Crown Xti4002 Pro Stereo Amplifier Review

[Hayabusa]

My #39 in the thread. I think that study was so interesting that I will take it again. The higher the frequency, the more sensitive we are to distortion. Those who participated in the study in the link below, at 10 kHz distortion was detected at 40-45 dB (1-0.5%) .

At lower frequencies, well a completely different ball game so to speak. "..mid-bass at 280 Hz and lower, the noise can be around -14 dB (20% distortion), about half as loud as the music itself, before we hear it....At 40 Hz, listeners accepted 100% distortion before they complained. The noise test tones had to reach 8,000 Hz and above before 1% distortion became audible, such is the masking effect of music.."

How Much Distortion Can We Hear With Music?

How much distortion can we hear with music? An experimental study at Axiom.

www.axiomaudio.com

a very flawed test?
Its not about distortion but about masking.
And the masking is calculated w.r.t. the average level.
No wonder that the higher frequencies score better as there is less energy that can mask..

 

[ocinn]

There's a guy on YT who measures mostly car amps with a "Dyno". How is using this different from the AP you use.

It will tell you max watts at:

- 1% (40hz or 1khz)
- Clipping (9 frequencies, spread between 25hz and 10khz)
- Burst (CEA-2010)

8, 4, 2.7, 2, 1.6, 1.3, 1.0, 0.8, 0.6, 0.5-ohm selections, up to 24,000w.

These are mostly used to test subwoofer amplifiers where performance metrics like noise and load dependency are completely irrelevant, however, it is an extremely stout and flexible load box, so adding an oscilloscope would turn it into a usable basic analyzer. Would be interesting if some of the owners would incorporate one.

I believe @peniku8 uses a voltage divider and an audio interface for an even higher-performing setup with his load box, and you don't need to deal with entry-level oscope ******, tacked-on FFTs...

Oh, and the E1DA ADC can do ~440W@4r and half that at 8R without the need for voltage dividers, for members who want to build their own load box and start doing basic measurements of amps below those power numbers (or any amplifier if you just want the 5w dashboard).

 

[Dan Clark]

Send Amir one of those Rockvilles....

I'll just measure it myself, I was actually planning to do a review for ASR as I not only have a 555B but a AP 40 class D amp filter.

 

[turbotuff]

I'd be curious how an old school Macrotech would do

 

[amirm]

There's a guy on YT who measures mostly car amps with a "Dyno". How is using this different from the AP you use @amirm?

He is a fun guy to watch! I don't like power measurements in absence of a sweep. Or other important things like noise, frequency response, load dependency, etc.. He is also too quick to throw out "non certified, certified" numbers as there is no such certification. I believe his "certified" numbers are 1% THD and non-certified is anything goes which has no value.

He comes from car audio where inflated numbers and wattage with a ton of distortion is acceptable. Our world of home audio is different.

 

[Spocko]

A brute force amp, clearly emphasizing quantity over quality!

Unless you define "quality" as lasting 10+ years of physical abuse!

 

[peniku8]

I believe @peniku8 uses a voltage divider and an audio interface for an even higher-performing setup with his load box, and you don't need to deal with entry-level oscope ******, tacked-on FFTs...

Oh, and the E1DA ADC can do ~440W@4r and half that at 8R without the need for voltage dividers, for members who want to build their own load box and start doing basic measurements of amps below those power numbers (or any amplifier if you just want the 5w dashboard).

Yea my setup is something like Topping EX5→DUT→50KW loadbank→pmillet SCI→Cosmos ADC
The SCI's performance metrics aren't good tho, sadly, so I can't get any precise THD+N measurements done with it in the loop.
I might build a switchable resistor network specifically for the APU, but I love the voltage display on the SCI...
First I gotta pester John to implement something into REW to be able to automate testing and to be able to measure burst power, because that's currently not possible with REW.

 

[DanielT]

a very flawed test?
Its not about distortion but about masking.
And the masking is calculated w.r.t. the average level.
No wonder that the higher frequencies score better as there is less energy that can mask..

What that study shows and what conclusions can be drawn based on those results can be debated (but in another thread in that case).

In general, apart from that study, few would dispute that distortion in the lower registers is more difficult to detect.

Speaking of distortion. Here you can test yourself, when distortion is detected:

Distortion Listening Test

Ran into this interesting listening test by Klippel with regards to how much distortion you can hear. This is the link: http://www.klippel.de/listeningtest/lt/ Just casually wanting to see the test, I went with the defaults and for some reason, the levels were exceptionally low. I had to set...

audiosciencereview.com

 

[Tovarich007]

Rugged, robust and powerful beast Ok, but In my opinion exclusively for heavy duty stage works for rock/hiphop and so.

Nothing here for domestic or monitoring use, even for passive subs. There are many better alternatives, and active subs includins DSPs are more convenient anyway and some are very very powerful too.

Relatively disappointing measurements for a brand like Crown : poor SNR and distorsion, polluted signals, and rather severe "plocs" on/off (I hate that, and hps hate that too !).

As for stage sound, it's easy to find much better at Powersoft, RAM, Labgruppen, Yamaha and others, at no extravagant prices (a little more expensive, but quite worthy the extra money for amps built for many years). So I don't undersand why Amir recommends it, pure power doesn't do it all.

 

[Deleted member 48726]

That's even more impressive...LoL. I was wondering about the heatsinks and such and figured hey! They really packed in the quality. No wonder they have a fan for cooling.
EDIT: So it's a switching power supply with class AB. Very unusual.

Not so unusual as you might think. Yamaha has made popular pro class A/B with SMPS such as P7000S and P5000S.

 

[Hayabusa]

What that study shows and what conclusions can be drawn based on those results can be debated (but in another thread in that case).

In general, apart from that study, few would dispute that distortion in the lower registers is more difficult to detect.

