I don't believe it. I need more power?

[DS-21]

Unlikely. The preamp is from Benchmark Media and the recording is from Telarc. I think it is far more likely to be amp clipping.

The recording, probably not. As for everything else, it's not the parts that are relevant, but the setup. Maybe turn the gain on the preamp down a bit and turn the amp down a bit?

Still, if you're clipping a 300W amp in your room and intend to keep the Revels, you should probably sell it and channel some of the proceeds into one of these, or one of these.

Or replace both in one swoop for a pair of Seaton Catalyists, which are both a lot more efficient (easily 10+ dB worth in the treble, 6+ dB worth in the mids, and probably a a couple dB worth from 70ish Hz up to the top of the woofer's bandwidth) and backed by a lot more power.

 

[TLS Guy]

The recording, probably not. As for everything else, it's not the parts that are relevant, but the setup. Maybe turn the gain on the preamp down a bit and turn the amp down a bit?

Still, if you're clipping a 300W amp in your room and intend to keep the Revels, you should probably sell it and channel some of the proceeds into one of these, or one of these.

Or replace both in one swoop for a pair of Seaton Catalyists, which are both a lot more efficient (easily 10+ dB worth in the treble, 6+ dB worth in the mids, and probably a a couple dB worth from 70ish Hz up to the top of the woofer's bandwidth) and backed by a lot more power.

Or as another respondent stated he could just turn it down and be happy.

He likes the speakers and that is a good start. To improve his situation, he would need an amp in the 900 to 1000 watt per channel with all the problems that entails, with installing high amp circuits. Also I think he would run into serious thermal compression problems in not only the drivers but the inductors in the crossover. At quick estimation, there will be two inductors in the signal path with combined inductance in the 7 to 10 mh range. These are huge and under the best of circumstances will have a combined resistance of the order of an ohm. If those are torched with 1000 watts, they will heat really quickly and will retain heat causing long term changes in parameters. The inductors have to be iron cored or the DC resistance would be through the roof.

So his cheapest solution is to stay put.

You must be joking about the Seaton catalyst?

This is the mid range coaxial driver.

The mid cone has a rolled surround with pretty much zero potential to cope with edge reflections and the HF unit a compression horn. This is a commercial driver for instruments and PAs by the way. Powerful and efficient yes, but accurate, forget it.

 

[DS-21]

To improve his situation, he would need an amp in the 900 to 1000 watt per channel with all the problems that entails, with installing high amp circuits.

(a) As he mentioned, he already has a high-amp (20A) circuit.
(b) The amps I mentioned (Powersoft, Lab Gruppen) are much more energy-efficient than the ATI one he already has. So they will be able to put out much more power as his giant (and excellent) ATI amp at the same current draw. They are also very expensive, though. Seven channels of Powersoft or Lab power is a five-figure investment.

Also I think he would run into serious thermal compression problems in not only the drivers but the inductors in the crossover.

No more than he already is, probably.
FWIW, my one criticism of the big Revels generally is that they sound a bit compressed on massed strings or voices. I'd blame that on the undersized mid, except...the JBL LSR32/LSR6332 has a similar-sized (better, but similar-sized) midrange and crossover points, but doesn't have the same issue.

So his cheapest solution is to stay put.

But if he mentioned it, that indicates some dissatisfaction. When dissatisfied, people are willing to settle, others are not. That's a judgement call.

You must be joking about the Seaton catalyst?

This is the mid range coaxial driver.

The mid cone has a rolled surround with pretty much zero potential to cope with edge reflections and the HF unit a compression horn. This is a commercial driver for instruments and PAs by the way. Powerful and efficient yes, but accurate, forget it.

From that, one can only assume that you've never heard or used the B&C 8CXT. It is an outstandingly good drive-unit in every respect. The cone controls tweeter directivity very well, and the FR niggles are nothing that a competent crossover design can't address. I would happily base my system around them. In fact, next time I visit my Salzburg flat and have time I'm going to convert the not-very-good speakers in there (DIY closed boxes with two Peerless HDS205's around an Expolinear ribbon, my own passive xo) into an "MCM" design with the Peerless woofers and the B&C coax. (The ones I bought for the purpose a few years ago and have sitting in my closet over there are technically branded "Hi-Level" and not B&C. They are, however, just rebadges of the 8CXT. Admittedly, if I didn't already have them I would probably use the new 8" KEF Q-series Uni-Q because it seems to be an extraordinary unit.)

It's way better than the primitive licensed copy of the Uni-Q that Seas offers. They're not even in the same league. You have experience with that one, right? Well, I've used both extensively for home audio, and I cannot fathom a situation in which the Seas driver would be preferred to the B&C.

Also, the target market is irrelevant. Though it's worth noting that the B&C coax has also been found in a few recording studio monitors.

