Axiom Audio A1400-8 Digital Multi-Channel Amplifier Review

[admin]

Axiom Audio has redefined performance expectations of Class D amplifiers with their A1400-8. They have proven that a highly efficient space saving digital amplifier design like this can not only hang with some of the best traditional linear amplifier designs, but also surpass them in some aspects such as dynamics, bass accuracy and power delivery. On the surface this amplifier seems pricey. However, when you think about the state of the art components that went into this baby to offer top notch fidelity at power levels unachievable in linear amplifier designs via a single power cord, the premium price tag begins to materialize. If you’re assembling an upscale home theater system with the design goals of uncompromised fidelity and dynamics, and your speakers are capable of handling its mighty power, you should definitely add the A1400-8 to your shortlist of high power multi-channel amplifiers for consideration. The digital revolution has come full circle with Axiom being one of the few pioneers truly breaking new ground with their first generation of high performance digital amplification.

Discuss "Axiom Audio A1400-8 Digital Multi-Channel Amplifier Review" here. Read the article.

 

[agarwalro]

I had been waiting for a long time for this review.

 

[6kids&adog]

Thanks for the review of a Class D amp. I have been looking forward to a comparison of Class AB and Class D. The only thing better would have been to have the comparison done in some way so that the listener was unaware of which amp was being used. I also went back and checked out the review of the ICE based Class D amp used in the Pioneer Elite SC-07. I would love to see a review of some of the ICE based Class D amps available - such as those from Wyrd4Sound, Seymour AV and D-Sonic.

Please consider setting up a shoot-out amp review using one or more of the above ICE based Class D amps, the Axiom Class D, and a conventional Class AB. It would be fantastic help to get a blinded listening evaluation comparing these competing technologies. I believe that once we had some reasonably objective comparison of the sound quality produced by the various technologies, then we could make better decisions concerning the importance of price and power and efficiency. Until the "how do they sound compared to...?" question is answered, the efficiency and price per watt of power is less helpful. What do you say Gene? Can Audioholics put a shoot-out type review together?

 

[gene]

Please consider setting up a shoot-out amp review using one or more of the above ICE based Class D amps, the Axiom Class D, and a conventional Class AB. It would be fantastic help to get a blinded listening evaluation comparing these competing technologies. I believe that once we had some reasonably objective comparison of the sound quality produced by the various technologies, then we could make better decisions concerning the importance of price and power and efficiency. Until the "how do they sound compared to...?" question is answered, the efficiency and price per watt of power is less helpful. What do you say Gene? Can Audioholics put a shoot-out type review together?

It's very difficult to do shoot outs of amplifiers since you need a device that can instantaneously switch cables and match levels while also not hindering performance in the process. It is doubtful that I will have that test capability anytime soon.

The listening comparisons I did do between the amps took me countless hours and some of them were blind when I asked one of my peers to swap out without me knowing. Anytime the Axiom amp was played I pretty much nailed it b/c of the tigher more transient bass response. Hearing differences in the upper frequencies was more difficult b/c of the time it took to swap out cables and the results being less obvious.

What was interesting however was when I brought in an independent listener whom has very little experience in this field and he noted the same sonic attributes of both amps I did and he had no clue what amps were playing at the time.

 

[davidtwotrees]

So the first amp caught on fire, and the second one blew out two channels whilst blowing sparks from the speaker terminals??!!

 

[mattburk]

I too would love to see a review of the dsonic and wyred4sound amps.

 

[devlin123]

"What was interesting however was when I brought in an independent listener whom has very little experience in this field and he noted the same sonic attributes of both amps I did and he had no clue what amps were playing at the time."

Wow. So this is basically like saying: Even my wife even heard a difference!

 

[gene]

Wow. So this is basically like saying: Even my wife even heard a difference!

Yes except this listener was sitting in the money seat, not cooking eggs in the kitchen

 

[PaulF]

Good review, it answer many questions. I was really hoping to see a very positive review of this amp as I am currently planning a new HT room and want to run a seven channel class D setup. I had expressed concerns about some of the problems you raised in this post Comment on A1400-8.

Before your review I had called Axiom to get better clarification about the 200W limit on protection and the thermal issues etc, but the answers provided were vague. As I understand it then the amps use an independent clock circuit which probably means it suffers the same output phase swings as all ICE powered amps. As far as I know only Nuforce and some Hypex based amps provide phase accurate output. I too was hoping the freq. response would be flatter.

The amp module design seems OK but the implementation of the complete product is poor, mechanics, protection, internal layout etc. I simply don't understand all those flying leads but could have overlooked it if the amp has little noise/hum problems... and while performance was good, the amp did not meet Axioms own SNR and power specs? One spec you did not mention was channel cross-talk. Can you provide this? Also did you try listening to a nearby FM receiver while the amp was running?

Sorry to say, unless Axion comes up with a cleaned up V2 real soon I will have to pass on this unit.

