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Bi-amping Revel Salon2 makes an ABX audible difference

pjug

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Changing the connections did not move the 150lb speakers.

If you think the differences were caused by background noise difference, or differing reflections due to me or some object having moved, or perhaps the mic temperature changed in the 15 minutes in between, or some other minor difference that is only subconscious in the recording, then you're saying these things are audible despite also being too weak to affect the frequency response (which is unchanged in every measurement), whereas separating the high and low crossover networks and drivers while and driving them essentially with half the output impedance is inaudible.
You might get at this by recording voltages with a two channel ADC. Measured at the amplifier speaker terminals, not at the other end of speaker cables.

1. Biamping one speaker, measure HF and LF as a two channel recording
2. Driving one speaker normally (with LF and HF strapped together), and driving the other one with just HF or LF driven, measure the two amplifier outputs.

If both channels in the first recording are the same, and both channels of the 2nd recording are the same, then bi-amping is not doing anything.

Then you can think about whether the bi-wiring does anything...
 

Pdxwayne

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You conducted the listening tests while you were fully aware of the speaker/amp wiring arrangements. You were not blinded. Claiming that your results were unaffected by such well-known sources of measurement bias is not enough. You must, at least, conduct the same tests while blinded and while unblinded, and compare them directly.

You must also compare results when there were no changes to the speaker/amp wiring arrangement. How many of those test showed you could detect the absence of changes? How many did not? Obviously, you must be blinded as you do those tests.

So far, your results demonstrate a modest capacity for mental masturbation, but little else. Your listening tests were far from convincing.

Edit: I admit, this sounds a bit harsh. But that's after I revised my comments. You should have seen what I took out.

You are certainly free to wire your speakers and amps however you please. No one would try to stop you. But, when you post online claiming you have evidence that you can hear differences between passive bi-amping and standard wiring, you should expect push-back. Try to make it more convincing than you have.
Do you even know what is ABX? You first sentence shows that you don't.....
 

Blumlein 88

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Changing the connections did not move the 150lb speakers.

If you think the differences were caused by background noise difference, or differing reflections due to me or some object having moved, or perhaps the mic temperature changed in the 15 minutes in between, or some other minor difference that is only subconscious in the recording, then you're saying these things are audible despite also being too weak to affect the frequency response (which is unchanged in every measurement), whereas separating the high and low crossover networks and drivers while and driving them essentially with half the output impedance is inaudible.
I mentioned background noises. Wouldn't take much especially at lower frequencies.
 

Lsc

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I tried bi-amping and bi-wiring my salons with ATI signature amps. In the end I went back to putting the jumpers on and using the top terminals. While there seemed to be a slight improvement in midrange performance with the bi-amping/bi-wiring, in the end I felt that the salons sounded the most balanced with the jumpers.

My next dilemma is the crossover point with my subs. I need DLBC but I only have Dirac Live, so I crossover at 40Hz and 70 Hz w the voice2.
 

rdenney

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I tried using two stereo amps for my Concerta F12's, which I realize are waaaaay at the other end of the Revel food chain. I used two B&K Reference 125.2 amps, each amp driving the mids and tweeters for one speaker out of one channel and the woofers out of the other channel. The problem is that the amps are still amplifying the full range of signals in each channel, but the crossover in the speaker attenuates (filters) the frequencies not used by that set of drivers. So, nothing is really gained. It didn't sound any different than using a single amp that I could hear even sighted, but it looked cooler.

Now, it actually runs cooler: I'm using a single Hypex NC502MP stereo amp, having reinstalled the jumpers.

Back when I was using stacked Advents and used a B&K camp for each pair, I really was getting more power using two amps. Kicking the second amp and second pair of speakers in doubled output, the equivalent of +3dB. It was a noticeable increase in listening level, at the expense of a lot of other issues.

Rick "Revel biamping is jes'fo'show" Denney
 

Pdxwayne

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I mentioned background noises. Wouldn't take much especially at lower frequencies.
I listened to both files and don't think I heard any lower freq background noise clues. Are you able to sense any such clues?
 

Pdxwayne

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It is strange that passive bi-amp has less lower bass output than normal connection, per Deltawave.

left_channel_original_spectrum_comparison.PNG


right_channel_original_spectrum_comparison.PNG
 

LightninBoy

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Did you do this using Audio DiffMaker? I did and there was music heard in both channels, just that when played in stereo the imaging seemed more left. The difference is mainly in high frequencies which is consistent with what I hear both live and in the recordings. I'll attach the diff here but I don't make any claims as to the validity of this program's output.
I used Reaper. I tried to render the difference as a file to share but the resulting file sounds different than the Reaper project playback. I think something is wonky with my system.
 

test1223

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Changing the connections did not move the 150lb speakers.

If you think the differences were caused by background noise difference, or differing reflections due to me or some object having moved, or perhaps the mic temperature changed in the 15 minutes in between, or some other minor difference that is only subconscious in the recording, then you're saying these things are audible despite also being too weak to affect the frequency response (which is unchanged in every measurement), whereas separating the high and low crossover networks and drivers while and driving them essentially with half the output impedance is inaudible.
Yes, if the amps are half decent the background noise difference most likely is the cause here. In ABX tests most of the amps can not be distinguished from another. Some amps have minor bass and treble tilts or channel level differences which are audible. But with compensation of this most amps are good enough. Especially if you test with music and don't use test tones.

