Summit, Bel Canto, The Who: bad juju

The house was empty, and I was casually listening to my system for a couple of hours. I inserted a Who compliation CD I'd had in my car and kind of forgot about for a long time. "Who Are You" comes on. Wicked grin appears. Preamp dial to 12 o'clock. Stat panels singing. Woofers visibly throbbing. Summits and 360 watts of Tripath power. Man am I groovin.' Having a blast. One of the best Who tunes IMO. I love the Who.

I'm immersed in the music thinking I'll have to play this again. Then: Roger Daltry starts singing to the left of the soundstage. Hmmm, I don't remember this happening before. I get up to check. Now total silence. Red light glowing on Bel Canto. Feels rather warm for a normally cool running amp. I check the Summits: both lights are green, no problem. I hit the reset switch on the amp and cycle it a few times, red light stays lit. I power down my Furman, leave for 10 min, then turn everything back on: back to normal. What was that?

I overheated my Bel Canto with the Who? That's never happened before. With 360 watts in 2 channel bridged, how could I have overloaded it and caused protection circuits to activate, or was it just heat? The sound was glorious, no clipping, no distortion. My previous Classe 70 ran quite hot with my much harder to drive Sequel II's, and would get harsh at high volumes but never click out like this. Granted I almost never listen this loud, but it still was disconcerting.

Any idea what happened?

Maybe playing at that volume may have cause the impedance in the summits to dip down very low for a certain amount of time which was enough to overheat your equipment.

jvitez said:

... I overheated my Bel Canto with the Who? That's never happened before. With 360 watts in 2 channel bridged, how could I have overloaded it and caused protection circuits to activate, or was it just heat? ...

Any idea what happened?

Click to expand...

Yes, your amp can't deliver sustained amounts of current for the durations you were asking it to, and overheated. Good thing it has decent protection circuits and didn't seem to suffer from it.

Typically, an amp run in bridged mode 'sees' speaker impedances at half of the normal loads, and therefore gets de-rated as to the minimum impedance they can run bridged.

However, the topology of the Evo4 s bit different, with them claiming to run the 2 bridged halves in differential mode (balanced), which may or may not reduce the impedance sensitivity.

Although the results speak for themselves, this amp can't sustain delivery of the current a Summit needs to play through an album or two at high volumes.

And if the amp does this when pushed, it’s probably distorting or underperforming even at moderate levels as well. Those Tripath amps have huge IMD at 20Khz, which also happens to be the point of lowest impedance on a ML ESL. With a large current sink at the frequency the amp is least stable, not surprising it will overheat.
Mind you, I think these amps are great on dynamic speakers, but as I keep repeating, ESL’s are different beasts presenting very unique load factors (including huge back EMF, which the TriPath might not like) and one should look for amps that designed with these factors specifically in mind.

If your goal is being able to do this regularly and without concern for the amp, then switching to a Sanders or Sunfire would be my recommendation. Those amps will deliver >60amps of current and be able to maintain high-output running conditions for hours.

My Monolith panels get 800w (@4 ohms) of Sunfire power, and I've never gotten the amp more than moderately warm after hours and hours of high-volume demos.

Something to consider.

Thanks! I was thinking the impedence curve of ML's may have something to do with it, though I thought with the powered woofers of the Summit, the total current required to run just the stat panel would be low enough to counterbalance any low plus dynamic impedance issues. Obviously I was wrong! Thanks for the clear explanation.

Sunfire's website lists no Canadian dealers. Locally, I have Bryston, Simaudio, Krell, McIntosh and Manley available as higher end products, with Arcam, Exposure, Cambridge Audio and Rega available in more mid-fi levels. There was a Plinius dealer in Saskatchewan, but I think he got out of that line.

I'm going to reinstall my old Classe 70 and see how it sounds. It was very good for many years with my Sequel II's, and I really don't listen at such high levels often. I'm torn which way to go with amp upgrades. I'd love to try a nice tube amp, but I'd also like to try the quintessential detail oriented amp, and try a Krell. I was thinking of keeping my eVo4, as I'm planning on a home theatre setup in the basement and keeping my 2 channel system on the main floor. Ah, the dilemma of choice. :music:

With Sunfire, you could just go for a used one from AudioGon, as there are usually one or two of Sunfire signature stereo amps there.

