[Sedona Sky Sound]

Hello KJ,
Hello me try to answer your question more specifically. The specs on the SoA are very significant and absolutely amazing. As I mentioned before, the SoA have some of the best specs of any amp at any price (particularly for distortion which has the primary at .00001% !!!!   ). The Ampzilla 2000 specs are not quite as good as the SoA but still highly respectable. Generally speaking, the better specs equate to lower "grain" and less coloration in real-world listening. I think the quote from James was "my amps have all the best aspecs of tube amps but without the distortion and harmonics.

If I am still not answering your question, please rephrase it so that I can better understand wat you are looking for. Thanks.

Julian
www.sedonaskysound.com

[KJ]

Julian,

Thanks for the quick response.  That helps answer my questions.  I was never able to find the THD for the SoAs, only the Ampzilla 2000s.  This confused me given the distortion of the A2Ks were rated at <.05% and numerous competitors were significantly lower.

As you pointed out, the A2K's distortion is not quite as superb as the SoAs.  For clarification, is there a difference between primary distortion and overall distortion (or THD)?  Ie, is the THD of the SoAs really .00001%??  

Changing gears slightly, is the kVA rating for the SoA considered to be a continuous rating?

-KJ

[Sedona Sky Sound]

Hello KJ,
I had assumed you had been looking at the graphs which seems to have been a bad assumption on my part   . Here are all the graphs that specifically show the specs of the SoA and Ampzilla:

http://www.ampzilla2000.com/songraphs.html
http://www.ampzilla2000.com/graphs.html

When just using words, James rates his stuff very, very conservatively. If you matched graph for graph, you would likely see that the specs are MUCH better for the Ampzilla and SoA than the other amps that are claiming the lower specs. If you really want to see this, check out the Stereophile website for the graphs on the amps they have reviewed in past issues. Make sure to look at the graph scale closely since they are all different.  

If you look at the THD+N graph for the Ampzilla 2000, you will see that THD+N is actually only .005% into 500 W output at 4 ohms   !! If you look at the other graph you will see that the peak for the first harmonic at 2K Hz is still less than .0008%. The SoA graphs are slightly different but equally impressive. You will also notice that even thought the SoA is rated at 100W (it was originally rated by James at 80W), its actual output is closer to 120W+.  

As for your other question, like most people, I think you are confusing kVa with watts. kVa is just the rating of the transformer which provides the uppermost limit on the power available for long-term discharge by the amp. If there were no losses in the amp, the SoA could theoretically deliver 2500W+ continuously into some ungodly low ohm load. In the real world, the SoA could deliver a great deal more than that instantaneously (by discharge of the massive capacitor bank) and perhaps 2000 total watts continuously (but you could probably fry an egg on the top of the amp). You would also probably blow your homes circuit breaker long before the amp ran out of steam. I can only think of a few speakers that have a low enough ohm load to actually cause the SoA to run at anywhere close to full output (I have heard of a few of the original plasma tweeters that were .5 ohm load but do not know of anthing on the market today).  

I hope that helps.

Julian
www.sedonaskysound.com

[KJ]

Julian,

If I am understanding your explanation correctly, both Ampzillas are capable of supporting "heavy" loads due to:
  a) a high kVa rating of the output transformers allowing for longevity of discharge (due to such a high limit)
  b) quantity/size of capacitors permitting significant and instant power reserve

When asking my last question (is the kVA rating for the SoA considered to be a continuous rating) I didn't craft it quite right.  What I meant to ask was if the power ratings for all SST amplifiers are measured as a continuous power rating.  To my understanding, some manufacturers will measure an amp's power rating at a given instant rather than what it can continually dish out.  Perhaps this is due to the instant power available via their capacitors making the available power appear more than it is?

Thanks for the all the great information.  The graphs definitely put distortion in a different light when compared to a single metric.

-KJ

[Sedona Sky Sound]

Hello KJ,
Yes, you understood my explanation correctly. The only addition is that the high kVa transformer also allows the wattage to continue to double as you halve the impedance of the speakers. This is particularly important for many of the harder drive (i.e., lower ohm) speakers that tend to be especially prevelent in the high-end market.

As for the output ratings by SST, they will play at their stated rate all day (but will likely become somewhat hot to the touch if you did that). In fact, my understanding is that both the Ampzilla and SoA will both play at least 120% of the stated output indefinitely (see the graphs on the website) but you would never want to do this due to the heat buildup (i.e., the heat sink may become the limiting factor especialy for really low ohm loads).

