Request for pro amp reviews

[Adam]

Gene,

I respect that you wanted a dedicated thread for this. Based on discussions in other threads, I for one would appreciate it if AH would review some pro amps and compare them against consumer amps. Some people believe that the pro amps perform just as well for less money/less weight/less size. I'm very intrigued, but I'm not sold on it. I almost tried some Crown amps a month or so ago, but I honestly didn't like the looks of them.

To me, putting this to the test is right up the alley of "pursuing the truth in audio and video...." If people could save money and get the same (at least, same in their system) performance, then to me that's just like looking at cables. Why buy expensive cables when much cheaper ones do the same thing? To me, AH is about doing the right measurements to allow good comparisons between products. If the links that ADTG provided don't compare apples to apples, I'm confident that you can.

Now - who's going to help get some amps for Gene and AH to review?

 

[KEW]

I agree with Adam's post and think a multi amp comparison would be ideal.
However, that is asking for a major commitment of time and effort which may not be practicable.
AH already has reviews of competent consumer amps.
I'm thinking it would be more practical to review/test a single pro amp and use the results to decide what is next.
Crown XLS is often recommended, but I'd leave it to some of the more knowledgeable members to suggest a pro amp.

I can offer to ship either a Yamaha P3500S or Yamaha P7000S, but am not confident they are the best choices (their ability to run down to 2 ohms isn't near so rigorous as many other pro amps).

 

[Irvrobinson]

To me, putting this to the test is right up the alley of "pursuing the truth in audio and video...." If people could save money and get the same (at least, same in their system) performance, then to me that's just like looking at cables. Why buy expensive cables when much cheaper ones do the same thing? To me, AH is about doing the right measurements to allow good comparisons between products. If the links that ADTG provided don't compare apples to apples, I'm confident that you can.

There's more to Gene's comments than measurements though, even his. To quote Gene from the previous thread:

That said HIGHER power doesn't always mean better sound. I've measured lower rated power amps that sound better than higher rated power amps. Measurements don't always give a total picture on how an amp can sound. I learned long ago to NOT just rely on measurements alone since measurements represent an ideal load condition with a worse case test signal. Real music and real speakers behave much differently.

Gene is sounding a bit like Gordon Holt here, but I don't mind saying that I have felt there were qualitative differences between properly functioning amplifiers that affected my relative satisfaction with them. I always felt that any audio product that didn't measure well wasn't worth consideration, but that there was a level of discernment beyond just frequency response and THD. Not that I think that these qualitative differences can't be measured, but it might take one heck of a battery of tests to figure it out, and then I doubt the results will be definitive.

My point is that if this thread is just yet another they-all-measure-approximately-alike-so-they-must-sound-indistinguishable thread then it seems we're missing Gene's point (and perhaps mine, though to a lesser degree I suppose).

 

[AcuDefTechGuy]

This would be another great example of Audioholics doing something that no other publications would do!

It would be a fantastic and enlightening learning experience for sure.

The reason so many people love Emotiva is because of their performance & value.

So how does a $350 Crown XLS 1500 300wpc x 2ch 8ohm amp compare to an $800 Emotiva XPA-2 300wpc x 2ch 8ohm amp?

 

[fuzz092888]

My point is that if this thread is just yet another they-all-measure-approximately-alike-so-they-must-sound-indistinguishable thread then it seems we're missing Gene's point (and perhaps mine, though to a lesser degree I suppose).

I don't think that very many of the comments I've read regarding pro amps have gone the way of "they-all-measure-approximately-alike-so-they-must-sound-indistinguishable." However I think there is a valid argument for including pro-amps in the conversation when we're talking about what to use to power our home speakers. Many times guys will recommend running certain speakers right off of the AVR to many new comers just starting out, but if you can get a crown or what have you for cheap ($200-300) and it measures at least as well as the AVRs and provides much more headroom, then I think they should be included.

I have a pro amp and while it isn't class D, it's still a pro amp and I've taken it with me to a few auditions just for laughs to see how it performs against some "high end" stuff in a few stores around me. There is definitely more noise through the tweeters with the pro amp I have, but other than that I have a tough time distinguishing many differences between it and other "home audio" amps.

So I'm with Adam and ADTG on this one and I'd like to see at least one pro amp review just to see where, if anywhere, it leads. I can't think of a better way to "pursue the truth..." in anything (explore as many possibilities and avenues that is).

 

[Adam]

There's more to Gene's comments than measurements though, even his.

I got that from the other thread, too...so I added the "doing the right measurements to allow good comparisons between products" part. Perhaps a bit of a challenge to find the correct measurements, but it's worth the pursuit, I think. If we're just going to go the way of "measurements don't matter - I can hear a difference," then let's grab some popcorn, invite over our favorite golden ears, and line up the power cords 'cause it's time to have some fun.

