Impressions on Crown XLi vs XLS for Hi-Fi mains

[PENG]

The XLS has the same frequency response spec; THD is the same spec, IM is "(60 Hz and 7 kHz at 4:1) from full rated output to –30 dB: < 0.3%"; don't see a slew rate spec, tho. So how does this show the XLi being inferior?

I don't know. The OP said the XLi series are class AB amps so I wouldn't want their THD to be higher than 0.1% at rated output and IMD to be anywhere near 0.35% under any conditions. The XLS drive core amps are class D that I don't know much about the nature of their THD so I have no comments other than you and ADTG seems to think they are good.

 

[PENG]

@PENG, Would you care to explain this a bit in detail. Specifically what spec would you expect for a home amp, and let's target more typical AVR amp, not Passlabs spec
I get the 1st one - FR - home amp should be ideally flat 20hz-20khz, not rated up to -1db.
Reading spec for Benchmark Amp, even that one is not absolutely flat 20hz-20khz for both 8 and 4 ohm loads. https://benchmarkmedia.com/products/benchmark-ahb2-power-amplifier
THD spec seems a bit high but is it really audible?
ID and SR I have no idea what "normal"/avr like number should be like

I don't know if the XLi's 0.5% THD and 0.35% IMD are audible, but I prefer 0.1/0.05% (THD/IMD) or better. I am concerned (again, not sure) that the effect of 0.35% IMD would be audible so I would avoid it because I can.

 

[lovinthehd]

I don't know. The OP said the XLi series are class AB amps so I wouldn't want their THD to be higher than 0.1% at rated output and IMD to be anywhere near 0.35% under any conditions. The XLS drive core amps are class D that I don't know much about the nature of their THD so I have no comments other than you and ADTG seems to think they are good.

You'll just have to lower yourself and try one perhaps? As to the separate type/design amp, yeah, they could be important....or not, they could still have the same general specs. Still goes to what's audible. I'd really like to see comprehensive bench test of the XLS Drive Core amps but I haven't seen one....and if they're different from an amp with better specs, as I've used, it's not apparent audibly. To me.

 

[PENG]

You'll just have to lower yourself and try one perhaps? As to the separate type/design amp, yeah, they could be important....or not, they could still have the same general specs. Still goes to what's audible. I'd really like to see comprehensive bench test of the XLS Drive Core amps but I haven't seen one....and if they're different from an amp with better specs, as I've used, it's not apparent audibly. To me.

May be you guys can convince Gene to bench test one of yours.

 

[PENG]

I paid C$299 for my QSC RMXa. C$=0.77 US$

https://www.qsc.com/live-sound/products/power-amplifiers/rmxa-series/rmx-850a/

THD 0.1%, IMD 0.01%.

It sounds as good as my other amps including the one that costs >>10X

 

[lovinthehd]

May be you guys can convince Gene to bench test one of yours.

I actually have one not in regular use at the moment....

 

[kanebane]

https://www.abeltronics.co.uk/amptesting.php?z=crown_XTI-1000

https://www.abeltronics.co.uk/amptesting.php?z=crown_XTI-4000

Regarding the test above, I have done some digging.

In any amplifier using switching supplies, the RF noise effects the audio HF. That is why whenever Stereophile measures HF square waves, they use low pass filter on the switching frequencies which is still far above the HF bandwidth of the amplifier.

Most likely the people making the above test didn't do that. It could make the ripples and ringing in the square waves much lower. But that still doesn't explain 10KHz square waves looking like sine waves unless the amp is like -6dB in the top octave.

 

[kanebane]

I actually have one not in regular use at the moment....

XLS has got so much attention till date that it deserves a test bench hot seat.
But usually amplifier reviews in audioholics does not see phase response & square wave measurements and those 2 are the measurements I am particularly interested in, not THD.

The IMD in crown amplifiers at < = 0.3% at full output to -30dB is unusually high. & not just in class D amps, even the class AB amps shows such ratings. I am not saying 0.3 % IMD is audible, but when it comes to competition it is oddly very high

 

[PENG]

https://www.abeltronics.co.uk/amptesting.php?z=crown_XTI-1000

https://www.abeltronics.co.uk/amptesting.php?z=crown_XTI-4000

Regarding the test above, I have done some digging.

In any amplifier using switching supplies, the RF noise effects the audio HF. That is why whenever Stereophile measures HF square waves, they use low pass filter on the switching frequencies which is still far above the HF bandwidth of the amplifier.

Most likely the people making the above test didn't do that. It could make the ripples and ringing in the square waves much lower. But that still doesn't explain 10KHz square waves looking like sine waves unless the amp is like -6dB in the top octave.

