So I tried bi-amping my Salon(1)s...

[RichB]

If you have hard and fast notions about the efficacy of bi-amping or believe anecdotal listening sessions have no meaning, I suggest that you read no further because what follows will just upset you, and what's the point in that.

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I have read the rational behind bi-amping have been in general agreement that it seems best to just get a bigger amp. Bi-amping with passive crossovers is often discounted but as has been pointed out, If there is no load there is no power used. So, the power benefit remains, though small and unpredictable. I came into this expecting no benefit and possibly a degradation.

The Salons 3x 8" woofers are crossed 24/DB per octave at 125Hz so that seems to be a good candidate for bi-amping.
In the past, I have tried bi-amping then with the Sunfire 7400 because I had the channels left over and really did not find any audible difference.
That was with different amp and preamp. At the time, I used the Onkyo PR-SC5507 bi-amped setting and later found that it degraded the sound. I am guessing that the processor engaged the DSP's to duplicate the signal which might have had side-effects. Bi-amping sounded better 5507 splitting the XLR's with a Y-cable.

Since I am considering mono-blocking the Salons with 2x A21's, I wanted to make sure that splitting the signal did not have a negative effect.
Only the right speaker was used with the system, swapping the speaker in and out of bi-amp.
The signal remained split to both channels even when using only one amp channel.
I also swapped channels cables so different channels and cables were used for the upper/lower frequencies.
There was a noticeable difference in the sound quality.

I cajoled and friend (who is a good listener) into a single-blind test switching between tracks and setups about 8 or ten times. It was not at all difficult to tell the difference. He described the bi-amp speaker as clearer and with more bass. I felt the same, a cleaner better defined upper end and with tighter (not more) bass.

The next day, I repeated the experiment with my friend, this time using the other (left) speaker and the results were the same; Clear up upper end and tighter bass. We also tried the A31, single/bi-amped with similar results.

During the single speaker tests the HA-1 was directly connected A21 with volume set to -18.
To rule out volume difference we tested the voltages with the HA-1 set to -30 (so as not to harm anything, including our ears) with the following results:

Tone: Single amp / Bi-amped High End/ Bi-amped Low End
100Hz: 2.48 / 2.49 / 2.45
250Hz: 2.49 / 2.49 / 2.52
1kHz: 2.49 / 2.49 / 2.51

This is to be expected and it rules out volume differences accounting for our observations.

I am not an EE but here are some theories:

• Bi-amped remained in Class-a for the upper section.
• The A21 and A31 prefer the load for some reason.
• There is an interaction between the crossovers that does not occur with bi-amped. They are close the 15 years old.

Of course, this proves nothing about the overall efficacy of bi-amping and that is not my purpose. My purpose is was to see if there may be a value with in my system to doing so. I am just about there. What I have is certainly very good. But, another A21 seems to be better.

As for JC-1’s, I would need an in-home trial before going there.
If these observations are due to class-a, then the JC-1 would sound as good or better. If they are do something going on in the Salons, then I the adding an A21 is the best choice.

For the record, I don't have any audiophile jewelry. BJC and monoprice interconnects, original Monster speaker cables, and standard power cables connected to two 20 amp circuits connoted to the a dual breaker. I am using a Kimber USB DAC cable, but that;s a story for another time

- Rich

 

[Swerd]

Trying to understand your lengthy post…

Did you split things so the three 8" woofers were amped separately from all the rest? And that crossover point is at 125 Hz?

 

[RichB]

Trying to understand your lengthy post…

Did you split things so the three 8" woofers were amped separately from all the rest? And that crossover point is at 125 Hz?

The Salons are crossed at 125HZ to the 3 eight inch woofers. When you remove the connecting bands on the Salons and bi-amp, the 3 woofers are driven by one amp and the other drives the mid-bass, midrange, and tweeters.

- Rich

 

[walter duque]

How much power are you running into each??

 

[RichB]

How much power are you running into each??

The A21 is 250 WPC into 8 ohms and 400 watts into 4 ohms.
During listening sessions with one speaker, the Radio Shake meter measured between 80 DB and 100 DB at 2 meters (C weighted/Fast).

- Rich

 

[Irvrobinson]

With my original Legacy Focus, which had three paralleled 12" woofers per channel, I heard a definite improvement in mid/upper range listenability, as measured by my tendency to listen longer, when passive bi-amping with Levinson 334 amps. With the Salon2s, no improvement at all. It was very interesting, since the Foci are about 8db more sensitive than the Salon2s. I haven't tried it even once since getting the ATI amp, and I even have the extra channels just sitting there idle.

