Crown XLi 800 Power Amplifier Review

[RichB]

I can live with this.

It is interesting that the same people who rationalize poor PA specs sharply disapprove of including fan noise in SNR. Noise is noise, right? Why should fan noise be excluded?

Because the Audio Precision instrument does not have ears

- Rich

 

[GrimSurfer]

Low price, high power, built in DSP and militant stupidity, of course.

By the way your prefs are ordered, and the fact that you didn't mention fidelity, there is nothing militantly stupid at all with your choice Ron.

Not that I need to tell you that; my original post made that clear with the qualifier "critical listening". A critical listener would likely include high fidelity in the top three list of priorities. You didn't, so clearly my remarks were not directed at you.

 

[GrimSurfer]

Because the Audio Precision instrument does not have ears

- Rich

Which is why we can trust it. It looks past feelings, bad hearing, faith, budgets, and subjective prefs.

In other words, it tells us things. Not the things we like to hear, but the ones we need to know.

 

[restorer-john]

It is interesting that the same people who rationalize poor PA specs sharply disapprove of including fan noise in SNR. Noise is noise, right? Why should fan noise be excluded?

I agree with you. The S/N in some gear, in a practical usage situation, is dictated by the fan noise or the transformer buzz.

In the early days of CD, much effort was expended to acoustically isolate the mechanism and silence the focus/tracking components to ensure quiet parts of (particularly) classical recording weren't compromised by noises from the players themselves.

There's no point shooting for -120dB electrically if the equipment itself is making noise 30dB above that.

 

[raif71]

I'm not taking a pot shot. Amir made the same point. The issue is how you square the test results with high fidelity.

You're entitled to your opinion... and it's your money.

Alas it is about the money (at least to me). Compromises in audio quality have to be made to meet budget. That is why this site is important to me as I hope to enjoy hi-res audio, spending as wisely as possible.

 

[ahofer]

Because the Audio Precision instrument does not have ears

- Rich

The best part is it doesn’t have an ego, or genitalia.

 

[GrimSurfer]

Alas it is about the money (at least to me). Compromises in audio quality have to be made to meet budget. That is why this site is important to me as I hope to enjoy hi-res audio spending as wisely as possible.

Price is not a requirement. It is a constraint... and something most of us live with on a day to day basis.

 

[RichB]

I agree with you. The S/N in some gear, in a practical usage situation, is dictated by the fan noise or the transformer buzz.

In the early days of CD, much effort was expended to acoustically isolate the mechanism and silence the focus/tracking components to ensure quiet parts of (particularly) classical recording weren't compromised by noises from the players themselves.

There's no point shooting for -120dB electrically if the equipment itself is making noise 30dB above that.

I complete agree but it is not certain that all products with fans will engage them during use.
I have read many reports from owners that claim they never turn on.

It's different with amplifier transformers. These amps have had audible hum from my listening position: Sunfire Cinema Grand, Outlaw 7500, ATI AT3005, Parasound A21/31/51, and ATI AT6002's. The Parasound were much better than the others.

I had an ATI AT6006 with custom wound transformers that has almost no hum most of the time but was sensitive to DC from a cabinet fan. This would oscillate with a 30 second period. Again, there are mixed reports from owners. Unit to unit variance and power quality are factors.

I found the answer, stop buying amps with transformers or fans. It's militantly stupid person proof

- Rich

 

[RichB]

The best part is it doesn’t have an ego, or genitalia.

People without them are dull.

- Rich

 

[LTig]

This is most likely crossover distortion, which gives odd harmonics. Crossover distortion is typical of class B amplifiers, which this is. The classical solution to this problem is the class AB amp.

The only reason to make a class B is to have low power usage, especially when amplifying silence, and low cost probably. I don't think class B is ever a good idea in hifi.

I don't think that a little more bias current to push a class B amp into AB mode has any serious effect on the overall thermal dissipation. The highest dissipation is at much higher loads where the bias current definitely plays no role in the sum of all dissipated power.

@amirm: is it possible that there are bias trimming pots in the amp which have not been calibrated at all? If yes it may make sense to increase the bias while watching THD to see if it drops.

 

[GrimSurfer]

I complete agree but it is not certain that all products with fans will engage them during use.
I have read many reports from owners that claim they never turn on.

