Output Transformer polarity whats up

[guitardude57]

The speaker being built on a suspension, obviously goes forward and back.
Production of a sound wave going positive first>forward. That's how I prefer to wire them.

Try wiring a 15 or 18 sub backwards. You will be replacing the speaker......
they are not designed for the same energy to go backwards. Unless specially built for the other.

Give it a pulse, it will return to neutral position. Not go backwards with the same force, past resting position. If the amp dampening is goofy, it may move too much the other way.....you will replace the speaker before long.

30 years in SR experience, I've seen it.

[heisthl]

so your saying as an example a 60 hz sine wave into a subwoofer means the peak of the positive part of the wave means pushed out and the peak of the negative part of the wave would ideally be at spider/surround rest - man that speaker is one smart device to compute the center point for all frequencies at all amplitudes. Or are you saying at the least, the positive portions are reproduced much better than the negative portions. ( i.e. you must be mistaken)

[guitardude57]

I must have mistakenly found the argument portion of the program. You must be thinking that all speakers are high compliance huh? Most are not. Smart speakers.....LOL

Like I said earlier, my opinion. You do what works for you......me too.

[heisthl]

Believe it or not I'm just trying to understand the phenomenon. In school when I wrapped the nail and hooked it up to flashlight batteries it attracted and lifted the same amount of tacks no matter which polarity I observed on the battery connection. Why would a speaker work any differently?

[paulster]

Try wiring a 15 or 18 sub backwards. You will be replacing the speaker......
they are not designed for the same energy to go backwards. Unless specially built for the other.

Sorry, but that's absolute tripe.

Speakers are designed for AC signals, which causes them to push and pull equally around the resting point of the suspension. Whether the initial attack of a note pushes or pulls the speaker makes no difference whatsoever to how long it'll last, how good it'll sound or anything along those lines. It's job is purely to reproduce the AC waveform fed to it to a greater or lesser (in guitar applications) degree of accuracy.

I've designed enough high power subwoofer enclosures in my time (including isobaric and bandpass) to know that the only reason you'd be replacing a speaker if you wired it out of phase to the other speakers is because you'd likely be overpowering it to get over the lack of bass when it's trying to cancel out the one that's been wired in phase.

Many of the classic guitar amps we use and love are actually phase inverting, and I don't see a high level of speaker attrition attributed to these, nor a crap sound as a result of a 'design error'. They are what they are, and as Henry said, the difference is whether you get constructive or destructive feedback in the position you are playing in.

Take the Trainwreck Express for example. One of the amps best known for the ability to bloom into harmonic feedback and being able to 'play' the feedback. Inverting.

[Structo]

Wow, I don't understand why this subject is so controversial.

OK, I just tried the speakers with a 9v battery.
With the tip to + the speakers suck in.
This is what I expected since yesterday I reversed the speaker wires in the cab.
Later when when I won't piss off the wife, I will try the amp again to be sure that the speaker pushes out when I strike a note.

Then I will compare that to my Carvin Belair combo to see if it pushes on the initial attack.

Somebody said that a cathode follower does not invert the phase.
So on a Dumbleator, you have the CF then a plate loaded stage.
So that is inverting the phase right?
So if the speaker pushes out without the D'lator that should indicate the D'lator is inverting the phase to the speaker.

Later when I'm able I will try it again with the D'lator in the circuit then I will unplug that and try just the amp to see if it is the same.

We can quote all the science we want but it should be easy to see if the speaker pushes or pulls in with or without the D'lator.

My thought is, when I use another amp I have here and use one or more of my stereo effects, I want both amp speakers to be in phase with each other.
That is, I want the speakers in phase with each other or there will be some cancellation if they are opposite. Right?

[dobbhill]

That is correct, Tom.
To quickly test 2 speakers, I place them face to face with an inch or 2 clearance. Then I play some music. Then I reverse the phase of one driver and play the same music. One way will sound better than the other.
I don't find much difference in absolute phase, if any, although many others have indicated a preference one way or the other. By absolute phase, I mean whether the cone moves in or out with the phase of the driving signal.
Hope that make sense,
D

[Structo]

Well I understand when you have more than one speaker on an amp that you want them to all be in phase with each other or you will get cancelling that sounds bad or at least at a lower volume.
But my question is, does it make any difference in the quality of the sound if the speakers on one amp suck in on the attack of a note or push out?