 

[Swerd]

I am not an EE but here are some theories:

• Bi-amped remained in Class-a for the upper section.
• The A21 and A31 prefer the load for some reason.
• There is an interaction between the crossovers that does not occur with bi-amped. They are close the 15 years old.

Of course, I don't really have a clue as to why you hear a difference. Those speakers are quite different from what I listen to. So I can only think out loud and guess.

I would avoid a possible explanation like your first idea, about amps remaining in Class A mode, unless you can first demonstrate that you can readily distinguish the sound of a Class A amp vs. a Class AB. That is another controversial subject, with many opinions, but little solid evidence for it or against it.

Your second and third ideas seem on face value more reasonable explanations. Are those three 8" woofers in parallel to each other? That, and what must be a very large inductor coil in the 125 Hz hi-pass filter (Edit: that should say low-pass filter) must be a tough load to drive. In less expensive speakers, a passive crossover that low is avoided primarily for the high cost of inductors and capacitors needed for that frequency. Plus the fact that it may heat up a lot, requiring even higher power.

 

[RichB]

With my original Legacy Focus, which had three paralleled 12" woofers per channel, I heard a definite improvement in mid/upper range listenability, as measured by my tendency to listen longer, when passive bi-amping with Levinson 334 amps. With the Salon2s, no improvement at all. It was very interesting, since the Foci are about 8db more sensitive than the Salon2s. I haven't tried it even once since getting the ATI amp, and I even have the extra channels just sitting there idle.

I suspect this might be something about the original Salons (or age) but it is interesting when not everything fits into neat containers.

- Rich

 

[RichB]

Of course, I don't really have a clue as to why you hear a difference. Those speakers are quite different from what I listen to. So I can only think out loud and guess.

I would avoid a possible explanation like your first idea, about amps remaining in Class A mode, unless you can first demonstrate that you can readily distinguish the sound of a Class A amp vs. a Class AB. That is another controversial subject, with many opinions, but little solid evidence for it or against it.

Your second and third ideas seem on face value more reasonable explanations. Are those three 8" woofers in parallel to each other? That, and what must be a very large inductor coil in the 125 Hz hi-pass filter must be a tough load to drive. In less expensive speakers, a passive crossover that low is avoided primarily for the high cost of inductors and capacitors needed for that frequency. Plus the fact that it may heat up a lot, requiring even higher power.

The class-a theory is not likely since at low levels bi-amped the difference is still present.

I don't know how the woofers are wired but the Salons are 3 ohms minimum.

- Rich

 

[AcuDefTechGuy]

When you remove the connecting bands on the Salons and bi-amp, the 3 woofers are driven by one amp and the other drives the mid-bass, midrange, and tweeters.

- Rich

I thought when you remove the jumpers, all the drivers are still connected to the same crossover system. If the 3 woofers were disconnected from the crossover and the rest of the drivers, they would be ACTIVELY bi-amp.

 

[RichB]

I thought when you remove the jumpers, all the drivers are still connected to the same crossover system. If the 3 woofers were disconnected from the crossover and the rest of the drivers, they would be ACTIVELY bi-amp.

Active bi-amping puts the crossovers in front of the amps limiting the signal that is amplified.

Disconnecting the straps uncouples the woofers from higher-frequency drivers but the crossovers remain in place so this is passive bi-amping.

The amp driving the mid-bass and above is no longer driving the woofers and there is no load below the crossover so less power is required.

- Rich

 

[PENG]

Disconnecting the straps uncouples the woofers from higher-frequency drivers but the crossovers remain in place so this is passive bi-amping.

Remained, but I believe the crossover would be split into two parts, one half low pass, the other half high pass.

The amp driving the mid-bass and above is no longer driving the woofers and there is no load below the crossover so less power is required.

- Rich

Agree, those the high pass filter is not a brick wall.

 

[Irvrobinson]

I suspect this might be something about the original Salons (or age) but it is interesting when not everything fits into neat containers.

- Rich

I know around here passive bi-amping is a first cousin of thinking properly sized speaker cables sound different, but

Active bi-amping puts the crossovers in front of the amps limiting the signal that is amplified.

Disconnecting the straps uncouples the woofers from higher-frequency drivers but the crossovers remain in place so this is passive bi-amping.

