Bi-amping Revel Salon2 makes an ABX audible difference

[pjug]

Very nice.

Curious, what is your listening chain?

At what listening level do you sense the rumble? Regular level where you typically listening to music or louder?

Thanks!

In this case just my work PC straight into budget headphones. PSB M4U2 that I keep here mainly for ANC if things get noisy outside. And louder than normal, a little below uncomfortable.

 

[Blumlein 88]

It turns out I can post the entire file if I separate them into individual zips. Here is the actual two files I ABX'd, and you'll see the same SHA1 as in my logs.

Once again differences below 100 hz. Not as large as the other files and maybe too low in level to hear. Again non-biamped has more low end rumble. There is a persistent .24 ppm speed difference in your files. Are the biamped files being played from the same source as non-biamped?

I'll mention again perhaps some REW sweeps would show something useful. Maybe your non-biamped setup has more low end rumble.

 

[Pdxwayne]

In this case just my work PC straight into budget headphones. PSB M4U2 that I keep here mainly for ANC if things get noisy outside. And louder than normal, a little below uncomfortable.

I see. I listened at normal to lower than normal volume yesterday. I just listened louder than normal and I can easily sensed the rumble using my headphone chain.
: )

Thanks!

 

[neutralguy]

Once again differences below 100 hz. Not as large as the other files and maybe too low in level to hear. Again non-biamped has more low end rumble. There is a persistent .24 ppm speed difference in your files. Are the biamped files being played from the same source as non-biamped?

I'll mention again perhaps some REW sweeps would show something useful. Maybe your non-biamped setup has more low end rumble.

The normal/biamped files are recorded using the exact same setup using jRiver playing a flac, 15 minutes apart, where the only thing changed was me going to change the connections. In fact I purposedly did the REW measurements separately so I wouldn't have to touch the mics. If by .24 ppm speed difference you mean one recording is sped up by 0.24 parts per million, that's 0.616 samples of difference in a 14 second 44khz recording so I'm not sure how you calculated that or how that's significant.

In any case, these are the files I ABX'd by listening to the high notes. If you find some noise or rumble that you can ABX, let me know.

 

[Blumlein 88]

The normal/biamped files are recorded using the exact same setup using jRiver playing a flac, 15 minutes apart, where the only thing changed was me going to change the connections. In fact I purposedly did the REW measurements separately so I wouldn't have to touch the mics. If by .24 ppm speed difference you mean one recording is sped up by 0.24 parts per million, that's 0.616 samples of difference in a 14 second 44khz recording so I'm not sure how you calculated that or how that's significant.

In any case, these are the files I ABX'd by listening to the high notes. If you find some noise or rumble that you can ABX, let me know.

I would expect with the same playback chain the two files to have the same speed. Yet in both the regular connection was .24 ppm faster. Deltawave gives this info (and perhaps on such a short file it is a bit off).

Maybe I missed it earlier in the thread, did you provide some REW measurements? Okay forgot you had them in the first post. Looks like nothing to see there. I still think fluctuations in background noise are the most likely explanation. That is why I mentioned making a few recordings, and then checking them to see if the response is the same on some and corrupted at the low end in others. Discard the corrupted ones and see if you can still hear the difference?

 

[billyjoebob]

It’s all one big system. The speaker cable companies want to sell cables, so advocate for bi-wiring. The speaker companies give them the means to do that, and it gives them an extra marketing opportunity to show of the dual or triple terminals some more that the magazines tout as the best thing since sliced bread. The thing is: speakers with dual terminals sell better than with single terminals. You can’t sell a respectable speaker without at least dual terminals. So yes, there is a lot of incentive to put these thing in!

Yea. I dunno.
Thats a lot of speculation.

Can't sell a respectable speaker without dual terminals?
That is for sure not true!
Neither of my last 2 speaker purchases had dual post.
Only singles.
Guess it depends on whats deemed respectable.

 

[Chrispy]

I've seen several comments from speaker folk saying it is definitely a plus for their marketing to have the bi-wiring type terminals. Even the avr guys sort of encourage the almost as silly passive bi-amping thing. Many people are sure they are doubling the power with a passive bi-amp and maybe even bi-wiring. Marketing works well for these sorts of assumptions. Plus they're cheap to implement.

 

[blueone]

I've seen several comments from speaker folk saying it is definitely a plus for their marketing to have the bi-wiring type terminals. Even the avr guys sort of encourage the almost as silly passive bi-amping thing. Many people are sure they are doubling the power with a passive bi-amp and maybe even bi-wiring. Marketing works well for these sorts of assumptions. Plus they're cheap to implement.

The only good thing one can say which applies to both bi-wiring and passive bi-amping is that they generally do no audible harm. I've run into several people who also think bi-amping and/or bi-wiring look cool.

 

[voodooless]

Can't sell a respectable speaker without dual terminals?
That is for sure not true!
Neither of my last 2 speaker purchases had dual post.
Only singles.

It was a generalization. Obviously there will be exceptions. But in general the lower tier speaker will come with a single terminal, and higher tiers will incorporate dual terminals. That is the case for just about every brand.

 

[pjug]

It turns out I can post the entire file if I separate them into individual zips. Here is the actual two files I ABX'd, and you'll see the same SHA1 as in my logs.

I did ABX on these and was only able to get 10/16 (I think not worth posting results, but I can if you want. I also got 10/16 guessing without playing anything). I don't think your 9/10 is luck, but I'm not able to hear any difference or find any tells from background noise.

Edit: I was 6/7 though at the beginning. Did I get tired? I don't think so, I think my odds just evened out over 16 tries. You might do a couple more runs with 16 tries each.

 

[blueone]

Buy speakers with one set of connectors and there will be no urge to test bi-wiring.......

