Active Or At Least 'clean' Splitter Box

[GregP]

Hi there,

With the recent addition of the GDI21 amp sim pedal to my recording rig, I find myself missing the ability to record a clean signal for later modification. I know that there are active splitter boxes available, and that they're fairly cheap to begin with.

I wouldn't mind saving a buck or two, but considering the amount of money I spend on movies, etc., $10 saved isn't really the issue, and I'd be fine with breaking even. I'm more interested in trying my hand at making a butt-simple piece of equipment just for the sake of seeing if it can be done.

Ideally, I'd like it to be powered by 9V or 6V AC because I already have 2 spare wall-warts that I don't mind cutting the plug from, etc..

Is this doable? Easy? Futile?

Passive solutions are fine, too, but I don't imagine there being a passive solution that would be any better than simply using a Y-cable Could be wrong about that one, too.

Ideas? Pointers?

Thanks!

[ansil]

geofex.com has a nice active splitter that should run you about 6usd in parts.

[GregP]

Thanks, ansil, I'm off to check it out!

Back! Cool-- I can 'imagine' that the schematic isn't overly complex by looking at it even though I don't understand it. Now I just have to learn to read it and make a parts list and I can give this project a try.

Greg

[GregP]

This is the one that interests me:

Just the upper right. I don't need indicator lights or switches. However, the diagram isn't even labelled-- how do I find out what all the parts are? Where is the voltage coming in? If it turns out to be 9V, can I use this DC power adapter I have here, or would I have to find a different power source? Batteries aren't an option for me, though I'd be happy modifying a "Battery eliminator" adapter, as they only run $10 CDN.

Greg

[GregP]

*bump*

The rectangles marked with an "R" are 10K resistors, but is it important what type of resistor to use? Any idea what the triangles are? Sometimes they can be IC's, no?

Greg

[thedoctor]

The triangles are operational amp ICs. The resistors in this circuit only need to be 1/4 watt carbons.

[lovekraft]

I guess I must have misssed something - why do you need a splitter? Are you having ground loop problems or losing clarity when hooked in direct? If not, a simple Y-cord is a lot less expensive and probably quieter (for recording purposes) than a homebrew splitter. Actually, if you wanted to record clean and preamped sounds simultaneously, using a mixer with the preamp in the F/X loop and assigning the F/X return to a separate track is probably the easiest, simplest and quietest solution.

If you're going to build that splitter for recording, I strongly recommend that you use metal film 1% resistors, a low noise dual opamp and a hefty, quiet power supply.

[GregP]

I could be wrong about my whole concept, then-- I was told by people (and I just took them at their word) that a Y-cable will fark with the <insert technical term here> and was therefore NOT a good idea for recording purposes. It seems to be common wisdom that an active splitter IS the way to go, and that the mistake is thinking that a Y-cable will actually work.

If I'm wrong, I'll happily just buy a Y cable.

I'm not sure how the mixer would help me solve my problem, but if it COULD, that would be an even better solution.

If I hook the GDI21 into the effects loop, then I will only be able to control the wet/dry amount, which will still be a signal that gets blended into one. Ie: I'll then be able to adjust clean vs. dirty if I want to mix some clean signal back in, but I don't see how I can record the clean and the dirty as two discrete signals using the mixer I have. (A UB802).

Greg

[lovekraft]

Try this - plug the guitar into channel 1, pan it hard left and turn the F/X send to max, then plug the preamp input up to the F/X Send jack and plug the preamp output into channel 2's line input (make sure the F/X send is all the way down on channel 2), and pan channel 2 hard right. You now should have clean in the left main and dirty in the right. HTH

Edited May 8, 2005 by lovekraft

[GregP]

Yeah, physically looping it back to a different input instead of the return jack should do the trick! Looking at the mixer, another idea presents itself-- the send is mono, but the return is stereo. One of the return jacks (I think the left?) defaults to mono return for a mono signal, but if I use the other jack, it should trick the mixer into thinking that it's half of a stereo return. That means that the effected signal will only be on the right channel. The end result is that if I pan my channel centre, the left signal should be clean and the right signal effected. In my sequencer, I can treat a stereo pair as 2 mono signals instead, so that gives me my 2 discrete channels, I think. I'll have to test it out to know for sure.

Then again, just routing it to another input is just as easy, so the way I've described is possibly just being unecessarily clever.

I've tried a Y-cable (I actually had one, though it's not high quality or anything) and it seems to work fairly well. The clean signal's waveform is showing clear signs of DC offset problems, but it's nothing that can't be worked at.

Still, the mixer idea appeals to me, so I'll give that one a try, too! Cheers for the help, Lovekraft.

Now that I've started doing some research for the project, though, I'm still interested in trying out some sort of electronics project. If anyone knows of a very simple and inexpensive project I could try out to get my feet wet with, I'm open to suggestions.

Greg