ABY splitter help!

[eexdm2]

Hey guys!

New to this place but not new to the wonderful world of stompbox building!

I do have an issue though, im currently building a ABY splitter over the easter weekend and am having some problems with the output!

Im using a transformer to avoid Hums and to be isolated and safe but dont get any output.

The transformer may not be ideal but its the only one i have in my scrap box its P:20K and S:1K, i want to feed my pedals into it and then split the output into my two amps. Any ideas how to get this working? im copying the following schematics

http://www.geofex.com/FX_images/spltr2.gif

but with out the gain stage!

hope some one can help!

Regards
Damon

[R.G.]

OK. So you're an experienced pedal builder.

New to this place but not new to the wonderful world of stompbox building!

And you have a problem; you 're building a splitter in limited time over a holiday weekend and it's not working.

I do have an issue though, im currently building a ABY splitter over the easter weekend and am having some problems with the output!

And you want to use a transformer isolator to avoid hum and ?shock hazard? and the output doesn't work.

Im using a transformer to avoid Hums and to be isolated and safe but dont get any output.

The transformer you're using is not intended for this use, just one that's been buried in the parts box.

The transformer may not be ideal but its the only one i have in my scrap box

It's known to be the wrong ratio for an isolator.

its P:20K and S:1K

You are using schematics you found on the net but have never built before.

im copying the following schematics http://www.geofex.com/FX_images/spltr2.gif

But ignoring and leaving out a major part of the circuit.

but with out the gain stage!

It's your first post here

eexdm2
Posts: 1

And you want someone to help.

hope some one can help!

All that correct? 

Just off hand, I'd say that
(1) the transformer is going to cause a 1:4.47 change in voltage level going from primary to secondary; the signal will drop by about 5 to 1 on the 1K side.

(2) if you can by some chance drive it with one of your effect outputs. You will need to use an effect with a buffered output because you need to get a driving impedance of a maximum of 20K to get a reasonable output. Even that will cut your output further, to 1/10 because you lose half the signal in the impedance matching on the primary.

(3) the frequency response you get will be chancy at best, probably a lot of loss of lows. That pesky gain stuff you left out of the schematic was there to make the (proper) transformer work with any source impedance, even a high one like a guitar, and preserve good low frequency response by actively driving the primary.

(4) you may be able to get usable output if one of your pedals is a nominally clean boost and provides a full rail to rail output signal into the 20K side of the transformer to get a usable signal on the 1K side. That pedal will replace the silly gain stuff.

(5) your transformer may be internally shorted or open from it's semi-burial in the junk box; did you check it?

(6) trying to drive the 1K side to get a 4.47 to 1 signal step UP will make the requirements for low impedance drive and potential loss of bass worse; but a good, tough, burly buffer in front of it might get it to working.

Mother Nature has several roadblocks in front of you for getting it running on anything except a tinkering basis this weekend. Still, you might be able to get it to do something on an experimental basis.

[eexdm2]

Its nice to see we are all friendly are sarcastic here.

Just asking a few questions. Cheers anyway.

[R.G.]

And cheers. Just answering a few questions.

I believe points 1-6 are pretty accurate as to what you'll find.

[Austin73]

eexdm,

sorry you didn't put your name on . Where you been if your not new to building? Any good sites or info we might have missed.

RG is right mate, if you search on the forum you'll find plenty of info I'm sure but you really need a 1k : 1k or something similar as that seems to be the norm for isolation (I think!)

As pointed out by RG (who has a great site with LOTS of info on it) maybe tinker with it and see what you get - you might even get a random effect or octave up that you didn't want - think jawari etc

Welcome aboard and don't loose faith RG is just having a bit of fun with you but he will help you and has done in the above post.

We are friendlier than harmony centrals DIY pages lol

Aus