Impressions on Crown XLi vs XLS for Hi-Fi mains

[kanebane]

@PENG

Oh, I had forgotten about the fact that a passive crossover does affect the phase angle curve of a loudspeaker.
After building some passive crossovers, I did notice that they will modify the phase angle response of the driver, but this alteration mostly occurs around the filter frequency. The higher the order of the filter, the greater the phase shift.
In addition, a vented box will also modify the the phase curve.

That is what I was talking about.
It is easy to confuse and mix up acoustic phase (transfer function phase) and electrical phase ( impedance phase).

Every analog crossover ( active or passive ) cause acoustic phase shift. In DSP, IIR filters causes phase shift similar to analog filters. Only FIR is phase linear.

Active crossover filters does not effect the electrical phase of a loudspeaker. But elements of a passive crossover dominantly effects the electrical phase. The driver's contribution is very benign and mostly flat other than at resonance. Port makes its fair share of contribution too.

Passive crossover elements on its own dissipates lots of power.

See section 4.3 & 7 of this article:
http://sound.whsites.net/lr-passive.htm#s3.0

A loudspeaker is always a complex load ( much more so with passive crossover elements). So I should not have used the term " complex load". What I meant was a demanding load for the amplifier, say for example 3 Ohms at -45 Deg at 60Hz.

Loudspeaker drivers ( ie transducers) are always passive load.

Peng,

That extra 'us' was a typo addition. If I were working for Crown I would not be wondering if I should buy XLi or XLS!

Audioholics tests don't show phase responses and that is what I want to see for this amp. I do not care much about THD. Anything less than 0.1% is fine for me. IMD is much more important but rarely tested. Even stereophile does not test for SMPTE- IMD.

THD at 1KHz doesn't show the whole picture even if you care for 0.0000x THD. Check out the datasheet for IcePower 125ASX2 or 1000ASP. THD is different for different frequencies!

 

[PENG]

Loudspeaker drivers ( ie transducers) are always passive load.

Technically speaking, woofers and even some midrange/midbass drivers that could produce significant enough back should not be considered a passive load. So don't be so sure.

That extra 'us' was a typo addition. If I were working for Crown I would not be wondering if I should buy XLi or XLS!

Thank you for clarifying it, just didn't want to assume..

THD at 1KHz doesn't show the whole picture even if you care for 0.0000x THD. Check out the datasheet for IcePower 125ASX2 or 1000ASP. THD is different for different frequencies!

Again that is well understood around here, but at least most test bench use 1 KHz. Audioholics.com is one of the very few who also typically provide the CFP-BW measurements. If not, from what I have seen over the years, if you discount the 1 kHz measurements by 15-30% (30% to be on the safe side), you should be in the ball park.

Just a friendly suggestion, if you are new on this site, it may be a good idea to browse around, especially under the AV research heading. You may be surprised people around here know more than you think they do. It may save you a lot of typing..

 

[kanebane]

Okay Peng, now I see where you are coming from regarding transducer being a active load. Back in the old days when drivers were dependent mostly on electric damping, back EMF was significant. With today's advanced mechanical damping back EMF has significantly reduced.

Back EMF in a driver is just an inductor (hence the huge impedance peak at resonance). Inductors always has an back EMF. Is an inductor an active load?

Regarding discounting 1KHz measurements by 30%, yes that might mostly work and comes in handy when there are other measurements unavailable. But there are some special cases, mostly in class D amps where things happen a little differently. I suggested the datasheets of Icepower 125ASX2 and 1000ASP for that very particular reason. The distortion figures at 1KHz and 6.67KHz are considerably different for those modules

Just a friendly suggestion, if you are new on this site, it may be a good idea to browse around, especially under the AV research heading. You may be surprised people around here know more than you think they do. It may save you a lot of typing..

Yes I know it does not feel very good when someone else is posting elementary explanation. But a while ago I posted I stated two facts- 1. passive crossovers effects loudspeaker phase. 2. Output stage of an amplifier has its current limits, independant of PSU current limits. & then a gentlemen had to press the "disagree" button. If someone disagrees with my subjective comments & views, I can take it.
But when someone objects to preliminary facts, you start wondering.

I am used to hanging out in diyaudio where you are forced to think twice before posting anything or the big boys ( Like Gedlee or Danley or the AES guys) comes out with their big guns. So no, I have never discounted or underestimated the knowledge of everyone around here. That would be really awful on my part.

Regarding the Original topic of this thread, counting impressions of XLS vs XLi did not have a chance as few people have experience with the XLi. Though I hoped to find at least one comparision

Anyone interested in bypassing the AD-DA stage of highly praised XLS amps, check out the all analog stage XLC series amps.

Peace out

 

[PENG]

Back EMF in a driver is just an inductor (hence the huge impedance peak at resonance). Inductors always has an back EMF. Is an inductor an active load?

That's a great point! No, an inductor is not an active load. The difference is, when a good size driver is in motion, it behaves, to an extent, like a motor. In this case you have a magnetic field and motion involved, not just an idling coil.