And it also seems that if you are playing in a band with a bass and another guitar, if your speaker is out of phase with the others will that cause problems or not?

Say you all play an open E (Bass, second fret on D string), how will that sound if one or two speakers are out of phase with the other players?

I would think a speaker would be more efficient if it is pushing on the initial attack.
Since speakers are made to project sound out the front of the cone.

Or in a sealed enclosure where the trapped air aids in the suspension.
What did they used to call that? Air suspension or was that bass reflex?
Anyway, I would think in a sealed box, it would be even more critical to have the speakers phasing correct.

Sure, I've seen guys with the backward firing subwoofers in their car stereos but that is also in a ported enclosure.

We're talking guitar amps and speakers here, not Hi Fi.
Closed back or open back.

I remember Scott saying something about this and that he had a speaker cable that had the polarity crossed.
I just can't remember if that was because the Dumbleator was inverting phase or not.

[paulster]

I would think a speaker would be more efficient if it is pushing on the initial attack.
Since speakers are made to project sound out the front of the cone.

Speakers cause a waveform to be produced in the air in front of them, which consists of compressions and rarefactions, occurring at the frequency of the note being produced.

To do this the speaker has to move outwards just as much as it moves inwards, around its centre of rest, which is the neutral point in the suspension with no signal applied. Even with a low E there will be 82 of these per second, so it'll be pretty difficult to actually see whether the cone is moving in or out at any moment in time.

In an open box there is no resistance to cone movement other than the atmospheric pressure in the room. In a sealed box there is resistance to the cone moving backwards as it has to compress the air in the box, and equally when it moves forward as it has to expand the air in the box.

This myth that speakers work better in one direction is just that, a myth, perpetuated by people who really don't understand loudspeaker design ot the physics behind what is actually taking place.

For completeness though the direction of the initial attack will depend on whether your picking motion pushes the string towards the pickup or away from it as you strike it, the winding and magnet direction of the pickup, the number of gain stages in the amp, the effect of any pedals or other effects (e.g. the Dubleator) en route, which way round the OT is connected in a non-NFB amp and finally the polarity you choose for your speaker wiring.

[Structo]

That may make scientific sense but it does not match up to what I have observed.

Today I had my amp on with the Dumbleator, and plugged in my five string bass.
First I tried playing the low B string.
I can see the cone moving but even at that low frequency it is hard to see.
So I clapped my hand on the strings while touching the speaker cone.
The cone moved outward or pushed when I did this.
I could feel the cone moving outward.

Then I disconnected the Dumbleator and repeated with the same action.
Bass straight into the amp, no loop connected.
The cone moved inward.

This is because I reversed the speaker wires in the cab so the sleeve part of the wire is now on the + of the speaker.

My theory is that the recovery side of the Dumbleator is inverting the signal.
We are told a cathode follower does not invert the signal so the only thing I can conclude is that the plate loaded recovery amp is inverting the phase of the signal.

On another note.
I have messed around with car audio as well as home theater for quite a few years.
Most powered subwoofers have a phase switch.
Usually you just listen and choose the way it sounds best.
This is determined by a few things such as the size of the listening area, standing waves and general acoustics of the room.

Pretty simple, in one position the sub bass will sound louder and more woofy.
The other switch position the bass will seem tighter and less boomy.
I believe when the bass is tight and less boomy is when the speaker is in phase.

[heisthl]

This is because I reversed the speaker wires in the cab so the sleeve part of the wire is now on the + of the speaker.

.

I hope you are not implying you are using shielded wire for a speaker cable - not a good idea.

[talbany]

Note: With the exception of the transformers the JTM was a copy of the Bassman. An interesting discovery came to our attention here. It seems that most of the amps made during that era had the output leads connected in reverse phase (backwards). Was it by intent or a happy accident? We and a number of pro players seemed to prefer the reverse phase connection after many A/B tests. We had the impression that the speaker cabs sounded better, more articulate.

