Question about bi-wire and bi-amp

[mulester7]

So what? Is that supposed to be a good thing? Going from 8 ohms to 4 ohms makes the load harder to drive. The receiver now has to deliver twice as much current and twice as much power. It won't be any louder and it doesn't affect sound quality in any way. 100 watts into 8 ohms = 200 watts into 4 ohms = the same SPL.

.....MDS, it's not twice as much current draw increase....it's more, but not twice....DDigitalGuy said the speaker improved in it's sound quality....I know it works, and reports in multiple forums here say it works....once again, your head is saying it doesn't compute......

 

[WmAx]

100 watts into 8 ohms = 200 watts into 4 ohms = the same SPL.

I think you typed this in a hurry because this is an erroneous conclusion if the 4 ohm and 8 ohm speaker compared have the same power sensitivity. The 4 ohm version would be 3dB louder if twice the power was delivered to it, compared to an 8 ohm version with the same 1 watt/meter rating.

-Chris

 

[MDS]

I think you typed this in a hurry because this is an erroneous conclusion if the 4 ohm and 8 ohm speaker compared have the same power sensitivity. The 4 ohm version would be 3dB louder if twice the power was delivered to it, compared to an 8 ohm version with the same 1 watt/meter rating.

-Chris

Yes, thanks for keeping me honest. In the context of this discussion it was about bi-wiring the speakers using the A+B outputs and not a general comparison of two different speakers. The point I failed to convey was the answer to the question 'Are 4 ohm speakers louder than 8 ohm speakers'? If the sensitivities are equal, then the answer is no even though the receiver is putting out twice as much power.

Mulester doesn't believe in math and won't accept that. One of these days we are going to convince you mule - you will be assimilated.

 

[mtrycrafts]

OTE=mulester7] DDigitalGuy said the speaker improved in it's sound quality...

Very subjective report and may be biased?


I know it works,

From empirical evidence or similar very subjective experience?



and reports in multiple forums here say it works..........

Ah, facts derived by a vote?

 

[mulester7]

Yes, thanks for keeping me honest. In the context of this discussion it was about bi-wiring the speakers using the A+B outputs and not a general comparison of two different speakers. The point I failed to convey was the answer to the question 'Are 4 ohm speakers louder than 8 ohm speakers'? If the sensitivities are equal, then the answer is no even though the receiver is putting out twice as much power.

Mulester doesn't believe in math and won't accept that. One of these days we are going to convince you mule - you will be assimilated.

.....hey, I DO believe in math, 8+8=4, and who said anything about an 8 ohm speaker will be louder with the top and bottom halves paralleled making the speaker a 4 ohm speaker?....you guys need to forget spl's....we're talking sound quality, derived from cleanness and authority....you're making educated guesses....sound quality must be experienced, and can't be metered....try some of this stuff.....

 

[mtrycrafts]

.....hey, I DO believe in math, 8+8=4,

Oh, but this isn't simple math. this was discussed and hatched to death elsewhere when one suggested that because they measure 8 ohms on the low section and 8 ohms on the high section and the two are paralleled, the speakers must be a 4 ohm load. BS.
One must have forgotten about the frequency aspect of impedance. The lows and highs in parallel are not two resistors in parallel. So, the speaker is indeed still 8 ohms when they are paralleled.




and who said anything about an 8 ohm speaker will be louder with the top and bottom halves paralleled making the speaker a 4 ohm speaker?.


Not sure, who did???


...you guys need to forget spl's...


Forget science?


.we're talking sound quality, derived from cleanness and authority..

And? You will get this from what, exactly?

..you're making educated guesses....sound quality must be experienced, and can't be metered...

But, you certainly can evaluate sound quality ion an objective manner to get results you can count on, not from guesswork from derived from unreliable evaluation.



.try some of this stuff.....

Great speaker companies do it all the time, but not your way. That doesn't work.

