Zu speakers with Atma-Sphere M60 amplifiers


I own the latest version of the Atma-Sphere M60 amplifiers. Arriving soon are a pair of Zu Definition speakers. Does anyone here have any experience driving the Definitions with the Atma-Sphere M60 amps. Observations are most welcome. I am given to understand the Definitions are approximately 6 ohms. I'm hopeful this will still work satisfactorily.
frontier1
IMO, M-60 amps are overkill for the Definitions. An S30 would do the job.

However, if you specifically want monoblocks, the M-60 amps can be run lower power with only six or four tubes per chassis.
No disrespect but,shouldn't you have researched this before buying?Just a thought.Good luck.
You can safely remove output tubes from each amplifier to reduce power output and heat.

Good luck.

Dealer disclaimer.
If you have to much gain (very little volume control) you can also replace V2 with a jumper plug to lower the amps gain. I run Avantgarde Duo Omegas with M60s with only 4 tubes per amp and V2 jumper-ed out. Atma-Sphere can set you up with a pair of plugs or you can DIY them if needed.
you might ask Zu (Sean) to make sure the impedance is correct for OTLs---as I recall, you can have this adjusted at the factory.
05-09-10: Keithr
you might ask Zu (Sean) to make sure the impedance is correct for OTLs---as I recall, you can have this adjusted at the factory.
That's a good point. Certainly worth checking with Zu Audio, but be certain to tell them specifically which amp is being used.

As I recall from a dealer who once sold Zu Audio and still sells Atma-Sphere, the tweaked Zu impedance was more important for use with an Atma-Sphere S-30 amplifier. The output impedance of the M-60 amps is lower than the S-30.
Hi folks:

Thanks for the guidance here. I know the factory can implement a mod that increases the impedance but I thought that if I changed amps for any reason, the factory configuration would be more forgiving with most other amplifiers. I'm happy to hear the M60s will drive these speakers adequately.
Check out this thread, toward the bottom:

http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1259232779&openfrom&10&4#10

Ralph says he likes the Druid better with the M60s than the S30. If the Definitions are similar, they might follow suit.

David
Regarding impedance, which is what is important when discussing matching to Atma-Sphere amplifiers, the Definition and Druid are two completely different speakers.

Definition MK2 - 6 Ω nominal full bandwidth; 8 Ω nominal from 40 Hz - 35 kHz equal weighting

Druid - 12 Ω (nominal full bandwidth)

Considering these specs, and the fact that the S-30 has a higher output impedance than the M-60, it stands to reason Ralph would prefer the Druid with the S-30.
M60's (HOT) in Canada will work just fine with Zu speakers but here in FL. the S30 will have to do.

The AS/Zu combo will be a treat to hear everytime you fire them up.
Tvad,

Read the thread again; Ralph preferred the M60s with the Druids, not the S30. Not sure how that corresponds with the respective output impedances. I agree with you that the science says the S30 would be better with the Druid, but his statement seems to contradict that. Maybe the extra power and headroom overcome the effect of the impedance mismatch.

David
05-09-10: Armstrod
Tvad,

Read the thread again; Ralph preferred the M60s with the Druids...
You're right. Can't explain it. Maybe Ralph can.

More than ever, I'm convinced in audio that 1+1 does not necessarily equal 2.
as an aside, I have heard the Pass X-30.5 isn't a perfect power match with Definitions as well. perhaps it's related.
I used to own Druids and I auditioned an S30 with them. The sound was excellent, but if you like loud music occasionally, the S30 runs out of steam a little bit early for my tastes. I think 60 watts would be more than enough to blow the roof off with Zu speakers.

For the record, I now run highly modded Infinity RSIIb speakers (power hungry) with 500 WPC monoblocks. There are so many options for great sound...
>>05-10-10: Keithr
as an aside, I have heard the Pass X-30.5 isn't a perfect power match with Definitions as well. perhaps it's related.<<

Very interesting.

First of all, the XA30.5 is a very powerful amplifier. I don't believe you can clip it with a pair of Definitions.

Second, I ran a pair of Definitions with the XA30.5, among other amplifiers, and found the match to be sublime. It actually outperformed a handful of tube amplifiers to my ears.

As always YMMV

Dealer disclaimer
Regarding the use of 60wpc amps (like the Atma-Sphere M-60s), my Druid pair performs very nicely with a pair of Dynaco MKIIIs (re-built and ammended). Overkill, perhaps, but it's like having horsepower under the hood you'll never need. I know, SET refinement in flea power suits some better and there is no point belaboring that.