Dual (not bi) wiring speakers?

gidrah · May 2003

Lemme know what you guys think of this one:

On a standard amp or receiver that has speaker A+B capability, connecting both A&B to the same speaker terminals. In theory it should'nt change the impedence and only serve to double the surface area of the terminals.

Of course any differences in wire/cable length should be kept to a bare minimum.

RuSsMaN · May 2003

BOOM!

VR3 · May 2003

Are you saying...you want to plug 2 pairs of speakers into one pair of terminals???/ WAAAAAAAAAAAAAAAAAAAAAAAAAAAAA!

LOL!

Get 2 pairs of speakers (exactly the same), 2 subs (exactly the same), 2 receiver (exactly the same), and a cd player, and 2 sets of y splitters! Work from there!

F1nut · May 2003

Ok, I've had trouble with this one in the past, but I do recall that idea being refered to as ghetto bi-amping.

RuSsMaN · May 2003

Both A & B terminals on the amp to ONE set of terminals on a speaker.

Like I said, BOOM!

rs159 · May 2003

Originally posted by F1nut
Ok, I've had trouble with this one in the past, but I do recall that idea being refered to as ghetto bi-amping.

Bi amping would be if both termnals fed power to different drivers - "B" to the tweets and "A" to the woofers or whatever. We are talking about taking two terminals to one set of binding posts. You could get the same effect by liberally spreading gas on the ground and lighting a match.

BeginnersLuck · May 2003

And then, of course, you would have to drop the match....BOOM!!!
(for those that were not sure of what to do next)

F1nut · May 2003

Ok, one's a ghetto job and the other goes BOOM....don't know why I was having trouble with that one, it's so simple.

Tour2ma · May 2003

As long as the wires for each channel are run correctly, i.e., one is not run + to + while the other is + to - (effectively a dead short across the amp outputs for that channel), why would it go Boom?

All the speaker selector switch does is split the output of the two ch's. If wired properly, all you are doing is recombining that output. Doesn't equal BOOM in my book.

On the other hand, should not produce any advantage either. If it did, then the speaker wire is too light a gauge for the length you are running. Buy a lower gauge wire...

RuSsMaN · May 2003

YOU try it then.

Perhaps I have an old rec and some trashable speaks around here, let me look.

Cheers,
Russ

hoosier21 · May 2003

no boom, there is only one amp in a receiver, A & B terminals are really the same connection.

mantis · May 2003

There is no need to wire your system this way.Speaker B is designed to run a seperate pair of speakers in another room or as Stereo pair in the home theater room if the A speakrs are micro in size..........

RuSsMaN · May 2003

Thanks Tour/Hoosier.

I actually did test it late this afternoon, worked fine. No improvement, but no 'boom' either.

Cheers,
Russ

Tour2ma · May 2003

Excellent RuSs"Enquiring minds want to know"Man...

It's just circuit analysis. Now you see that double runs of wire to the two sets of posts on a speaker with the jumpers still in place will not produce the other of the Club's mythical booms.

Now settle a bet between hoosier and me by completing the experiment... switch the leads on one of the rec outputs and report what color the flames are...

GuitarheadCA · May 2003

Things you didn't want to know about what CC salemen do during slow times:

We used to pick a reciever we wanted to torture (usually a sony)tie positive and negative ends of the speaker wire to each other, and see how far we could turn the volume up before something fun happened. A few times we got sparks, but most of the time the protection circuit just went on. So kinda "boom"

hoosier21 · May 2003

That's it no more "open box" purchases for me

BeginnersLuck · May 2003

Yeah...I guess I was just assmuing that the receiver has discrete amplifier stages for both a and b connections. If the amplifications stages were dicrete then the unit would kick out some smoke...because most manufactures don't put protection on the individual discrete amps, you run the risk of frying the discrete amp circuit board. It would be like hooking up left and right terminals on the receiver to one speaker terminal. A well designed receiver will see a short and go into protect mode. A poorly designed unit will make some fireworks...

However, I think it is safe to assume most a + b terminals on receivers are parallel connections and thus doing this would casue very little effect on the overall system, worst case senario being an impedence drop seen by the receiver (if you run two sets of wires to two 8 Ohm loads...and you switch on A+B at the same time the receiver will see the 4 Ohm load).

If you hook up the speakers as gidrah mentioned in his first post...all you are doing is essentially increaing the gauge of your wire...

