Anyone Using Atma Sphere amps

[stesom]

I am going all tube and now comes the amp upgrade. I really like the way the atma sphere amps are built and love that they are all triode OTL class A amps. Just wondering how they will handle the impedence swings of the ML Summits or for that matter any of the ML panels.

Otherwise, since the rest of my system is ARC, I could go that way, but transformers scare me for some unexplained reason .

 

[jtwrace]

I spoke with Ralph Karsten yesterday. He said ML or any electrostatic will be no problem for his amps. He went into why buy I'm not that technical to explain why though. I was going to post this thread....how weird is that? Anyone have any thoughts?? I'm also interested in the preamps.

 

[aliveatfive]

FWIW -

The new ARC Ref series amps sound magnificent on MLs - the best I've ever heard. You should audition one before making your choice.

 

[Tj Bassi]

I spoke to Ralph in the past, maybe a bit over two years ago, concerning a pair if MA1 MK2's for sale in my area. He suggested that although the amplifiers would be a good match for my reQuests, their nominal impedance was a bit on the low side to keep an OTL amp happy. The solution was a pair of "Zero" matching transformers (or autoformer as often called) which would raise the speakers impedance for best performance. Odd that you would need a to purchase transformers for use with an output transformer LESS amp, but thats how the conversation went. Do a goog on zero autoformers to dig up more info.
Tj

 

[rtagle]

I spoke to Ralph in the past, maybe a bit over two years ago, concerning a pair if MA1 MK2's for sale in my area. He suggested that although the amplifiers would be a good match for my reQuests, their nominal impedance was a bit on the low side to keep an OTL amp happy. The solution was a pair of "Zero" matching transformers (or autoformer as often called) which would raise the speakers impedance for best performance. Odd that you would need a to purchase transformers for use with an output transformer LESS amp, but thats how the conversation went. Do a goog on zero autoformers to dig up more info.
Tj

Try this link: http://www.anticables.com/products.html

 

[stesom]

Was hoping to avoid the transformer

The atma-sphere still would be all class A fully differential but I like the idea of no transformer even though the bandwidth of these devices have become remarkably wide.

My dealer is getting a pair of MA-1 MK2v3 tuned up for me to try. I will see how it goes. Otherwise I am going to try the VTM200s next and then a ref 110.

I know ARC is introducing a hybrid HD-220 that also may be of interest. I think the research stage is fun, so we will see how it goes......Steve

 

[Tj Bassi]

Try this link: http://www.anticables.com/products.html

Thats the link.....

T-

 

[risabet]

The atma-sphere still would be all class A fully differential but I like the idea of no transformer even though the bandwidth of these devices have become remarkably wide.

My dealer is getting a pair of MA-1 MK2v3 tuned up for me to try. I will see how it goes. Otherwise I am going to try the VTM200s next and then a ref 110.

I know ARC is introducing a hybrid HD-220 that also may be of interest. I think the research stage is fun, so we will see how it goes......Steve

Fear not the transformer grasshopper, for they are truly good now. I would seriously question the suitability of an OTL of any make to suitably drive a sub 4 ohms speaker that dips towards 1 ohm with anywhere near a flat FR. The high output impedance of the amp will interfere with the impedance of the speaker to cause a varied response with frequency. My $.02. YMMV

 

[stesom]

Fear not the transformer grasshopper, for they are truly good now. I would seriously question the suitability of an OTL of any make to suitably drive a sub 4 ohms speaker that dips towards 1 ohm with anywhere near a flat FR. The high output impedance of the amp will interfere with the impedance of the speaker to cause a varied response with frequency. My $.02. YMMV

I guess I will have to order a pair to ensure the OTL amp performs its best. I know that any panel speaker is a demanding load with noteable impedence dips which will draw mucho current from an unsuspecting amplifier. That is why I know that my CA-400 is not taxed by these speakers since the mostly double down to two ohm. Thanks for your help everyone, it should be fun to listen to the differences. Maybe my 8 year old CA-400 still will hold its own. I don't have to spend more money, do I??? :devil: :devil: :devil:

 

[gander222]

Zero autoformers with tube amps and ML speakers

I use Paul Speltz Zero Autoformers. I think that is what you are talking about.

While I don't have atma-sphere OTL amp (any more), for the moment I drive my ML Sequel 2 speakers with a 20W EL84 amp by Promitheus Audio, with massive c-core output transformers. A really nice sounding amp, but as I said, only about 20W output. The Sequel 2 impedance wanders all over the place, from 3.5 ohms at 20Hz, up to 10 ohms at 40Hz, down to 3.5 ohms at 50Hz, up to 8 ohms at 200Hz, down to 3 ohms at 500Hz, up to 13 ohms at 1200Hz, down to 4 ohms at 5000Hz, and then lower after that. I got this info from an impedance chart that a ML tech sent to me.

To help my tube amp be happier with the load I am using Paul Speltz Zero Autoformers, one on each speaker, which allows the 3-13 ohm speakers appear to be 6-26 ohm speakers (autoformer wired for X2), doubling the dampening factor. I can set it up for X2, X3, X4, and other multiples in between.

I have a TVC (transformer volume control) passive preamp, so max zero gain there, but still with almost all sources (CDs), their record level is plenty high to drive the tube amp, and the MLs to too-loud. Of course, 100W tube amps are in the future, but for now, this works well for me.

Check out the Zero Autoformers for use with tube amps and ML. Works for me.

Gary

I spoke to Ralph in the past, maybe a bit over two years ago, concerning a pair if MA1 MK2's for sale in my area. He suggested that although the amplifiers would be a good match for my reQuests, their nominal impedance was a bit on the low side to keep an OTL amp happy. The solution was a pair of "Zero" matching transformers (or autoformer as often called) which would raise the speakers impedance for best performance. Odd that you would need a to purchase transformers for use with an output transformer LESS amp, but thats how the conversation went. Do a goog on zero autoformers to dig up more info.
Tj