Output Transformer polarity whats up

[talbany]

Regurgitating an old topic brought up by Scott L.(.Couldn't find it so I'll start a fresh one) a while back as it pertains to reversing speaker polarity.. I started checking into the polarities of different output transformers and sure enough found that not all transformers are wound in the same direction.. Some north some south..I found that the ones that are wound north are in phase(Speaker moves out) and the the ones south are out with respect to Celestion"s winding direction .. Switching the cables on the south made an audible difference...I did the test on 4 different amps and want to try several more but thought I would post the findings and see if anyone else has discovered this to be the case as well..No conclusions on tone have been drawn as of yet though it makes sense...Check your transformers,,, Performed with G12H-65 2X12


Tony

[j-po]

Difference with also low volume or only when pushing the cone into distortion?
The cone jumping out may distort differently than when being pulled in which would make a difference in sound if the signal is already asymmetrically clipped when going into the speaker.

[hitchcaster]

dumbles and their clones in general fire "backwards"... different speaker manufactures all fire different too, ev, jensen, jbl etc..... celestions fire backwards in general. so if you wire up a celestion normally with a dumble it should be in phase. im pretty sure tone tubbies fire the opposite, so if you wire those up with your dumble you need to wire them up "backwards" to work right and be in phase.. thats why say, two rock, wires their dumble cabs backwards. this may all sound like nonsense to some.. so what id recommend is making a short 1/4" to 1/4" jumper that reverses polarity and then putting a female to female adapter on it (or however you want to accomplish it).. and then going thru your cabs and amps and listening to the change in sound when you reverse the polarity. IMHO its not a apples and oranges difference.. one way clearly sounds better then the other. in combo's when you hear it you can just wire it up the correct way and forget about it.. with heads and cabs you'll have to take notes of which amps are in phase with which speakers.. and if you want to use an out of phase head with a in phase cab just use your handy dandy adapter, or make up a phase reversed speaker cable. once you hear it you'll never go back... i haven't taken note of the OT polarity thing, but it seems theres many elements that flip flop the phase back and forth before it gets to the speaker which is a wildcard phasewise anyways. the phase of your guitar pickups being the first thing id guess.
good luck!

[ontariomaximus]

If the ot's are wound backwards, wouldn't the negative feedback loop turn into a positive feedback loop?

[bluesy]

......(or to straighten a noob up)--the direction of wind on the transformer can cause a reverse polarity situation at the speakers/the "stuff" in an amp circuit can reverse the polarity at the speakers/pedals can do the same/pick-up wind- ditto. So when all is said and done, you have to, lastly, check the direction of speaker travel with everything hooked up to know what the heck's up with regard to speaker polarity? Can I add or subtract a pedal up front and reverse things? Can flipping the pick-up switch on a Strat do the same thing?
________
Honda Varadero history

[ontariomaximus]

dumbles and their clones in general fire "backwards"... different speaker manufactures all fire different too, ev, jensen, jbl etc..... celestions fire backwards in general. so if you wire up a celestion normally with a dumble it should be in phase. im pretty sure tone tubbies fire the opposite, so if you wire those up with your dumble you need to wire them up "backwards" to work right and be in phase.. thats why say, two rock, wires their dumble cabs backwards. this may all sound like nonsense to some.. so what id recommend is making a short 1/4" to 1/4" jumper that reverses polarity and then putting a female to female adapter on it (or however you want to accomplish it).. and then going thru your cabs and amps and listening to the change in sound when you reverse the polarity. IMHO its not a apples and oranges difference.. one way clearly sounds better then the other. in combo's when you hear it you can just wire it up the correct way and forget about it.. with heads and cabs you'll have to take notes of which amps are in phase with which speakers.. and if you want to use an out of phase head with a in phase cab just use your handy dandy adapter, or make up a phase reversed speaker cable. once you hear it you'll never go back... i haven't taken note of the OT polarity thing, but it seems theres many elements that flip flop the phase back and forth before it gets to the speaker which is a wildcard phasewise anyways. the phase of your guitar pickups being the first thing id guess.
good luck!

I have never encountered a speaker that fired backwards. When mixing and matching speakers I always test with a battery and without fail + to + and - to - results in the cone moving out. Why on earth would any speaker manufacturer label them wrong?

Amps can change the phasing. Consider that the typical LTPI + output stage is consistently in phase, otherwise the negative feedback would be positive feedback. Therefore we are left with the pre stage that determines if the amp is inverting or not.
Even # of gain stages in pre = non-inverting (Dumble, Plexi)
Odd # of gain stages = inverting (JCM800, Express)

But pickups can be wiring as inverting, so it is 50/50 whether or not your speaker cone will move out when you hit a power chord (non-inverting) vs. sucking in when you hit the same power chord (inverting).

Best thing to do is to experiment with speaker phasing, and make up a speaker cable that is reverse connected ie. tip on one end connected to sleeve/barrel on the other end. Compare that to a regular speaker cable and what sounds good IS good.

[paulster]

If the ot's are wound backwards, wouldn't the negative feedback loop turn into a positive feedback loop?

Exactly. There is no way you can alter the direction a speaker will fire in without flipping the overall input/output phase relationship of the transformer. And that would change NFB into PFB, which you'd soon notice.

[greiswig]

dumbles and their clones in general fire "backwards"... different speaker manufactures all fire different too, ev, jensen, jbl etc..... celestions fire backwards in general.

