Crown XLS2502 Stereo Amplifier Review

[restorer-john]

@March Audio

Alan, it is impossible to respond to your posts at face value in a timely and sequential manner when you continually go back and edit them after the fact to include new content. I've called you on it before, it's not a fair or reasonable way of conducting a discussion.

 

[March Audio]

@March Audio

Alan, it is impossible to respond to your posts at face value in a timely and sequential manner when you continually go back and edit them after the fact to include new content. I've called you on it before, it's not a fair or reasonable way of conducting a discussion.

My thoughts develop, I think of additional relevant points to the particular post. Any additional comments won't change the thrust of the post. Call it as much as you like. This won't change

If this is a problem for you then just wait a short while before responding.

 

[DonH56]

Shouldn't standards evolve?

When required, sure. But in this case it feels more like dumbing it down. Most standards I have been involved with become more stringent, not less, over time as technology evolves. I realize a case can be made for restricting bandwidth, power, etc. I just don't agree with it. Personal opinion, not backed by any standard.

 

[restorer-john]

If this is a problem for you then just wait a short while before responding.

How long Alan? At what point will you let your comments stand and not employ the De-Lorean to go back in time to change the past?

 

[March Audio]

When required, sure. But in this case it feels more like dumbing it down. Most standards I have been involved with become more stringent, not less, over time as technology evolves. I realize a case can be made for restricting bandwidth, power, etc. I just don't agree with it. Personal opinion, not backed by any standard.

Does it? I might disagree with that if anything I think it's the converse. I think by evolving to more relevant tests we are improving the quality of judgements.

If an amp will never be required to reproduce 20kHz at its 1kHz rated power, why is it relevant to a qualitive judgement?

 

[restorer-john]

When required, sure. But in this case it feels more like dumbing it down. Most standards I have been involved with become more stringent, not less, over time as technology evolves. I realize a case can be made for restricting bandwidth, power, etc. I just don't agree with it. Personal opinion, not backed by any standard.

Cases can be made for dumbing down standards, but they are usually extolled by industry with short-term commercial vested interests and often have little to do with truly advancing the state of the art.

There is absolutely zero excuse for not measuring an amplifier at full rated power across the 20-20KHz bandwidth.

 

[March Audio]

How long Alan? At what point will you let your comments stand and not employ the De-Lorean to go back in time to change the past?

As I said, it will just be some extra thoughts, it doesn't change the thrust of the post. Your subsequent posts/points won't be invalidated by them. So just chill and use the time to compose your thoughts for your response.

 

[restorer-john]

If an amp will never be required to reproduce 20kHz at its 1kHz rated power, why is it relevant to a qualitive judgement?

You do know that an amplifier that cannot produce exactly the same power at 1KHz and 20KHz is not linear don't you?

 

[March Audio]

Cases can be made for dumbing down standards, but they are usually extolled by industry with short-term commercial vested interests and often have little to do with truly advancing the state of the art.

There is absolutely zero excuse for not measuring an amplifier at full rated power across the 20-20KHz bandwidth.

There is a very good reason. An amp will never be required to produce its 1kHz rated power at 20kHz.

20kHz music levels would probably be 40dB + down.

 

[March Audio]

You do know that an amplifier that cannot produce exactly the same power at 1KHz and 20KHz is not linear don't you?

No. That's a straw man. See above. The real world operating conditions never require this. Its a false requirement.

 

[March Audio]

From Don's calculation earlier 600watts - 45dB is about 18mWatts.

 

[restorer-john]

No. That's a straw man. See above. The real world operating conditions never require this. Its a false requirement.

Not remotely straw. Right on topic Alan.

Linearity is a key tenet of everything in high fidelity. Equal response to any frequency within the audible bandwidth.

 

[March Audio]

Not remotely straw. Right on topic Alan.

Linearity is a key tenet of everything in high fidelity. Equal response to any frequency within the audible bandwidth.

Nope. It really isn't. If you only need 20mW at 20kHz*, and if it does so with flat FR and low in band distortion, what do you think you are gaining by able to reproduce 600 watts?

You are blindly applying a standard which has no real world relevance.


*just an example number, not saying that is all that should be required or expected.

 

[March Audio]

Just as an example, have a think about active speakers. Do they all have same power amps for the different drivers? No they don't.

My 3 way active dsp speakers have two 250 watt amps for the woofer and mid but only a 100 watt amp fir the tweeter. Are they broken as a result? Of course not, quite the contrary.

 

[Francis Vaughan]

There is also a sense of tautological definition here. "Linear" isn't well defined, and seems to be being defined in terms of the goal. In the strict meaning (y =ax + b) no amplifier is linear, ever. The universe can't hold such a device. All amplifiers have bandwidth limits, and in addition to being a natural consequence of existing, any properly designed amplifier will impose a bandwidth limit in order to ensure stability.
Power delivery is a slippery problem. No amplifier used for audio purposes needs to deliver its rated power continuously across the audio spectrum. All that does is require that the amplifier be able to fry tweeters. OTOH, the instantaneous power delivery does need to be there. But only for milliseconds. The power spectrum of the humble triangle is something to behold.
Modern switching topology amplifiers need more care in imposing requirements, as simple naive metrics that were satisfied trivially as a consequence of the design of conventional amplifiers may become hard, and yet for the purposes of actual audible results useless. Within in a fixed budget (and they all are) a requirement for flat power delivery across the aubible spectrum may well be detrimental to the performance of the final product, as it will be in competition with other goals, goals that have an audible impact.

 

[Matias]

Same arguments, different review... As if we did not have a topic for that already.

 

[restorer-john]

Which amplifier do you want?

 

[oldsysop]

There is absolutely zero excuse for not measuring an amplifier at full rated power across the 20-20KHz bandwidth.

Agree.
+ Slew Rate and Damping Factor.

 

[March Audio]

Which amplifier do you want?

View attachment 44095

John, the fact that you resort to this demonstrates you know the flaw in your argument.

You are even conflating power output and frequency response.

 

[restorer-john]

Same arguments, different review... As if we did not have a topic for that already.

Not same arguments, Amir is proposing to top out power vs frequency at 6KHz- that's the core of this discussion.