It's different with amplifier transformers. These amps have had audible hum from my listening position: Sunfire Cinema Grand, Outlaw 7500, ATI AT3005, Parasound A21/31/51, and ATI AT6002's. The Parasound were much better than the others.

I had an ATI AT6006 with custom wound transformers that has almost no hum most of the time but was sensitive to DC from a cabinet fan. This would oscillate with a 30 second period. Again, there are mixed reports from owners. Unit to unit variance and power quality are factors.

I found the answer, stop buying amps with transformers or fans. It's militantly stupid person proof

- Rich

If one buys a high powered PA amp whose fan never turns on, could we say that they're not being worked hard enough? And if they're not working it hard enough, then why did they need a PA amp with all that power in the first place?

These are mostly Class D amps, intended to be rack mounted and used in a large space. The manufacturer's don't put fans in to be kind. They know that, when driven within designed specs, some additional air exchange is needed that only a fan can supply.

So we might be talking about products that are poorly scaled to a user requirement. This is certainly more plausible than amps containing spare parts that are never used.

 

[RayDunzl]

Argument Clinic...

 

[LTig]

If one buys a high powered PA amp whose fan never turns on, could we say that they're not being worked hard enough? And if they're not working it hard enough, then why did they need a PA amp with all that power in the first place?

These are mostly Class D amps, intended to be rack mounted

which is exactly the environment where air exchange is limited and the other units in the rack create heat as well. For rack mount fans are probably an inevitable requirement.

 

[Ron Texas]

Fans turn on in PA amps. It's just that they aren't loud to begin with and when they finally turn on the music is loud enough to make their sound irrelevant.

 

[RichB]

If one buys a high powered PA amp whose fan never turns on, could we say that their not working it hard enough? And if they're not working it hard enough, then why did they need a PA amp in the first place?

These are mostly Class D amps, intended to be rack mounted and used in a large space. The manufacturer's don't put fans in to be kind. They know that, when driven normally, some additional air exchange is needed.

This is not complicated. If you don't like fans, don't buy products with fans.

If you listen to dynamic non-compressed music and the amp is on an open shelf, the fans may not engage.
If you listen to heavy metal at 11 and tight-pack your gear, the fans will probably engage.
If you listen to well record classical music, you should not have reached page 3 of this review

ASR is providing measurement data that cannot be found elsewhere. It adds critical information that should be part of an educated consumer's product research.

- Rich

 

[GrimSurfer]

which is exactly the environment where air exchange is limited and the other units in the rack create heat as well. For rack mount fans are probably an inevitable requirement.

Rack mounting offers far more airflow than cabinet mounting, the latter of which is quite common in HT and HA to pass the WAF. And if the fans are not kicking in when cabinet mounted, then they definitely are operating at idle.

When used as designed, fans are almost certainly needed.

 

[GrimSurfer]

Fans turn on in PA amps. It's just that they aren't loud to begin with and when they finally turn on the music is loud enough to make their sound irrelevant.

Maybe, maybe not. Either way, I'd like @amirm to measure fan noise as part of his tests, when so equipped of course.

 

[PaulD]

Maybe, maybe not. Either way, I'd like @amirm to measure fan noise as part of his tests, when so equipped of course.

I have a couple of similar amps, the Crown I-Tech 4x3500 in studios, and the fans are too loud even for isolation boxes in a studio and we had to relocate them out of the rooms. To be fair Crown do say this is the case, a point I overlooked . The fan noise of the Crown amps is one of the reasons that the JBL M2 is not suitable for home use, unless the amps can be put in another room, as the xover etc is all done in a Crown professional amp (and they will not release it for others to replicate in another way).

 

[amirm]

@amirm: is it possible that there are bias trimming pots in the amp which have not been calibrated at all? If yes it may make sense to increase the bias while watching THD to see if it drops.

I found this picture of its guts:

I don't see a pot on it to adjust but it may be hidden.

 

[amirm]

JBL M2 is not suitable for home use, unless the amps can be put in another room, as the xover etc is all done in a Crown professional amp (and they will not release it for others to replicate in another way).

I think either JBL has documented it or people have figured it out as I know some that are using it with their own DSP.