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Discussion Starter · #1 ·
I just received my new Crown XLS 1000 DriveCore Class D pro amp. You can find more info at crown's web site here:

http://www.crownaudio.com/amp_htm/xls_drivecore.htm


These are very lightweight and very efficient amps because of their Class D operation. My XLS is 9lbs. I am also using a Panasonic BX500 Receiver which is also a class D amp that uses similar TI chips as the crown amp in the rest of my setup.


I am using the Crown XLS 1000 to power my dual HSU TN1220HO passive subwoofers. I am also using a HSU Bass Optimizer which is required to provide the proper EQ of the HSU passive sub when used with a non-HSU amplifier. Previously I drove my TN1220's with a used Parasound HCA-1000A 2 channel amp. I also have a BFD1124 PEQ in the signal path.


The short take, is that I am very happy with the new amp. I feel that the Crown is providing better control of the sub's woofer driver and giving tighter bass. In particular, I am using a great chinese drum album, "Poems of Thunder" Which has some great drum tracks for bass testing. With the crown amp I am hearing subtleties in the initial strike and post strike drum skin vibration I had not heard clearly before.


Poems of Thunder Album here:
http://www.amazon.com/Poems-Thunder-...1435546&sr=1-2


Some further info:


1. The XLS 1000 is a pro amp. It does have a fan. However, I cannot hear the fan at all and I don't even believe that it has spun up with my home sound level listening.


2. Being a pro amp is wants higher level signal inputs. Even tho it does have RCA inputs (in addition to the pro XLR). I posted on the crown forum and verified that even on the RCA inputs it is looking for the +4dBu pro levels. (see here: http://www.crownaudio.com/forums/ind...showtopic=3759 ) I have a HSU Bass Optimizer that also has a gain knob that can add +14dB to the LFE signal. So I can get enough gain thru the amp. But if your LFE signal is coming from a home -10dBV style consumer receiver you may have a problem.


3. I have setup the XLS with the following settings:

AMP Mode: Y input

Y input turned out to be an important feature. I have one LFE out on my reciever and I was splitting it into two with a RCA Y cable to drive both HSU subwoofers thru the two channels of the crown. However this seemed to lower my signal level and gave me problems getting enough gain thru the amp. Using the Crown built in Y function helped. I was able to feed just channel 1 and let the Crown Y function copy the signal to Channel 2. Even with the Y Mode, I can use the two crown channel gain knobs separately to balance between my two HSU's.


FILTER: LOW PASS

freq: 250Hz

I am only using the amp to power a subwoofer. My receiver is already crossing the LFE signal at 80hz. I initially was using the filter in BYPASS (disabled) mode. However I was getting some higher frequency noise (very low volume, only could hear if you put your ear to the speaker during pauses in the music). By engaging the LOW PASS filter I now have dead silence at my subwoofers during music pauses.


4. I have an Entech WB powerline noise analyzer. I also use quietline noise shunt devices as well as Powervar isolation transformers for cleaning up or isolating powerline noise in my home. I previously plugged my Parasound HCA1000 directly into the wall since it was one of the high power draw devices in my system. I used the Entech analyzer to compare the parasound and crown noise-wise. The parasound did not add a appreciable amount of noise to my powerline. However, the crown with it's Class D and switching power supply does add noise to my power line. I use the powervar isolation transformers to separate the rest of my audio gear from the powergrid, so I have not noticed any negative impacts to my system. But with the entech I can definately measure the additional noise dumped into my home power lines from the crown. The crown itself is designed for pro environments and at least the marketing literature says that it can tolerate sags and dirty lines without issue.


I am purchasing a samson S Convert box that will allow me to increase my LFE RCA -10dBV signal to a pro XLR +4dBU signal. It is fairly cheap at less then $50. This box is discountinued but highly regarded and has been tested by a user on another forum to be fairly flat down to 10 hz. (see here: http://www.hometheatershack.com/foru...-cleanbox.html ) I am concerned since I am using the HSU bass optimizer at near it's max +14dB of gain I might get some distoration during loud bass heavy passages of music or movies. So I am hoping that the S Convert box will help adjust the signal gain in my path to the inputs of the amp. I will report back once I get the samson box in the mail.


Samson S Convert:
http://www.samsontech.com/products/p...fm?prodID=1699
 

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Sounds good as I've read little about these.


But how about some further impressions, objective, subjective. What load level are you driving, and what's the difference in previous pieces you've used etc..


Thanks
 

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Discussion Starter · #4 ·

Quote:
Originally Posted by FOH /forum/post/19594612


Sounds good as I've read little about these.


But how about some further impressions, objective, subjective. What load level are you driving, and what's the difference in previous pieces you've used etc..


Thanks

I am just getting started with the amp, I just installed it two days ago. I will post additional impressions as I listen to more movies and music.


The two HSU TN1220 subwoofers are a 4 ohm load each one per channel of the crown 2 channel amp.


The crown amp seems to have additional protection or relay's since when I power cycle the BFD1124 parametric EQ I no longer get a "thump" sound out of my subwoofers. Previously with the Parasound HCA1000 I had to be careful with the order in which I powered up and down my equipment driving my subwoofers.
 