If you wish to hear a commercial implementation of this driver with a crossover designed by someone with a very good ear and world-class technical chops, find some Seaton Catalysts or Sparks. Or Danley SH-100's.

 

[Irvrobinson]

The recording, probably not. As for everything else, it's not the parts that are relevant, but the setup. Maybe turn the gain on the preamp down a bit and turn the amp down a bit?

I must be missing some obvious point you're making... how do the I turn the amp down? The AT3000 does not have any documented means of level adjustment. Anyway, the preamp isn't clipping. It's operating *well* within its specifications even when the amp is clipping. You can read the specs and the manual for yourself, and I've talked with a Benchmark engineer about the set-up.

Still, if you're clipping a 300W amp in your room and intend to keep the Revels, you should probably sell it and channel some of the proceeds into one of these, or one of these.

Or replace both in one swoop for a pair of Seaton Catalyists, which are both a lot more efficient (easily 10+ dB worth in the treble, 6+ dB worth in the mids, and probably a a couple dB worth from 70ish Hz up to the top of the woofer's bandwidth) and backed by a lot more power.

No thanks to either choice. So far that Telarc disc is the only one I've noticed clipping with. If it happens more often perhaps I'll consider a change. I was just quite surprised I *ever* saw clipping with such a powerful amplifier.

 

[TLS Guy]

(a) As he mentioned, he already has a high-amp (20A) circuit.
(b) The amps I mentioned (Powersoft, Lab Gruppen) are much more energy-efficient than the ATI one he already has. So they will be able to put out much more power as his giant (and excellent) ATI amp at the same current draw. They are also very expensive, though. Seven channels of Powersoft or Lab power is a five-figure investment.



No more than he already is, probably.
FWIW, my one criticism of the big Revels generally is that they sound a bit compressed on massed strings or voices. I'd blame that on the undersized mid, except...the JBL LSR32/LSR6332 has a similar-sized (better, but similar-sized) midrange and crossover points, but doesn't have the same issue.



But if he mentioned it, that indicates some dissatisfaction. When dissatisfied, people are willing to settle, others are not. That's a judgement call.



From that, one can only assume that you've never heard or used the B&C 8CXT. It is an outstandingly good drive-unit in every respect. The cone controls tweeter directivity very well, and the FR niggles are nothing that a competent crossover design can't address. I would happily base my system around them. In fact, next time I visit my Salzburg flat and have time I'm going to convert the not-very-good speakers in there (DIY closed boxes with two Peerless HDS205's around an Expolinear ribbon, my own passive xo) into an "MCM" design with the Peerless woofers and the B&C coax. (The ones I bought for the purpose a few years ago and have sitting in my closet over there are technically branded "Hi-Level" and not B&C. They are, however, just rebadges of the 8CXT. Admittedly, if I didn't already have them I would probably use the new 8" KEF Q-series Uni-Q because it seems to be an extraordinary unit.)

It's way better than the primitive licensed copy of the Uni-Q that Seas offers. They're not even in the same league. You have experience with that one, right? Well, I've used both extensively for home audio, and I cannot fathom a situation in which the Seas driver would be preferred to the B&C.

Also, the target market is irrelevant. Though it's worth noting that the B&C coax has also been found in a few recording studio monitors.

If you wish to hear a commercial implementation of this driver with a crossover designed by someone with a very good ear and world-class technical chops, find some Seaton Catalysts or Sparks. Or Danley SH-100's.

The SEAS coaxial is very good driver, in the right application. I think you have KEF SEAS reversed. SEAS I'm pretty sure were making coaxial drivers before KEF.

If you look at the spec sheet and graphs, it as a lot more promising than the B & C driver. Compression drivers all sound pretty dreadful and need confining to commercial applications and not critical listening applications. The response published by B & C is typical of the response of compression horn drivers and so is the directivity pattern.

The SEAS unit response.

The trick with that driver is to use two of them and use one driver for BSC and bass augmentation. In my hands the driver sound excellent in that center channel speaker and I would not consider using a compression driver.

 

[DS-21]

I must be missing some obvious point you're making... how do the I turn the amp down? The AT3000 does not have any documented means of level adjustment.**.

Ah, that changes things. I hate that "consumer" amps don't have proper level controls.

The SEAS coaxial is very good driver, in the right application. I think you have KEF SEAS reversed. SEAS I'm pretty sure were making coaxial drivers before KEF.

I suppose we have different standards.

And you're 100% wrong about KEF and Seas. While Seas may well have been making "coaxials" first, their current coincident design uses IP licensed and paid-for from KEF, based on their Uni-Q patents.

That is simply a fact. Ask someone from Seas in a position to know, and that is the answer s/he will give you.

Unfortunately, the license does not give Seas the right to use more recent KEF innovations, such as the phase plug. It would be nice to see other drivers on the market on the cutting edge like that.

If you look at the spec sheet and graphs, it as a lot more promising than the B & C driver.

