software

Artie's effects bypass box worked so well I now want to build an amp switcher box so I can stomp using my DD-5 as the output to my amps. Can someone give me schematic for it? I want to be able to turn each amp on and off with 2 switches. I assume you just plug the guitar into a stereo jack and then run each pole to separate switches and then to 2 output jacks. But I don't know how to wire the terminals on the stomp switches or how to ground the jacks.

Thanks in advance for any help.
I've gotta go to work, I'll check this tonight.

Actually, its not quite that simple. You really don't want to connect the grounds of the two amps together. Let me see if I can doodle something up, and post it later.

You're talking about a guitar A/B box, right?

Edit: Ok, I've got it drawn up. It'll require a 3PDT footswitch. I'll post the diagram when I get home tonight.

Wow quick reply Artie. I was afraid you were going to say something like that. I want to be able to plug my guitar into the box and then hook the box up to 2 amps and switch them in and out with a stomp switch assigned to each amp.

Its not really difficult. It just needs to be done just right. And it requires a 3PDT switch, as I editted above.

Thanks Artie. Yeah I want to able to use both amps at the same time or one at a time, so what is called A/B/Y box I guess. Anyway thanks alot. I'll check it out later tonight.

Ah . . . both at the same time. Thats different. I'll go ahead and post the simple A/B diagram anyway, but A/B/Y is a little more difficult. The problem is, I don't know any inexpensive way to overcome the quot;common groundquot; problem of having both amps connected at once. It may not be that difficult, I just haven't done it, and its not as simple as it sounds.

I'll see what I can come up with.

btw - As an example, look at this website:

Jensen Transformers

Scroll down to the application note AS013: JT-11P-1 in 2-Way Passive quot;Guitar Splitterquot;

Download, and view that PDF file. Thats one way to do it . . . that uses a $70 transformer to isolate the grounds.

You can also use this- from : localhost/for a simple A/B box.
However, building a clean A/B/Y is much trickier as it requires a transformer, and several other components.
The transformer will provide isolation of the two outputs to prevent hum coming from the amps that is sometimes caused by ground reference differences in the amps.
There probably are several A/B/Y drawings out there on the web- have fun!EDIT- OOPS- I didnt see that the previous post had most of this info in it already.Dennis

OK thanks guys. This may be one to put on the back burner for a while, but I look forward to any ideas you come up with Artie.
Could you hook up the stereo jack to two mono jacks with no switching and just run both amps all the time?

Assuming that the jacks are isolated from the case, wouldn't a ground lift (for one of the box's outputs, not the amp) work--kinda like the trick where you disconnect the ground at one end of a guitar cable? The quot;liftedquot; amp would still be getting a signal that has a reference to ground but not through the signal cable.


Originally Posted by ProTonePedalsEDIT- OOPS- I didnt see that the previous post had most of this info in it already.

But its always nice to have confirmation. Originally Posted by El DoradoOK thanks guys. This may be one to put on the back burner for a while, but I look forward to any ideas you come up with Artie.
Could you hook up the stereo jack to two mono jacks with no switching and just run both amps all the time?

Not really. I mean, you can try it, but you risk having a nasty buzz/hum in both amps.


Originally Posted by ArtieTooNot really. I mean, you can try it, but you risk having a nasty buzz/hum in both amps.Exactly.


Originally Posted by alecleeAssuming that the jacks are isolated from the case, wouldn't a ground lift (for one of the box's outputs, not the amp) work--kinda like the trick where you disconnect the ground at one end of a guitar cable? The quot;liftedquot; amp would still be getting a signal that has a reference to ground but not through the signal cable.

I didn't catch this the first time through. Thats not a bad idea and could work. You'ld just have to try it and see.

Here's the simple A/B box. I posted it in another thread:

Simple A/B box.

The problem I've run into with simple circuit AB boxes is ground loops and hum. It's so irritating that you may be better off buying something with isolated transformers and ground lifts. The best is a Lehle Amp Switcher, but they're expensive.

Check into the new George Lynch Morley Tripler. For $99 you can switch between 3 amps, or combinations. Plus each channel has a trim pot. It may be what you need.


Originally Posted by GearjoneserThe problem I've run into with simple circuit AB boxes is ground loops and hum.

The one I just posted should alleviate both those problems. But I must concede, at present, the design exists only on paper . . . er . . . CRT.

GJ is right...AB boxes always seem to make noise! Mike Fuller has posted on his site a very simple AB box that he says is very quite. He has even posted a parts list and Mouser part numbers...it costs less that $30.00 to build it, and I hear good things...I will be building 2 of them very soon!

Almost ever brand I've tried either makes a nasty hum, or even worse, I shock my lips on a mic! LOL Then my face becomes the ground! ha ha

Hmmm . . . his design still connects the two grounds together. Mine isolates the grounds with a smaller, simpler parts count. My design also mutes the unused input, and only requires 3 mono jacks. For some reason he uses a stereo input jack, but doesn't use the extra lug. Odd.

quick question-would you still need all this fancy stuff to prevent noise when switching between 2 channels of one amp? IE: normal and vibrato inputs of a BF fender amp

Probably not. Both channels on a single amp would already share a common ground. So the next consideration is, does each channel have its own gain-stage? If it does, you'ld probably still want to mute the unselected channel.

So, a simple DPDT switch would fill the bill.