If James wanted to use the same wattage convention that some of the "mass market" amplifier makers use, he could theoretically call the Ampzilla a 3000 watt per channel amp (12x250W output devices per monobloc). Of course, James is far above those type of games.      

Julian
www.sedonaskysound.com

[James Romeyn]

John,
Getting back to the title of this thread: somehow I think you might know the answer to this.  Why do all cigars I've tried except the ones from Cuba make me sick?  A bummer cause you just can't find Cuban cigars here.

I remember at CES at least two maybe three years ago, even then Bongiorno let it slip out that the SoA had newer technology in it vs. the A2K, implying that it might have higher performance (if less power).  Customers at Brian's had to look for themselves to confirm it was one stereo amp driving the RM40s.  Brian drove the amp directly with a fixed full-gain output from a CD player.  Quite loud, almost painful, no distortion.  

It's no accident or coincidence that the designers of my two favorite brands of electronics are close personal friends, with only the very highest regard & respect for each other's engineering abilities & impact on the advance of the high-end (Bongiorno & Bob Carver).

[doug s.]

John,
Getting back to the title of this thread: somehow I think you might know the answer to this.  Why do all cigars I've tried except the ones from Cuba make me sick?

cuz yure a commie & dint even know it!  

doug s.

[zybar]

John,
Getting back to the title of this thread: somehow I think you might know the answer to this.  Why do all cigars I've tried except the ones from Cuba make me sick?  A bummer cause you just can't find Cuban cigars here.

I remember at CES at least two maybe three years ago, even then Bongiorno let it slip out that the SoA had newer technology in it vs. the A2K, implying that it might have higher performance (if less power).  Customers at Brian's had to look for themselves to confirm it was one stereo ...

Jim,

I talked with James and he made it very clear to me that the SOA was in no way superior to the A2K (even if you went with 2 SOA and did a bi-amp).  Since that config would cost more than a pair of A2K, I tend to believe that is how James feels.

This of course takes nothing away from SOA.

George

[James Romeyn]

I was around James quite a bit that year at CES.  He only said it once, almost under his breath, & there may have been nobody else in the room at that time except Brian & Shirley.  It's very possible the A2K has been upgraded since then.  

I'm pretty familiar with the sound at Brian's place, & I owned A2Ks for a year.  From my auditions, even though no A-B was performed, I'd take the SoA over A2K in a hearbeat driving anything under the RMX fullrange.  The SoA is special.

[John Casler]

John,
Getting back to the title of this thread: somehow I think you might know the answer to this.  Why do all cigars I've tried except the ones from Cuba make me sick?  A bummer cause you just can't find Cuban cigars here.

I remember at CES at least two maybe three years ago, even then Bongiorno let it slip out that the SoA had newer technology in it vs. the A2K, implying that it might have higher performance (if less power).  Customers at Brian's had to look for themselves to confirm it was one stereo ...

Have no idea about cigars since I don't smokem'

As far as the differences between the A2K and SOA, I think Jim upgrades both models as he finds nessessary.

The two main differences that I'm aware of "were" the dual purpose inputs of the SoA allowing both single ended and balanced sources without the toggle (I think this is now a feature on the A2K) and the new transformer is 2.5Kva on the Son, which is also the same one "now" used in the A2.5K (which formerly had a 2Kva, then 2.4Kva)

If you look at the performance graphs for both

http://www.ampzilla2000.com/graphs.html
http://www.ampzilla2000.com/songraphs.html

you will see that both measure as good or better than most any amp made at any price.

As a result of some of the listening sessions here in So CA, two reviewers have requested review samples of both A2K and SoA, and shall undertake a 90 day review of both.  So sometime after CES, I would project some interesting reading on the two.

[Sa-dono]

This may have been mentioned in the past, but how do the A2K and SoA compare in the highs and bass?

[James Romeyn]

Remember, I never A-Bd the two amps.  The A2K had the best bass performance I had heard till the SoA arrived, which I think is better.  Ditto above that range.  The A2K has an incredible rightness, it just gets out of the way & let's the music through.  Yet another viel is lifted with the SoA.  In a way, the SoA sounds simultaneously drier, with less hash, less noise, less THD, & yet even more musical.  All the A2Ks I've heard were early to middle production numbers.  The SoA is as close to the perfect amp as I've heard.  It's gotta be the high end reference in affordable new amps.  

I respect anyone who loves their tubes, because I still respect some things about them.  But I could never see myself taking a tube amp seriously since the arrival of the best SS amps available now.  Heat, wear, noise, current draw, current & voltage limitations, expense, weight, bulk, yech, just my opinion.  

Anyone want a nice EL34 integrated cheap?