 

[agarwalro]

I would like to see a Class D amp implementation (ICE Power, UcD, Class T, etc.) article. What are the pros and cons of each approach. Maybe, the article can also cover Class H? Maybe, the article can cover class A, AB too?

This would be great in helping make an informed decision on which implementation to choose when buying into this "new" technology.

EDIT: Found these AH article after the post, Switching Amplifier (Class D) Basics and Switching Amplifiers: The Technology and the Issues

DOH! Well, it's a start.

 

[rmk]

A1400-8

After the initial DOA A1400-8 and the second blowing a couple of channels (not caused by a short) I decided to return the 3rd amp to Axiom. I found it comparable to my Sunfire TGA 400/7 in terms of dynamics and any differences in audio quality were indiscernible (by me anyway). As it turns out I was scared off by the problems I had with the first two amps even though the third preformed perfectly (no hum) for the two weeks I used it.

Through all this, I found Axiom’s CS to be top notch and I had mixed emotions about returning A1400-8 but I use my system a lot and I need the Amp to be rock solid reliable. YMMV

 

[gene]

and while performance was good, the amp did not meet Axioms own SNR and power specs? One spec you did not mention was channel cross-talk.

I extensively discuss crosstalk in this review, show measurements and even talk about the issue I found on adjacent channels with regards to higher crosstalk. Please re-read the measurements portion of my review.

As for phase accurate, I haven't seen a Class D yet that does to 20kHz.

One important difference of this amp vs ICE is the Axiom truly delivers full power bandwidth into 4 ohm loads continuously. NO ICE module can do this.

 

[PaulF]

Gene, you're right, I read your review late night just after you posted it and forgot the details on the cross talk. I am unable to zoom the cross-talk charts so the details did not stick.

I agree with you on the frequency response, I am yet to see a class D amp where the output filter's reaction with the load does not create a less than desirable freq. response. Even the best feedback mechanisms are not able to overcome that. However the self-oscillating designs like Nuforce and I believe some Hypex UcD amps claim to present a phase accurate output.

The ICE amp's lack of ability to deliver true continuous power at their rated spec is one reason I no longer consider them. Add the widely swinging phase output and large variation in damping factor and THD with frequency and you have a fairly bad performing amp.

I don't claim the Nuforce is great as I have not heard one, but mention it because it is not ICEpower based and streets for about the same price as the Axiom.

 

[bandphan]

Gene, I know you have talked about this before but I just wanted to add this for reading..

thanks

scott
http://focus.ti.com.cn/cn/lit/an/sloa107/sloa107.pdf

 

[gene]

Gene, you're right, I read your review late night just after you posted it and forgot the details on the cross talk. I am unable to zoom the cross-talk charts so the details did not stick.

I agree with you on the frequency response, I am yet to see a class D amp where the output filter's reaction with the load does not create a less than desirable freq. response. Even the best feedback mechanisms are not able to overcome that. However the self-oscillating designs like Nuforce and I believe some Hypex UcD amps claim to present a phase accurate output.

The ICE amp's lack of ability to deliver true continuous power at their rated spec is one reason I no longer consider them. Add the widely swinging phase output and large variation in damping factor and THD with frequency and you have a fairly bad performing amp.

I don't claim the Nuforce is great as I have not heard one, but mention it because it is not ICEpower based and streets for about the same price as the Axiom.

You should be able to click on any of the graphs to get an expanded view. If one isn't working let me know.

ICE is phenominal for bass and ideal for subwoofers. Its also a very good bulletproof design for fullrange but IMO doesn't compete with the very best linear amp designs with respect to transparency. Of course I will get bashed at AVS for saying that

I need to check out the hypex and Nuforce amps. I know Bruno Putzey is involved with Hypex and he knows his stuff!

 

[engtaz]

Yes, I was not suprised to hear that the fan turned on because of heat. The inside of that amp is so full that I can't see it having good ventalation. Thanks for the review.

 

[PaulF]

Gene, as currently posted, the cross-talk charts do not have the option to zoom.

 

[gene]

Gene, as currently posted, the cross-talk charts do not have the option to zoom.

Good catch. I fixed it.

 

[ned]

Its also a very good bulletproof design for fullrange but IMO doesn't compete with the very best linear amp designs with respect to transparency.

Great article Gene!

Can you provide a list of linear amps you consider to be the best?

Would you rank transparency as the most important quality in an amp design?

Thanks.

 

[chriscmore]

Gene, I'd like to make a point of clarification in your design overview:

"It switches at a much higher frequency than most other switching amps, which in this case is between 450kHz – 500kHz."

How your worded this paragraph seemed to me to imply that they are switching in this frequency range in contrast to ICEpower's design. ICEpower in fact also switches their output stage in the similar 60kHz-510kHz range.

I agree with your subsequent statements about the advantages of this switching frequency range. It's way out of the audio band, easy to filter, and stays below the RF-generating MHz frequencies used in some class D designs.

Cheers,
Chris