Amps Atma-Sphere M-60 Mono blocks OTL design

steakster,

First off I am getting older and my Eggleston Andra 2 speakers were 215lbs each. Moving them around the room is no fun. I always wanted to try tube amps but I knew that my Andra’s required a fairly hefty amp to drive them properly.

Once I got the DEQX Premate with its built in subwoofer crossover, my brain juices started to flow. BTW, I also retired 2 years ago so I now have extra tinkering time available.

Anyway, I wanted to make a very easy to drive stand mounted speakers to use with my JL Audio subs. I made a prototype with some drivers I bought on EBay. They actually sounded pretty good but the cabinets still looked very DIY (I own a jig saw and a circular saw and haven’t changed the blade in 30 years)!

I then found on Parts Express some really nice Hi Gloss cabinets with the internal volume and size I was looking for. So keeping with Parts Express, they sell the Aurum Cantus G1 ribbon tweeters that can handle 100 watts rms. (I have always loved the sound of ribbon tweeters). I then thought keeping within that family line was the top of the line Arum Cantus 6.5 mid woofer. It had the specs that I was looking for. Well, the 6.5 mid woofer really turned out to be a 7" size and the High Gloss cabinets were a pain to cut. The front baffles are 1 1/2" thick !

But I did it, and they look great. I stuffed them with " acousta stuff". I wanted to be able to experiment with different crossover settings so I built an external crossover box. Well as I started trying more and larger caps and inductors that box became too small and I made a larger one with spikes! ( BTW, I ended up with all Mundorf silver, Gold, Oil caps).

Anyway, it has been a fun challenging project that I am really proud of. I have listened to many systems and I think I have a winning combination! Total cost about $2600.

Thank you for asking...

ozzy

steakster,

Thanks for your info. The Grand Prix amp stands that I am using have little pads that go between the acrylic 3/4" shelf and the carbon fiber stand. They are available in different "squishy" pads for different weight loads. I did try Stillpoints Ultra SS under my Pass labs amp and I did not like the sound with them with my Grand Prix amp stand.

o_holter,

Thanks for your post. My DIY speakers have a very flat 8 ohm load and a high sensitivity rating. Couple that with the high crossover setting , I think they are easy to drive.

ozzy

gdnrbob,

The rated FR is 37 to 4000hz. But that is probably with a ported design and to me would be very subjective anyway. I would say reasonable / usable low end and a non ported design would be about 50-60hz.

ozzy