Two Rock 2x12 cab speaker wiring...sounds great, but...

[MinuteMan]

I picked up a used Two Rock Signature Cab. It sounds great, but wiring looks a bit strange to me.

One lead from the jack goes to speaker # 1 while the other lead goes to speaker # 2. It looks like a somewhat unconventional, parallel wiring to me.

Any thoughts?

[pgissi]

If one lead of only 2 that should be on the jack goes to each speaker (one is connected to a + term and the other wire to the other speakers - term) it sounds like series, if there is a wire speaker to speaker also, connecting the remaining - and + terminals.

There really is nothing unconventional about parallel unless its a parallel-series or series-parallel 4x12.

[MinuteMan]

The speaker to speaker connections are positive to positive and negative to negative. Isn't that parallel?

[pgissi]

yep but ur description sounded like a partial descript of series since you only said the 2 leads from the jack go to different speakers

One lead from the jack goes to speaker # 1 while the other lead goes to speaker # 2

If its parallel the way you describe, you should see 4 leads at the jack, 2 from each speaker

[Red Suede]

What I was told when I bought my Opal was to wire the speakers so they moved backwards instead of forwards. I had two 65 watt Celestions that I was going to put in a Two Rock cabinet and that's what they told me to do. I notice it sounds pretty bassy so I think with the air moving back into the cabinet you get more of the sound of the cabinet vs just the sound of the speaker. I can't think of any other reason for the Two Rock guys telling me to do it this way.

[batlash]

That is a paralell wiring. 16 // 16 omh gives you 8 ohm.

[pgissi]

The whole polarity topic has been debated here. I could see it sound more bassy and IMO your not hearing more of the cab, your just altering the acoustic properties of the pic motion to speaker/cab interaction.

I would think its more bassy because the initial attack has been altered with the speakers moving backwards air is being moved differently to where the highs are masked some or is it simply altered perception, a psychoacoustic trick?

I can't think of any other reason for the Two Rock guys telling me to do it this way.

I am only gonna speculate, the TR tone is what, dare I say it part of that whole D tone movement.

D tone is what, well we know its not the upper mid and top end aggression of a plexi or its descendants and variants so its a darker smoother tonality but yet a dirty od'ven tone.

I have not tried it myself but I tend to believe that a polarity reversal may deliver darker smoother but why?

Then again, the nature of the pick on the strings, up and down motion creates an ac signal which is constantly changing polarity so how would speaker polarity reversal where cones are moving backward on lets say a downpick really change anything, its just flipping the cone excursion to pick stroke motion relationship IMO.

Does that really change the tone or does it change our perception?

Does our brain want to hear outward cone excursion for downstrokes?

And when it does not, it alters our perception of tonality

I have not tried this but do enjoy the D tone, the darker and smoother and try to accomplish that with imp mismatches, darker speakers and cabs etc.

I may take my RTA mic and see if I can get it to capture any tonal differences and if possible plot it.

[SReynolds]

Somebodys altered the wiring of the cab obviously (extension). All my Two-Rock cabs the leads from the jack go to the upper speaker and then wired series or parallel from there.

[traviswalk]

What head are you using with it? Many of the d-style amps are wired in reverse phase at the output jack of the head itself due to the number of gain stages (that's what I've been told). Therefore Two-Rock wires the cabs in reverse phase in order to keep the absolute phase of the head-cab intact. When you mix and match with other heads you may be reversing the phase, in which case you can use a reverse phase speaker cable (buy any cable from Lava and tell them in the instructions to reverse it).

This was provided by Gary at Glaswerks who was very helpful in determining phase in heads & cabs:

"Depends on the speakers you are using. The whole deal is revolved around absolute phase. Some can hear the effect and some can’t. If you place a 9v battery with the + to the + or red on the speaker and – on the battery to the – or black of the speaker and the cone moves out (towards the grill) then a reverse cable should be used with the SOD for best performance.