Unlike you, I've actually used them both. The Seas isn't even close to the same league. If the B&C is heavily favored in the NCAA tourney, the Seas is a mediocre high school basketball team...in a small town in Alaska.

The Seas is great for car audio, where it's often harder to fit a larger driver.

Compression drivers all sound pretty dreadful

Wrong. Change that to "most" and I'd agree with you, though. That, however, has more to do with the horns than the drivers. A good comp driver in a low-diffraction waveguide makes every dome (which includes ScanSpeak, Seas Milleniuum, Dynaudio Esotar, etc) sound like the second-rate device it is. Dome tweeters really have no place in a high-fidelity system.

The trick with that driver is to use two of them and use one driver for BSC and bass augmentation.

I'm quite aware of the need to limit midrange cone motion in any coincident or Dual Concentric design. That doesn't change the fact that the Seas drivers are basically up to KEF ca. 1997 standards. At best. (Andrew Jones' 4th gen Uni-Qs do some things better than the current Seas coaxes. The current KEF Uni-Q's with the Tangerine phase plug and more recessed tweeter are much better.)

That's not to say a great speaker can't be made from the Seas coaxes, mind. While not quite stock a stock driver (it uses the Seas "G" cone) the Gradient Revolution proves that.

In my hands the driver sound excellent in that center channel speaker and I would not consider using a compression driver.

I'm sure it's fine, but if you can do well with that driver, you could do better with superior parts such as the B&C 8CXT and a suitable partnering bass driver.

 

[TLS Guy]

Ah, that changes things. I hate that "consumer" amps don't have proper level controls.



I suppose we have different standards.

And you're 100% wrong about KEF and Seas. While Seas may well have been making "coaxials" first, their current coincident design uses IP licensed and paid-for from KEF, based on their Uni-Q patents.

That is simply a fact. Ask someone from Seas in a position to know, and that is the answer s/he will give you.

Unfortunately, the license does not give Seas the right to use more recent KEF innovations, such as the phase plug. It would be nice to see other drivers on the market on the cutting edge like that.



Unlike you, I've actually used them both. The Seas isn't even close to the same league. If the B&C is heavily favored in the NCAA tourney, the Seas is a mediocre high school basketball team...in a small town in Alaska.

The Seas is great for car audio, where it's often harder to fit a larger driver.



Wrong. Change that to "most" and I'd agree with you, though. That, however, has more to do with the horns than the drivers. A good comp driver in a low-diffraction waveguide makes every dome (which includes ScanSpeak, Seas Milleniuum, Dynaudio Esotar, etc) sound like the second-rate device it is. Dome tweeters really have no place in a high-fidelity system.



I'm quite aware of the need to limit midrange cone motion in any coincident or Dual Concentric design. That doesn't change the fact that the Seas drivers are basically up to KEF ca. 1997 standards. At best. (Andrew Jones' 4th gen Uni-Qs do some things better than the current Seas coaxes. The current KEF Uni-Q's with the Tangerine phase plug and more recessed tweeter are much better.)

That's not to say a great speaker can't be made from the Seas coaxes, mind. While not quite stock a stock driver (it uses the Seas "G" cone) the Gradient Revolution proves that.



I'm sure it's fine, but if you can do well with that driver, you could do better with superior parts such as the B&C 8CXT and a suitable partnering bass driver.

Well, I'm not about to rearrange the studio to find out! The current center matches and partners with the mains perfectly. I seriously doubt I could blend in the B & C driver with the mains. It might be alright ofr pop music, but I seriously doubt they would be happy, with Bach and Mozart. I would bet they would draw attention to themselves.

In any event the SEAS drivers have T/S parameters in the perfect sweet spot for a compact TL. As you can tall here. For measurements the drivers were paralleled, so the impedance each amp sees is double below around 600 Hz. The drivers are driven from different amps as BSC is active.

 

[DS-21]

I seriously doubt I could blend in the B & C driver with the mains. It might be alright ofr pop music, but I seriously doubt they would be happy, with Bach and Mozart. I would bet they would draw attention to themselves.

I'm honestly surprised you're using a different center from the left and right speakers, though. That strikes me as little different from using identical speakers for left and center, and a different right.

Besides, I'd never recommend using a superstar driver like the B&C coax for the center, and more pedestrian (more expensive, but more pedestrian) Seas Excel stuff for the left and right speakers. I would - and do - use the same coincident or Dual Concentric driver for mids/highs in both mains channels, in the same orientation and at the same height.

 

[TLS Guy]

I'm honestly surprised you're using a different center from the left and right speakers, though. That strikes me as little different from using identical speakers for left and center, and a different right.

Besides, I'd never recommend using a superstar driver like the B&C coax for the center, and more pedestrian (more expensive, but more pedestrian) Seas Excel stuff for the left and right speakers. I would - and do - use the same coincident or Dual Concentric driver for mids/highs in both mains channels, in the same orientation and at the same height.