If the slew rate is in fact around 10 V/microsecond, the square wave is not going to be pretty. Square wave test (dv/dt=∞) is a tough test and in theory no audio amplifier can reproduce it 100% accurately.

For a 200 W into 8 ohm amp, I would like to see slew rate >30 V/uS.

 

[PENG]

But usually amplifier reviews in audioholics does not see phase response & square wave measurements and those 2 are the measurements I am particularly interested in, not THD.

I wouldn't worry about phase too much mainly because if no DSP/filtering is involved there shouldn't be phase shift, or very insignificant if there is. Also, how audible it is, appears to remain controversial, and I can understand why people are still more concerned about amplitude distortions. If DSPs and filtering are in the signal path, then I would be concerned and would like to see some measurements.

https://www.audioholics.com/room-acoustics/human-hearing-phase-distortion-audibility-part-2

The IMD in crown amplifiers at < = 0.3% at full output to -30dB is unusually high. & not just in class D amps, even the class AB amps shows such ratings. I am not saying 0.3 % IMD is audible, but when it comes to competition it is oddly very high

Glad to see that you agree with me.

 

[Out-Of-Phase]

I paid C$299 for my QSC RMXa. C$=0.77 US$

https://www.qsc.com/live-sound/products/power-amplifiers/rmxa-series/rmx-850a/

THD 0.1%, IMD 0.01%.

It sounds as good as my other amps including the one that costs >>10X

How is the fan noise?

 

[PENG]

How is the fan noise?

If you are in the same room and say less than 20 ft away, it would like bother you. Not as loud as when the HVAC system (heat or AC) turns on but still way too loud. So set aside $30 for a quieter fan and a trim pot and accept that the warranty will probably be void after, but the overall cost saving is still fantastic comparing to even Emo amps.

 

[TLS Guy]

Can you elaborate?
Which measurements do you find unacceptable?
Thanks!

The Crown XTi 1000 has serious time shift and therefore phase issues. A 10 KHz square wave is converted to a sine wave.

Whilst I realize quite a few speakers to the same thing that is unacceptable. I'm sure on my speakers that amp would sound a dud.

 

[AcuDefTechGuy]

How is the fan noise?

The fans never even came on when I owned the Crown XLS 2500s.

But if I were perturbed by the fans, I would have just removed them from the amp.

 

[kanebane]

The Crown XTi 1000 has serious time shift and therefore phase issues. A 10 KHz square wave is converted to a sine wave.

Whilst I realize quite a few speakers to the same thing that is unacceptable. I'm sure on my speakers that amp would sound a dud.

Yes, that is why I am hoping to see a phase response measurement for the XLS.

All multi driver based speakers has phase anomalies. And they don't do the same thing as amplifiers having phase issues does. They do way way way worse.... ( that too usually in the 2-3KHz region).

But still I am looking for an amplifier with good phase response. Irony

 

[PENG]

The fans never even came on when I owned the Crown XLS 2500s.

But if I were perturbed by the fans, I would have just removed them from the amp.

Being a

"Class D amp with Crown's ultraefficient DriveCore technology weighs less than 11 lbs (5 kg)"

no wonder your 775 W amp outputting a few watts never needed the fan on.

 

[Out-Of-Phase]

The fans never even came on when I owned the Crown XLS 2500s.

But if I were perturbed by the fans, I would have just removed them from the amp.

I hate to ask a subjective question without performing a blind listening test, but how did that Class D XLS 2500 sound compared to a traditional Class AB amp?

 

[AcuDefTechGuy]

I hate to ask a subjective question without performing a blind listening test, but how did that Class D XLS 2500 sound compared to a traditional Class AB amp?

It sounded great.

 

[kanebane]

It sound great.

Almost everyone likes the XLS. The only criticism it occasionally gets is regarding less soundstage width & depth. What is your opinion on that?

I think even better than the XLS would be the XLC series. Internally it is same as XLS but without the AD-DA conversion & DSP filters. i.e. the XLC works fully in the analog domain.

The only problem with XLC is cost. It should cost lower than the XLS because there is no DSP and LCD but for some reason the original list price is same. On top of that XLS always comes with around 45% discount everywhere.

XLC 2500 = $700. XLS 1502= $400 Internally they have the same amplifier section.
XLC 2800 =$1100. XLS2502= $600 same amplifier.

XLC does not come with with RCA input but it easy to manage with the neutrik terminals. Its gain adjustment ( pots ) are in the backside.

 

[lovinthehd]

Where does this soundstage/width/depth talk come into the discussion of amps (or this amp)?