But, to keep things correct, the SOD does invert the guitar signal. So to keep things in absolute phase a reverse wired cable (swapped wires) is the best approach when using speakers that “push” out on a positive signal."

[pgissi]

I just saw the included pic for the 1st time, its parallel and is a way to wire parallel using less wire, clever.

Each terminal on each speaker has a clear path to the jack

[traviswalk]

Originally Posted by MinuteMan

I picked up a used Two Rock Signature Cab. It sounds great, but wiring looks a bit strange to me.

One lead from the jack goes to speaker # 1 while the other lead goes to speaker # 2. It looks like a somewhat unconventional, parallel wiring to me.

Any thoughts?

Were those speakers changed at any time? That wiring does not look nearly as neat as all the new Two-Rock cabs I've seen.

[pgissi]

The soldering is sub par, I see some cold solder joints, redo them

[MinuteMan]

Agree, will tidy this up with some clean solder.

Speakers are TR 12-65 and 12-65B . The B is on the bottom. Should be on the top. So I suspect it was installed after original purchase.

That being said, this cab is very sweet. Sounds fabulous through both my Pure '64 (6L6 Mean Street) and my TR CR Artist.

[traviswalk]

The Mean Street should be regular polarity and the CR Artist reverse polarity at the speaker output jack of the head, try a reverse phase cable and see what sounds best!

[kimock]

Originally Posted by pgissi

The whole polarity topic has been debated here. I could see it sound more bassy and IMO your not hearing more of the cab, your just altering the acoustic properties of the pic motion to speaker/cab interaction.

I would think its more bassy because the initial attack has been altered with the speakers moving backwards air is being moved differently to where the highs are masked some or is it simply altered perception, a psychoacoustic trick?

nah, that's not it.

I have not tried it myself but I tend to believe that a polarity reversal may deliver darker smoother but why?

Yes and no, maybe. Why is the tricky part, it's not cut and dried.

Then again, the nature of the pick on the strings, up and down motion creates an ac signal which is constantly changing polarity so how would speaker polarity reversal where cones are moving backward on lets say a downpick really change anything, its just flipping the cone excursion to pick stroke motion relationship IMO.

Nah, that's not it either.

Does that really change the tone or does it change our perception?

It changes the timbre and the response of the guitar, but you may or may not perceive that depending on a whole host of factors. On the other hand it might just bite you on the ass, but I wouldn't count on that.

Does our brain want to hear outward cone excursion for downstrokes?

Doesn't work like that at all.

And when it does not, it alters our perception of tonality

If it does, it's timbre, not tonality.

I have not tried this but do enjoy the D tone, the darker and smoother and try to accomplish that with imp mismatches, darker speakers and cabs etc.

Yeah, me too, but that's not the audible effect of speaker polarity on the electric guitar.

I may take my RTA mic and see if I can get it to capture any tonal differences and if possible plot it.

You can do it just with amplitude in pro tools or logic looking at the waveform asymmetry.
It's positive feedback, more everything.

This is a real can of worms to describe accurately from a technical perspective, although the effect is real and robust and is worth investigating.
It has to do with the guitar and amp summing acoustically, being in a positive feedback loop below the threshold of runaway feedback.
The amp is either driving the guitar or damping it, you can get a handle on that with the speaker phase, but it also depends on the node anti-node relationships of the pickup locations, so what is driving your front pickup positive will drive your treble pickup negative.
It's a real mess, but if you can sort it out and keep track of it you can optimize the performance of the guitar and amp under any circumstance.
If this isn't making any sense right now, ignore it.
We can pick it back up later.

If you really have a hair up your ass on the subject, maybe PM Jay Mitchell.
He's the only guy here that's got it all under one roof. I suspect I may have a little more real world experience with it in terms of the sheer number of instruments and amps that I've sorted out in terms of the usefulness of the effect, but I'm way too much of a caveman to give you the straight poop on the physics.