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Amps Atma-Sphere M-60 Mono blocks OTL design

I just purchased a used OTL Atma-Sphere M-60 mono blocks that I have sent to Atma-Sphere to be upgraded to the current model 3.3 and I also added the option of a higher quality power supply and V caps.

I have sold my old trusted Eggleston Andra 2’s speakers and have built some monitors using Aurum Cantus ribbons (102db) and Aurum Cantus midwoofers (90db) that are both rated as 8 ohm nominal. I have a DEQX Premate and will be crossing over to (2) JL Audio F-113 subs at 80hz.

Currently I am using a solid state high power stereo amp (Pass Labs) that I used with the Andra 2’s.

The Atma-Sphere M-60 is rated at 60 watts class A and is said to work better with higher impedance loads.

It will probably be a few weeks until I get the M-60 and was hoping someone could provide opinions of what to expect.

I listen to late 60 early 70’s classic rock music mostly. Sometimes loud.

ozzy

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bigboltz
48 posts
 
ozzy

I heard from Ralph today ( ok, he emailed back cuz I bug him once a week) and he said he's done the initial testing and expects to have it in the system next week.  Maybe my pre and your amps will end up testing together!    Anyway, I can't say enough about the level of customer service AtmaSphere has given me.
ozzy's avatar
ozzy OP
3,650 posts
 

jond,

Thanks! Believe me I'm savoring...

bigboltz,

Though I don't have the Quatros, I will be using subs and just the signal from 80hz and up will be powered by the M-60's. Do you know the crossover frequency of your subs / Quatros?

And, thanks for your update, mine is still on the work bench waiting for parts.

ozzy

bigboltz
48 posts
 
ozzy

The Quatros require -3db at 100hz.  Ralph is actually building that into one of the outputs for me, so i wont need to use the external crossover(m5hp) that goes between the pre and power amps. Vandersteen has a rather unique way of hi-passing their speakers, whether it be the Quatro and up or model 3 and down used with seperate subs
alexysflores
8 posts
 
You might have to upgrade or replace your current preamp that you are using at the moment since you will be missing the finest tubey sound.  If you have 8 ohms speaker that will work fine with M-60 but if you ask Ralph he recommend to use 8 and16 ohms speakers.  High end 16 ohms speaker such Classic with built-in horn mid range and tweeters are pricey.  The only alternative way to gain 16 ohms is through Zero transformers.

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gdnrbob
2,421 posts
 
@bigboltz
The remote is nice, but I find the range is limited (10 feet or so). I have to contact Ralph and see if the remote needs batteries or if I need to situate the preamp differently.
I am glad to hear the M-60's have enough punch for quatro's. I was going to get them, but my, then 3a sigs were more power hungry, and he had a pair of upgraded MA-1 v2's for sale at a good price, so I went with those. I probably should have had the hi pass incorporated, in hindsight. Those stupid M5-HP's are not very attractive hanging off the inputs. @alexysflores 
Vandersteens are pretty stable with Atma-Sphere amps, more so when using the crossovers. I think Ralph says his amps should be good with even 4 ohm loads. 
@ozzy 
If Bigboltz is doing good with M60's, I am pretty sure you will be okay.
Of course the best info would be from Ralph himself. But, if Almarg says you have been using very little power with your current amp, then I wouldn't be concerned.-Ralph's designs are not only refined, but they are tough (as in, well built).
B

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