I R & D this rig a long time. That center ended up being the best solution to avoid interference with the mains. The center with its cone shaped delivery area covers the seating area just fine and everyone hears good dialog.

The problem is height. The mains have their tweeters at 36" which is optimal. I did not want to use projection, so I have a screen in the way at 36". So I then had to decide to put the center above or below the screen. Above was the best choice with the drivers angled to the seating position.

The SEAS drivers are no way pedestrian. I agree because of the very rigid cones, they have sudden nasty break up modes. However that can, and has been dealt with. The bonus of a rigid cone is excellent dispersion in the pass band. The other issue is that the SEAS EXEL drivers I chose have ideal parameters for TL loading. I have been making TLs for over 50 years, and the range of TS parameters for good loading is narrower than most imagine.

The SEAS drivers take a lot of power cleanly and have many virtues.

Now the surrounds and rears are legacy speakers, however they all match. The surrounds use drivers sourced from Dynaudio, the rears, the venerable KEF B139s on the bass and the other drivers sourced from Dynaudio. I have had many go round all speakers and they are always amazed how the speakers sound virtually identical. No speaker draws any attention to itself.

The end result is a speaker system that make the walls disappear. Put on a fine multichannel recording and you have a huge sonic sound stage with excellent front to back perspective, and extended clean dynamic range.

I call this my magic carpet, as it takes me to opera houses and concert halls all over the world.

I don't understand pop music and hate it, so I don't cater to it. I have always kept my speaker designs well rooted in the British tradition and especially BBC practice. I just can't imagine the BBC having anytime at all for a speaker built round those B & C contraptions.

The strange thing is though, recording and mix engineers come here to check their mixes.

A mix engineer who has a lake home 3/4 mile from here, and has mixed for famous artists and mastered platinum discs now always pays a visit to check a final mix, and has brought artists here. He now mixes and teaches mixing at the Minnesota Media Institute. He seems to really like the sound of this studio.

So all in all I think I did pretty well with "pedestrian drivers".

 

[DS-21]

I R & D this rig a long time.

I'm sure you have it working quite well.

The problem is height. The mains have their tweeters at 36" which is optimal. I did not want to use projection, so I have a screen in the way at 36". So I then had to decide to put the center above or below the screen. Above was the best choice with the drivers angled to the seating position.

Ah. I would make a different compromise. I would make the mains identical, and put them at the identical height/orientation either above or below the screen.

The SEAS drivers are no way pedestrian.

They're nothing special, really. Or, at any rate I'm Im far less impressed with the Seas drivers than you are. Not because of the rigid cones, which are arguably better for those who know how to notch out the peaks. There's probably a reason why the data-driven speaker-makers that make their own drivers (Revel, KEF) have been consistently moving in that direction.

But one of my driver comparisons that really surprised me happened during my search for an 8" driver to use in my car as part of augmented wideband system with an Aura Whisper on top and a subwoofer below, to replace a set of Peerless 850136 "CSX 8's", which had a smaller vc and simpler motor design than any of the four potential replacements. (They also had a stamped frame. Sounded good enough, to be honest, but I suspected I could get better.)

I had narrowed it down to four drivers: two very expensive 8" Seas drivers, the L0011 ("Lotus" is Seas-speak for "4Ω Excel") and the E0022 (8" mag cone Excel), B&C's 8NDL51…and an ancient paper-cone JBL 116H-1, which was used in their relatively unheralded 4408 monitor and L60T home tower. (It was also sold separately, I've been told, as their "T80" car-fi midbass in the late 1980s or early 1990s.) The L0011 was the only nominally 4Ω driver in the quartet.

The two Seas drivers were in excess of $400/pr (new from Madisound), the B&C's were under $300 from US Speaker...the JBL's were about $65 shipped for the pair (used, eBay).The JBL drivers were only on my radar screen because of some words by a local master reconer, Gordon Waters.

The differences between the Seas L0011 and E0022 are the frame (E0022 has a bigger flange, and venting under the spider) and the cone (L0011 is aluminum, E0022 is magnesium. By eyeball, they seemed to have the same cone profile, though I didn't take any angular measurements. Both of them have the same motor design, with an identical large copper ring above the polepiece press-fit in between the pole and screwed-in phase plug. Both have a 16mm high 39mm diameter voice coil.

The B&C had a smooth paper cone with a double-roll rubber surround, cast frame with octagonal flange, and a beautiful neo motor with a 2" voicecoil.

The JBL has a ribbed paper cone, thick cast aluminum frame, foam surround, and JBL's Symmetrical Field Geometry motor, i.e. the design ScanSpeak ripped off for their "SD-1" motor, with a 2" diameter voicecoil.

