[geowak]

One of the things I like about audio is the difference in sound moving from one piece of gear to another. I think it's great that there are so many variations of sound, some very colorful and some subtle.

Does it really matter if one kind of amp is more neutral, warm or cool? Does it matter if the graph checks out perfectly? I mean.. just enjoy the music. When you stop getting a kick out of the music and think it's the gear, thank goodness there is another kind, brand, or different piece of equipment you can swap in to alter the sound, so you like it again.

Also... everyone should get a hearing test. How well do you hear those sounds?

BTW last year I was using a Marantz 2230 to power my Snell Tower speakers (86/87db sensitivity). Sounded pretty good and I liked it!

[Davey]

I am not rejecting your opinion Dave. And you are raising important technical points about these amps. However two things stand out in my mind (and please don't read this as being confrontational. I don't mean it in that way.):

1) How should opinions of those who haven't experienced something first hand be regarded in your opinion?

2) To have no desire to hear an amp that has received such high praise seems odd.

1.  Are you saying that folks who haven't experienced something firsthand can't have an opinion?  I hope not. 
I've never driven a Ferrari (probably you haven't either) but that doesn't mean I can't have an opinion on the concept/engineering/price/etc/etc, does it?

2.  High praise from whom? 

You might want to re-read my postings carefully.  I never dismissed the Atma-Sphere amps out-of-hand....except for price.  I said the high output impedance would impart frequency response shifts relative to other amplifiers.  "It may or may not be beneficial, but that's beside the point of the OP's original query.".....or words to that effect.

How I made the transition to "absolutist" in your eyes is a mystery to me. 

Cheers,

Dave.

[James Romeyn]

Lower powered amps recover to zero faster than higher powered amps.  This is why music lovers sometimes prefer the former vs. the latter.  This is also related to Nelson Pass's "First Watt" line of low power amps...the first watt is the most critical (so this goes) because this is the most useful and most used watt of all the watts required...if you averaged all usage, the amp's average output power hovers around 1W. 

On a critical related matter: If I understand him correctly, Duke LeJeune of AudioKinesis generally takes a speaker driver's "Wrms" power rating and divides that figure by 10 to arrive at the input power equal to the speaker thermally compressing the signal by 1 dB.  Continuous maximum input power may be true, but it may also be highly misleading to determine useful input power.  Duke designs speakers that play live music levels with input power equal to about 1/10th the Wrms rating.  Lynn Olson said Duke's Dream Maker played louder and cleaner than anything he ever auditioned prior.   

My speakers are rated 200Wrms @ 4 Ohm nominal.  For about a year I had amps capable of 400W @ 4 Ohm (1/3rd duty cycle).  Interestingly, there is little difference in maximum enjoyable/useful level "downgrading" to amp capable of only 50Wrms. 

With the former amp, as level increases, tonal balance stays linear up to a certain threshold I'll call X.  Past X, level does increase, but a keen ear notices that transients dull (and other qualities decrease) per each further unit of increased level.  IOW, level increases in a linear manner prior to X, then past X level increases in non-linear fashion.

I also noticed stage and image qualities decrease as level increased past threshold X. 

After careful observation and consideration I'm now a believer in Duke's philosophy.  I tend to think it ideal to divide a speaker's "Wrms" rating by 10 and presume that input power = threshold X as defined above.  Yes, the speaker may safely handle 10x that power up to the "Wrms" rating, and the speaker may increase in level beyond threshold X, but beyond threshold X each unit of increased level decreases quality.  IOW, continuous power rating is just as misleading in speakers as it is in power amps.  For power amps, continuous power is useful only for test tones because music is dynamic and almost never mimics test tones.  I very much think "1/3rd duty cycle" is ideal amp power rating spec.  For speakers Wrms/10 seems most useful.  The "peak" input power rating for speakers is completely useless in this scenario, because the speaker is probably thermally compressing 20 dB at such figure, or much worse.  IOW, yes, the speaker can withstand such input for 10ms, but it does not properly reproduce this signal and it rather converts this signal into useless heat.  These figures are all worse than useless because they mislead and obfuscate the true useful meaning.     

Except for the smallest rooms I tend to think live SPL always accompanies gross audible thermal compression unless speaker sensitivity is in the low-90 dB range anechoic or higher.  If the room is moderate or larger in volume (floor space area is useless, you must consider volume which is three dimensions) the speaker will never have enough power handling to make up for low sensitivity. 

Just one opinion, open to revision at any moment.  Never heard SP Tech but some users with seemingly reliable ears love them.  They are moderatley low sensitivity but seem to have endless power handling.     

