Any other big amps that should be considered?

[InterMechanico]

Yeah, I've been told the W4S amps are pretty good. I seriously considered a 4 channel from them to go active, but I get better value with the plate amps from MiniDsp, and ofcourse I get DSP.

My best deal has to be my Vistas, which I purchased in 2011, New in box, for 1500 (pair).

 

[RUR]

Yeah, I've been told the W4S amps are pretty good. I seriously considered a 4 channel from them to go active, but I get better value with the plate amps from MiniDsp, and ofcourse I get DSP.

Are the W4S amps used in this ASX2 version, or earlier? The earlier versions had impedence issues @ VHF which affected FR linearity. This was fixed with ASX2.

 

[InterMechanico]

The model I had looked at is the 4 channel (250 watt) MC Amplifier. You've noticed an important detail that I'd missed, though. The MC amps use the first gen modules; I had assumed that all the models used the 2nd Gen modules, like the ST-500/1000 amps do. I wonder why they're still running the 1st gen? Old stock I suppose?

 

[RUR]

If you're using these on an ESL model, you might want to check out the Hypex plate amps, which use their UcD modules e.g. http://www.hypex.nl/product/2012-11-23-13-44-01/2012-11-23-13-46-04/psc2-400.html. I know the nCores are load invariant 20-20kHz, but the UcD datasheet only shows 4/8 Ohms: http://www.hypex.nl/docs/UcD400HG_datasheet.pdf , and you want to know how they perform @ 2 Ohms. Feature set may differ from W4S, too, so there's some homework to be done.

 

[InterMechanico]

If you're using these on an ESL model, you might want to check out the Hypex plate amps, which use their UcD modules e.g. http://www.hypex.nl/product/2012-11-23-13-44-01/2012-11-23-13-46-04/psc2-400.html. I know the nCores are load invariant 20-20kHz, but the UcD datasheet only shows 4/8 Ohms: http://www.hypex.nl/docs/UcD400HG_datasheet.pdf , and you want to know how they perform @ 2 Ohms. Feature set may differ from W4S, too, so there's some homework to be done.

I couldn't find any reference to the performance of the ICE Power 250 ASX2 modules below 4 ohms either. For me, it's an experiment, hopefully a fruitful one. I'm waiting on 2 MiniDSP PWR-ICE250's.
http://www.minidsp.com/products/plate-amplifiers/pwr-ice250
The next step is figuring out how to bypass my Vistas' panel crossovers. I've read a thread by JonFo on bypassing the crossovers on the Quest, but the subsequent models are much more difficult, from what I've read. I'm going to keep poking around here to see what I can find. I may contact ML, but only as a last resort. My Vistas are still under warranty for a few years. I'm not terribly concerned with keeping the warranty valid though, as I have so little invested in them.

 

[RUR]

Quick and dirty 'cuz I gotta run....

Here's ASP: http://www.icepower.bang-olufsen.com/files/solutions/icepower1000aspdata.pdf see pg. 9

and ASX2: http://www.icepower.bang-olufsen.com/files/solutions/icepower250asx2_datasheet_1_1.pdf see pg. 10

Compare 10kHz-20kHz. Neither shows 2Ω, which is IIRC where things get interesting. If I can make time later I'll dig up some independent measurements which better show what I'm talking about. If you're buying ASX2 modules, anyway, it's all moot.

 

[InterMechanico]

Quick and dirty 'cuz I gotta run....

Here's ASP: http://www.icepower.bang-olufsen.com/files/solutions/icepower1000aspdata.pdf see pg. 9

and ASX2: http://www.icepower.bang-olufsen.com/files/solutions/icepower250asx2_datasheet_1_1.pdf see pg. 10

Compare 10kHz-20kHz. Neither shows 2Ω, which is IIRC where things get interesting. If I can make time later I'll dig up some independent measurements which better show what I'm talking about. If you're buying ASX2 modules, anyway, it's all moot.

Thanks Ken. The modules won't ship until at lease Tuesday, so I can change my mind, or return them and purchase something else. I'd really appreciate it if you could dig up some more details specifications.
Enjoy your afternoon.

 

[RUR]

OK, back from picking up a zippy precision mitre gauge. OB subwoofer build continues....slowly.

Here's a good example of what happens @ 2Ω with the ASP Ice module. In this case a Bel Canto amp:


http://www.stereophile.com/content/bel-canto-ref1000m-monoblock-power-amplifier-measurements Red line is 2Ω load.

FR is down ~2dB @ 16kHz, and a bit more than 3dB @ 20kHz. We don't know how much more with a typical ESL load of <1Ω because who the heck would design a speaker like that. Not ideal, IMHO.

Couldn't quickly find any 2Ω FR plot for the ASX2, but it's been well reported that B&O have improved this issue in these later modules.

 

[InterMechanico]

Thanks for the info, Ken. I'll take some measurements when they arrive and I get them set up. I may use them to go active on a pair of Totems I have before I tear at the guts of my ML'S. That way I can get used to setting up the crossover point and the other variables.

Have you been working on the enclosure of your OB Subwoofer enclosure?

 

[RUR]

Have you been working on the enclosure of your OB Subwoofer enclosure?

Yeah, I knocked out the plate amp boxes (can't insert plate amps into OB boxes, eh?) in a day, then spent weeks futzing around trying to get a good stain on the Baltic Birch. Took forever to get what I wanted and I ended up using my HVLP to spray the dye.

I thought I had all the pieces of the sub boxes done, but I was too casual and I need to re-make a few pieces "by the book", including jointed edges, etc. etc. to get a proper fit, else the two 12" drivers will tear the things apart. These will be equally hard to finish, since I want black dye internal and merlot on the sides/tops. Much PITA masking to be done.

I may even have them done in another two months!

 

[InterMechanico]

I thought I had all the pieces of the sub boxes done, but I was too casual and I need to re-make a few pieces "by the book", including jointed edges, etc. etc. to get a proper fit, else the two 12" drivers will tear the things apart.
I may even have them done in another two months!

HA, I've been there before. My projects can really drag on if I'm unable to complete them in a day or so.
I'm curious what kind of plate amps you've settled on. I apologize if you've covered this already, with me no less...

 

[RUR]

HA, I've been there before. My projects can really drag on if I'm unable to complete them in a day or so.
I'm curious what kind of plate amps you've settled on. I apologize if you've covered this already, with me no less...

Julian, the problem is I work in fits and starts - 2-3 days work, 2-3 weeks off. Everything takes far more time than it could/should.

Amps are Rythmik A370-XLR3, found here: http://www.rythmikaudio.com/amplifiers.html DSP functionality is minimal, but I have to have the servo control for the GR Research drivers I'm using: http://gr-research.com/sw-12-16fr.aspx . Can't do that with miniDSP or Hypex plates.

 

[Joey_V]

Hahaha... Came back to a huge thread. Nice responses from buying the $200,000 boulder and buying all 3 local amps and testing them.

I have a part time job interview tomorrow, if I get it then I will call the guy with the 211 and buy it. First amp on the batter's plate. Gotta figure out what's next.