Atma-Sphere Class D Mono blocks

[Kingrex]

I can also say, I had friends over to listen this weekend. I took the Atmasphere out and put my Dartzeel back in. The following day I turned my system back on with the Dartzeel in and found myself wanting to put the Atmasphere on, so I swapped the amps out. That is when it hit me again about tilting my head.

 

[morricab]

I can also say, I had friends over to listen this weekend. I took the Atmasphere out and put my Dartzeel back in. The following day I turned my system back on with the Dartzeel in and found myself wanting to put the Atmasphere on, so I swapped the amps out. That is when it hit me again about tilting my head.

So, the friends didn’t get to compare the two? Opportunity lost i would say… Does this mean you are leaning towards an Atmasphere preference?

 

[jeffreybehr]

My pair is arriving today, I hope within an hour or 2 (of noon, MST). Pics soon.

 

[Gregadd]

The sample size continues to grow.

 

[Kingrex]

So, the friends didn’t get to compare the two? Opportunity lost i would say… Does this mean you are leaning towards an Atmasphere preference?

Opportunity was not lost. The Atmasphere are not ready.

I have no idea what one amp really sounds like compared to the other. Its not a 20 second switch. Its an hour. I have many other projects on my plate of much higher value. I will circle around after a couple weeks when my schedule allows. Then I may do a back and forth and see if I have a preference.

I guess another thing you could say is they are very similar. I really have heard nothing that stands apart in either.

 

[jeffreybehr]

Mine arrived, well-packaged in one carton and in excellent condition.. Of course I pulled a cover off and fotografed the guts.






Each weighs 13 pounds, 2 ounces.. The pair draws so little current, I can hardly see the 2000-Watt meter change after turning them on...maybe 150 Watts! The top cover rings quite a bit, and I'll be applying some SoundCoat-the-thicker* to its inner side and probably some to the bottom of the bottom, too.. The power inlet includes a fuse and appears to be a noise-filtering type.. The amps are dead quiet both physically and electronically, and I'm pleased to see the chassis earthed.

Even brand new and cold, they sound just fine--that is, there's nothing wrong with the sounds--driving my HHR TLS-2s..They'll be burning in for maybe-500 hours; after all, they'll NOT be heating the room!!!

Showing that I know virtually nothing about class-D amplifiers, I have to wonder where the output transistors are!

* 50% off at Sonic Craft now... https://www.soniccraft.com/index.php/accessories-damping-c-157_25

 

[Tuckers]

I have about 240 hours on a pair of Atmasphere monos. I have not built up a opinion yet, but I keep coming back to an interesting listening observation. I have always listened with most any system I can remember by sitting on the end of my ottoman with my head forward and face to the floor. Basically the top of my head aimed at the speakers. The Atmasphere are the first amps where I find I sit in the same place but my head is up with my face directly at the speakers. I am thinking it has something to do with the distortion being so low.

I feel I need to let these amps go for 2 more weeks before I really start listening in ernest.

Could surmise that it could be due to your unique ear shape (everybody is unique), or phase relationships in your system. I listen with my head down a lot, things seems to gel spatially a bit better sometimes.

 

[Atmasphere]

Showing that I know virtually nothing about class-D amplifiers, I have to wonder where the output transistors are!

The output transistors are not visible, being on the bottom side of the module's circuit board which is integrated to the heatsink which is custom fitted to the module. Do not attempt to remove the board from the heatsink to take a peek! Otherwise it will have to make a trip back here to get repaired.

 

[jeffreybehr]

Got them running and then couldn't resist adding that SoundCoat-the-thicker to the bottoms of the tops and bottoms of the bottoms; the tops no longer ring like bells.. Already had some Cardas CCRR (rhodium) binding posts and replaced the Cardas coppers.
The Magic Bricks and stainless-steel blocks aren't atop the amps because the tops still 'ring', I'm just compulsive about using my collection of that heavy stuff.. (BTW, all of those heavy things have Herbies little soft discs on their bottoms.)

They'll be playing music 24/7 for weeks.

Speaking of PS Audio M1200s, that pair draws about 200 Watts in standby and about 210 Watts idling; the A-Ds' numbers are zero and about 150.

 

[Atmasphere]

Speaking of PS Audio M1200s, that pair draws about 200 Watts in standby and about 210 Watts idling; the A-Ds' numbers are zero and about 150.

The '150' sounds like full power to me. At idle they really don't draw much power at all; just a few milliamps.

 

[jeffreybehr]

The '150' sounds like full power to me. At idle they really don't draw much power at all; just a few milliamps.

Hi Ralph! These 'measurements' were observed on my PS Audio P20 regenerator's 2000-Watt meter and are only approximations, and all were done with NO music playing.

 

[Atmasphere]

If that's the case, the reading may have been in milliwatts?