Sensitivity-wise, the 1W/1M ratings of the drivers were as follows:

Seas L0011: 87dB,
Seas E0022: 88dB,
B&C 8NDL51: 94dB.

I measured the JBL 116H-1 at about 87dB, using an impedance jig and FuzzMeasure Pro.

I did three tests of the drivers, in the following order:

(1) "Simulated Miata doors."
I took each pair, and in random order listened to them in the same leaky, thin box of about 2 cubic feet, with an Aura NSW2 "Whisper" in the same spatial relationship as they'd have in my car. Crossover (set at 800Hz, 2d order) and room correction (Audyssey MultEQ XT) was effected by an Alpine PXE-H650, run off a 12V power supply. Power was provided by a Pioneer Elite VSX-50 AVR (not the current one, but the old silver one from their old EX500), feeding the multichannel input. Sub-bass was provided by an Exodus Maelstrom-X Mk. I in a 110L closed box, powered and EQ'ed by a Crown XTi2000, simply because that was the subwoofer already in use in my home office. Each setup was calibrated using the Alpine/Audyssey software over Parallels on my MacBook before listening. I accepted the subwoofer crossover setting Audyssey decided upon.

(2) In car.
Each midbass was attached to a CLD baffle made from 1/4" plastic cutting board, Liquid Nails, and 1/4" luan ply, which was screwed to the car using the mounting holes for the stock Bose 8" woofer. (Interestingly, the JBL's mounting holes were in the same spots.) Crossover was as above (though a second unit). Midbasses were powered by a bridged Class H mini-amp OEM'ed by Ubuy Industrial that has been tested to put out >150W/8Ω and >240W/4Ω when bridged. Whispers were powered (at the time) by a 2-channel variant of the same Ubuy Industrial Class H mini-amp (different brand on the heatsink), which probably does about 40W/8Ω. I accepted the subwoofer crossover setting Audyssey picked. Wideband/midbass crossover was 800Hz, 2d order, the highest I could go without dragging the soundstage down to the midbasses.

(3) Power compression.
Third was power compression. Each pair of drivers spent about 4 hours on my 8th floor balcony, playing noise bandwidth-limited to 50-1.5kHz at about 85dB/1, powered by a Crown XTi2000.

When I started the test, I suspected it would be between the B&C and one of the Seas drivers. But performance-wise, both high-priced Seas drivers were (a) basically the same, and (b) were outclassed at every step.

At home, the B&C dominated. It had by far the best jump factor, the best microdynamic shading, and the most natural reproduction of massed strings and male voice. It did, however, cry out for something better on top. (Something better on top wouldn't fit in my door, alas.) The JBL was second best. The Seas drivers worked about the same, but consistently sounded a little a little rounded-off compared to the B&C and JBL. The JBL sounded a little warmer than the B&C, which also made it blend a bit better with the Whispers.

In car, the JBL took over, with the Seas fairly far behind and the B&C bringing up the rear. The basic reason was that the B&C was to play low enough to mate with my footwell sub (usable to maybe 120Hz) the B&C would've needed EQ the Alpine Audyssey box couldn't/wouldn't provide. So there was a comparative lack of midbass impact and grunt. I was really surprised that the old ribbed paper cone driver sounded so right. (In a closed car, as opposed to an open roadster, the B&C would've been the ideal 8" midbass.)

In the power compression test, the B&C did best, with the JBL barely behind (within 0.5dB average of the two). The Seas drivers, however, both dropped in level by about 4dB more than the B&C and JBL drivers. I also burned my finger on one of their phase plugs! On a lark, I ran the same compression test on the well-used Peerlesses. The pair of them were only about a dB worse than the two Seas drivers.

The other issue is that the SEAS EXEL drivers I chose have ideal parameters for TL loading. I have been making TLs for over 50 years, and the range of TS parameters for good loading is narrower than most imagine.

I see you're clearly wedded to a particular loading. The only "real" TL's* I've heard were a pair of vintage Frieds with KEF B139's under two other drivers (I think also KEF) haphazardly strewn across the baffle, driven by Plinius electronics with all kinds of voodoo around (speaker wire stands, for instance). They didn't have much of an effect on me. Certainly I didn't come away thinking that every other way of reproducing bass was obsolete, the way I did when I started playing with closed-box multisub systems.

[edit]*Unless some of the big Shahinian speakers are TL's too. They really sucked, but not because of the bass loading.[/edit]

The SEAS drivers take a lot of power cleanly

Not really, compared to better drivers such as those made by B&C, and even obsolete JBLs. See above.

I don't understand pop music and hate it, so I don't cater to it. I have always kept my speaker designs well rooted in the British tradition and especially BBC practice. I just can't imagine the BBC having anytime at all for a speaker built round those B & C contraptions.

That's just prejudice. The B&C's can easily be voiced to a BBC-type sound.
The strange thing is though, recording and mix engineers come here to check their mixes.

