Low Z to High Z transformer?

[korinastratkyle]

Can anyone tell me where I can find a low impedance to high impedance audio transformer that ISN'T built into an XLR-TS adapter? Something preferably under $20 and compact enough to fit into a Strat cavity? (if it can fit into a Tele route that would be even better!) I just wound some low Z strat pickups and they sound great but running into a balanced preamp makes for positions 2 and 4 to be WAY louder than the rest of the positions because of how the differential amp works... So I'm planning on going passive and unbalanced with this one. Thank you ahead of time!

[Mike Sulzer]

...but running into a balanced preamp makes for positions 2 and 4 to be WAY louder than the rest of the positions because of how the differential amp works...

Why?

[korinastratkyle]

Why?

Because I had it wired up to where the bridge and neck pups ran to the + and the middle pup to the -, so when combined, they summed up in the balancing amp because of the pups being out of phase. If they were in phase they would cancel out!

[David Schwab]

you could have just wired the middle pickup out of phase (with reverse magnetic polarity) and then summed them to the op amp's input like a mixer, with isolation resistors.

Or as long as you are using an op amp and all, use a dummy coil on the differential input.

[korinastratkyle]

you could have just wired the middle pickup out of phase (with reverse magnetic polarity) and then summed them to the op amp's input like a mixer, with isolation resistors.

Or as long as you are using an op amp and all, use a dummy coil on the differential input.

That's a great idea David! Thank you! I was literally using a mic preamp to try them out but an op-amp based preamp and a dummy coil sounds like my cup of tea seeing as I've always been a humbucker guy! Those 2 years of electronics at the trade school is paying off now!

[Mike Sulzer]

Because I had it wired up to where the bridge and neck pups ran to the + and the middle pup to the -, so when combined, they summed up in the balancing amp because of the pups being out of phase. If they were in phase they would cancel out!

So why not just ground one input of the diff amp and wire it in the normal way.

[korinastratkyle]

Alright so I built an opamp based preamp and it works great! The dummy coil didn't work well enough to justify using it (although I probably should have added a shunt resistor to match impedances), so I'm basically using true single coil actives. It sounds like I picture a strat sounding so I'm quite pleased. As far as op-amps go I used a JRC4558D because that's what I could find, but it generates a little bit of white noise that is audible at high gain settings (as in 5150 type distortion, which I never use single coils with anyways). However, I found some NE5532P's which I believe are considerably lower noise and plan to try that on my next preamp which will be for a pair of humbuckers going into a Les Paul. I still gotta check the datasheet to see just how much less noise to expect. Thank you everyone for the help!