Posted on Mercury Magnetics website..
Not so sure we can label this as Marketing hype since IMO making this statement really doesn't buy them much in the way of sales... though you draw your own conclusions..Anyway interesting comment This to me would imply the direction of current flow on a particular set of speakers may effect tone..

FWIW.. To find if the pickup/amp is in the proper phase..Initial attack outward pushing the string tword the pickup should extend the speaker cone.. Lindy Fralin..

Tom thanks for the test results..So here is the magic question.. is there a different effect by using the D-lator(signal) vs changing speaker polarity(altering current flow OPT-Speaker)?
Tony

[Bob-I]

On another note.
I have messed around with car audio as well as home theater for quite a few years.
Most powered subwoofers have a phase switch.
Usually you just listen and choose the way it sounds best.
This is determined by a few things such as the size of the listening area, standing waves and general acoustics of the room.

Pretty simple, in one position the sub bass will sound louder and more woofy.
The other switch position the bass will seem tighter and less boomy.
I believe when the bass is tight and less boomy is when the speaker is in phase.

Relative phase is more important even than absolute phase. You can survive speakers moving the wrong way, as long as they all move the wrong way, but if one moves the opposite of another it destroys the sound.

A top notch sound man I knew years ago demonstrated another phase factor to me. The relative distance from the speaker's voice coil or diaphram to the listener. He insisted on lining up the drivers by the voice coil or driver, not the cone or lens. He showed me by moving the horns relative to the woofers he could actually cancel out frequencies, demonstrated with a sine wave function generator. By lining up the drivers correctly he removed the phase cancelation.

[paulster]

My theory is that the recovery side of the Dumbleator is inverting the signal.
We are told a cathode follower does not invert the signal so the only thing I can conclude is that the plate loaded recovery amp is inverting the phase of the signal.

The recovery stage of the Dumbleator will invert the signal, so you've changed your system phase from inverting to non-inverting or vice versa.

Most powered subwoofers have a phase switch.
Usually you just listen and choose the way it sounds best.
This is determined by a few things such as the size of the listening area, standing waves and general acoustics of the room.

Pretty simple, in one position the sub bass will sound louder and more woofy.
The other switch position the bass will seem tighter and less boomy.
I believe when the bass is tight and less boomy is when the speaker is in phase.

This is true when the remainder of the system is playing, so the subwoofer ends up in or out of phase with the main speaker system. With just the sub on its own you won't tell any difference with the phase switch.

[Structo]

This is because I reversed the speaker wires in the cab so the sleeve part of the wire is now on the + of the speaker.

I hope you are not implying you are using shielded wire for a speaker cable - not a good idea.

No, I just meant that I reversed the wires in the speaker cab at the input jack.

FWIW.. To find if the pickup/amp is in the proper phase..Initial attack outward pushing the string toward the pickup should extend the speaker cone.. Lindy Fralin..

Tom thanks for the test results..So here is the magic question.. is there a different effect by using the D-lator(signal) vs changing speaker polarity(altering current flow OPT-Speaker)?
Tony

I have read here that it depends on how you pick or strike the strings and that pushing the string towards the pickup results in a positive wave.
But, how many of us pick a string so the string goes towards the pickup?
Most pick the string so the string goes side to side, so how does that translate to phasing of the signal?
I suppose there is either a slight pressure either towards or away from the string.
I always thought a string vibrated in an elliptical pattern that is more or less a circle.
Would it really depend how the string cuts into the magnetic flux (lines of force) of the pickup magetic field to generate voltage?

In other words, doesn't the ac generated always start with a positive ac wave form?
I wonder if this could be seen with an oscilloscope?

Most powered subwoofers have a phase switch.
Usually you just listen and choose the way it sounds best.
This is determined by a few things such as the size of the listening area, standing waves and general acoustics of the room.

Pretty simple, in one position the sub bass will sound louder and more woofy.
The other switch position the bass will seem tighter and less boomy.
I believe when the bass is tight and less boomy is when the speaker is in phase.

This is true when the remainder of the system is playing, so the subwoofer ends up in or out of phase with the main speaker system. With just the sub on its own you won't tell any difference with the phase switch.

Yes, so if you are playing in a group of two or more other amplified instruments, wouldn't the correct phasing of the speakers also be critical for the best total sound of the group?