So all in all I think I did pretty well with "pedestrian drivers".

I don't doubt that you did. My contention is merely that the success comes from the designer and the in-room optimization, not the parts. And perhaps even greater heights could be reached with better parts.

 

[MidnightSensi2]

I'm sitting here listening to one of my favorite rock albums, California Project, by Papa Doo Run Run, on Telarc. Beach Boys / Jan & Dean covers. The speakers are my trusty Revel Salon 2s crossed over to a Velodyne DD18+ at 60Hz low-pass, 80Hz high-pass, with the Revels powered by four channels of an ATI AT3005 plugged into a dedicated 20amp circuit. I just don't believe it, the sound is so clean and perfect, but the red "Peak" LED on the amp is lighting up momentarily now and then. ATI says of that light:



I'm busting the chops of at least one 300w channel? It couldn't be. No wonder those 125w/ch Levinsons sounded weak.

There goes that LED again. I'll be damned.

Double your IEC of 1000-watts, I'd probably try this:
Crown Audio XTi 6002 Power Amplifier XTI 6002 B&H Photo Video

Variable speed fan, stable to 2-ohm.

 

[Irvrobinson]

Double your IEC of 1000-watts, I'd probably try this:
Crown Audio XTi 6002 Power Amplifier XTI 6002 B&H Photo Video

Variable speed fan, stable to 2-ohm.

I looked at the Crowns before I chose the ATI. The XTi amps aren't really for home audio systems. Sub-harmonic synthesis? But the real turn-offs were fans (my amps are out in the listening room, and since the amp idles at 180w I assume those fans will run almost continuously), 33db of gain (about 6-7db higher than what works well for consumer preamps), and a lousy SNR spec (perhaps real world performance is better, but how would I know that?). The Macro-Tech line is better, but the specs still look more like sound reinforcement stuff than SOTA home audio. I was concerned more about the SQ at 1 watt than having 2000w/ch; I didn't think I'd ever need that sort of power.

 

[MidnightSensi2]

I looked at the Crowns before I chose the ATI. The XTi amps aren't really for home audio systems. Sub-harmonic synthesis? But the real turn-offs were fans (my amps are out in the listening room, and since the amp idles at 180w I assume those fans will run almost continuously), 33db of gain (about 6-7db higher than what works well for consumer preamps), and a lousy SNR spec (perhaps real world performance is better, but how would I know that?). The Macro-Tech line is better, but the specs still look more like sound reinforcement stuff than SOTA home audio. I was concerned more about the SQ at 1 watt than having 2000w/ch; I didn't think I'd ever need that sort of power.

If you can afford the Macro-Tech it does have better specs. I've used both, and don't think at home it would be anything noticeable.

Yes, it's a prosound amp, but, my ear isn't keen enough to tell the difference. Maybe some elses is. I've actually found a lot of the prosound amps from the major brands to be built better than home audio amplifiers. I don't just recommend prosound amps to recommend them, but your speakers need some serious horsepower to drive them. Not only do they dip below 4-ohms, but at some difficult phase angles as well.

As far as subharmonic synthesis, you probably wouldn't use that. It's nice in prosound because if you are in a lounge or have the volume lower it can add some extra 'energy' to the music. In a home, you'll likely leave it off (except to play and see what it does hehe, it just adds another note one octave down to give the bass some extra fullness - nothing special but applicable in certain applications).

There are also high end home amps that will power your speakers, and plenty of other prosound amps to choose from.

 

[TLS Guy]

If you can afford the Macro-Tech it does have better specs. I've used both, and don't think at home it would be anything noticeable.

Yes, it's a prosound amp, but, my ear isn't keen enough to tell the difference. Maybe some elses is. I've actually found a lot of the prosound amps from the major brands to be built better than home audio amplifiers. I don't just recommend prosound amps to recommend them, but your speakers need some serious horsepower to drive them. Not only do they dip below 4-ohms, but at some difficult phase angles as well.

As far as subharmonic synthesis, you probably wouldn't use that. It's nice in prosound because if you are in a lounge or have the volume lower it can add some extra 'energy' to the music. In a home, you'll likely leave it off (except to play and see what it does hehe, it just adds another note one octave down to give the bass some extra fullness - nothing special but applicable in certain applications).

There are also high end home amps that will power your speakers, and plenty of other prosound amps to choose from.

Actually the phase angles are quite kind. They are in positive territory most of the time, and when negative impedance is on the high side.

His problem is that his speakers are very inefficient below 600 Hz, much more so than the specs would suggest.

I'm far from convinced a lot more power would help him. The way it is set up there will be huge thermal compression issue that won't be transient of you really put the pedal to the metal.

He likes his speakers so the best thing is to turn it down.

 

[MidnightSensi2]

Actually the phase angles are quite kind. They are in positive territory most of the time, and when negative impedance is on the high side.

