Potential downsides of bi-amping? - Page 3 - AVS Forum
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post #61 of 76 Old 02-28-2014, 12:43 PM
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Originally Posted by DonH50 View Post

It is not recommended due to the potential problem of cancellation with multiple sources across the front. They may interfere with each other instead of helping to smooth the response
With subs the wavelengths are far too long for that to be an issue. In general you would get a better result running the mains full range along with the subs, if the mains were able to keep up. But most mains won't. Using the mains down into the subwoofer region also eats up headroom in the AVR amps and the main speakers, which can lead to distortion from both.

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post #62 of 76 Old 02-28-2014, 01:17 PM
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Good points Bill. Should've thought more before I posted.

Most main speakers, even if rated to 20'ish Hz, will exhibit very high distortion down low. And the headroom issue is a significant concern as well.

Thanks! - Don

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #63 of 76 Old 02-28-2014, 08:20 PM
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Just get a nice beefy amp that doubles its power into 4 ohms. I like amps that are class A in the first 20 watts or more. I really appreciated class A with higher sensitivity speakers.

Honestly the best thing you can do is buy a crappy amp and see how you like it. You wont know how good a pass labs amp is unless you have a basis for comparison.

Everything "high end" seems overpriced with no reference point for quality.

Blazar!
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post #64 of 76 Old 03-01-2014, 05:58 AM - Thread Starter
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Just get a nice beefy amp that doubles its power into 4 ohms. I like amps that are class A in the first 20 watts or more. I really appreciated class A with higher sensitivity speakers.

Honestly the best thing you can do is buy a crappy amp and see how you like it. You wont know how good a pass labs amp is unless you have a basis for comparison.

Everything "high end" seems overpriced with no reference point for quality.
Ha, great minds... I Actually just picked up an Emotiva XPA-200... I'm enjoying it so far...

Running it via singles with jumpers. Albeit nicer aftermarket jumpers... Not snake oil nice, just thicker gauge copper and copper/gold spades.

The bi-amping experiment got boring...
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post #65 of 76 Old 03-01-2014, 06:46 AM
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Running it via singles with jumpers. Albeit nicer aftermarket jumpers... Not snake oil nice, just thicker gauge copper and copper/gold spades.
Not that it matters to you now, but for the benefit of others 'upgraded' jumpers don't do a thing. If you were to open up your speakers you'd find them wired with at best 16 gauge plain copper wire, and anything in excess of that on the jumpers two inches upstream won't work any better.

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post #66 of 76 Old 03-01-2014, 07:15 AM
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Originally Posted by DonH50 View Post

Good points Bill. Should've thought more before I posted.

Most main speakers, even if rated to 20'ish Hz, will exhibit very high distortion down low. And the headroom issue is a significant concern as well.

Thanks! - Don

+1

If you check web sites that post THD tests for speakers a common trend is:

(1) Speaker THD numbers are scary-high period. -40 dB is a good number and that is 1% THD

(2) Even very good speakers distortion have distortion that rises rapidly blow 200 to 100 Hz

Offloading even large floorstanders below 80 Hz is doing them a big favor, and even fairly humble subwoofers perform far better at those frequencies.
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post #67 of 76 Old 03-01-2014, 07:24 AM
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A downside? My house could collapse with 33 krell 900E's ;-) (11 channel, tri-amping each speaker)

Krell Evolution 900e x 7

Bose Jewel speakers.

 

Jealous of my speakers?

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post #68 of 76 Old 03-01-2014, 07:31 AM
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A downside? My house could collapse with 33 krell 900E's ;-) (11 channel, tri-amping each speaker)

If there were Engineering Gods they'd do something even worse first, for flaunting them so badly! ;-)
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post #69 of 76 Old 03-01-2014, 10:15 AM
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Originally Posted by arnyk View Post

Quote:
Originally Posted by DonH50 View Post

Good points Bill. Should've thought more before I posted.

Most main speakers, even if rated to 20'ish Hz, will exhibit very high distortion down low. And the headroom issue is a significant concern as well.

Thanks! - Don

+1

If you check web sites that post THD tests for speakers a common trend is:

(1) Speaker THD numbers are scary-high period. -40 dB is a good number and that is 1% THD

(2) Even very good speakers distortion have distortion that rises rapidly blow 200 to 100 Hz

Offloading even large floorstanders below 80 Hz is doing them a big favor, and even fairly humble subwoofers perform far better at those frequencies.

I was looking at B&W's specs for one of their 800-series speakers recently and noticed an interesting point. They specified <0.5 % THD at 90 dB/1 m from 100 Hz on up, and 1% THD for the same output from 80 Hz on up. Now, that is excellent performance from a speaker, but I found it very interesting that THD doubled when they dropped from 100 Hz to 80 Hz.

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post #70 of 76 Old 03-01-2014, 01:21 PM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

Not that it matters to you now, but for the benefit of others 'upgraded' jumpers don't do a thing. If you were to open up your speakers you'd find them wired with at best 16 gauge plain copper wire, and anything in excess of that on the jumpers two inches upstream won't work any better.

He *will*...???

I opened mine up and found 12 gauge inside. The same as the standard jumpers...

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post #71 of 76 Old 03-01-2014, 02:14 PM - Thread Starter
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Quote:
Originally Posted by Bill Fitzmaurice View Post

Not that it matters to you now, but for the benefit of others 'upgraded' jumpers don't do a thing. If you were to open up your speakers you'd find them wired with at best 16 gauge plain copper wire, and anything in excess of that on the jumpers two inches upstream won't work any better.
The stock LSiM jumpers are actually pretty nice, 10 gauge and gold-plated brass, but those went on my LSi7s... The only pair I had lying around (I can't remember what speakers they came off of) were just unfinished steel... I don't go in for a lot of the mumbo-jumbo (hence this thread, and my question regarding the more exotic cable options), but I figured copper and gold has to be a reasonable upgrade from plain steel, even in that very short run...?
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post #72 of 76 Old 03-01-2014, 04:25 PM
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but I figured copper and gold has to be a reasonable upgrade from plain steel, even in that very short run...?
Depends on what you mean by upgrade. Audible or measured difference? Then no.
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post #73 of 76 Old 03-01-2014, 05:42 PM - Thread Starter
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Depends on what you mean by upgrade. Audible or measured difference? Then no.
Not trying to be argumentative, but is this established? I mean, copper is literally almost six times as conductive as steel... I could understand no measurable difference between brass and gold or copper jumper tabs, but steel?
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post #74 of 76 Old 03-01-2014, 06:21 PM
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Run the numbers for the cross-sectional area and length of the jumpers using steel and copper and see if there is a significant difference relative to the rest of the wiring. I don't know, but that is where I would start to answer your question.

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post #75 of 76 Old 03-01-2014, 07:04 PM
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Not trying to be argumentative, but is this established? I mean, copper is literally almost six times as conductive as steel... I could understand no measurable difference between brass and gold or copper jumper tabs, but steel?
Steel has approximately ten times the resistance of copper, which is one reason why we use copper for wire and not steel. But the resistance of two inches of 16 ga steel is about 0.008 ohms, which is about 1/50th what it would have to be to be audible.
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post #76 of 76 Old 03-02-2014, 03:45 PM - Thread Starter
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Originally Posted by Bill Fitzmaurice View Post

Steel has approximately ten times the resistance of copper, which is one reason why we use copper for wire and not steel. But the resistance of two inches of 16 ga steel is about 0.008 ohms, which is about 1/50th what it would have to be to be audible.
Thanks for clearing that up for me... This stuff is fascinating. I'm going to figure out some resources and start boning up. Cheers!
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