-BL

gidrah · May 2003

I'm glad Russ tried it. I didn't think it would go boom, but I currently don't have an amp/receiver that has A/B that I'm willing to risk. Actually, now that I think about it, I don't have any around that do A/B with the same amp.

Discrete (separate) amps are a different subject. I can see where not removing the jumper for bi-wire might even be beneficial, but for bi-amping I would assume there would be a boom. As of about 20hrs ago I've been using my B for my horn supertweeters.

Thanks for those that had faith! You will be spared.

Russ - You've got mail. It should be there shortly after I actually send it. I'll assume you don't want the nOrhs. That's cool I like 'em. I sense a center channel or computer speakers in my future.

Tour2ma · May 2003

Originally posted by gidrah
Actually, now that I think about it, I don't have any around that do A/B with the same amp.

THAT is Classic...

... and I agree with hoosier about open stock...

GuitarheadCA · May 2003

Well ya'll deserve to know- there's a critical question you should ask when considering open box.

Was this a customer return? or a display model?

Now, Customer returns are usually fine, usually the wife didn't approve, or they couldn't get it to work (even though it does), or some other reason, And those don't get hooked up as displays, but sit there in peace untill someone buys it.

Displays on the other hand- you couldn't pay me to take some of those. Not only have curious salesmen performed all kinds of wiring tests to many of them, they have been running 16 hours a day since the day they were set up, and everyone and their dog has fiddled with it. Hidden deep in under one of the computers in our audio department was our "digital bass CD of death". This was our invaluble tool to test all new speakers by. Yes I know better, but it was still fun.

gidrah · May 2003

If I actually did half of what I thought about doing I'd be done.

Tour2ma · May 2003

Originally posted by gidrah
If I actually did half of what I thought about doing I'd be done.

Actually I think that's the definition of half-way done...

However, in the midst of the levity let's not be remiss in thanking GHeadCA for the inside scoop on dealer demo's... Thanks...

Airplay355 · May 2003

when i have the A and B speakers running at the same time the signal seems weaker...maybe a drop in watts? there is clearly a difference in the amount of bass produced and the loudness. just curious to see what that is because theres nothing about it in the specs of my rec. the speakers are rti100's and some yamaha bookshelfs. the rec. is an aiwa avd57. whatcha think?

Tour2ma · May 2003

Yup, you're straining your amp.

A+B puts the two pair of speakers in parallel.
Parallel circuits produce less impedance. For example:
- if both pairs of speakers are 8 ohm, the amp is "seeing" 4 ohm;
- if both pair are 4 ohm, sees 2 ohms; and
- if one pair is 4 and the other 8, sees 2.67 ohm.

Reduced impedance means the amp's current output must rise to produce the same power (spl). If the amp is not very powerful and does not have high enough current output capability, it's going to run out of juice, sound weak and clip its ****$ off. VERY bad for your tweeters.

burdette · May 2003

Originally posted by Tour2ma
Yup, you're straining your amp.

A+B puts the two pair of speakers in parallel.

I do believe that it is up to the manufacturer whether the A/B terminals are wired in parallel or series. I've read enough to know that both occur, because you may need to know the wiring in order to know if two certain pair of speakers should be connected to the A and B outputs.

Edit... sorry... if you know for sure about his specific amp, then I took your comment too generally. My general comment is that it can be either.

I don't agree that a reduction in volume is *necessarily* straining his amp. It makes sense that if you connect two pairs of speakers to the same power, they have to share and neither will be as loud. AND, when speakers aren't playing as loud, bass appears to drop away more quickly. BUT... strain on the amp wouldn't be a given if it was still operating within a safe zone. He just may not be able to turn the volume up as loud with both connected. IMO, of course.

Tour2ma · May 2003

Truth be told, it did not occur to me that the A+B position could be in series. Actually makes more sense to design that way for lower power amps. I have only encountered parallel designs.

You are correct, burdette, if the A+B was a series arrangement, the impedances sum and a volume reduction for the same volume setting with just one-pair of speakers would occur uniformly across the entire volume range. Good point about the bass rolloff with reduced power.

In parallel, the spl would not drop at low volume settings, it should actually increase. And this would be true until clipping is approached at higher voume settings. There the volume gains would stop at lower settings than you'd experience with one-pair.

Good observation...

Dual (not bi) wiring speakers?

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