 

[mulester7]

Oh, but this isn't simple math. this was discussed and hatched to death elsewhere when one suggested that because they measure 8 ohms on the low section and 8 ohms on the high section and the two are paralleled, the speakers must be a 4 ohm load. BS.
One must have forgotten about the frequency aspect of impedance. The lows and highs in parallel are not two resistors in parallel. So, the speaker is indeed still 8 ohms when they are paralleled.

.....Mtry, one is forgetting that you're paralleling two 8 ohm elements on "seperate" passive crossovers, not a "common" passive crossover in sections, and only piezo elements don't enter into impedence averaging....in essence, you're paralleling two seperate passive crossovers, and that which is attached to them....which in this case, is two seperate 8 ohm elements....take the seperate passive crossovers out of the picture, and you'll see it.....

 

[mulester7]

I am sure Mulester meant 'forget to listening at high levels.' So go ahead and throw spl out of this. He meant more clarity is where its at. So by listening and measuring a speakers max spl (that will never be used) you are not sitting down to the real science of speakers. Individuality, of each persons ear. And they should decide on the clarity rather than the amount of decibels that a speaker can produce.

.....well, Muffin, that too, but the point was being kicked around whether making a speaker 4 ohms made it louder....who cares?....it's the sound quality we're after......

 

[mtrycrafts]

.....Mtry, one is forgetting that you're paralleling two 8 ohm elements on "seperate" passive crossovers, not a "common" passive crossover in sections, and only piezo elements don't enter into impedence averaging....in essence, you're paralleling two seperate passive crossovers, and that which is attached to them....which in this case, is two seperate 8 ohm elements....take the seperate passive crossovers out of the picture, and you'll see it.....

Sorry. That amp still sees the impedance as frequency dependent. You cannot combine it as a resistor since it is frequency dependent. Whether you parallel them by buy-wire mode, or with the strap at the terminal, it is still parallel and you still don't add as if they were resistors in parallel. Call a respected speaker maker, or an amp designer at Bryston, Chris Russell and see what they have to say.

Don't forget that a low end section exposed to the high end frequency will have very high resistance, that is what the filters do. What happens when you parallel a high resistance with a low resistance? It ain't 4 ohms but almost the 8 ohms of the high section, or 8 ohms of the low section. So, you still have the impedance of the high section and the low section.

Now, on the other hand, if you paralleled the high section of two speakers, then you are parallelling two similar segments of frequency dependent speakers and you will have 4 ohm that an amp sees. We had this discussion when someone measure the resistance of the two sections and called the speaker's 4 ohms, yet the maker calls it 8 ohms. It is 8 ohms.

 

[bfalls]

I bi-amp my home theater Legacy Focus mains using my Denon's main channels for the mid/highs and a Yamaha M-65 (170W) for the 3-12" woofers/ch. I use the sub-out as the input for the subs.

 

[mulester7]

I bi-amp my home theater Legacy Focus mains using my Denon's main channels for the mid/highs and a Yamaha M-65 (170W) for the 3-12" woofers/ch. I use the sub-out as the input for the subs.

.....and you liked this arrangement better than bi-wiring?....you actually should, in most cases....changing the ohmage of a speaker changes the presence/sonic signature of the speaker.....sometimes this is good, most times it's not....opinion based on experience......

 

[bfalls]

Actually, for my situation it's better. Since my Silver Screen center channel is identical to the mid/high portion of the Focus, my impedances are more exactly matched instead of the having the Focus' woofers in parallel with the mid/high section. It also provides independent control of the bass and insertion of a processor if desired.

If I understand bi-wire correctly (running two wires from the same receiver/amp terminals to the separated woofer and mid-high terminals of the speaker) how does this help anything except to put a length of wire in the path? What difference does it make if the woofer and mid/high is paralleled at the receiver's output, or joined at the speaker's terminals? I understand it minimizes electrical interaction between the two xover sections and allows use of different cables for bass and mid/high (which in actuallity just imposes the specific cable's sonic signature (different impedance depending whether it's a difference in resistance, inductance-voltage leading current, or capacitance-current leading voltage) to that section of the speaker). If loving my setup is wrong, I don't want to be right, because it sounds so good. Reminds me of a song

 

[MDS]

If I understand bi-wire correctly (running two wires from the same receiver/amp terminals to the separated woofer and mid-high terminals of the speaker) how does this help anything except to put a length of wire in the path? What difference does it make if the woofer and mid/high is paralleled at the receiver's output, or joined at the speaker's terminals?