Krell, while nice, has not been worth the $$$'s in book. I tried one back in '02 and it was not any better than the Sunfire.

If looking for new, Sanders will ship you a new ESL amp with a full 30-day money-back guarantee for an in-home trial. Nothing to lose.
And there is probably no better amp for an ESL than those.

So, I recreated my Who experience with my analytical hat on. I had the tuner on FM for an hour or so at low to mid volumes, then put the Who CD in. I listened to 2 tracks on upper mid volumes, then put on Who Are You, with the pre amp at 12o'clock. Definitely noted some graininess I didn't last time. I guess I was just groovin' too much, but that's what music is supposed to do:guitarman:

Anyway, my cheapie SPL meter read a peak of.....105.3 dB Good thing for my ossicles and cochlea that I do this really infrequently. The amp survived, and only felt a little warm. Clearly doing this is on the asymptotic part of the logarithmic curve of power vs SPL. Still a bit disappointing with supposed 360 wpc of 2 channel power with powered woofers, but I now understand more about the nuances of class D amps. At mid to mid/high volumes everything is fine. Good thing I'm not a headbanger!

Thanks again for all the clear explantions and great advice. This forum is fabulous.

JonFo said:

With Sunfire, you could just go for a used one from AudioGon, as there are usually one or two of Sunfire signature stereo amps there.

Krell, while nice, has not been worth the $$$'s in book. I tried one back in '02 and it was not any better than the Sunfire.

If looking for new, Sanders will ship you a new ESL amp with a full 30-day money-back guarantee for an in-home trial. Nothing to lose.
And there is probably no better amp for an ESL than those.

Click to expand...

How does the Sanders amp sound ? Warmish ? does it eliminate the
edginess that sometimes creeps up in the hi frequencies. Wonder
if it would mate ok with the preamp section of my Musical Fid A5 ?

Sanders hooking thru the A5 integrated or the Simaudio I7 ?

Mantana said:

How does the Sanders amp sound ? Warmish ? does it eliminate the
edginess that sometimes creeps up in the hi frequencies. Wonder
if it would mate ok with the preamp section of my Musical Fid A5 ?

Sanders hooking thru the A5 integrated or the Simaudio I7 ?

Click to expand...

The Sanders sound neutral, very neutral. It should eliminate the harshness at high frequencies, assuming that they are caused by your current amps protection circuitry cutting in when the impedance drops at high frequencies. The Sanders does not have protective circuits. It has mated fine with all of the preamps I have tried (only about 4 or 5 so far). You can search for comparisons that have been done so far. IF you are interested give Rodger a call and audition for yourself.

Ive got a pair of BelCanto 500 watt monos, that I haven't hooked up to the CLX's yet. Time for some torture testing to see. Magnepans too...

McIntosh and Simaudio

I was doing some errands this aft, and drove by one of the local dealers that so happens to sell McIntosh and Simaudio. In I went. I listened to a pair of Vantages with a McIntosh MC402 amp. It was nice, smooth, natural, great lively bass without being excessively punchy. The meters showed peaks of only a bit over 4 watts. I guess 400 wpc may be a bit overkill.

Then I listened to a MC275 all tube amp, though it only powered a pair of Vienna Hayden Grand speakers, so hardly at all the ML sound. But, I certainly noticed the liquid midrange and very calm, laid back presentation. Very euphonic

Last was a Simaudio W-7 SS 150 wpc amp powering B&W 802 speakers. Much more bass impact, much livelier presentation, crisper highs. More inner detail than both the McIntosh's. But darn, it was the most expensive.

To do an in home demo, this dealer wants me to pay for their demo model, and will credit my card when I return the amp. I might just have to use up the whole credit line on my Visa and buy all three to demo....

It was fun to experiment. I've got a bit more tweaking of cables/isolation to do, then I'll focus on a new amp. Darn this expensive hobby. But it sure is fun