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Post subject: Foot-switch Query
Posted: Tue Jan 31, 2017 2:21 pm
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Like many of us I have membership in a couple of other forums besides this one.
That said, I have not run into any other forums with better info on amps, that a layman can comprehend, than this one.
There are some pretty tech-savvy forums out there and I do lurk once in a while but much of it is over my head.

(I may be an amp snob and I do have some know-how but I don't pretend to be a full fledged amp tech.)

I ran across a discussion about using a simple latching foot-switch on a non-switching amplifier.
The theory goes, if you have a single channel amp and it has two or more inputs with one being higher gain than the other, you can plug into the low gain input with your guitar and then plug a foot-switch into the high gain jack.
This is said to allow you to switch between the inputs to achieve a clean-ish boost of 3dB or whatever the difference is between them.
On the one hand it sounds like a great way to get a boost without buying a pedal because a simple one button foot-switch would be so much cheaper.
On the other hand I have no desire whatsoever to experiment with something like this without first hearing from our local pros here on the board.
I know we used to run a 6" jumper patch sometimes on the 4-jack amps of old but the switch idea gives me pause.

Anybody ever heard of doing this?
Does it make sense from an amp design perspective?

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Post subject: Re: Foot-switch Query
Posted: Tue Jan 31, 2017 2:48 pm
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The cable typically used to connect a footswitch to an amp (conventionally or otherwise) is not shielded. Thus if you use it for the purpose you hypothesize, you can expect lots of hum, buzz, and other extraneous noise. As to whether or not it would actually work per your theory, I do not know. I would opine that it would depend upon how the amp's two input jacks were configured.

Arjay

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Post subject: Re: Foot-switch Query
Posted: Tue Jan 31, 2017 5:00 pm
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A foot switch on high gain input !

A basic footswitch is a contact wich you can close or open.
A input jack have alway a shorting contact to ground thru a 1 meg resistor when no wire ( guitar ) is plug to stop hum and noise.


My understanding;
With FS contact open is plug to the jack you'll hear noise, like guitar wire not plug at guitar en.
With FS contact close, it like the input jack shorting contact, you'll get no sound.


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Post subject: Re: Foot-switch Query
Posted: Tue Jan 31, 2017 5:23 pm
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BMW-KTM wrote:
Like many of us I have membership in a couple of other forums besides this one.
That said, I have not run into any other forums with better info on amps, that a layman can comprehend, than this one.
There are some pretty tech-savvy forums out there and I do lurk once in a while but much of it is over my head.

(I may be an amp snob and I do have some know-how but I don't pretend to be a full fledged amp tech.)

I ran across a discussion about using a simple latching foot-switch on a non-switching amplifier.
The theory goes, if you have a single channel amp and it has two or more inputs with one being higher gain than the other, you can plug into the low gain input with your guitar and then plug a foot-switch into the high gain jack.
This is said to allow you to switch between the inputs to achieve a clean-ish boost of 3dB or whatever the difference is between them.
On the one hand it sounds like a great way to get a boost without buying a pedal because a simple one button foot-switch would be so much cheaper.
On the other hand I have no desire whatsoever to experiment with something like this without first hearing from our local pros here on the board.
I know we used to run a 6" jumper patch sometimes on the 4-jack amps of old but the switch idea gives me pause.

Anybody ever heard of doing this?
Does it make sense from an amp design perspective?


I'm prolly missing something here... but, can't you use an ABY switch? Instead of plugging the two outputs into two amps --- plug the two outputs into the two different inputs on a single amp?

Not sure if this is going to cause a ground loop, but there must be a way that the ABY pedal avoids loops between two amps?


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Post subject: Re: Foot-switch Query
Posted: Tue Jan 31, 2017 5:39 pm
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BMW2002Ti wrote:
Not sure if this is going to cause a ground loop, but there must be a way that the ABY pedal avoids loops between two amps?


The A/B/Y types offered by Radial feature a switchable isolation transformer to eliminate ground loops.

Arjay

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Post subject: Re: Foot-switch Query
Posted: Tue Jan 31, 2017 7:20 pm
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Thanks guys, I kinda thought it might be a bunch of BS but I wasn't sure.
stratele went where I was thinking this would go.

My thought was that a switch wouldn't be the same as an old school jumper because it would be isolated to one input only.
- Open or closed, the jacks would see no difference in signal.
- It would be either like no input at all or a guitar plugged in with the volume on the guitar rolled all the way off.
- I'm assuming Arjay and stratele's noise concern would be from the switch cabling acting as an antenna.

Is my thinking pretty much correct here?

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Post subject: Re: Foot-switch Query
Posted: Tue Jan 31, 2017 7:48 pm
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Joined: Wed Mar 31, 2010 12:48 am
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BMW-KTM wrote:
I'm assuming Arjay and stratele's noise concern would be from the switch cabling acting as an antenna.

Is my thinking pretty much correct here?


100% correct.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Foot-switch Query
Posted: Tue Jan 31, 2017 7:50 pm
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Joined: Tue Jan 31, 2017 3:49 am
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I have an old 80s era Peavey amp that works close to how you describe. Plug into the low gain and put a mono 1/4" single latching footswitch into the high gain and it will switch into overdrive. But...for some reason the manual says to only plug the jack in until you feel the first detent, and not all the way in.
It's a Peavey Decade if you want to research this idea further.


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