The amp driving the mid-bass and above is no longer driving the woofers and there is no load below the crossover so less power is required.

- Rich

Actually, Rich, from looking at the owners manual it is not clear whether the midranges are driven by the same feed as the woofers or from the feed for the tweeters. If you want to be sure I'd call Revel and ask.

 

[RichB]

Actually, Rich, from looking at the owners manual it is not clear whether the midranges are driven by the same feed as the woofers or from the feed for the tweeters. If you want to be sure I'd call Revel and ask.

From trouble-shooting the mid-bass and disconnecting the straps, the mid-bass was tied to the upper frequency drivers and not the three woofers. Is that what you mean?

I am going to call Revel support today to try to get a better understanding. If crossovers are not hard to get to, I would happily replace them if that is the recommendation.

I have attached some drawings provided by Revel.

- Rich

 

[PENG]

From trouble-shooting the mid-bass and disconnecting the straps, the mid-bass was tied to the upper frequency drivers and not the three woofers.
- Rich

My two pairs of 3 way tower speakers are like that too, that is mid range with the tweeter and bass on their own, so I am not surprised.

 

[Irvrobinson]

Calling Revel is your best bet. I'm just bringing it up because in the owners manual there's some wording that could be interpreted as the mids being driven by the woofer board.

 

[Swerd]

The best info I could find is in the Stereophile review of these speakers http://www.stereophile.com/floorloudspeakers/96/

"The Revel Salon is a four-way system with seven drive-units: two tweeters (1.1" on the front and 0.75" on the back), one 4" midrange, one 6.5" midbass, and three 8" woofers."

"The crossover uses fourth-order slopes, the drivers operated in their optimal range to yield the flattest off-axis and first-reflection responses. Each major section—tweeter, midrange, midbass, woofers—has its own crossover board populated with high-quality individual components. The crossover elements of each Salon are individually trimmed and matched to within 0.5dB of a design reference."

It describes two pair of speaker terminals that allow for biwiring, but it doesn't say which drivers are wired to the upper or lower terminals.

To my thinking, it would make sense to have the 3 woofers separable from the rest of the drivers, but I didn't make this speaker, Revel did.

Here is the impedance curve from that review:

And the frequency response curve showing the port, woofers, upper bass driver, and mid range driver:

 

[RichB]

The best info I could find is in the Stereophile review of these speakers http://www.stereophile.com/floorloudspeakers/96/

"The Revel Salon is a four-way system with seven drive-units: two tweeters (1.1" on the front and 0.75" on the back), one 4" midrange, one 6.5" midbass, and three 8" woofers."

"The crossover uses fourth-order slopes, the drivers operated in their optimal range to yield the flattest off-axis and first-reflection responses. Each major section—tweeter, midrange, midbass, woofers—has its own crossover board populated with high-quality individual components. The crossover elements of each Salon are individually trimmed and matched to within 0.5dB of a design reference."

It describes two pair of speaker terminals that allow for biwiring, but it doesn't say which drivers are wired to the upper or lower terminals.

To my thinking, it would make sense to have the 3 woofers separable from the rest of the drivers, but I didn't make this speaker, Revel did.

Here is the impedance curve from that review:

And the frequency response curve showing the port, woofers, upper bass driver, and mid range driver:

Disconnecting the jumper straps proves conclusively that 3 woofers are separate.
The woofers have a separate crossover board.
I am not sure what the separate resistor board does.

- Rich

 

[Swerd]

Disconnecting the jumper straps proves conclusively that 3 woofers are separate.

Mystery solved!

Those 3 woofers are likely to be the most difficult part of those speakers for an amp to drive. So it makes sense to separate them – if you plan to biamp – from the rest of the system.

I don't remember looking at the impedance curves of speakers with 3 woofers, especially if they are crossed at 125 Hz. But I wonder why I see those large impedance ripples of ±4 ohms, between 20 and 200 Hz. In the same frequency range, the impedance phase angle makes a fairly large shift, greater than 45°, but not greater than 90°. All of this suggests, but does not guarantee, that the woofers are difficult to drive.

If all this speculation is true, then I wouldn't be surprised if bi-amping these speakers, as you did, makes for an audible improvement.

 

[AcuDefTechGuy]

And even when you remove the jumpers, all the internal crossovers are still connected to all the drivers and you can only Passive bi-amp.

This means after all is said and done, you really get no significant benefit from passive bi-amp.