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Classes DR-2 for stacked ESL 57?

210.6.10.114
Posted on April 25, 2017 at 22:33:38
SuperB
Audiophile

Posts: 328
Joined: March 21, 2002
 Some has been recommended to use Classe audio DR-2 to drive single pair ESL57, what about stacked ESL57? Whether the Classe DR-2 have enough juice for the job?

 

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RE: Classes DR-2 for stacked ESL 57?, posted on April 26, 2017 at 05:45:21
kentaja
Manufacturer

Posts: 4614
Joined: March 26, 2001
 In terms of power it will be fine. The question when using stacked Quads with any given solid state amp is will the amp be happy with the load? At 20kHz the load will be .9 ohm. Not much energy at 20kHz but some solid state amps won't like to see .9 ohm and will either go into protection mode or damage the output stage.

I would contact Classe and seek their advice.

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 26, 2017 at 06:44:16
SuperB
Audiophile

Posts: 328
Joined: March 21, 2002
 I know people uses Classe Audio DR2 to drive the Apogee Scintilla that has a load impedance continuous at one ohm.

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 26, 2017 at 08:13:04
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 The classe DR2 DR3 and DR3VHC are all great options for driving low impedance loads. the DR9 is also capable and has more power reserves since it is biased less heavily into class A. The Krell KSA models can do it too.

Tube amps with 2 ohm taps will do it too. Otherwise a Speltz zero zutoformer will solve the problem at minor cost to detail.

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 26, 2017 at 09:10:34
SuperB
Audiophile

Posts: 328
Joined: March 21, 2002
 I have told that the Classe' Audio DR2 likes to see low load impedance.

Since the Classe DR2 is able to drive single ESL 57 perfectly, so I guess it should be no problem to drive the 2 x ESL 57 in stacking and wired in parallel.

But what I concern whether it has enough power or voltage to handle the task (2 in stacking).

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 26, 2017 at 11:46:07
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Well, DR3 would have more power.

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 27, 2017 at 00:55:39
SuperB
Audiophile

Posts: 328
Joined: March 21, 2002
 Sorry. IMO, the DR3 doesn't sound as good as the DR2.

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 27, 2017 at 07:43:35
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 If it makes such a difference then stick with the DR2 . Do consider some of the Theta multichannel amps that were also designed by David Reich with the same general approach. Though voiced differently, the Mark Levinson ML2 and the Lexicon multichannel amps use similar design approaches and are similarly overbuilt.

I don't expect you would overload the DR2 with two quads stacked, you will come closer to the amp's limits if you play them loud at full range. .

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 27, 2017 at 11:19:23
SuperB
Audiophile

Posts: 328
Joined: March 21, 2002
 A fellow gives me a suggestion by having Gradient SW-D blend into the double Quad system and it's official crossover is set at 110hz. First, the Classe doesn't have to handle the bottom end, this means the very high impedance no longer an issue.

Since the Gradient comes with an electronic crossover, and he recommended a auto former passive line amp before the crossover for purity.

Is the Classe really acting more powered this way?

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 27, 2017 at 18:34:38
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Yes, it will produce more power (watts) into a lower impedance load so long as it is within its limits. So if you don't use it in the speaker's high impedance range then you will be 1. using it for the less energetic portion of the signal, 2. where the impedance is closer to making use of the amps full power capacity.

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 28, 2017 at 06:40:40
SuperB
Audiophile

Posts: 328
Joined: March 21, 2002
 He also claimed that the Gradient SW-D / double Quad ESL 57 combo sounds better than 4 × ESL in stacking.

But it has another issue, whether allow uses different amp to drive the Gradient SW-D as it demands more control from the amp for four 12" dipole bass drivers per channel.

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 28, 2017 at 08:30:25
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 I would have used the Gradients with a biamp setup. Didn't even occur to me you would want to integrate it passively. But yes, you could run it with the Gradient's passive crossover and get the benefit you are after not to choke the DR2 on high impedances of the ESL Bass. But the DR2 is a more powerful amp than its specs imply.

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 29, 2017 at 07:57:35
SuperB
Audiophile

Posts: 328
Joined: March 21, 2002
 I meant amplifier other than Classe Dr2 for the Gradient woofer tower, however I worried it'll have another issue --- coherent.

As those 12" woofers required more power to drive than the Quad panels.

If the Quad mate with the Gradient, the stacked Quad only have to play above 110Hz, what is the nominal impedances will be as the high impedance portion would be hand over to the Gradient through the cutoff by the electronic crossover?

I expected it will be pretty low especially for stacking.

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 29, 2017 at 10:16:32
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 The biamping approach is by far better here. The top amp and the speaker will not see much energy in the high impedance section of the quad panels because they are not pushing much energy at those frequencies so are not getting the speaker's reactance below the XO point.

As to the preferred amps for the gradient subs I suggest you look at forum discussions on the gradients. There have been a few elsewhere but I don't recall a detailed one here,, at least not in the last decade. But it is worth a try to search here too.

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 29, 2017 at 11:15:30
SuperB
Audiophile

Posts: 328
Joined: March 21, 2002



What is the nominal impedance of Quad ESL 57 with 110Hz cutoff by the electronic crossover? I guess it will be much lower without the "very high" portion.

 

RE: Classes DR-2 for stacked ESL 57?, posted on April 30, 2017 at 11:59:32
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Actually it looks like a slightly higher crossover freq would help more since you still have 20ohm impedance at 110 hz. So something closer to 200 hz would be a great help to the DR2 operating as a mid/tweeter amp. but even at 110 hz the crossover cuts off the very high impedance portion.

 

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