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Bi-wire questions.

J

justjed

Active Member
I've been reading a lot about bi-wiring speakers, and have a couple of questions.

First, and most specific, my bi-wire capable speakers are 8 ohm nominal, when single wired with jumpers. My amp has A & B speaker outputs. I run the A out to the woofers, the B out to the MTM. Does my amp react as if it has a 4 ohm load(2 parallel 8 ohm loads)?

The second, more general question, refers to running a single wire out, and splitting to bi-wire configuration at the speaker. While the circuit is electrically the same as running separate wires to hi/lo, some people claim that there is a noticeable difference between the two configurations, and some say it's impossible to hear the difference. I would assume that I gain an electrical advantage at the amp by increasing the the effective wire gauge by running two sets of wires. Could this be enough difference to be audible, in some systems, versus the extremely short(relatively) split in a single/bi-wire set-up?
 
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1. No, it is still 8 Ohms, as your drivers are 8 Ohms, you will have to run the drivers parallel to get 4 Ohms. By bi-wiring in a 2-way MTM speaker, you run the two woofers with one amp, and most probably those two woofers are already connected in series to run in 8 Ohms. And, the tweeter is run directly by a second amplifier. The power from both amps passes thru the x-over first in order to filter the signal to the appropriate
Hz for the mid/low and highs. When bi-amping, remember to take out the bridge connecting the upper and lower speaker connectors. This is the basic explanation, for more specifics there are more knowledgeable people here that can get into that.

2. I have never done it, might do a quick set of DIY speaker cables for those purposes. But, I have heard some people that hear the difference, others that don't notice a difference. I'm sure that people from both camps will post. My uneducated opinion is that in short runs there shouldn't be a difference to a very slight improvement.
 
Not bi-amping, I'm running both speakers off of the same amp, which has two speaker outputs/channel instead of using two wires from a single terminal. Output A(l/r) goes to the woofers, output B(l/r) to the MTM. It's two 8ohm loads per channel.
 
Why would it make a difference running two wires from a single terminal vs the way I am running it now?
 
Bi-wiring can have a cross-over influence in the power amp I'm told. I have done this a couple of times thru the years, but I just didn't realize any benefit, other then having more copper delivering the goods.

Try it and you may like it. If not, then at least you can tell yourself that you tried it.

Wayner
 
justjed said:
Why would it make a difference running two wires from a single terminal vs the way I am running it now?
Click to expand...

Because I don't know how your amp is wired.

The instructions for my DQ-20s and 30s both say to use a common amp terminal.

The reason why you bi-wire is because speaker drivers are also generators in addition to being motors and the electricity generated by a woofer returning to its resting position can sometimes be enough to effect the high frequency signal being fed to the tweeters.

It made a difference on the DQ-20s and 30s I had.

It may not in yours.

Enjoy

Eric
 
Some amps, especially Kenwoods, run their As and Bs in series, not parallel. This would make a difference as you would be running 16 ohm which would theoretically lower your amp's output power. I know this because I blew a set of woofers using my KR-8010. The way to test this would be to hookup a set of speakers just on the B terminals. If they don't play then you know the wiring is in series.

I must say that I have always viewed bi-wiring as so much voodoo, but what do I know. I've read the theory behind it and it just didn't sink in and make sense to me.
 
It's a Soundcraftsmen amp, single L/R rca inputs, with A & B switches and terminals for the speakers. Run 1 set of speakers on A, another set on B, or both at the same time. In my estimation, bi-wiring this way is no different from running two sets of 8 ohm speakers at the same time, they're just in the same cabinets. My guess is that the configuration is parallel, the amp reacts as if to a 4 ohm load and outputs more power, tho not necessarily more volume. In other words, the speaker gets THIS loud with THIS much power when single-wired with jumpers. Remove the jumpers, you now have two speakers(in one cabinet), wired in parallel from the amp. Instead of a crossover, it's now two separate filter networks, each with its own 8 ohm driver array. Now, to get THIS loud(same SPL as before), it takes THIS much(usually more) power. Am I missing something in the theory?
 
Biwiring does not effect the impedance seen by the amp. In your case, the nominal impedance is still 8 ohms. The woofer connection and mid/tweeter connection are effectively in parallel, whether you wire to one set of jumpered terminals on the speakers or individually to two sets of speaker terminals (that is, the woofer terminals and the mid/tweet terminals).

I don't know much about your amp, but as noted by another poster, some amps - primarily lower-end units - put A and B in series when B is activated. Also, some amps use resistors to drop power output when second pair is activated (as a form of protection from low impedance loads). I would guess that the A and B terminals of your amp are in parallel.
 
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