is too close to the DC supply. When 'on' the cable to the footswitch is like a giant antenna for the grid of preamp tube V4 - it can be pretty sensitive.
Ok... so? Options? :lol:

That level of techhy is above me. Do you think the footswitch isn't suitable for the job? Dodgy cable?

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RectifiedAmps
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Re: Fender 68 Vibrolux footswitch

Post by RectifiedAmps »

It could be the cable shielding or it could be the footswitch. Unplug the footswitch but leave the TRS plugged into the amp and see if the reverb makes the same hum. Usually an old-school two button latching footswitch (no LEDs, etc) works fine with minimal noise issues so I'd say try that - should be ~$50 from your local shop. Make sure it's one with buttons that 'click' when you press them- i.e. not the momentary-type switches that don't click. Or make one yourself out of a couple SPST pushbutton switches.

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