software

Alright i got this idea from an item i saw on ebay.
The basic function is a volume box that goes into the FX loop of a tube amp to allowing the tubes to be driven but it controls the overall volume (like a volume pedal).
I drew up a diagram to figure out the wiring, all i figure that i need is two jacks, a volume pot, and some type of housing. here's the diagram, is my wiring correct? this should work right?

The only way I see this working better than a master volume (I'd guess your amp has one since it has an FX loop) is if you have a tube-driven FX loop. Other than that, you're just adding another master volume control.

If this goes between your guitar and your amp, how is it any different to just using the volume control on your guitar?

put a bypass switch and it will be much more useful. you dial in how much volume you want to cut with the pot activated, but with the pot on you get a relative boost.


Originally Posted by ForbesIf this goes between your guitar and your amp, how is it any different to just using the volume control on your guitar?

Good question. it will help me to clarify.
i want this to be placed in my FX loop of my amp rather then being between my guitar and amp.
My purpose is to get all the sweet spot of the driven tubes while not having to have the excessive volume that goes with it.


Originally Posted by Quencho092put a bypass switch and it will be much more useful. you dial in how much volume you want to cut with the pot activated, but with the pot on you get a relative boost.

Thanks Quencho.
If i put a bypass switch in does it have to become powered (with an AC adaptor)?
Does anyone know how to wire that bypas switch in?

unless you want an LED light, i dont think it's necessary. The bypass will simply act as a 2 way switch, volume pot in the circuit, and no volume pot in the circuit.


Originally Posted by bbking1021My purpose is to get all the sweet spot of the driven tubes while not having to have the excessive volume that goes with it.

In case you missed my statement above, it's not going to work the power tubes any more than they are with the master volume turned down.

Yeah...I don't get it.

yea....your gonna need to put that between the amp speaker out, and the speakers........and that would be a big no no lol......you need a attenuator

The tubes need to see a hot signal to get saturated, not a high level on the volume control. Turning down the volume before hitting the power amp isn't going to make any difference to the tubes. To get the power tubes saturated, but to not have the volume be so high, you'll just have to get an attenuator.

alrighty, thanks guys for the suggestions. I just wanted to see if it was feasible but by the looks of it really isn't any different then a master volume control like aleclee said. I was thinking about getting an attenuator but not right now but maybe in the future. Thanks again everyone.

As others have stated, you'll only be driving the preamp tubes harder.

But, that diagram looks wrong to me. Both grounds should go to the right lug, the input hot to the left lug, and the output hot to the middle lug.

I made one of these too. I have info about it here with a diagram.

from : localhost/home.earthlink.net/~ehansen3/diy/fxloopbox.htm

The main purpose of it is to help with those amps where 0 is off and 1 is still too damn loud due to the taper of the master volume pot, like what Fender amps have.

sweet erik, thanks for the info. but still the volume box won't allow you to drive the poweramp tubes more right? just the preamp


Originally Posted by bbking1021sweet erik, thanks for the info. but still the volume box won't allow you to drive the poweramp tubes more right? just the preamp

It doesn't even allow you to drive the preamp tubes more. The preamp tubes are driven by the amount of preamp gain or volume you allow plus whatever other OD pedals or boosters you use to slam the front end harder.

The effects loop of your amp is between the preamp and poweramp. On master volume amps, like my Marshall, the master volume is right at the tail end of the preamp section but after the effects loop. Essentially, using this box just gives you another master volume. It won't drive the power amp tubes any harder because even though you crank the amp's master volume to say 5, with this box in the effects loop, you're pulling back some of that signal before it even gets to the master volume and then on to the power amp section.

It's pretty much for what my project page says. I find it useful considering my Marshall's master volume is kinda touchy.


Originally Posted by DeadSkinSlayer3But, that diagram looks wrong to me. Both grounds should go to the right lug, the input hot to the left lug, and the output hot to the middle lug.

No, he does have it wired correctly, but like everyone else said, it won't do what he thinks.

Really? It must be quite different from a standard volume pot in a guitar.

How about this. I'm not talking about slammin the front end, but how about placing the SD Pickup booster in the fx loop, wouldn't that drive the pa tubes more (max 20db)? This is after the preamp gain and voicing and used as a clean boost just prior to the return jack and power amp tube(s). Actually I prefer to place a parametric eq in the fx loop, and now I'm suggesting putting the booster last in the loop. What are your opinions? Is this quite different from the original thread question?