 

[KEW]

Gene,
Your comments on this in the XPR-5 thread were a bit vague. I can understand that you did not want to start a detailed discussion on other hardware. Can you get more specific on the differences in SQ between pro and consumer amps and which models you have experience with?
Thanks!

 

[gene]

Guys I love this thread! You have me intrigued not only to start reviewing some of the budget pro amps but to do a listening comparison and tech article to try to understand why they sound different.

As soon as I am done with the Status Titus 8T, Pass Labs, Classe and Emotiva amp reviews, I will get on it. God help me, I'm gonna be buried for the next 4-5 months

 

[Irvrobinson]

If we're just going to go the way of "measurements don't matter - I can hear a difference," then let's grab some popcorn, invite over our favorite golden ears, and line up the power cords 'cause it's time to have some fun.

I didn't hear that sentiment expressed, though don't let me stop you from comparing power cords. Be sure to include those Pangea things, that for some stupid reason are composed of a variety of conductor sizes...

 

[Adam]

Be sure to include those Pangea things, that for some stupid reason are composed of a variety of conductor sizes...

Pangea...check. Amazon even carries them.

Although, I might save some money and just use a 14 gauge extension cable with a 16 gauge power cord - bam, sonic bliss.

 

[KEW]

I wanted to bring this quote into this thread in case anyone missed it in the XPR-5 thread:

As far as the crowns go, all I really know is that it seems to be good a module enough for Lexicon to use in their amps.

Of course, you can click on the arrow after GranteedEV's name to see it in the context of his post. (it is the last line)

 

[MosesMalone]

AcuDefTechGuy
How does your Crown XLS2500 compare to your ATI 3002? Would you be able to tell the difference in a blind switched A/B test?

 

[DS-21]

Guys I love this thread! You have me intrigued not only to start reviewing some of the budget pro amps but to do a listening comparison and tech article to try to understand why they sound different.

You mean IF, Gene, not WHY. A "review" that starts with that bias is going to read just like one of your hagiographic love-letters to whatever mediocrities that RDH or whatever speaker company tosses out.

IF competently designed and non-broken amps do in fact sound different, where are the level-matched blind test results attesting to that fact?

There's no doubt, mind, that crappy amps (for example, amps with high output impedance, or a high noise floor) can sound different from well designed amps.

Some pro amps may indeed be crappy amps, with high noise floor, output impedance high enough to materially affect the frequency response into a loudspeaker, high crossover distortion, or FR non-linearities. But frankly I would wager that the ratio of high-fidelity to crap in pro amps is higher than the ratio of high-fidelity to crap in "high end" amps.

Irv mentioned Stereophile founder J. Gordon Holt in an earlier post. It's worth showing where JGH stood at the end of his life:

***As far as the real world is concerned, high-end audio lost its credibility during the 1980s, when it flatly refused to submit to the kind of basic honesty controls (double-blind testing, for example) that had legitimized every other serious scientific endeavor since Pascal. [This refusal] is a source of endless derisive amusement among rational people and of perpetual embarrassment for me, because I am associated by so many people with the mess my disciples made of spreading my gospel.***

Source.

 

[AcuDefTechGuy]

AcuDefTechGuy
How does your Crown XLS2500 compare to your ATI 3002? Would you be able to tell the difference in a blind switched A/B test?

The Harman Crown XLS sounds the same to me as the ATI 3002.

There is some speaker hiss (secondary to gain?) from the Crown @ less than 6 inches away, while the ATI is dead silent.

But they sound the same to my hears.

And I say "Harman Crown" to remind us that Harman makes them - Harman as in JBL Everest, Revel Salon, Mark Levinson, & Lexicon - that Harman.

 

[Stutz320]

I always wondered how a pro amp would sound in my stereo

 

[its phillip]

See if you can get a Lab Gruppen

 

[cpp]

There's more to Gene's comments than measurements though, even his. To quote Gene from the previous thread:



Gene is sounding a bit like Gordon Holt here, but I don't mind saying that I have felt there were qualitative differences between properly functioning amplifiers that affected my relative satisfaction with them. I always felt that any audio product that didn't measure well wasn't worth consideration, but that there was a level of discernment beyond just frequency response and THD. Not that I think that these qualitative differences can't be measured, but it might take one heck of a battery of tests to figure it out, and then I doubt the results will be definitive.

My point is that if this thread is just yet another they-all-measure-approximately-alike-so-they-must-sound-indistinguishable thread then it seems we're missing Gene's point (and perhaps mine, though to a lesser degree I suppose).