Speaking of distortion. Here you can test yourself, when distortion is detected:

Distortion Listening Test

Ran into this interesting listening test by Klippel with regards to how much distortion you can hear. This is the link: http://www.klippel.de/listeningtest/lt/ Just casually wanting to see the test, I went with the defaults and for some reason, the levels were exceptionally low. I had to set...

audiosciencereview.com

Sensitivity of the ear is the highest in the 3KHz region, above that sensitivity for hearing distortion will also be lower the same as for lower frequencies
At 10kHz the second harmonic is 20kHz which most of us can not hear.

 

[pseudoid]

He is a fun guy to watch! ...
He comes from car audio where inflated numbers and wattage with a ton of distortion is acceptable. Our world of home audio is different.

Indeed.
We don't have to worry about the contributions of the rear license plate acting like a hi-hat and adding to the THD.

 

[Dan Clark]

Sensitivity of the ear is the highest in the 3KHz region, above that sensitivity for hearing distortion will also be lower the same as for lower frequencies
At 10kHz the second harmonic is 20kHz which most of us can not hear.

When Tyll was doing Innerfidelity he stopped his THD as an at 7.5KHz for this reason…

 

[prerich]

Rugged, robust and powerful beast Ok, but In my opinion exclusively for heavy duty stage works for rock/hiphop and so.

Nothing here for domestic or monitoring use, even for passive subs. There are many better alternatives, and active subs includins DSPs are more convenient anyway and some are very very powerful too.

Relatively disappointing measurements for a brand like Crown : poor SNR and distorsion, polluted signals, and rather severe "plocs" on/off (I hate that, and hps hate that too !).

As for stage sound, it's easy to find much better at Powersoft, RAM, Labgruppen, Yamaha and others, at no extravagant prices (a little more expensive, but quite worthy the extra money for amps built for many years). So I don't undersand why Amir recommends it, pure power doesn't do it all.

A little off thread here, but I didn't know that Behringer owns Lab Gruppen. Wow!!! I'm still keeping my Crown XLI2500 for my subs. I can't hear it from my seated position and it has never gone into protection, even when I crank it (I use it for my passive subs).

 

[Tovarich007]

Behringer has bought Labgruppen, but as far as I know, the quality standard of Labgruppen hasn't lowered since. I hope that won't change.

 

[Alice of Old Vincennes]

No, some of them read these measurements

They need to be held accountable for such crap performance

Maybe one day @MC_RME will get into amps and show the pro companies how it should be done

Yea. I'm sure Crown needs accounbility from a "user."

 

[Alice of Old Vincennes]

If you’re playing loud music through a PA to a bunch of drunks clubbing, I suppose this amp fits the bill. I’m really quite surprised at how poorly it performs relative to what we expect at ASR.

A brute force amp, clearly emphasizing quantity over quality!

I doubt you can hear any difference. Amp will control any speaker.

 

[Alice of Old Vincennes]

You'd better use Speakon connectors, indeed.

Or Autozone battery terminals.

 

[Alice of Old Vincennes]

Right! Remarks that Crown is crap and needs to learn from home HiFi mfg. miss the point. Specs are extremely important to successful pro manufacturers like Crown; I would guess they are more important than they are to most consumer mfg. The specs important to Crown are totally different from those important to home HiFi.

If the XTi4002's fan is as loud as the fan on my class D Behringer NX1000D pro amp; the S/N spec is not the biggest noise barrier for home use. It is likely suitable for homes only when located in a separate equipment room. In the case of the Behringer, switching to a quiet fan was easy to do.

The fact is, Crown just did not care about high S/N or low fan noise for its intended use.

Crown cares. They know "high" S/N is not audible.

 

[Alice of Old Vincennes]

I work full-time in live sound, Class D/switching amps are industry standard, period these days.

32,800W (4ch) out of 2U enclosure - https://www.powersoft.com/en/products/touring-amps/x-series/x4l#specifications

20,800W (16ch) out of 2U - https://www.l-acoustics.com/products/la7-16/ (note: L'Acoustics notoriously under-rates their products in almost every aspect)

This is a good read: https://forums.melaudia.net/attachment.php?aid=30627
Note Page 22's graph on power vs. time.

I will say subjectively (and every professional I've ever met will agree), no amplifier on subwoofers works as well as a big, old, heavy, inefficient A/B amp with a huge transformer and enough capacitors to instantly kill 15 people (assuming the same total watts vs a Class D solution). Unfortunately, they are impractical to tour with and require far larger generator rentals ($$$), so there is no market for them apart from individuals who run their own system (mostly dub/bass/genre sound systems which need to play 35hz full-scale for 3 minutes straight with zero output sag).

For reference, the most powerful non-switching amplifiers were the:

1) Crown Macro-Tech 10000 (3 phase, designed for <1ohm subwoofer arrays, specs, page 30 as well as this sheet)
2) Crest 100001 (specs, AFAIK, truly class A/B linear supply, no rail switching!!)
3) Void Infinite 8 Mk2 (class G, specs also independent bench test)
4) Crown Macro-Tech 5000VZ/5002VZ (class G, specs)
5) EV P3000 (true class A/B, linear supply, no rail switching, specs)

Honorable/borderline not qualifiable mentions (no headroom, so no benefits/merits):

Matrix XT6004 (SMPS single rail voltage, Class A/B)
The MC2 E45 and Lab Gruppen 20K44 both use tracking rail SMPS. Lab's Class TD implementation works quite a bit better than MC2's traditional Class H, which is how it manages 20kw while still using A/B output stages.

Edit: The Lab Gruppen design is so good, that it's been successfully cloned. And yes these amps actually do make all that power for that price. It's incredible.

https://www.aliexpress.us/item/2251832706148644.html

I don't believe you.