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XLS series amps - is there analog to digital conversion present?


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#1 Kuja

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Posted 14 November 2012 - 06:58 PM

Hello! :)

I'm interested in trying a XLS1500 in my home music system.

I need a strong amp for my power hungry vintage Acoustic Research AR9 speakers.

I want to run XLS1500 full range,  just the way I would use any "normal" power amplifier.


I have read about additional high pass/low pass crossover functions that XLS amps have,
but I'm not interested in using them.

How these crossover functions are implemented? Through some DSP?

If the answer is yes, how is it done?
Is conversion of analog music signal to digital and then back to analog, always present in the background?

Can the digital conversion be defeated if I'm not using the crossover functions?


I listen to a lot of vinyl records and I would like to have the analog sound chain unbroken by unnecessary AD DA conversions.

Is this possible with modern pro amps?

Thanks in advance,

Aleksandar

#2 dakos

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Posted 15 November 2012 - 03:01 PM

Hello Alex,
Currently all Crown amps have some kind of conversion and processing that can't really be turned off, that includes the XLS series.
Avi

#3 Kuja

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Posted 15 November 2012 - 06:36 PM

Thanks for the fast answer!

That's too bad. :(

I know this is a Crown forum, but what about other manufacturers?

Arte there any good sounding amps that are analog all the way?

What about Yamaha P series?

Yamaha P5000 looks good on paper.

#4 dakos

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Posted 16 November 2012 - 12:32 AM

Well, if it's good sound you're looking for then the subject of AD/DA conversions have been beat to the ground, the recomendations are as follows:
At 48khz sampling rate, no more then one AD/DA conversion.
At 96khz sampling rate, no more then two AD/DA conversions.
At 192khz sampling rate, no more then four AD/DA conversions.
You will not be able to hear the difference even if you break these rules of thumb in A/B test unless you're a super audiophile. After all a CD is just 44.1khz so even the lowest quality converter has better sampling rate. My suggestion to you is to go to a pro audio shop that caries the products you consider and try the out for yourself with music that you know how it's supposed to sound and test it for yourself.

I'll update later about other amps but if memory serves me correctly you'll have to step up the budget or go the used route or both.

#5 Kuja

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Posted 16 November 2012 - 07:12 AM

Thanks! :)

More than 50% of my music listening is done with turntable spinning vinyl,
so there are no sample rates of any kind.

If I have multiple digital conversions (AD, then DA) going on in the background,
it could nullify some benefits of having the analog playback.

Also, in my present setup I can hear differences between different DACs,
I've auditioned many different models and I have carefully chosen one that suits me.

I doubt that additional (in my case unnecessary) AD/DA conversions in Crown amps will be 100% transparent
and not bringing some sound signature of their own,
thus (partly) defeating the care I have put in choosing my present DAC.

In my part of the world, the choice of available models is limited and shops are not so enthusiastic about home testing.

I might end up ordering and buying abroad, so I would like to avoid making some big mistake.

#6 dakos

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Posted 16 November 2012 - 10:54 AM

Well, I can tell you that quality of a DAC is not only mesured by sampling rate nor bits per sample, there are many more things that factor in that equasion.

My solution to you is, since you're not into tour sound, meaning you don't need to carry the amp from one location or the other, I would suggest you try getting one of the older generation Macro Techs such as these. They are compleatly analog and are of great quality, price/watt is also great.

If you want me to take a look at other amps from other vendors please list them, there are just too many options. As for the Yamaha P series, they are quite good amps, reliable, soundwise I just don't know. If you are looking at amps such as these I would concentrate on the three major players which are Crown, Crest and QSC. Yamaha is also good but not as common and someday when you might need a repair that would become a major consideration.

#7 Kuja

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Posted 16 November 2012 - 05:31 PM

What do you think about QSC RMX series amps?

http://www.qscaudio....mps/rmx/rmx.htm

Lower powered models are class AB, higher powered models are class H.

Conservative audiophile in me says that I should go for class AB design... Is he wrong? :)

What will sound better in my home?