[Russell Dawkins]

Andy-c,
Let's not put down the perspectives of others please. You are newer to AC, but one of the things I like here is the sense of audio community.

Newer? He registered in June 2003; you registered in May 2008.

andy_c seems to have a sensitive BS meter and a slightly short fuse, as do I. It's one thing to be deluded; it's another to spread it around, intentionally or not. I positively detest intentional obfuscation.

[Russell Dawkins]

Andy, I think you actually believe what you wrote, sad.   In corroboration of the link you call pure BS and wherein you slander the author:

http://lenardaudio.com/education/14_valve_amps_7.html

Jim

I can't believe you are citing Lenard as a reference in this matter. Have you read the material on his site? Does it convince you?

[James Romeyn]

I get extremely irritated by anything posted or in print lacking date reference.  (lenard audio site).  Nothing gives text as much context as the date it was authored. 

[medium jim]

I can't believe you are citing Lenard as a reference in this matter. Have you read the material on his site? Does it convince you?

Just as much as any other, meaning, I don't put much stock in any as I prefer my ears over science.   This is not meant to discount the science of audio altogether.  It all goes back to what sounds best for me and not what sounds best for you.  The talk that this topology is superior to another is baseless.

Jim

[James Romeyn]

I've never heard one audio-freak say "Man, what I need is less watts."

Get the very most of the very best watts you can afford. Your speakers, whatever they may be, will thank you for it.

Have fun,

Jerry

True dat!  But some users of high sensitivity speakers require less "gain" because of increased noise. 

[Russell Dawkins]

Just as much as any other, meaning, I don't put much stock in any as I prefer my ears over science.   This is not meant to discount the science of audio altogether.  It all goes back to what sounds best for me and not what sounds best for you.  The talk that this topology is superior to another is baseless.

Jim

Then I still don't see how the link to Lenard corroborates the Atma-sphere reference, as you suggest it does. What specifically are you finding convincing in the Lenard material, such that you would single it out and provide a link to it?

[James Romeyn]

It kind of depends on the vinyl. Does anyone remember the Telarc 1812 Overture recording.
Scotty

I worked with a vendor who used to love that disc at shows.

The real live canons recorded for Master And Commander absolutely kick butt and IMO beat the above disc (which is good btw).  You can't beat M&C canons played back on a four-sub Distributed Array properly installed: no modal effects/no waveform hangover/no bass ringing.  Look ma: no wall effects!  Next time I play that movie I'll make sure the wife isn't home.  Canons in the basement: no domestic bliss!   

[medium jim]

Then I still don't see how the link to Lenard corroborates the Atma-sphere reference, as you suggest it does. What specifically are you finding convincing in the Lenard material, such that you would single it out and provide a link to it?

For one how different topologies respond to impedance curves....

Jim

[Rclark]

Andy-c,

Let's not put down the perspectives of others please. You are newer to AC, but one of the things I like here is the sense of audio community. Comments like "brazen BS artist", "complete nonsense" "utterly incompetent and unlikely to have the ability to design a decent amp to begin with.  So I think this is conscious BS artistry and not an attempt to describe legitimate engineering" are unnecessary, and contribute little to the discussion or the community here.

The author is Ralph Karten of Atma-Sphere. I rank him in the top ranks of amp designers. Right up there with Nelson Pass, John Curl, Bruno at Hypex and other great amp geniuses.  He is the preminent builder of OTL tube amps at the present.

Have you ever heard an Atma-sphere amp? They are sublime. Maybe not to everyone's tastes, but what amp is? And his amps, like any amp, need to be paired with an appropriate speaker. But with the right speaker and if it was in my budget, I would buy another Atma-sphere amp in a second. Check the reviews if you aren't able to hear an Atma-sphere yourself.

And really, the article is describing paradigms being used. Each of which is suited to different types of speakers, and each of which may have different design goals. And it is conceptually useful to think about the different paradigms being used by different amp (or speaker or turntable or any component) manufacturers.

Atma-Spere monoblocks were the exact amps Mgalusha sold to move into Ncore 400's and then 1200's. Take that for what it is. Definitely not lacking in "fleshing out detail", lacking in anthing, but rather they were an improvement.

And pretty sure Atma-Sphere's are nicer than most. They sure aren't cheap. Technology moves on, the leap has been made, deal with it or look foolish.

[medium jim]

So 99.9% of us are fools according to Reza.

