Questions?....A/B/Y splitter(s) by R.G. Keen on GEO

[KMS]

I have found three different designs for splitters over on GEO and I'm not really sure what is best for my purpose. I'm not real sure about my purpose either (chain set up). I have a real nice box custom made to put all this stuff in (12" x 24" x 3" tall slanted down to 1.5" in front).

My plan is to come out of the guitar, go through a noise gate, then split my signal into six paths (chains).

Three paths will then individually be filtered into LF, MF, and HF chains through separate equalizers combined with notch filters. Each of those chains will next have individual distortion and compression circuits. Then each of those chains will go into a mixer and mixed back to one signal.

One of the three remaining chains will go through a full range equalizer/notch filter and then into the Roctave. Then that chain will go in to the same mixer also.

Of the two remaining chains neither will be equalized (prior to the amp) and one will be dedicated to tremolo, auto wah, chorus, flanger, phaser, and my Cry Baby and then back into the mixer (most items on this chain would be used one at a time).

The last chain will be clean and have the option of mixing into the same mixer or output to a separate amp.

The mixer output will go into a delay unit, a reverb boost, and then a master volume foot pedal and then to the amp.

This plan is indoubitably subject to changes, especially if anyone sees that I'm making a big mistake and is willing to speak up.  I have not had very good luck designing chains using one (un-split) signal.

I'm trying to decide how (what cuircuit (s)) to spit the signal and noticing that the transformer grounds need to be isolated in R.G. Keens circuit makes me ponder that as soon as the signal leaves the splitter circuit it then goes into a another circuit where the grounds can potentially loose their isolation.

I can have a separate power supply for the 9V+ and 9V- (for Keens splitter) but all the remaining FX will have the same power supply (Big 9V DC bat) and then all of my amps (solid state) have the same 110V AC wall supply with the casings all on 3rd prong ground connected to "in the dirt" ground rod. So sooner or later these isolated grounds loose their isolation. RIGHT?  So at what point is the isolation of the transformers no longer significant?

Also, does anyone know if I can cascade (daisy chain) Keen's splitters together (three... three way splitters) to make six separate chains?  I plan to use the same 9V+ and 9V- power supply for all three splitters.  Or is there a better splitter out there for my insane ideas?

[R.G.]

That's a very aggressive setup, with some really good ideas.

My experience with complex setups like that is that grounding problems are the things you need to solve last.

If I were building what you describe, I would get the whole mess working until it was satisfactory by ear before trying to integrate it into a neat, tidy custom built box with zero residual hum. I typically find that my ideas about how it will sound either need some revision or were flatly wrong in some respects; going directly to the final boxes means that I not only have to build the final setup, I also have to tear at least part of it down. This depresses me to no end.

[KMS]

Ok, I guess I got lucky again (maybe).  Things just seem to be going my way lately. Hooked up the GEO A/B/Y by R.G. Keen and it worked the first time.

I don’t have my Kustom or Peavey PA here at home to test the A/B/Y to full potential so I made a ¾ watt practice amp on my RShack 301 experiment board to test the splitter (used the 546 Audio IC  that comes with the kit).  I just blew the speaker after about 2 hours playing time, and loved every minute of it! 

I get a little noise out of the amp with the 546 but that is probably because: I did not shield any leads, I used leads that are real long, it is a fundamental amp with no buffers or anything extra at all, so on and so forth.  When I hooked the splitter up, the “same” noise just got louder.  Nice that the splitter has a little extra gain (actually it has a lot of gain).  I’ll use shielded wire when I put it in the box, just to be sure.   

One mistake was to power the amp with the same +9v of the splitter.  Not as much gain (and head room) as using a separate 9V bat to power the amp.

I had no problems at all with +9V / -9V power supplier, not sure what all the hype is about: that most folks not don’t to use two batteries. It is real simple to do and this was the first time I have attempted it.

I could notice no difference in sound by isolating the ground or not isolating it but the amp is only about 1-inch away from the splitter plus I’m only using one amp.  I hooked up all three outputs one by one and two by one and then all three and could not detect any difference in gain or noise at all except the direct output seemed to sound slightly different (not sure how to describe it).

One thing is baffling; I hooked up my Boss OD2 between the splitter and my pickups and “all of the noise” from the amp was gone and it made no difference if the OD2 was in expression mode or bypass as long as it was plugged in (on). Anyone have any answers for that?

Usually in the last year I notice the exact opposite when I use the OD2, it has been making more noise in expression mode (but the bypass is always quiet).  I guess it needs a couple new caps (purchased in 1993).

I’ll go pick up my Kustom tomorrow and test it out on that next. 

I might as well try the 2005 improved R.G. Keen A/B/Y circuit and see how that works too.

If my luck holds out, I will be etching a board Sunday night for a 6 way splitter.

This is the first circuit I have made by R.G. and it works great.  Thanks R.G.!