Freaky speaker experience:


I have the Nuforce 9SE pre's and amps. I had them attached to my Focal JMLABS 936; bi-wired at the speaker but single ended at the amp. They sounded soooo crappy (tinny, bright, fatiguing) that I was ready to toss them off the second floor window. :) Could'nt understand. For kicks, I single wired it using the original jumpers. Now they sound awesome. About 10 cd's later still awesome.????? They sound different but as good as my Totom Mani's. Any ideas about the bi-wiring? Too much juice going to the high end?
cepages
Rleff -- Interesting thought, but I wouldn't think so. From the amp's perspective, the speaker load impedance should appear to be the same in both cases, with the VERY slight exceptions that:

-- The total wire resistance and inductance, being greater in the non-biwired configuration, would cause the amp to see a VERY slightly heavier load in the biwired configuration.

-- The amp would see a VERY slightly greater amount of load capacitance in the biwired configuration.

-- The amp would have to deal with a VERY slightly greater amount of back-emf from the woofer section in the biwired configuration, because a VERY slightly greater fraction of it would be absorbed by the high frequency section of the speaker in the non-biwired configuration.

But I would think that all of those differences would be extremely minute, probably not audible at all, and certainly not enough to account for what Cepages seems to be describing. And having the amp deal with woofer back-emf, rather than the mid/tweeter parts of the speaker, normally improves rather than degrades the sound.

In saying these things I'm assuming, of course, that the wires do not have extreme, outlandish values of either resistance, inductance, or capacitance.

Greg said:
he told me that when you bi wire the current of your amp gets divided between the two wires and that only half the current would get to the woofers and half to the highs

He mis-stated that to you. What happens when you biwire is that the low frequency part of the crossover network in the speaker, being in series with the low frequency wires between the speaker and amp, keeps the high frequencies from going through the low frequency wires. And the high frequency part of the crossover network in the speaker, being in series with the high frequency wires between the speaker and amp, keeps the low frequencies from going through the high frequency wires. The result is less interaction between high frequency and low frequency currents, which normally results in a slight benefit. Also, as I noted above, back-emf from the woofer is conducted entirely to the amplifier, rather than some fraction of it being conducted to the mid/high speaker elements.

It's easy to understand how bi-wiring can result in either slight improvement or no improvement, but frankly I have no idea how it could result in significantly worse sound (assuming, again, that the cables have reasonably conventional parameters).

Regards,
-- Al
So cool that your wife is going to conduct this experiment with you. I would get the "oh, my husband's an idiot sigh". Any results yet? I have Forests and have not bi-wired.
great point Al, but what i don't understand is why then when i added a second amp, two pass lab x-250's, the speakers had way more dynamics and punch, the bass from the woofer was much tighter, quicker and more controlled and the transaction into the midbass was smoother giving the speaker a warmer and fuller sound quality that i like as compared to when i had them bi wired they sounded much like as cepages describes, also when using the two amps there is a noticeable improvement in the midbass driver as compared to using one amp bi wired, i would think that by using two amps there would be more current to power the woofers because the amp no longer has to power the mid bass, midrange and tweeter and the second amp would power the mid bass, midrange and tweeter much easier too, makes me wonder if the guy who sold me the speaker wire was right about the current dividing in the two wires when you bi wire as two amps sound so much better than when you use one, anyhow for me it sounded better with using two amps, just my thoughts.
greg
Hi Greg --

Biamping, as you no doubt realize, is simply a whole different thing compared to either biwiring or single-wiring from a single amp. It has lots of potential benefits, and a search of this and other forums will turn up lots of interesting reading on it. Although, of course, some of the advantages that are often mentioned for biamping only apply to active biamping, where an electronic crossover ahead of the amplifiers replaces the passive crossovers in the speakers. But "passive biamping," which I suspect is what you are doing, has lots of potential advantages, too, which biwiring doesn't provide.

Not sure if you are doing it "vertically" (one amp driving the highs and lows of one speaker, and the other amp driving the highs and lows of the other speaker), or "horizontally" (one amp driving the lows of both speakers; the other amp driving the highs of both speakers). The noted designer Steve McCormack has made the point in posts here that the vertical arrangement is probably preferable because in that arrangement each amplifier sees an identical signal at both of its inputs. That eliminates possible interactions within the amplifier between channels, via power supplies, grounds, and other paths, that can impact the sound when a single amp is handling two different input signals for two different channels.

In either arrangement, biamping reduces or eliminates the possibility of interaction between highs and lows in the amplifier output stages; it provides more total power; it presents each amplifier channel with a less complex load; and there are undoubtedly other advantages which I'm not thinking of right now. As I say, its a whole different thing compared to bi-wiring, which just basically separates the highs and lows so that they travel through different wires.

Best regards,
-- Al
very interesting, thanks for the info Al, the amps in my system are set up horizontally, i will have to try setting them up vertically one day to see what it sounds like.
greg