So back emf alone does not make an idling coil/inductor "active", a moving coil under the influence of magnetic field does. In fact, bi-amp believers often uses avoiding the motor back emf effects of bass and mid range drivers on the tweeter as one of their argued benefits. I am referring to moving coil loudspeakers only.

This is off topic but it is your thread, though I have nothing further to add on this topic.

Yes I know it does not feel very good when someone else is posting elementary explanation.

To be clear, I have no such feeling. As I said it was just a friendly suggestion and now I realized I wasn't clear about what I really wanted to convey.

 

[kanebane]

Peng, sorry to break out to you, but a motor/generator is also a passive device.
I know it can be very confusing, but some things are.

Still don't believe me?
Scroll down to magnetic (Inductive) devices in the list of passive components >> motors/ generators.
btw, transformer is also passive!

https://en.wikipedia.org/wiki/Electronic_component#Active_components

Have a good day!

 

[PENG]

But a while ago I posted I stated two facts- 1. passive crossovers effects loudspeaker phase. 2. Output stage of an amplifier has its current limits, independant of PSU current limits. & then a gentlemen had to press the "disagree" button. If someone disagrees with my subjective comments & views, I can take it.
But when someone objects to preliminary facts, you start wondering.

I was puzzled by that post#51. No idea what you two gentlemen disagreed on, seemed to me a communication issue. He obviously know you were right on both points. He might have clicked the wrong button. I had done it before myself, was asked about it, replaced the rating with the one I intended, apologized for it and moved on.

By the way, why do you think most, if not all reviewers do not measure the phase responses of amplifiers?

 

[kanebane]

By the way, why do you think most, if not all reviewers do not measure the phase responses of amplifiers?

I don't know. But phase of all amplifiers are almost always linear, particularly in the telephonic band. And compared to that the phase response of speakers are very very bad, thanks to crossovers ( passive or active, except FIR). So no matter how good the phase response of your amplifier is, the real acoustic phase out of the speakers would always be ugly. And there is no definite proof that phase non-linearty is audible to humans. So, maybe this is the reason, but I am not sure.

Why am I looking for perfect phase response then? Maybe I use a loudspeaker which is phase perfect 20-20KHz . But that is only possible with FIR. That means, I can correct the phase anomalies of the amplifier too, if any

 

[Verdinut]

That is what I was talking about.
It is easy to confuse and mix up acoustic phase (transfer function phase) and electrical phase ( impedance phase).

Every analog crossover ( active or passive ) cause acoustic phase shift. In DSP, IIR filters causes phase shift similar to analog filters. Only FIR is phase linear.

Active crossover filters does not effect the electrical phase of a loudspeaker. But elements of a passive crossover dominantly effects the electrical phase. The driver's contribution is very benign and mostly flat other than at resonance. Port makes its fair share of contribution too.

Passive crossover elements on its own dissipates lots of power.

See section 4.3 & 7 of this article:
http://sound.whsites.net/lr-passive.htm#s3.0

A loudspeaker is always a complex load ( much more so with passive crossover elements). So I should not have used the term " complex load". What I meant was a demanding load for the amplifier, say for example 3 Ohms at -45 Deg at 60Hz.

Loudspeaker drivers ( ie transducers) are always passive load.

Peng,

That extra 'us' was a typo addition. If I were working for Crown I would not be wondering if I should buy XLi or XLS!

Audioholics tests don't show phase responses and that is what I want to see for this amp. I do not care much about THD. Anything less than 0.1% is fine for me. IMD is much more important but rarely tested. Even stereophile does not test for SMPTE- IMD.

THD at 1KHz doesn't show the whole picture even if you care for 0.0000x THD. Check out the datasheet for IcePower 125ASX2 or 1000ASP. THD is different for different frequencies!

@kanebane
I'm sorry for the disagreement comment and I have removed it because it was a mistake.

 

[kanebane]

Verdinut, its okay. I realized that from your later post. I just had to explain why I was writing basic stuff that everyone already knew.

Peng, just in case you missed post #65 while typing #66

 

[Verdinut]

I don't know. But phase of all amplifiers are almost always linear, particularly in the telephonic band. And compared to that the phase response of speakers are very very bad, thanks to crossovers ( passive or active, except FIR). So no matter how good the phase response of your amplifier is, the real acoustic phase out of the speakers would always be ugly. And there is no definite proof that phase non-linearty is audible to humans. So, maybe this is the reason, but I am not sure.

Why am I looking for perfect phase response then? Maybe I use a loudspeaker which is phase perfect 20-20KHz . But that is only possible with FIR. That means, I can correct the phase anomalies of the amplifier too, if any

Did you have a look at my Avatar? It shows the phase angle curve of a two-way loudspeaker design that I built a couple of years ago. I figure that it is kind of hard to obtain as good a curve which is almost straight and it was a vented box. . As a matter of fact, maybe some audioholics have, but I have never seen as good as that on a commercial speaker.

 

[PENG]

Verdinut, its okay. I realized that from your later post. I just had to explain why I was writing basic stuff that everyone already knew.

