Skip to main content ↑ ↓

Notice

Please note that most of the software linked on this forum is likely to be safe to use. If you are unsure, feel free to ask in the relevant topics, or send a private message to an administrator or moderator. To help curb the problems of false positives, or in the event that you do find actual malware, you can contribute through the article linked here.
Topic: Passive bi-amping with AVR (Read 99378 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

Passive bi-amping with AVR

Reply #475 –
Quote from: pdq on
I wonder how closely matched the gains are between separate channels in an amplifier? Even if 1% resistors are used throughout, the errors are cumulative so the difference could possibly be larger that 0.1 dB.

One easy way to check would be to place a voltmeter between two outputs while driving them with the same signal and read the difference.

Edit: I also wonder how much the difference in loading could affect the amplitude. If the output impedance of the amplifier is a few tenths of an ohm then this could possibly be significant.


The gain of an amp is usually set by 2 resistors in the feedback loop. If they are 1% resistors their actual ratio which is what sets the gain is consistent within better  than 1% because of the mean convergence theorem, and because resistors are usually made to closer tolerances than minimum spec so that it is sure that they meet spec.

Passive bi-amping with AVR

Reply #476 –
Quote from: Rich B on
I've posted the question on Audioholics, directed to Gene himself. Will report back with feedback from a well respected EE.


So it's been over two weeks. Did he ever respond?

Passive bi-amping with AVR

Reply #477 –
Quote from: mzil on
Quote from: Rich B on
I've posted the question on Audioholics, directed to Gene himself. Will report back with feedback from a well respected EE.


So it's been over two weeks. Did he ever respond?
He did.  He pretty much backed up what he was told here.  I don't see where crossovers were mentioned here, though.  Was he trying to put words in your* mouth?

http://forums.audioholics.com/forums/threa...for-gene.95122/

Other very experienced and knowledgeable members responded as well.  Apparently, they are less tolerant of rich's games there.

*The web sites, not yours personally.

Passive bi-amping with AVR

Reply #478 –
The example used is similar to previous ones discussed.

I'm surprised however that no one commented:
If you add another amp with 3 dB less power and do passive bi-amping, even if you achieved a 2 dB gain (due to the HF amp seeing an easier load) the total gain would be ... wait for it ... -3 + 2 = -1 dB. Yes. 1 dB less power.
"I hear it when I see it."

Passive bi-amping with AVR

Reply #479 –
It is annoying that Gene says things like this:
Quote
Well your speakers will typically suck more power in the bass than the mids/highs so it could benefit you.
It "could"? Really Gene? Do you mean audibly?

And later when asked about how much additional reserve power is achieved by passive bi-amping, measured in dB, thanks to my urging, we get this:

Quote
As others have pointed out, not much
So any gullible readers in that forum, conned by the passive bi-amp pushing audio industry, hears that as "There may be some improvement, but maybe not very much", reinforced by the notion that he suggests people might attempt to wire things up to test it out for themselves, [sighted, of course!]:

Quote
You can try it if you want...


Which makes them then conclude, "So some people might hear it, even if I can't with my system and ears, otherwise he never would have suggested that I give it a go." ARGH!

This inevitably gives any naïve readers on their forum a glimmer of false hope that doubling their amp budget and passive bi-biamping, using an additional, full power, 100 wpc stereo amp on top of the first one (instead of just one 100 wpc stereo amp used in normal mono-amp configuration), may have at least some legitimacy: "Well, he says it may not be a big increase, certainly not like 3 dB, but it does make a small difference." This completely overlooks three key questions:

A) Is the increase merely measurable, say a fraction of a dB,  but certainly not audible in any conceivable real world situation even designed specifically to show off the difference by using hand selected, esoteric music material?

B) Is this already completely insignificant, tiny bump in increased reserve power over the entire 20-20kHz range [as it truly would be if we instead substituted the 100 wpc stereo amp with a 200 wpc stereo amp, giving three dB more]? Or is it instead only over a small band of frequencies with a center peak at the crossover point, a small part of the entire audible range, and never even remotely close to 3 dB at this peak? Here's a hint Gene: It's the second one.

C) If there is some "small" improvement in at least some very specific conditions, why in the over half century that we have had speakers with bi-amp capable speaker posts sold at the consumer level, have we never seen a single study, or for that matter an individual, who can discern any difference, using any material they want, under blind conditions?

Passive bi-amping with AVR

Reply #480 –
Quote from: mzil on
Didn't this page, I assume written by him, cover all you needed or did you ask him to cite actual blind listening studies and/or "How many dB output improvement might I expect by passive bi-amping, roughly speaking?" questions (like I suggested earlier and I'm confident you won't get direct answers for, but we'll see)?


I called it! [the part I put in bold text above.] No direct answers regarding dB figures of increased reserve power (roughly speaking) were provided, nor were any listening studies cited, in any of his responses, despite my success in getting Rich to bring up both of these concepts in his query over there:

Quote
If you had to estimate how much additional headroom I could expect in such a scenario, would you suspect 1 dB extra, less or more?...

...They [Hydrogenaudio forum] also basically told me that passive bi-amping is utterly worthless and that no person could, under any circumstances, hear the difference. No audibility studies... etc.

Passive bi-amping with AVR

Reply #481 –
You're making far too much out of this. Kool-aid faithful pacebophiles couldn't give a shit about what we say here. They'd ignore or attack Gene too if he didn't provide them with any hope and find solace in some other "supreme authority," placing him on a pedastal over the rest of the community that doesn't provide them with hope.

This whole, "let's wait and see what Gene says" business was pathetic anyhow.

Passive bi-amping with AVR

Reply #482 –
I knew from the get go Gene didn't get it. That's how I knew in advance when challenged to provide a rough dB figure for the "increase in reserve power", he'd fail to answer the question directly, and I was proven right. I certainly never endorsed him, nor his site, in fact just yesterday at AVS, in a discussion with an audio novice about computerized room calibration/EQ systems using calibrated mics, such as Audyssey, I wrote:

Quote
Now that I know there are Audioholic articles which suggest instead of using instrumentation one should ignore them and tweak their dials until it sounds best to their ear, I will never cite another Audioholics article, as  reference for others to go explore, for as long as I live*. It's no wonder billions of people are confused about audio with such mythology being spread by so-called "experts".


[Not that I'm claiming Audyssey and other such systems are infallible.]