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  #1  
Old 02-22-2011, 06:39 PM
groovybenny groovybenny is offline
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Default Midi control 1/4 jacks on guitar amp.

Hi,

I want to be able to switch my guitar amp channels using midi, but I'm not entirely sure exactly what to do, so...

The amp uses 1/4 mono jacks for switching channels. I'll need 3 mono 1/4 jacks from the midi decoder.

Any help with making this will be appreciated! Also, is it possible to have it also switch one or two pedals off/on like the iPatch?

Cheers!
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Old 02-22-2011, 10:03 PM
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Hi Benny,

During normal use, the 1/4" jacks on the amp are connected to a footswitch that is a simple normally-open switch, correct? (Sorry for my ignorance!)

In that case, if you have an MSA-R or MSA-P, you'll simply connect the tip and ring to the "A" and "B" terminals of the MSA output. Or visa-versa. The MSA-P and MSA-R terminals are just like the terminals of a simple toggle switch.

To switch all 3 output states at once, check out "preset operation" in the MSA firmware manual. This way, you can assign an MSA 8-output output state to each program number 0-127.

Does this help? Let me know...
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Old 02-23-2011, 03:27 AM
groovybenny groovybenny is offline
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Thanks for the quick reply!

Anyway,

This is the footswitch for my amp:
http://www.mesaboogie.com/Product_In...tswitch-LG.jpg

Pressing the momentary switches changes channel/eq etc.

So I just wire a 1/4 mono jack to the relay output of the msa-r (or p which is better?). Simple as that? Will popping will be a problem?

I'm inexperienced at electronics, but I'm keen on doing this if I have specific instructions on how to do this, as I don't want to spend the money on a msa and then realise its too hard to do. If theres anything you need to know about the amp etc just let me know.

Thanks again for the help.
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Old 02-23-2011, 03:35 PM
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Quote:
Originally Posted by groovybenny View Post
Thanks for the quick reply!

Anyway,

This is the footswitch for my amp:
http://www.mesaboogie.com/Product_In...tswitch-LG.jpg

Pressing the momentary switches changes channel/eq etc.

So I just wire a 1/4 mono jack to the relay output of the msa-r (or p which is better?). Simple as that? Will popping will be a problem?

I'm inexperienced at electronics, but I'm keen on doing this if I have specific instructions on how to do this, as I don't want to spend the money on a msa and then realise its too hard to do. If theres anything you need to know about the amp etc just let me know.

Thanks again for the help.
Hi Benny,

I'm not an expert on guitar amps, but my understanding is that the footswitch jack on a guitar amp simply monitors the switch state (open vs closed)--the audio signal is not routed thru the footswitch. So things like popping shouldn't be a problem.

I'd recommend sending a message to wabbitguy or the others who participated in this thread:

http://forum.highlyliquid.com/showthread.php?t=428

They have more experience with guitar amps.

I think the MSA-R would be the best choice in this application.

The A/B terminals of an MSA-R are just like the terminals of those stomp switches on the foot controller. So, if you can determine how the stomp switches in the foot controller are connected to the 1/4" jack, then you can simply copy the circuit, but substitute the MSA-R outputs for the stomp switches. That gives you instant MIDI control. Does that make sense?

If you can post a schematic for the (non-midi) footswitch controller, I can very easily show you how to convert the circuit to MIDI control via the MSA-R...
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Old 02-23-2011, 05:27 PM
groovybenny groovybenny is offline
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Here is a schematic:

http://i80.photobucket.com/albums/j1...yfunk/SPDT.gif

At the moment I may just stick to using the one relay, and add more on later, as I only really use two channels of my amp and I only need one relay to switch between them.

I appreciate you help!
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Old 02-23-2011, 10:22 PM
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This is the exact equivalent to the diagram in your post. The difference: instead of using your foot or your finger to "flip the switch", you can use MIDI commands.

Hope this helps.
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Old 02-27-2011, 08:15 AM
groovybenny groovybenny is offline
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Thanks!

Bit of a late reply for me, but would you recommend using batteries or a power supply? How long would the batteries last if they had an off/on switch? Cheers!
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Old 03-02-2011, 03:37 PM
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Quote:
Originally Posted by groovybenny View Post
Thanks!

Bit of a late reply for me, but would you recommend using batteries or a power supply? How long would the batteries last if they had an off/on switch? Cheers!
In this type of application (where relays are likely to be set to "on" for long periods of time) I'd recommend using a power supply. A 9VDC "wall wart" would work fine.

A battery would work fine, but it's tough to predict the exact lifespan of a battery--it depends a lot on the usage pattern.
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Old 06-03-2011, 02:39 PM
groovybenny groovybenny is offline
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Hi John again,

I really want to get this, but I'm scared away because I have no electronic knowledge! How much will it cost me to have you solder the 1/4 jacks/midi and everything else so I can just have to get enclosure? I can find the you the right jacks that I need. Appreciated!
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Old 06-06-2011, 02:21 PM
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Benny,

I'd like to encourage you to give this a try. The wiring will not be complicated at all, and we'll be able to draw up some complete wiring diagrams for you. Plus, you're welcome to take advantage of the money-back guarantee if things don't work out.

We can discuss some custom pre-wiring, but the extra cost will be much greater than that of the MSA and the other hardware required for the project. Please send a private message if you'd like to discuss further.
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