Peng, just in case you missed post #65 while typing #66

Fair enough, but you should know wiki is not always right and is not the authority. IMO motor/generator is hardly passive, literally even.. Still, don't be so sure, yet!

 

[kanebane]

Wiki is just to show you some easy reference because if I were to explain you in details why exactly a motor/generator is a passive device you still might not believe me (and that would be seriously off topic too). I don't have any doubt regarding any type of passive and active components ( being an EE ), just wanted to clear your misconception. Do your own digging, its always fun & learning, but I am not sure if it will add much to your understanding about driver damping EF as you seem to be right on point, except the active & passive confusion.

 

[PENG]

It's fine, I can google. Wiki's right most of the time. This is a matter of definition, in the EE world, it could be defined a little differently. It is not a matter of misconception.

It's been fun, great thread!
.

 

[kanebane]

Did you have a look at my Avatar? It shows the phase angle curve of a two-way loudspeaker design that I built a couple of years ago. I figure that it is kind of hard to obtain as good a curve which is almost straight and it was a vented box. . As a matter of fact, maybe some audioholics have, but I have never seen as good as that on a commercial speaker.

Flat phase is theoretically only possible with 1st order crossovers. I use FIR for flat 20-20KHz phase response in a closed box. Straightening a vented box phase response would take a lot of processing power. I can only guess your avatar because its too small to read the details.

But crossover phase distortion are hardly audible to us, IMO. What is audible is room reflections phase distortions which aren't minimum phase & my FIR processing solves both

 

[PENG]

Verdinut, its okay. I realized that from your later post. I just had to explain why I was writing basic stuff that everyone already knew.

In case you are referring to my previous comment, imo there is absolutely nothing wrong to write about basic stuff, even if everyone in fact know such "basic stuff". Many things I said were likely considered basic stuff by a lot of people too. I normally try to present my opinions, or even facts, in ways that won't annoy anyone. It may not work all the time, but I try..

 

[PENG]

I don't know. But phase of all amplifiers are almost always linear, particularly in the telephonic band. And compared to that the phase response of speakers are very very bad, thanks to crossovers ( passive or active, except FIR). So no matter how good the phase response of your amplifier is, the real acoustic phase out of the speakers would always be ugly. And there is no definite proof that phase non-linearty is audible to humans. So, maybe this is the reason, but I am not sure.

Why am I looking for perfect phase response then? Maybe I use a loudspeaker which is phase perfect 20-20KHz . But that is only possible with FIR. That means, I can correct the phase anomalies of the amplifier too, if any

As I mentioned in my earlier responses, as long as you avoid amps that use lots of filtering (DSP or not) and have very good slew rate specs, I doubt there will be phase anomalies to correct or worth correcting. On the other hand, that XLi amp appeared to have poor slew rate, the bandwidth was likely low, probably not much better than 20 kHz so it may in fact have enough phase distortions for you to worry about. This is just my educated speculation, I don't have proof, Crown audio website doesn't provide a lot of info and I could still be totally wrong.

 

[noway]

The only XLi measurements I've seen pertained to the XLi800, sold at Musician's Friend as the X1000, was at AVS Forums under the thread Cheap Crown Amp Power $99 (use the Google Custom Search on AVS). On Page 13 you will find some results of tests by mtg90. Not too pretty.

I think the fans are on all the time in the XLi series, which is a fan-wear drawback if you leave the amps running 24/7. So I wouldn't go XLi and as far as other models/makes, I would avoid amps that had built in DSP and/or A/D-->D/A conversion.

 

[Ernie Schmuntz]

I purchased a xli1500 as a sub amp. For kicks, I broke out an old Hafler SE100 and used the amp for two channel. My speakers are RBH MC-6CT towers.

My giggle turned into a laugh. Then I added a sub, and I am having so much fun stomping with them. This is a great sounding amp for the silly expense of 289.00. It does it ever have some nuts. Quiet fan. Love it.

 

[LetTonyRome]

I'm running 2 Crown XLI 800's with different pairs of floor model speakers in my Mastering Studio. Amps are quiet even when you push them. No fan noise. My other amps are Bryston, Nad , Yamaha all Class A. At first I had a little hum when I stacked both amps on top of each other. I ALSO USE THE XLR inputs. The hum completely disappeared after placing 2inches between them. there is no decrease in clean power using these amps vs my Audiophile amps. Actually I prefer the Crowns a slight bit over all 3 of my other amps. These amps don't get hot and they're classA/B . Audio is clean, smooth and punchy. My room is treated and maybe that makes a difference for my application. I highly recommend trying these out for yourselves. My speakers are Tekton Lores and Q acoustics 3050i. My convertors are Antelope audio and Heritage audio.

 

[Out-Of-Phase]

Crown XLi 800 Power Amplifier Review

This is a review and detailed measurements of the Crown XLi 800 pro Power Amplifier. It is on kind loan from a member. The XLi 800 costs just US $269 including free shipping. Hard to imagine so much electronics from a brand name company selling for so little. NOTE: my company (Madrona...

www.audiosciencereview.com

Interesting review on the XLi 800