Jim

[mgalusha]

Atma-Spere monoblocks were the exact amps Mgalusha sold to move into Ncore 400's and then 1200's. Take that for what it is. Definitely not lacking in "fleshing out detail", lacking in anthing, but rather they were an improvement.

And pretty sure Atma-Sphere's are nicer than most. They sure aren't cheap. Technology moves on, the leap has been made, deal with it or look foolish.

I've been following this thread with great amusement, simply because I have made the measurements in my system that assure me that most people don't have enough power, regardless of topology but now I've been dragged in.

1) I did prefer the NCore's over the Atma-Sphere but primarily from a heat and maintenance perspective. I sold my AS before I ever heard an NCore, so I was looking for a SS solution PRIOR to hearing the NCore amps. A Pass XA-30 was on my short list. Did I miss the M-60's after they were gone? Some and they did some things incredibly well but I don't miss the 24 tubes between them and the heat.

2) See this post for info about some measurements I made with the Atma-Sphere driving the Geddes Abbeys. One thing about tube amps is the rail voltage is much higher than an SS amp. This can allow them to produce higher power for very short periods. When an SS amp hits the rail voltage it's done, there is no more and the results are ugly.

My take is as stated in the linked post, if one is using SS, the more power on tap, the better, clipping is a very bad thing. Yes thermal and dynamic compression is ugly but if one actually looks at the short term peaks demanded by actual music, they are greater than expected, at least to me. The Atma-Sphere amps well exceeded their rated power of 60W for very brief periods. FWIW I still own the NCore's but with my DIY speakers I prefer tubes.

mike

[Rclark]

These were your initial impressions, they are still correct?

"Ignore for a moment the "class" designation of the new Ncore amplifiers from Hypex, think instead of how you would view them if described as high speed analog amplifiers with only two MOSFET output devices. That is exactly what they are and I've been fortunate enough to have spent the last few days with a pair on loan from Jason W. (jtwrace)

This is not a review, just a few comments about what I think of these, hence it's not in the critics circle. I have not been a fan of class D amplifiers and until now have not heard a pair that I thought I could live with for the long term. I believe I could be very happy with a set of these an assuming mine ship with the next batch I'll find out.

In terms of sound, these give the impression of being invisible. A lush, rich recording sounds lush and rich, compressed and lean recordings sound that way. My audiophile buddy Jerry (turk) came over on Saturday and we spent many happy hours listening to music and after a while both of us observed that we could not stay in an analytical mode. Instead of thinking about how it sounded, the thoughts were, my what an exquisite piece of music this is, how well played. I can think of no higher praise.

I tried to get some writing done on Saturday night, couldn't manage, I just kept falling into the music. Jerry used the word gravitas, meaning the music had more weight and emotion. I shared this with another friend who has heard these and his comment was "Gravitas yes indeed".

So rather than think of this as another class D amplifier, think of them as a high speed analog amplifier with only a pair of output devices. I was biased against class D but willing to listen, I'm delighted I did. The only sad part is I have to pack them up for shipping. "

http://www.audiocircle.com/index.php?topic=105310.0

[Rclark]

So 99.9% of us are fools according to Reza.

Jim

again

You've never had any of these in your system.

[medium jim]

again

Reza nor have you any tubes in yours.  Your comment is exactly what Roscoeiii and I are referring to as absolutism. 

Jim

[Rclark]

Hey, you're the expert.

[mgalusha]

These were your initial impressions, they are still correct?

Yes and nothing I said contradicts that, I still like the NCore based amps very much. The discussion was about sufficient power and I attempted to provide input on how much I believe is necessary and why, perhaps, that less continuous power may be OK with tube amps. I am not passing judgement or even questioning others opinion on what sounds "good". One thing I wish every person on this and other forums could experience is to run a demo room at a show for the weekend. In the span of a few minutes you will get comments from "best I've ever heard" to "not working for me" and the listener walks out thinking the system is awful. It can even be the same track, so it's not like people were hearing a different sound, just that perspectives and preferences differ and they also change and evolve. Sitting in that room for three days drove that firmly home.

[Rclark]

And there it is, good. We can talk about power requirements again, which is the OP. Just wanted to clarify that class d isn't some lowly tech, but it's right up there, clearly. They don't lack sound quality. You're using them, many here are. Even the low power variants get a lot of praise. It has even been demonstrated that if desired, they can mimick the "flaws" of tube amp reproduction.

Anyway, power. My experience with power is that more is better, clipping is bad, audible as fatigue, and prevalent on under powered systems. If more amps came with a clip light, people would be able to see it for themselves.