Anyone here ever used a transformer for phase reversal?

[zionstrat]

It's been quite the summer, I've got another single conductor pup and a need for switchable out of phase and this time it's an oldie (early 70s Dim SD) and it would be nice not to break the ground and add the second conductor.

Talking about this same issue earlier this summer, I received a really interesting out of the box idea- to flip phase with a transformer like this http://www.mouser.com/ProductDetail/Tamura/TTC-167/?qs=sGAEpiMZZMulXSgTW6Zin91CWb9SqjfZ1u6GbdxJYTs=

I'm wondering if anyone has tried this because I'm no EE and there's at least 3 things that I'm wondering about:

1. Yes the transformer can be wired backwords to flip phase, but why wouldn't that flip magnetic and coil phase simultaneously? ie, would I be back to square one with noise from signal running through the back plate?

2. Assuming I'm missing something on #1 and it will work (and it is likely that I am missing something), this is a passive circuit, so it's got to reduce gain, but I'm wondering how much? Would it be significant or negligible?

3. Same question with impedance, etc-it's a passive circuit and assuming it has to mess with Q, cutoff etc, but again, how much and is it significant?

We're just quoting this one right now, so I'm not in a position to try it out (or even know if customer will be interested) so any and all input appreciated!


Much peace,
ZStrat

 

[Zhangliqun]

Re: Anyone here ever used a transformer for phase reversal?

How would a transformer reverse the magnetic charge of a permanent magnet? And maybe I'm missing something but what does the transformer bring to the table that a plain ol' DPDT switch won't do?

 

[Joey Voltage]

Re: Anyone here ever used a transformer for phase reversal?

I'm just trying to confirm what you are actually trying to do before I answer, I'm confident I can lead you in the right direction. so by phase reversal, are you trying to do this in order for the pickup to play nice with the others in the guitar when switched in together?, also how are you planning to connect this all up, including the switching? If I know some of the details it's much better. For example are you trying to input the pickup in to the primary, and reverse the phase via the secondary? Also depending on how you connect it, and what you are planning to do, the turns ratio of the tranny, you can actually end up increasing the signal. yes transformers are magic!

 

[Joey Voltage]

Re: Anyone here ever used a transformer for phase reversal?

How would a transformer reverse the magnetic charge of a permanent magnet? And maybe I'm missing something but what does the transformer bring to the table that a plain ol' DPDT switch won't do?

It wont.

 

[zionstrat]

Re: Anyone here ever used a transformer for phase reversal?

Sounds like you guys are confirming that this is no different than flipping polarity of the wires, so it doesn't gain anything concerning a single conductor pup- exactly what I needed to know-

The purpose is to phase reverse 1 of 2 pups as part of an in series, out of phase mod, standard push pull wiring. The transformer idea was offered as a possible solution (to get around adding a second wire) when I had a similar opportunity earlier this summer. I would prefer to not rewire a classic (or expensive) pups when I can avoid it, but that sounds like the only option.

So Joey, it doesn't sound like a transformer will be of any help for this mod, but sounds like you have a lot of experience with transformers and I'm always interested in learning something new- can you point me to any passive mods or theory?

Thanks for fast response- you guys are great!
M

 

[Joey Voltage]

Re: Anyone here ever used a transformer for phase reversal?

So Joey, it doesn't sound like a transformer will be of any help for this mod, but sounds like you have a lot of experience with transformers and I'm always interested in learning something new- can you point me to any passive mods or theory?

Thanks for fast response- you guys are great!
M

Well again it really depends what on the application. If you were hoping to flip the magnetic polarity with it, than no, it's not going to do that for you. If you were hoping to use it like an isolation transformer, plugging the pickup into the primary, and taking a signal 180deg out of phase with the secondary it will do that for you but you also have to consider you now have essentially another coil in parallel or series with the pickup, so you will also have other parasitic properties of the transformer making their mark on the pickup. Like wise you can also change the phase of any signal with a number of passive filters in series set to the same frequency, each RC combination will give a 45degree shift in phase. This is essentially how some phase shift oscillators work in vibrato circuits.

As far reading goes, I can certainly give you some leads on transformer theory. RDH4 has a great section on it, but it is a little technical. If this is something of interest to you I would urge you to download it. Now that the copyright has run out, you can usually find it for free in PDF form. Another good book if you want to get your feet wet in electronics is the art of electronics. It's written with the assumption that the reader is a beginner. So I recommend that one for people who are starting out. As far as online links I can drum up some. I highly recommend Rod Elliot's site: http://sound.whsites.net/articles.htm
He has a huge library of articles that deal with audio. It might be worth noting that it is written from the perspective of hi-if, so some of the more opinionated things he brings up may not be very true or relevant for music instrumentation. Here are actually three articles on transformers from his site I linked above:
http://sound.whsites.net/xfmr.htm
http://sound.whsites.net/xfmr2.htm
http://sound.whsites.net/articles/xfmr3.htm
He also has others on audio transforms, such as isolation trannies

 

[zionstrat]

Re: Anyone here ever used a transformer for phase reversal?

Wow, great reading ahead! Much appreciated and will let you know if I learn anything that's likely to end up in a guitar

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