His problem is that his speakers are very inefficient below 600 Hz, much more so than the specs would suggest.

I'm far from convinced a lot more power would help him. The way it is set up there will be huge thermal compression issue that won't be transient of you really put the pedal to the metal.

He likes his speakers so the best thing is to turn it down.

Ah, your right, didn't have the graph on their website so I googled it and now I noticed looking back (to prove you wrong, lol) that I was looking at another speakers phase graph. Haha.

...

It's not sensitive throughout the whole frequency range, let alone below 600Hz, lol. The speaker looks excellent in the stereophile measurements, except for what your pointing out. But, engineering has it's tradeoffs. This is really a speaker that covers the entire audible spectrum with very flat response.

I know what your saying about the thermal compression, but if it's just with peak and it's a ported enclosure won't the voice coil cool pretty quickly?

Dub (Jamaican roots) and dubstep (English roots that came from Jungle) has most of it's energy in the low frequencies. When dubstep first gained popularity down here was some of the first times I'd seen subwoofers lock up in clubs from thermal expansion rather than over-excursion. The subs if run too hard will literally 'lock' (no pop, no noise, just stop playing) from the heat expanding the metal. Bass bin's and vented enclosures were far less susceptible because they let the heat out.


...


Have you trying calling Revel to see what they recommend?

I always double IEC on passive speakers, usually that seems to get me pretty close if the manufacturer doesn't offer some advice. But like TLS said, due to the nature of these speakers it might have such great diminishing returns that it may not be worth it. I'd call Revel and see what they say!

 

[TLS Guy]

Ah, your right, didn't have the graph on their website so I googled it and now I noticed looking back (to prove you wrong, lol) that I was looking at another speakers phase graph. Haha.

...

It's not sensitive throughout the whole frequency range, let alone below 600Hz, lol. The speaker looks excellent in the stereophile measurements, except for what your pointing out. But, engineering has it's tradeoffs. This is really a speaker that covers the entire audible spectrum with very flat response.

I know what your saying about the thermal compression, but if it's just with peak and it's a ported enclosure won't the voice coil cool pretty quickly?

Dub (Jamaican roots) and dubstep (English roots that came from Jungle) has most of it's energy in the low frequencies. When dubstep first gained popularity down here was some of the first times I'd seen subwoofers lock up in clubs from thermal expansion rather than over-excursion. The subs if run too hard will literally 'lock' (no pop, no noise, just stop playing) from the heat expanding the metal. Bass bin's and vented enclosures were far less susceptible because they let the heat out.


...


Have you trying calling Revel to see what they recommend?

I always double IEC on passive speakers, usually that seems to get me pretty close if the manufacturer doesn't offer some advice. But like TLS said, due to the nature of these speakers it might have such great diminishing returns that it may not be worth it. I'd call Revel and see what they say!

I'm more worried about the crossover inductors. The series inductors to the woofers, will be heavy copper on an iron former. 1000 watts is a lot of heat. It will heat a small bathroom pretty quickly. With the insertion losses those inductors are going to progressively heat up with repetitive peaks. They are in a closed box and will not quickly cool down. So resistance will increase and their values change. The thermal compression of the drivers will very much depend on design.

A loudspeaker magnet is bigger and at least on the woofers the voice coil is moving and there is some air flow.

Of course this is where low impedance really bites. If you halve the impedance current doubles, but the heat generated goes up by the square of the current. In electrical transmission parlance, this is known as the I squared R loss. This is why there is such a huge advantage in very high voltage transmission lines. Every time you double the voltage of the line, you half the current but you reduce line loss (waste of energy) by the square of the current reduction.

On my visit to Billy Woodman at ATC, they constantly reference to electric fires when talking loudspeakers. Billy Woodman's drivers have flattened wire, deeply set in the gap (under slung) and he has such fine precision engineering at his factory his voice coil air gaps are only 2000th of an inch. Yet he has hardly any failures.

 

[Irvrobinson]

I'm far from convinced a lot more power would help him. The way it is set up there will be huge thermal compression issue that won't be transient of you really put the pedal to the metal.

I agree with your base reasoning, but the high power requirements *are* transient. The peak light has never come on for more than a fraction of a second. I'm not discounting the importance of eliminating clipping on those peaks for realism one bit, but I can't believe those peaks will result in "huge thermal compression either". I've previously estimated the average dissipation levels at more like 8-12 watts. Given the number of drivers the speaker has I would think thermal issues wouldn't be a big factor in a typical two-hour loud listening session.

 

[Irvrobinson]

Have you trying calling Revel to see what they recommend?

I always double IEC on passive speakers, usually that seems to get me pretty close if the manufacturer doesn't offer some advice. But like TLS said, due to the nature of these speakers it might have such great diminishing returns that it may not be worth it. I'd call Revel and see what they say!