The frequency measurement method are designed to maximize the signal to noise ratio. Despite this there are differences in the bass, as you showed.

Since the music has some dynamics, background noise with much lower levels might be able to make a small difference.
 

pjug

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It is strange that passive bi-amp has less lower bass output than normal connection, per Deltawave.

View attachment 199292

View attachment 199293
Yes there is more rumble in one of the tracks than the other, not related to the music. I haven't tried it yet, but if you tune into that with headphones or speakers with good LF response I'm pretty sure you would score 100% on ABX.
 

Pdxwayne

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Yes there is more rumble in one of the tracks than the other, not related to the music. I haven't tried it yet, but if you tune into that with headphones or speakers with good LF response I'm pretty sure you would score 100% on ABX.
The rumble was not obvious at all when using my headphones chain:

KTB to L30 to K371.

Yesterday, I tried to listen to section with bass and thought one maybe slightly cleaner (bi amp) than the other (normal). But, I only got 11/16 first try, then 9/16 second try (I was really sleepy already).

OP did 3 rounds and all equal or better than 9/16. I did 2 rounds and all equal or better than 9/16.

So, what is the probability that all 5 rounds, testers can get at least 9/16? It is significant, it seems.

From https://stattrek.com/online-calculator/binomial.aspx, P is 0.0127.

Screenshot_20220412-075435_Samsung Internet.jpg



The question is now about the rumble. Where did it come from?
 
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neutralguy

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I mentioned background noises. Wouldn't take much especially at lower frequencies.

As I mentioned the differences were in high frequencies, and that's what I listened for. I mainly relied on one note from the violins/violas. I wouldn't go through the effort to set this up just to listen for differences in background noise between the notes or to listen for rumble, and nor would I come here to mislead about the results. I have nothing to sell.

As far as the diff output, what I posted above from Audio DiffMaker sounds consistent with what I perceive as the differences, concentrated in high frequencies. I could not hear a rumble even in the diff file.
 

pjug

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The rumble was not obvious at all when using my headphones chain:

KTB to L30 to K371.

Yesterday, I tried to listen to section with bass and thought one maybe slightly cleaner (bi amp) than the other (normal). But, I only got 11/16 first try, then 9/16 second try (I was really sleepy already).

OP did 3 rounds and all equal or better than 9/16. I did 2 rounds and all equal or better than 9/16.

So, what is the probability that all 5 rounds, testers can get at least 9/16? It is significant, it seems.

From https://stattrek.com/online-calculator/binomial.aspx, P is 0.0127.

View attachment 199386


The question is now about the rumble. Where did it come from?
If you apply a LP filter the tracks with 60Hz cutoff, you can get an idea of the difference and what to listen for. I thought I could easily hear the difference early this morning, but now with traffic outside my office it is difficult even with closed headphones. Hear is a visual of the rumble difference between the two tracks (LP filtered and 30dB amplification). Maybe the rumble is just road noise?
1649779093147.png
 

pjug

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As I mentioned the differences were in high frequencies, and that's what I listened for. I mainly relied on one note from the violins/violas. I wouldn't go through the effort to set this up just to listen for differences in background noise between the notes or to listen for rumble, and nor would I come here to mislead about the results. I have nothing to sell.

As far as the diff output, what I posted above from Audio DiffMaker sounds consistent with what I perceive as the differences, concentrated in high frequencies. I could not hear a rumble even in the diff file.
I don't at all doubt your intentions of trying to discern at higher frequencies. But there is no way of knowing whether you could have blocked out what was happening at the low end.
 
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neutralguy

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I don't at all doubt your intentions of trying to discern at higher frequencies. But there is no way of knowing whether you could have blocked out what was happening at the low end.
You couldn't distinguish it after identifying the difference and listening for it, and you think I was able to distinguish it subconscioiusly while listening to high notes?
 

Pogre

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Did you do this blind? Level matched? If it was sighted or you had knowledge of which was which while listening that pretty much voids any conclusions.
 

pjug

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You couldn't distinguish it after identifying the difference and listening for it, and you think I was able to distinguish it subconscioiusly while listening to high notes?
It is really loud in my office with traffic. My desk is about 30 ft from a busy road. I will do an ABX later and maybe at home.

Do you have any interest in doing voltage recordings as I suggested in an earlier post? That would be a better way to do this as I see it.
 

Pdxwayne

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If you apply a LP filter the tracks with 60Hz cutoff, you can get an idea of the difference and what to listen for. I thought I could easily hear the difference early this morning, but now with traffic outside my office it is difficult even with closed headphones. Hear is a visual of the rumble difference between the two tracks (LP filtered and 30dB amplification). Maybe the rumble is just road noise?
View attachment 199399
The rumble, since it is at lower level, likely masked by the music. At least for me, with k371 closed headphones in a quite room, when listening to the actual clips, pretty much can't tell if there is rumble or not....
 

pjug

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The rumble, since it is at lower level, likely masked by the music. At least for me, with k371 closed headphones in a quite room, when listening to the actual clips, pretty much can't tell if there is rumble or not....
For me it seemed very apparent. I guess ABX will tell if I heard what I thought I heard. There isn't much low end in the music to mask the rumble.
 
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