Hello all! My apologies for the newbie question, and thanks in advance for your help/knowledge. Here is some information before I ask the questions. I am hoping to build a Y splitter pedal (passive, no switching) to take a single instrument input into a Grace Design Felix (2 channel acoustic preamp). This preamp is essentially two completely separate preamps, with separate inputs for each channel. I do not need switching on the splitter pedal because the preamp already has channel switching. Both channels on the preamp have iso-transformers.

  My questions are:

1> If I build a basic passive splitter, will I be degrading the tone or losing signal?

2> Even with the iso-transformers in the pre-amp, will I be introducing the potential for ground loops?

3> Is building a basic Y splitter as simple as splitting the signal at the input jack to 2 output jacks and connecting all the grounds?

  I am good with a soldering iron, but do not know too much (yet) about electronic theory. Let me know any thoughts or questions. I appreciate any assistance!

Quote from: JBarlow12 on October 28, 2024, 11:08:00 PM3> Is building a basic Y splitter as simple as splitting the signal at the input jack to 2 output jacks and connecting all the grounds?

Yes.

Welcome.

@PRR -- I appreciate the response.

Any thoughts on the other points? So you do not have to look up the unit, I should add that the Felix has it's own switchable impedance on the inputs. Would this negate the reason to have a buffer before the splitter?

Thanks all!

Quote from: JBarlow12 on October 28, 2024, 11:08:00 PMI do not need switching on the splitter pedal because the preamp already has channel switching. Both channels on the preamp have iso-transformers.

Interesting. Good idea, if it's well executed and affordable.

Quote1> If I build a basic passive splitter, will I be degrading the tone or losing signal?

Probably not. I'm hedging that answer because the use of an isolation transformer in front of each preamp channel is such an unusual design.
Background: in the electronic sense, pickups look like a signal voltage source in series with a big inductance. The inductance part makes for treble loss (also called "tone-sucking" in the guitar amp biz) if the preamp it feeds has too little input resistance. This is why most guitar amps have 1M input resistances. Having the guitar cable plug into an isolation transformer means that the iso-transformer must be designed to present a high impedance too. It makes for a more complex design. The "probably" is based on my impression that someone putting in isolation transformers took the trouble to do it right, and use good quality transformers; it is possible to muck it up, but chances are they took the trouble.

Quote2> Even with the iso-transformers in the pre-amp, will I be introducing the potential for ground loops?

Probably not, although it depends on exactly how the isolation transformers are implemented. Isolation of ground loops is a primary use of isolation transformers; if the designer went to the trouble to use them, it bodes well for taking the effort to do the ground isolation in the wiring, jacks, etc.

Quote3> Is building a basic Y splitter as simple as splitting the signal at the input jack to 2 output jacks and connecting all the grounds?

As Paul says, yes. This would be a quick way for you to test the concepts I mentioned, and build some electronics skills. Try it out. If it sounds bad, we can delve more deeply into it.

Since it is an acoustic preamp, I am assuming he is talking about an acoustic instrument with an onboard preamp, therefore a low output impedance. In that case, an isolation transformer (well, any transformer really) is an easy addition.

Anyway, if it is an acoustic guitar/bass/upright/violin/whatever, you really don't need anything more than a Y cable.

@R.G. -- A few responses:

  Yes, the switching is executed well. I have used the same preamp on my bigger pedalboard for the last 8 years, and it works well. As well, he transformers got rid of some ground loop issues I was having with the previous version of the same thing that did not have the transformers. Affordable? It's pretty expensive, but also the best acoustic preamp I have played through, and I would 100% purchase it at full price. Here is a link if you want to check out the unit:

Grace Design Felix 2

  As far as all the other things, that is good information to know. It is probably a lack of knowledge causing me to overthink things.

@fryingpan -- Mostly passive pickups. I play violin, mandolin, and acoustic guitar through it mainly. The violins and mandolin are passive. The guitar is active, but plays well with the higher impedance (the unit has three switchable impedance settings).

  I should have probably mentioned what the ultimate use is. I am building a small acoustic pedalboard, and this splitter will basically be the input that splits the signal to the preamp.

  I appreciate everyone taking the time to share their knowledge. I will be working on it over the next week or so, and will get back to you with any questions. Thank you all!