fixing/improving an EHX switch blade



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fixing/improving an EHX switch blade

Postby MechaGodzilla » Mon Jul 08, 2019 9:58 am

A guy I play with has an old big box Switchblade (passive AB switcher) and amp output 1 is doing nothing. Tested for continuity, everything seems to be working fine (except grounds? everything is grounded through the chassis but my meter won't make a noise when testing between sleeve connections and chassis)

the other thing is that, as a passive switcher, it sounds pretty bad! would it help to put a buffer (eg klon-style buffer) on each output or is there no point in doing anything that doesn't have phase reversal/ground lift/fancy ABY options?
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Re: fixing/improving an EHX switch blade

Postby BetterOffShred » Mon Jul 08, 2019 12:03 pm

Explain sounds bad .. a passive switcher is fundamentally a couple of guitar cables and a toggle...

I'd test from the "in" to the out 1 through the switch, your toggle could be bad.
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Re: fixing/improving an EHX switch blade

Postby crochambeau » Mon Jul 08, 2019 12:31 pm

Is ground referenced through mechanical connection to the chassis only?

That's a terrible design from a longevity standpoint, if that's the design I'd start by running ground wires between the jacks.
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Re: fixing/improving an EHX switch blade

Postby MechaGodzilla » Mon Jul 08, 2019 12:36 pm

BetterOffShred wrote:Explain sounds bad .. a passive switcher is fundamentally a couple of guitar cables and a toggle...

I'd test from the "in" to the out 1 through the switch, your toggle could be bad.

did that, all seemed fine :idk:
crochambeau wrote:Is ground referenced through mechanical connection to the chassis only?

That's a terrible design from a longevity standpoint, if that's the design I'd start by running ground wires between the jacks.

yeah i know it sucks lol. i think i'm gonna tell him to just use something else for the time being, i don't want to start messing around inside it until I *know* why it isn't doing what it should do
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Re: fixing/improving an EHX switch blade

Postby eatyourguitar » Tue Jul 09, 2019 8:30 pm

it comes down to how tight you slam those lock washers into the metal chassis and what type of humid environment you have the chassis in. the two best arguments about using the chassis as a bus bar is first that it will have an oxide from the air, and second that it will get loose nuts and get an oxide. you don't even need to clean and sand your chassis if you just dig into it breaking through the oxide and mold release with the teeth of a lock washer. personally I always sand my boxes where the audio jack nuts go on the inside to prep them for this reason. I don't know if EH does that but I think they cast the boxes because they are owned by new sensor. it would not surprise me if they have a process to degrease them at the factory as part of the spec.
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Re: fixing/improving an EHX switch blade

Postby Bartimaeus » Fri Jul 12, 2019 9:56 am

You'd almost certainly get a better sound out of it by adding two tiny buffers between the switch and jacks, one for each output. This won't fix any phase or ground problems of course, but it'll mean you don't have any tone suck. And that'll help you hear the other problems if they exist haha

If continuity is all good then test the footswitch and see if that's the problem. If it's a dpdt switch, maybe just swap in a 3pdt and add an LED indicator.

Having a shared ground through the enclosure means you can't add a ground-lift switch unless you replace the jacks, which is frustrating since ground-lift can often help when using an aby for two amps.
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Re: fixing/improving an EHX switch blade

Postby eatyourguitar » Fri Jul 12, 2019 5:08 pm

https://lehle.com/EN/Lehle-P-Split-II

there is also this thing that has a transformer in it on only one of the outputs that will eliminate any potential (pun intended) problems with ground loop hum. that way you don't actually use the wall of the building as an audio conductor by using a ground lift switch.

or you can go with plastic jacks and 3PDT passive switching.
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Re: fixing/improving an EHX switch blade

Postby MechaGodzilla » Fri Jul 12, 2019 8:40 pm

At the minute, the solution is... use a zvex SHO with 2 outputs as a splitter instead!
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