#8 dakos

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Posted 16 November 2012 - 06:43 PM

I strongly believe that any amp topology would sound great if implimented correctly. Class A amps can sound terrible and there are class D/H/T/I that sound superb. I personally can't tell the difference even in an A/B comparison between two good amps (QSC RMX 1450 Vs 1850 for instance), besides your speakers need allot of power if I understand correctly, would the RMX 1450 have enough to run them? You might be shooting yourself in the leg with the 1450...

So bottom line, the RMX are great sounding beasts but in my opinion you'll need to get one of the H class amps.

One more thing is you remember that you'll need to convert phono signal levels to pro audio signal levels so you'll need a small preamp or a mixer.

Any other options?
Avi

#9 Kuja

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Posted 16 November 2012 - 08:30 PM

Avi,

Thanks a lot for your patience and help! :)

These are my speakers:

http://audio-databas...er/ar-90-e.html



They are closed boxes.
Four way, with dual woofers in a large enclosure which is tightly stuffed with damping material.
Nominal impedance is 4 ohms but it can drop to 3.2 ohms.
Sensitivity is 87dB.

Vintage big ARs were always notorious for their big power requirements.

The manual says that minimum 50W per channel is needed, I tried them with 160w and it was kind of OK-ish.
People that are using them say that they only really start to sing with amplifiers having 200W and more.
Their maximum power handling is 300W.

QSC RMX 1450 can output 400w pear channel at 4 ohms... Maybe it is enough?



Here are some links to local shops with some other options that are available in my country,
the pages are not in English, but amp models and descriptions are :) :

http://www.mitrosmus...269;i---SnagaĻi

http://www.player.rs...gory.php?ID=226

http://www.player.rs...PageNo=2&ID=226

http://www.skymusic.....html?limit=all

#10 Deromax

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Posted 16 November 2012 - 09:33 PM

Anything pro running in conventional class AB will have fans too noisy for home use.  Crown, QSC, Crest audio...  I had a Microtech 1000 who's fan was like a hair dryer!  I recently purchased an used CTs 600 to drive my surround channels, and even on this light duty, the variable fan is annoying.  I'm trying to resell it.  I tried PLX QSC and they're loud too.

Yamaha P serie is class AB with a twist and is very quiet and cool running, as are the Crown XLS of the Drivecore serie.  If used amp is acceptable, the Crown K serie is a variant of Class D, no DSP, no fan and have a very nice sound.

#11 dakos

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Posted 17 November 2012 - 12:24 AM

Thank you Deromax for your notes about the fan, very important aspect.

The XTI up to and including the 4000/4002 are class AB+B, they have a "Low noise" fan preset but they have the AD/DA conversion at 48Khz.

Life is all about the compromise...
Avi

#12 Kuja

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Posted 17 November 2012 - 06:42 AM

Thanks Deromax! :)

Your experience is invaluable!

Unfortunately there are no Crown Ks here.

Did you listen to Yamaha P series amps?

How do they sound?

My speakers are wee bit on coldish side of neutral, so I would like to avoid some further sound "cooling".


Lower powered Yamaha Ps have "classic" PSUs with toroid transformers, while higher powered models have switching power supplies.


Are their switching power supplies OK for home use?


It is said that some switching power supplies can inject some nasty(?) interferences through power lines into other hi-fi components in the rack.

I have no first hand experience with this and there is a lot of hearsay on the Internet regarding this subject.

I guess if a special care is given to switching power supply design
this bad influence can be avoided,
but since Yamahas are pro gear maybe this problem was not high on the designers' list...




Also,
the specs say that the input sensitivity  for higher povered model is +6dBu  and for lower powered model is +4dBu:
http://www.yamahapro...cifications.jsp

What does it mean?
Which amp needs higher voltage from the preamp (stronger preamp output)?

I also have a Mackie 402-vlz3 mixer that can be used for the preamp duties
http://www.mackie.co...oducts/402vlz3/

but I would like to try to use some "proper" :) hi-fi preamp too.


Thank you all for your patience with the newbie! :)

#13 Deromax

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Posted 17 November 2012 - 01:36 PM

Did you listen to Yamaha P series amps?