A comparison of equipment is as only as good as the honesty of the person performing the comparison. If Gene enters the test with a open mind I feel we will get a good honest comparison of the equipment and maybe some measurements to

of course I am a little partial to Bryston SST- Pro amps as well as Lab.gruppen with Lake processors

 

[GranteedEV]

- many pro amps have audible fan noise - it's the immediate tradeoff for a 10000lb heatsink. This instantly disqualifies them unless they will be in a different room (not a common or practical scenario IMO). Not that CD players / toroidal transformers / the world / HVAC / fridge etc can't raise the noise floor in their own uniquely annoying ways, but it's counterproductive to replace a heatsink with an audible fan. For this reason only an "emergency fan" really seems appropriate for home usage. I'm not sure which ones qualify. Still, the ones that do qualify deserve consideration for home usage. It's my understanding that the Crown's Drivecore amps fit this criteria.

- Class AB pro amps may be biased poorly to improve efficiency. This may be why many are un-enchanted by these kinds of amps. (Arguably an amp should need not be biased at all, as perceptual research suggests that the most offensive kind of distortion is zero-crossing distortion.). I think speaker sensitivity is a big indicator of how audible this will be - with more efficient speakers operating at lower drive levels.

- Traditionalists believe (don't ya looove that word?) switch mode power supplies are inferior to linear supplies. All I can really stress is - "implementation" not "theory". Adam certainly doesn't "love" the "high fidelity" hum produced by his toroidal transformer

- Do aesthetics dominate the purchase? For some of you guys maybe they do. It's my experience that regular people (IE female) don't even notice a tiny little amp like that the way they'll notice a "good looking" pair of 4 rack unit monoblocks. Sometimes discrete is good.

- Do pro audio divisons/companies really want to advertise with a home audio magazine? Probably not - their margins are smaller than their home brands, since they do larger volume. Harman/Kardon certainly doesn't want to "compete" with Crown. Yamaha doesn't really want to "compete" with Yamaha Professional. Certainly there's high priced pro gear targetted moreso at the studio community - IE Grimm Audio.

- I think it's disingenuous to say that PA companies are not engineering for fidelity. It's true that some PA companies will have poor SQ - especially at low price points. It's not like Onkyo/Pioneer haven't had their duds, though.

- Not all PA amps have poor aesthetics. I think these Face Audio amps are sexy

here is the inside:

 

[Irvrobinson]

- many pro amps have audible fan noise - it's the immediate tradeoff for a 10000lb heatsink. This instantly disqualifies them unless they will be in a different room (not a common or practical scenario IMO). Not that CD players / toroidal transformers / the world / HVAC / fridge etc can't raise the noise floor in their own uniquely annoying ways, but it's counterproductive to replace a heatsink with an audible fan. For this reason only an "emergency fan" really seems appropriate for home usage. I'm not sure which ones qualify. Still, the ones that do qualify deserve consideration for home usage. It's my understanding that the Crown's Drivecore amps fit this criteria.

Funny that you should bring up fans, because I have been directly affected by this consideration - in home audio equipment.

One of my all-time favorite amplifiers, SQ-wise, were the Krell KMA100-MKII mono blocks. I picked up a mint pair at an estate sale in 1992 with the intention of reselling them at a profit to some audiophile with more money than sense. To test them for proper operation I put them into my system, and much to my surprise they sounded better to me, in that they were less fatiguing after an hour or so of listening, than my then-current solid state amp, so I kept them and sold the other amp! I bring this up because the Krells had single-speed, constant operation fans that were quite audible in my listening room. I'd probably still have those amps to this day if not for the fans, which on classical music became quite annoying over time, and I sold them.

Years later, looking for more powerful amplifiers due to a larger room and a system upgrade, I auditioned the Levinson 436 in my home. I insisted on an audition only because the 436s use fans, albeit variable speed, firmware-controlled fans, and I didn't want a repeat of the Krell annoyance. No matter how I stressed the system the 436 fans were completely unobtrusive, and I decided to pass on the 436s only because I couldn't bring myself to spend that much on amplifiers.

The bottom line is that while I agree fans can be annoying in a home environment I think you have to qualify the warning only to dumb, constant-speed fans. I think all of the latest Crowns, for example, use variable-speed fans.

Since the mid-1990s I've used Class AB solid-state amps with massive heat sinks, like my current ATI, and perhaps I'm just getting old, but I'd rather have a design with firmware-controlled, variable speed fans than 40 or 50 pounds of heat sinks.

 

[AcuDefTechGuy]

Yup. The Crown XLS is darn quiet. The fan does not even turn on unless you use the amp for a while. Even then it is not audible from a feet away.

And I love ATI, but I do wish they were 10lbs, instead of 100lbs.