Check out Emotiva's new XPA-1L Class A/AB Amp!

[j_garcia]

I can confirm what your friend is saying too. My speakers are 4 Ohm and like plenty of power for my listening needs. The 7200 is fine for "average" listening levels (it is only 25W in class A), but when I want to step things up, I can tell that it runs out of steam. Compared to my XPA-3 with the same speakers same room, there's a definite difference with the bigger amp when I crank it up.

 

[internetmin]

First, I forgot to mention how I laughed when I saw your tag, "Seriously, I have no life." Hysterical.

Secondly, in your case, you do notice a difference with class A mode on the Marantz amp.

One of my friends who's not an electrical engineer but an engineer nonetheless basically said that the class A would yield a "better" (smoother, more accurate, etc) sound because of the purer wave in class A mode. However, he was also saying that if the speakers are really power hungry then having an amp with as much wattage as possible would exhibit more control and refinement.

I'm not the engineer but I just don't like going by audiophile folklore. I want to understand a bit of the science behind it as much as possible. Simple statements just don't do it for me.

So my current lexicon amp is rated at about 180wpc with two channels driven into 8ohms and 140wpc with all 7 channels driven and it's stable down to 2 ohms. Going up to a 250wpc Emotiva monoblock isn't a huge jump at all (given the physics as I understand it); however the difference in the wave form and the potential audible difference is what I'm just really curious about. I haven't listened to a tube amp or a class A amp so I can't relate to what the difference would be.

My speakers are nominal 6 ohms but dip down to 3 ohms. I've had a single channel on the Lexicon only go to thermal shutdown once in all the years I've owned it and when it did, there was no audible sign of strain at all (but I was playing it very loud and near reference level volume). I rarely do that ever.

 

[j_garcia]

So my current amp is rated at about 180wpc with two channels driven into 8ohms and it's stable down to 2 ohms. Going up to a 250wpc Emotiva monoblock isn't a huge jump at all (given the physics as I understand it); however the difference in the wave form and the potential audible difference is what I'm just really curious about. I haven't listened to a tube amp or a class A amp so I can't relate to what the difference would be.

It is kind of difficult to say exactly, IMHO, because there are a variety of factors. Each time I stepped up in power, I could tell the difference and I didn't necessarily double my power each time. I went from 120W AVR to 125W THX monoblocks (180W @ 4) and heard an improvement. Went from those to a 150W (240 @ 4) stereo amp, but with a much larger power supply and that was again a noticeable improvement. Once more from that 150W to the XPA-3 which is 200W (300 @ 4) and it was still an easily noticeable improvement. I've tried other amps in the system too and heard various minor differences, but so far I've concluded that the XPA-3 has been enough for what I need in every room I've had it in (all large) with these speakers.

If you look at it from the technical side you should need to double the power to get an appreciable difference, but as you mentioned, that control offered by a better or heftier amp can play a role as well. It almost comes down to trying it out in your setup, not unlike auditioning speakers, to really know. A buddy here lent me a beefy stereo amp (300W @8 or something like that) and I liked what it did, so when Emotiva had a sale on the XPA-3, I jumped on it

 

[jinjuku]

First, I forgot to mention how I laughed when I saw your tag, "Seriously, I have no life." Hysterical.

Secondly, in your case, you do notice a difference with class A mode on the Marantz amp.

One of my friends who's not an electrical engineer but an engineer nonetheless basically said that the class A would yield a "better" (smoother, more accurate, etc) sound because of the purer wave in class A mode. However, he was also saying that if the speakers are really power hungry then having an amp with as much wattage as possible would exhibit more control and refinement.

I'm not the engineer but I just don't like going by audiophile folklore. I want to understand a bit of the science behind it as much as possible. Simple statements just don't do it for me.

Class A's main talking point is there is no transistor crossover point. In non-class A amps (with the noted exception of Crown Audio's patented Class I topology) an A and B transistor each handling only one half of the full waveform. When that wave form is re-assembled from it's component halves you could have audible distortion from the waveforms not matching up.

Check out this video for a bit more information:

[video=youtube;9vxZcLhNfXA]http://www.youtube.com/watch?feature=player_detailpage&v=9vxZcLhNfXA[/video]

 

[internetmin]

Class A's main talking point is there is no transistor crossover point. In non-class A amps (with the noted exception of Crown Audio's patented Class I topology) an A and B transistor each handling only one half of the full waveform. When that wave form is re-assembled from it's component halves you could have audible distortion from the waveforms not matching up.

Check out this video for a bit more information:

[video=youtube;9vxZcLhNfXA]http://www.youtube.com/watch?feature=player_detailpage&v=9vxZcLhNfXA[/video]

Bingo! OK, there we go. Exactly what I was looking for. Now the logical follow-up question to this. According to this video, Class I has the sound fidelity of Class A with the energy benefits of a Class AB or D amplifier technology. Is this accurate?

I get exactly why a Class A amp would sound better in theory. But I've never heard of Class I (BCA)

 

[jinjuku]

You get mathematically the same waveform so yes, pardon the pun, it is accurate.

Crown's been doing this 'audio stuff' for quite a while know.

 

[internetmin]

You get mathematically the same waveform so yes, pardon the pun, it is accurate.

Crown's been doing this 'audio stuff' for quite a while know.

I've been very familiar with the crown name as an end user in higher end, commercial installations; but they get a bad rap in home theater and 2 channel; yet everyone that I've ever read giving them a bad rap has never done an A/B and I wonder if it's bias (no pun intended on my part) against the pro audio sector.

 

[jinjuku]

I've been very familiar with the crown name as an end user in higher end, commercial installations; but they get a bad rap in home theater and 2 channel; yet everyone that I've ever read giving them a bad rap has never done an A/B and I wonder if it's bias (no pun intended on my part) against the pro audio sector.

Crown also has over the years had studio oriented models: D/PS/Studio Reference.

When I came back around to Crown (XLS 402D) on a whim (a $179 closeout whim) after the dead silent nature on my Statements vs Parasound, well the Parasound amps had to go. Plus the Crown has more balls.

For three years I had a standing offer that anyone could come over and stone cold, SBT, 10 coin flips. If they could pick out the Audiophile amp 9/10 times they could have the Parasounds. I even tossed $500 on top of that at one point. I eventually sold them and made a profit which is why I never steer anyone away from used Parasound/Rotel/Adcom etc. You can always get your money back.

From a recent thread a Parts Express Tech Talk (PETT):


So is the 1000 staying, going, or switch up to the 1500 now that you have had some time on it?


The Crown is definitely a keeper for me. I'll be selling the Rotel and Adcom amplifiers that I've accumulated over the years.

I think I'll stick with the 1000 as I don't listen to music at higher levels and the hiss at lower levels is inaudible unless you're very close to the tweeters.

 

[Grador]

Bingo! OK, there we go. Exactly what I was looking for. Now the logical follow-up question to this. According to this video, Class I has the sound fidelity of Class A with the energy benefits of a Class AB or D amplifier technology. Is this accurate?

I get exactly why a Class A amp would sound better in theory. But I've never heard of Class I (BCA)

To be clear on this, from everything I've read if the A and B part of the waveform don't line up well [called crossover distortion] it's very audible and easily recognizable. It was far more of an issue in earlier days of class AB amps, but supposedly isn't much of one today.