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
Yes... Unless your speakers are very efficient (e.g. say 94db+) you will most likely want to get a set of Autoformers from Anti-cables to boost the impedence of your speakers to reduce the load on the M60's. http://anticables.com/autoformers |
Ozzy, You said the speakers you have built are 8 ohms. Assuming that there are no widely varying impedance dips below 5 or 6 ohms (particularly in the mid to upper bass region) I don’t see the necessity of using the Zero transformers. Someone above mentioned a 94 dB sensitivity as a cutoff point and I disagree with that. Zero transformers are used to increase speaker load impedance as seen by the power amplifier. It has no meaningful bearing on the speaker sensitivity. Charles |
@ozzy, the M60s are great amps and they should be a super match with your new speakers WITHOUT zero transformers. Congrats. @charles1dad is correct, it's all about the impedance match not about bass (sorry Meghan Trainor!) FWIW, IMHE those much praised zeros can cause a greyish, whitish haze over the music that really ruins it for me. I would never make them part of the solution. There are plenty of speakers better suited to OTLs, you shouldn't need them. Cheers, Spencer |