You understand correctly. If you passive bi-wire, each speaker will still get a full range signal and its xover will filter out the frequencies it can't use - so what does it accomplish? Now if you use active bi-wiring where an active xover filters out the frequencies first so that it only sends the highs to the tweeter and the lows to the woofer then there could be some benefit.

If loving my setup is wrong, I don't want to be right, because it sounds so good. Reminds me of a song

Showing your age. Sounds like Torn Between Two Lovers - Mary MacGregor.

 

[mulester7]

......as I understand things here, bi-wiring is paralleling of the top and bottom sections of a speaker to be pushed by one amp section....both sections have an independent passive crossover chopping at either the top or bottom of the respective sections, and you might as well do your paralleling at the posts of the speaker, and save wire rather than run two lengths from the amp section....but....paralleling brings a change in the ohmage presented for the entire speaker, and will change the voice of the speaker....this could be good in some cases, but probably not good in most cases....I suspect, in most cases, bi-amping with two amp sections, is the best route to leave impedences and voices as is, but speakers come in all grades, so try both methods....just don't ever try to send two independently amplified signals to the same posts, or you, your significant other, your kids, your dog, and your pocketbook, won't like the result......

 

[mulester7]

.....remember those booster amps for auto use that accepted an amplified signal from the deck?....they sounded good at the time, but the THD was terrible....could the smaller chamber of a car keeping things tight have been more forgiving?.....

 

[mulester7]

Now if you use active bi-wiring where an active xover filters out the frequencies first so that it only sends the highs to the tweeter and the lows to the woofer then there could be some benefit.

.....MDS, would this method and terminology not necessitate bi-amping?.....

 

[MDS]

.....MDS, would this method and terminology not necessitate bi-amping?.....

Yes, what I said actually applies to bi-amping and not bi-wiring.

 

[mtrycrafts]

......as I understand things here, bi-wiring is paralleling of the top and bottom sections of a speaker to be pushed by one amp section....both sections have an independent passive crossover chopping at either the top or bottom of the respective sections, and you might as well do your paralleling at the posts of the speaker, and save wire rather than run two lengths from the amp section....but....paralleling brings a change in the ohmage presented for the entire speaker, ....

The speaker in this case has its drivers in parallel whether or not you terminate at the amp terminal. And, the impedance is not handled the same formula as twp resistors in parallel. You have to take frequency into the formula. The high section offers high impedance at low frequencies, below the filter. Same applies for the low driver when it sees high frequency. So, if you parallel those high impedance with the corresponding lower impedance of the other section, you will still end up pretty much what the other end is by itself. So, the amp still sees the rated impedance of the speaker.

 

[mulester7]

The speaker in this case has its drivers in parallel whether or not you terminate at the amp terminal. And, the impedance is not handled the same formula as twp resistors in parallel. You have to take frequency into the formula. The high section offers high impedance at low frequencies, below the filter. Same applies for the low driver when it sees high frequency. So, if you parallel those high impedance with the corresponding lower impedance of the other section, you will still end up pretty much what the other end is by itself. So, the amp still sees the rated impedance of the speaker.

.....Mtry, no matter where the signals are cut, and no matter what section of the frequency response each section produces, you're paralleling two speaker elements from two different sections that have their own crossover....whatever ohmage they were individually before the action, they are then double-ohmaged toward the lesser efficient.....no?.....

 

[mulester7]

Yes, what I said actually applies to bi-amping and not bi-wiring.

.....sure, MDS, I felt that was what you meant, but this is important stuff imo....MDS, Audioholic Samurai Rare, me and you might PM a few if I ever get that processor decoder....it's obvious you know that pre-pro stuff well......