No, I haven't called Revel. I'm sure they will just say every situation is unique, and the Salon 2 has prodigious capabilities.

It is interesting to note that the street wisdom on Audiogon, where a lot of Salon 2 owners hang out, is that high power, as much as 700w/ch, is what it takes to make the Salon 2 "sing". It is also interesting to note that in his review John Atkinson set aside his favorite Mark Levinson 33H amplifiers and replaced them with a 750w/ch Musical Fidelity amp for the listening tests.

These anecdotal results lead one to think that very high power will not have diminishing returns on the Salon 2s.

 

[DS-21]

I looked at the Crowns before I chose the ATI. The XTi amps aren't really for home audio systems.

They are a fairly simple Class AB+B design. Not too different from the QSC in the last (?) paper TAC that Azcel thought was fine but about which Dr. Rich wrote "In summary, it is light, swings lots of current, cannot blow up, and has some dynamic distortion. Good for sound reinforcement applications, but ultimately other choices are better for consumer appli*cations."

But the real turn-offs were fans (my amps are out in the listening room, and since the amp idles at 180w I assume those fans will run almost continuously), 33db of gain (about 6-7db higher than what works well for consumer preamps), and a lousy SNR spec (perhaps real world performance is better, but how would I know that?).

FWIW, for a while I ran a Crown XTi2000 as my subwoofer amp in my home office system (first pushing a JBL W15GTi in about 4.5 cubic feet, and later a Maelstrom-X in a ~110L closed box), where the amp was literally within arm's reach. Even after beating on them with Massive Attack or Thievery Corporation at club-like SPL the fans only came on sporadically. I replaced it only because I bought a black AVR, and wanted a black amp to match it.

As for the SNR spec...see the amount of gain.

For full-range home audio, I do think their new XLS Drivecore stuff is better all around.

 

[TLS Guy]

No, I haven't called Revel. I'm sure they will just say every situation is unique, and the Salon 2 has prodigious capabilities.

It is interesting to note that the street wisdom on Audiogon, where a lot of Salon 2 owners hang out, is that high power, as much as 700w/ch, is what it takes to make the Salon 2 "sing". It is also interesting to note that in his review John Atkinson set aside his favorite Mark Levinson 33H amplifiers and replaced them with a 750w/ch Musical Fidelity amp for the listening tests.

These anecdotal results lead one to think that very high power will not have diminishing returns on the Salon 2s.

I don't know what your average listening levels are, but mine are between 65 and 75 db.

Your average power output would be five to 10 times higher than on most systems if your estimate is correct and it possibly is, but I would expect it is nearer 5 watts. That pretty much fits with the data on those speakers in my view.

So now lets go to 80 db you need 50 watts, now go to 90 db and you need 500, now take it to 100 db and you need 1000 watts. So 500 per channel. If you wanted to go to 110 db which I would not advise would require 10,000 watts, 5000 watts per channel.

If you really are averaging 10 watts average, then those figures are 100 watts, 1000 watts, 10,000 watts and you can't even think of getting to 110 db.

Now thermal compression is a huge issue with all speakers. Just think how quickly a coil of wire heats up with those sort of powers. It is a fraction of a second. Pop and rock music is a huge challenge as the average power demands are so high. Just think how much heat a 25 watt light bulb generates.

Now as I explained with the use of 150 Hz passive crossover the inductors in series with those woofers, the inductors will heat quickly.

Lets put 1000 watts into your speaker, that is going to be 16 amps, the lions share is below 600 Hz, and an awful lot will be below 150 Hz.

Under the best of circumstances the DC resistance of the inductor to the woofer, will be on the order of an ohm. Now lets assume only a third of the power goes to those three woofers, but it is likely to be at bit more, than that, will be a heat dissipation of 30 watts. Now I can tell you when you put 30 watts into a power resistor with heat fins out in the open, it heats up fast and those inductors will heat up faster, and they won't soon cool down. It will build one peak after the next as well as the average power dissipation. This is just one of numerous reasons why a low crossover point with a passive solution does not mix at all. And I think I have low balled the power losses to heat in the crossover.

I just can't see you gaining much going to a higher powered amp. 600 watts per channel buys you 3 db.

Now suppose you had a very nice high powered sealed speaker or TL with an F3 of 80Hz with a sensitivity of 93 db one watt 1 meter.

Then would gain 10 db, which would be better than driving your speakers with 3000 watts per channel, even if you could. It would be better because of far less thermal compression, remember heating is the square of the current times resistance.

Now a sealed speaker or properly designed TL will roll off 12 db per octave. Add the 12db high pass filter from the crossover and you have fourth order roll off, which will splice perfectly with the fourth order low pass filter to your sub.

If you want a high powered system, that is what it really takes, not pushing more watts through inefficient speakers.

If you go to the ATC web site, Billy Woodman has some very nice and well written white papers, in high powered loudspeakers in his professional section.