Passive speakers with a single set of connectors are difficult to find, but at least Dennis Murphy (@Dennis Murphy) had the good sense to include only one set in his BMR Tower.

Philharmonic Audio

www.philharmonicaudio.com

 

[izeek]

Does bi-amping make a difference? My Revel Salon2 speakers come with two pairs of binding posts, and the manual says:

Revel does not endorse one particular connection method over another.... The design of this loudspeaker is such that optimal performance can be attained using the standard connection method.

By connection method, do they mean bi-wiring, or is bi-amping included? When I switched to vertical bi-amping (one stereo amp per speaker), I sensed a subtle but definite improvement in clarity of high frequencies.

To start, let's compare frequency responses. In the vertical bi-amp configuration, each Salon2 is powered by one Benchmark AHB2 in its low gain mode, with the high and low frequency binding post each driven by one of the amp's two channels. In the normal configuration, the manufacturer supplied shorting bridge is used and the speaker is powered via one pair of binding posts. Note that in the normal configuration, each Salon2 is still powered by a separate AHB2, i.e. monoblocking using a single AHB2 channel per amp. This means any differences would be attributable solely to separation of high and low frequency amplification, and not to elimination of stereo crosstalk between the amp's two channels.


View attachment 199194

As we can see, frequency response is unchanged. Variations below 50hz are within usual variation on each measurement, so I wouldn't put any credence on differences there. Still, I was not convinced that the difference I was hearing was all placebo. It's impractical for me to do a blind test, given the time and effort required to change from bi-amp configuration to normal. An ABX with enough repetitions to prove audibility would take dozens of changes, each of which takes longer than ideal for our short audio memories.

Recently in my previous experiment, it was shown that recorded speaker outputs can be used in an ABX test to demonstrate an audible difference for a change of speaker feet, so I wanted to see if this ABX method would also work here. I recorded the output of my Revel Salon2 speakers playing music in stereo using a pair of high quality cardioid microphones (Shure SM81), each mic 2' in front of the tweeter's logo.

I've attached sample clips of the recordings. The original is available free on 2L.co. I think you'll agree upon listening that these recordings are a good enough representation of the original to plausibly reveal differences. I did the ABX test using a piece I'm more familiar with, another recording of a classical string quartet.

The difference was minute, and ABX is hard. There's the time, effort, and mental fatigue. The default of 16 trials requires at least 32 intense listenings of the same passage, likely more. It takes training to tease out perceived differences that are real and can be repeatedly ascertained, versus those that turn out to be due to memory blur or too weak to be detected repeatedly with sufficient accuracy. Repeated listening causes a kind of burn in of the senses and memory. Eat a bite sized piece of single-origin chocolate and you can taste the nuances down to the trees that were planted next to the cocoa. Now imagine eating 32 pieces in a row and then asked to distinguish the nuances between the last two pieces.

I only take a test when I'm able to get good accuracy in training mode, and still my first two tests were only 10/16 and 9/16 correct, which led me to devise techniques to limit fatigue and its effects. It helped to identify an extremely short passage of 2 seconds and to limit listenings by reducing trials from 16 to 10, which is a tradeoff that requires a higher accuracy for statistical significance. I did the third test after training and improved to 9/10 trials correct (p = 0.0107).

View attachment 198976

It's no wonder to me now that ABX tests have come up null for all manners of changes. If I were a random subject brought in off the street, with no practice and no incentive to get the right answer, I would have performed even worse than my initial trials and we would have concluded there was no difference.

I do think the real difference is greater than is captured by the recordings, but that cannot be shown by this ABX setup.


TLDR

Vertical bi-amping of Revel Salon2 using 2x Benchmark AHB2 has the same frequency response but makes an audible difference.

if you liked the results, thats whats most important.
my kit is also vertically bi-amped. i felt the same.

 

[RichB]

if you liked the results, thats whats most important.
my kit is also vertically bi-amped. i felt the same.

Folks who are interested in bi-amping can easily setup a SBT with friends.
I have done so by using Y-splitting a channel to drive a single speaker and switching between a short patch cable and the duplicated input.
3 of us could select single versus bi-amped, largely based on the midrange/treble clarity.

Of course, anyone who decides to bi-amp after such a test or decides not to is fine by me.

- Rich

 

[Chrispy]

Folks who are interested in bi-amping can easily setup a SBT with friends.
I have done so by using Y-splitting a channel to drive a single speaker and switching between a short patch cable and the duplicated input.
3 of us could select single versus bi-amped, largely based on the midrange/treble clarity.

Of course, anyone who decides to bi-amp after such a test or decides not to is fine by me.

- Rich

So how was that test conducted level wise?

 

[RichB]

So how was that test conducted level wise?

Relatively low level, peaks at about 85 dB at 5 feet. That would be about 1 watt.

- Rich

 

[Chrispy]

Relatively low level, peaks at about 85 dB at3 feet. That would be about 1 watt.

- Rich

In terms of level matching/quick switching between such?

 

[neutralguy]

In terms of level matching/quick switching between such?

You can see in the REW graph in the original post that any overall level difference is too minute to be visible.

 

[Chrispy]

You can see in the REW graph in the original post that any overall level difference is too minute to be visible.

That graphic would be hard to justify audibility of any meaningful difference, too.

 

[neutralguy]

That graphic would be hard to justify audibility of any meaningful difference, too.

The graphic does not justify a difference. Rather, differences are in spite of the seemingly identical frequency response, as discussed in the original post.

 

[Chrispy]

The graphic does not justify a difference. Rather, differences are in spite of the seemingly identical frequency response, as discussed in the original post.

Don't know a lot about conditions, just asking questions. And how conclusive are "differences" Is one actually better than the other or a simple preference or just guided thoughts in the first place?