How do they sound?

--->  I have used them in a pro setting for sound reinforcement with great results.  I have not listened to them in my home system.  I really should be!

My speakers are wee bit on coldish side of neutral, so I would like to avoid some further sound "cooling".

---> I'm affraid I'm not the one to qualify sound by such audiophile vocabulary!  You won't catch me in a cable sound discussion either!  :)  If it's full range, clean and not noisy it will do OK for me!  I kinda like a high damping factor for sub amps however, and THAT can be discussed hahah!!

Are their switching power supplies OK for home use?

---> Switching power supplies are becoming the norm, we better get used to it.  They use way less copper and steel in their construction (expensive metals!), are weighting a lot less (economy in transportation) and permit such niceties as automatic worldwide voltage compatibility (90V to 250V), regulation and power factor correction when implemented.  In the hifi world, I think the Linn company began using them as soon as the late 90s in their products, but I have not followed the hifi scene for a long time, don't quote me on this!

It is said that some switching power supplies can inject some nasty(?) interferences through power lines into other hi-fi components in the rack.

---> I wouldn't think so, else they wouldn't meet safety agencies certifications for noise generation.  This is filtered out fine.  Maybe trying to receive a distant AM station with such an amp near could be an issue!

I have no first hand experience with this and there is a lot of hearsay on the Internet regarding this subject.

--->  Misconceptions abounds, don't be ashamed!  Old saying die hard!  We still hear that class D is only for subwoofer car amps, which is really an astonishing thing to hear in this day and age !  :)

Also, the specs say that the input sensitivity  for higher povered model is +6dBu  and for lower powered model is +4dBu:
http://www.yamahapro...cifications.jsp

What does it mean?
Which amp needs higher voltage from the preamp (stronger preamp output)?

---> Amps designers who designs an amp serie have two choice : they can have all models in a serie accepting a given voltage input for producing their rated output (like, say, the Crown XLS serie) so each model will have a different gain, the higher powered model having more gain.  Or they could make the serie with all the same gain so the input level will have to be higher voltage on the higner powered model (like Yamaha do with their P serie).  One implementation is not better or worst than the other, it's just a choice they make.  In your case, I would think any resonable pre-amp will be able to drive any of those amps, including the biggest Yamaha.  We're talking like 1.2V vs 1.9V.  My Outlaw audio pre-pro will output 9V (+23 dBu).  You just got to get used to put the volume knob a tad higher!

Personnally, I would be hesitant to use the XLS serie as my main L-R amp.  My Brystons have distortion figures two order of magnitude lower than the XLS and they are mostly silent.  This is nice to have for serious music listening.  But for sub, center and surround channels duty, most any pro amps will do better because sheer power is more important for movies than a very refined sound, IMHO.

#14 dakos

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Posted 17 November 2012 - 03:32 PM

View PostDeromax, on 17 November 2012 - 01:36 PM, said:

It is said that some switching power supplies can inject some nasty(?) interferences through power lines into other hi-fi components in the rack.

---> I wouldn't think so, else they wouldn't meet safety agencies certifications for noise generation.  This is filtered out fine.  Maybe trying to receive a distant AM station with such an amp near could be an issue!
Just one correction, this actually happens but it is due to a flaw in the design of the amp and not inherent to switching power supplies in general, the only one that comes to mind right now is Peaveys early IPR series amps, if you had a few of them in the same rack or on the same electrical circuit then one amp would inject noise to the other amps. That problem is long gone and most of the faulty amps were fixed within the warranty. None of the amps discussed here have had this problem.

#15 Kuja

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Posted 17 November 2012 - 07:59 PM

Thanks a lot! You made many things much clearer! :)

I think I should try a Yamaha P amp.

Do you have any idea how would it compare sound-wise to your (since you mentioned it)  Brystons?

I'm not into movie sound effects, the amp will be used only for (refined :) ) music listening.

What PSU type should I choose for home use?
Switching or classic (toroid), or in Yamaha's case it doesn't matter?