I respectfully disagree, if I interpret you right regarding "firing backwards": most (not all) models of JBL drivers are the only ones I have ever encountered which, when you put a 9V battery with positive to red terminal, the cone moves in instead of out. Every other speaker I've seen has the cone moving out under those conditions, Celestions included.

[BobW]

Regurgitating an old topic brought up by Scott L

Why?

The dot references on the XFMR schematics are there for a purpose.

[mlp-mx6]

If the ot's are wound backwards, wouldn't the negative feedback loop turn into a positive feedback loop?

Exactly. There is no way you can alter the direction a speaker will fire in without flipping the overall input/output phase relationship of the transformer. And that would change NFB into PFB, which you'd soon notice.

Perhaps I'm not understanding this, but it would seem to me that if you wired a speaker cable that swapped ring and tip between the two ends the speaker "polarity" would be flipped, but the xfmr would remain unchanged. What am I missing?

[ayan]

Regurgitating an old topic brought up by Scott L.(.Couldn't find it so I'll start a fresh one) a while back as it pertains to reversing speaker polarity.. I started checking into the polarities of different output transformers and sure enough found that not all transformers are wound in the same direction.. Some north some south..I found that the ones that are wound north are in phase(Speaker moves out) and the the ones south are out with respect to Celestion"s winding direction .. Switching the cables on the south made an audible difference...I did the test on 4 different amps and want to try several more but thought I would post the findings and see if anyone else has discovered this to be the case as well..No conclusions on tone have been drawn as of yet though it makes sense...Check your transformers,,, Performed with G12H-65 2X12


Tony

Got a question, Tony. How do you test to see if the windings are wound oppostie to what would be "normal?" And, if that is the case, if the magnet is also backwards, you get the same overall polarity of the induced signal on the secondary. Not sure if you mean just the windings.

As people stated above, if you get an overall polarity reversal between different transformers, the feedback loop would also be backwards and you'd get a sequealing amp! As per my experience, polarity at the speaker does make a very pronounced difference, and the only speakers I have ever used that are truly backwards are Celestions. Not a big surpise, considering what side of the road our Brit brothers drive on.

The one area where all this theory falls apart on me is... what about polarity of a guitar's pickups? Electrically that would cause the very same effect, however, I don't know that anyone has determined this to be a culprit too -- psychoacoustics aside, that is. I know that Lindy Fralin humbuckers are opposite polarity to Gibsons (and most aftermarket HBs), and I flipped the magnet on mine to be "in phase." However, before doing so I never felt there was any issue with the "sound" like I can hear when I flip the polarity of the speaker. And, last wrench in the works, what about if you pick downward VS upward? That would cause the guitar signal to start on opposite halves of the cycle as well...

Cheers,

Gil

[Zippy]

And, last wrench in the works, what about if you pick downward VS upward? That would cause the guitar signal to start on opposite halves of the cycle as well...

Thanks. I have been plagued by that thought for years. Hearing it come from someone else is a great relief. Time to get out the 'scope, I s'pose, and sit there pickin', poppin', and pullin'.

IF there is a difference in "attack polarity" and IF swappin' polarity at the speaker is tangible, then what makes one matter and the other not?

Is this why Jimi Hendrix sounded as he did?

[paulster]

And, last wrench in the works, what about if you pick downward VS upward? That would cause the guitar signal to start on opposite halves of the cycle as well...

Thanks. I have been plagued by that thought for years. Hearing it come from someone else is a great relief. Time to get out the 'scope, I s'pose, and sit there pickin', poppin', and pullin'.

IF there is a difference in "attack polarity" and IF swappin' polarity at the speaker is tangible, then what makes one matter and the other not?

There was a big TGP debate about this with Steve Kimock getting very passionate about how it worked 'his' way, even when proven the opposite was true with scope capture plots.

Essentially the polarity is determined by the string movement towards or away from the pickup, not up or down.

Whichever way you pick, up or down, you initially press the string towards the pickup, so a note will always begin with the same polarity. The only likely exception to this would be popping, but that's really for the 4-stringers. Then it's just a question of which way your pickups are wound or which direction the magnets face.

[BobW]

In the case of a single coil, inductor or pickup, reversing the dot reference, aside from noise issues has little consequence to phase. It's the interaction of two coils aiding or bucking that makes the phase difference, whether or not it's two pickups (humbucker), 2 XFMR windings (primary or secondary) or a secondary and a speaker coil.

I agree with Gil, during the OT manufacturing, one of the primary winding polarities (dot references) may have been simply swapped when the CT tap was formed on your particular XFMR. This would affect phase regardless of how the primary windings were built LH or RH winding. How did you determine if the winding was either LH or RH?

"Got a question, Tony. How do you test to see if the windings are wound oppostie to what would be "normal?" And, if that is the case, if the magnet is also backwards, you get the same overall polarity of the induced signal on the secondary. Not sure if you mean just the windings."

[greiswig]

...the only speakers I have ever used that are truly backwards are Celestions. Not a big surpise, considering what side of the road our Brit brothers drive on.

Gil, just wanting to double-check this. I swear I've tested several models of Celestions, and positive to red with a 9V battery always had the cone moving out, not in. This was also the case on, for example, EVM-12L's. JBL's are a different story in my experience. I use a 2x12 cab right now with a G12-65 and a ScumNiCo in it, both wired as though red were positive, and they are most definitely not out of phase.