 

[jeffreybehr]

The output transistors are not visible, being on the bottom side of the module's circuit board which is integrated to the heatsink which is custom fitted to the module. Do not attempt to remove the board from the heatsink to take a peek! Otherwise it will have to make a trip back here to get repaired.

TY, Ralph, I will NOT try anything with that board.. How about a pic of its bottom?

 

[Atmasphere]

All of our in-stock modules are already married to their heatsinks. The heatsink is a machined aluminum bit that also supports the module for mounting. It has machined 'islands' that contact the GaNFETs and are machined to a 1 mil tolerance. The GaNFETs are treated with a once-use heatsink compound and have to be precision mounted to insure that the module is both properly grounded and has proper contact to the heatsink. Due to variance in the GaNFETs themselves as well as the flow soldering, this procedure isn't trivial.

 

[Zoso69]

After waiting 12 months for a Decware Zen 25th Anniversary amp, and at least another 6 months wait time left, and my 12 month old Willsenton R8 red-plating on me after only 10 months of use (with upgraded Psvane EL34's) I decided to put my order in for a pair of AtmaSphere Class D's today. I LOVE tubes, I love how they sound, how they look, and the history and science behind them is fascinating to me. I just don't like living with something that takes 30-60 minutes to warm up before it sounds it's best, how I have to manually bias them a couple times a month, how their sound is always slowly degrading over time and must be replaced every few years, how dangerous it is to accidentally leave them on, etc., etc. I may eat my words and go back to tubes when the Decware finally arrives, but for now I'm ready for a change.

 

[jeffreybehr]

After waiting...I decided to put my order in for a pair of AtmaSphere Class D's today. ...

Welcome to the club.. My pair with about 26 hours on them sounded mighty fine last nite.

 

[ecolnago]

Just ordered a pair of A-S Class D's. Told they're 4-6 weeks out. Gives time to re-tube/re-bias my M-60's for comparison.

Not one that makes a lot of changes (too many other hobbies in my little system. Not necessarily in quest of the Holy Audio Grail here. Generally find something that makes me smile and live with it to I find it no longer makes me smile as much. M-60's still make me smile. Always a big smile. But if I can something that can make me smile just as big without tube's periodic hassles, I'm all over it.

Took a stab at a used AR DS-225 a while back. Bought it not having heard it. Lived with it for a couple weeks. Did not make me smile. It's new owner told me he was quite pleased with it. That made me smile . Hope those of you having acquired Mr. Karsten's latest amps will continue to sharing your thoughts on them. Needing something to get me through the next 4-6 weeks during this bleak midwinter (Indianapolis).

 

[Gregadd]

Ok. I assume you would be satisfied as with a lateral move. I am looking forward to your evaluation. Congratulations!

 

[orchardaudio]

Also, if your distortion is not increasing with frequency, you might again have the only Class D amp in the world that doesn’t do that.

On my amps distortion does not increase with frequency, you can see proof in this AudioXpress article: see figure 7.

Also here is my own measurement of the Starkrimson Ultra, it is taken at 10W of output power.

 

[Kingrex]

Ok, I have had the Atmasphere running for a couple weeks. They have only been out of the system a couple times for a day or 2.
I have played them back to back with my 12 year old Dartzeel NHB108 model 1 with SCNP network. First thing is to say, they are very close in sound. Its not easy to tell them apart. What I do feel I notice is the Atmasphere is more clean and has a tad bit tighter bass. The Dartzeel seems to have just a touch more background noise and plays a little smoother. The Dartzeel may have a hair more richness, but that may also be the perceived background noise.

The space around instruments and sound stage is almost exactly the same.
The bass to treble extension seems the same.
Neither have any perceived peaks, dips, hardness or fatigue.
Both are very balanced and musical.

You would not mistake either of these for a tube amp.

If you like SS amps, I was very surprised at how well the Atmasphere plays. I had preconceived notions of class D. I don't think you could tell it from any Class A or AB amp, outside how the manufacture of any other amp has decided to tune their equipment. In other words, there is nothing to let you know what Class amp this is. It could be Class A, AB or D.

The build quality reflects the price. Its a solid amp but has no flash. I have no idea the quality of components inside the case. If Ralph wanted he could add a lot of anodized aluminum or copper fins and up the price by thousands. But I doubt it would make the sound different. I perceive nothing saying heavier metal or damping would impact the sonics.

I did very little to try different foundations under it. I did put a set of feet under it and heard nothing. They currently sit on my wood floor.

I am going to be bummed to send them back to the owner. In all honesty, I may sell all the amps I have on hand and get a set of Atmasphere monos. I like the fact I can leave them on 24x7 and never worry. They are always warmed up and ready to go. There is nothing I hear to say the quality of sound is less than the Dartzeel. I actually like the clean and speed in the bass.