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Discussion Starter · #5 ·
One of the better articles (although mostly a marketing type piece) is here:

http://www.prosoundweb.com/article/d...er_amplifiers/


In particular in the article:


"As a type, Class D amplifiers are notable for extraordinarily high efficiency, approaching 90 percent. In addition, inherently low output impedance makes Class D well suited to driving difficult reactive loads such as subwoofers."


and


"Applying our latest developments in power FET semiconductor technology, along with an advanced differential drive circuit topology, means that the XLS Series can deliver the efficiency of Class D but with the lower distortion and residual noise typical of Class AB designs.


Feedback and PWM modulation circuits enable fast recovery on peak transients, accurate reproduction of low-level detail, and precise tracking of low frequencies at high power levels for maximum subwoofer output. "
 

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I ordered one of these from an internet dealer. Demo model with cosmetic damage I guess, full warranty.


I could not resist, in spite of the fact I have NO idea where there's room for it in my rack.


I was told it had RCA ins and standard binding posts, and the price was right.


I will evaluate it's fan noise, and it's power. I was mostly interested in it's clipping indicator, as it should give me some very rough idea of how close I am to clipping. If it never lights up, that will give me more info than I have now I think.
 

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Discussion Starter · #8 ·

Quote:
Originally Posted by MichaelJHuman /forum/post/19628696


I ordered one of these from an internet dealer. Demo model with cosmetic damage I guess, full warranty.


I could not resist, in spite of the fact I have NO idea where there's room for it in my rack.


I was told it had RCA ins and standard binding posts, and the price was right.


I will evaluate it's fan noise, and it's power. I was mostly interested in it's clipping indicator, as it should give me some very rough idea of how close I am to clipping. If it never lights up, that will give me more info than I have now I think.

Welcome to the party!


The XLS drivecore series does have RCA IN's. However, they are expecting Pro Amp higher signal levels. Depending on the signal level coming off your receiver pre-outs/LFE outs you may or may not be able to see the clipping levels light up.
 

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Quote:
Originally Posted by dm /forum/post/19630434


Welcome to the party!


The XLS drivecore series does have RCA IN's. However, they are expecting Pro Amp higher signal levels. Depending on the signal level coming off your receiver pre-outs/LFE outs you may or may not be able to see the clipping levels light up.

Geez....with these urban myths never cease.



The input sensitivity for full output is 1.4V. This is right in the same range as other amps, regardless if "consumer" or pro audio.
 

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I noticed 1.4 V for sensitivity. I am pretty sure my Yamaha Z7 can swing that.
 

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Discussion Starter · #11 ·
Is this the correct math in the consumer vs pro amp story?


PRO:

+ 4 dBu = 20 * log (voltage / .775 V)

voltage = 1.228 Volts


Consumer:

- 10 dBV = 20 * log (voltage / 1V)

voltage = 0.3162 Volts


It would appear that the nominal levels on the consumer gear are lower and may cause issues driving the pro amps to full gain. Although a pro amp driven to even a percentage of it's maximum is probably still alot of power.
 

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Quote:
Originally Posted by dm
Is this the correct math in the consumer vs pro amp story?


PRO:

+ 4 dBu = 20 * log (voltage / .775 V)

voltage = 1.228 Volts


Consumer:

- 10 dBV = 20 * log (voltage / 1V)

voltage = 0.3162 Volts


It would appear that the nominal levels on the consumer gear are lower and may cause issues driving the pro amps to full gain. Although a pro amp driven to even a percentage of it's maximum is probably still alot of power.
Ah math, I love math. Especially amplifier math.


And as I recall, you are correct. The annoying proliferation of different ways of measuring signal levels seems to have originated from way back in the day with phone systems (hence the seemingly random numbers like 600 ohms for dBu.)


The standard spec given for receiver line outputs is 1 volt RMS. I read something not long ago which suggests that those numbers may not be reliable. I believe bench tests have often indicated much higher voltage than 1 volt RMS from the pre outs.


I think that also implies that pre out level is higher than consumer line level.


Too bad this has not been better standardized. People should not have to worry about clipping their pre amp stage.
 
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Got the XLS 1000 in. Fit into my rack, but I had to remove the tape deck until I find another spot for it.


I was a bit annoyed by the binding posts. There was a plug where I should have been able to insert a banana plug. I was able to insert the plugs in a hole after unscrewing the posts all the way. Odd...the plugs are vertical now, and touch the cabinet, which never seems good. I read something in the manual about safety plugs for Euro use, due to their power connectors there, but I am in the good ole USA!


I hooked up the amp to my receiver (Yamaha RX-Z7) via RCA. I flipped through the front panel options, and saw nothing I had to change. Display says 'stereo bypass.' I am thinking that means the amp is in stereo, and the filters are off (bypassed.)


I turned the gain to max. I manually calibrated channel levels with an SPL meter as I don't have the energy at the moment to re-run YPAO.


I turned the volume up to reference level for Monsters v Aliens. All seems well so far. I never saw the clipping light go on. I believe it peaks at -10. I found the lights a bit hard to read I admit, though. Just to see the amp go to clipping, I unhooked the speakers. I had to almost max out my receiver's volume control to see that on a song. Not going to clip under normal use I guess.


I would expect no audible difference between this and my Emotiva XPA-3, nor were any obvious playing some music.


My plan is probably to hook up my surround speakers to the crown using the Emotiva XPA-3 for the front channels, and the Z7 will do the rear surround channels.


This is probably MUCH more power than I will ever require. At some point I may move the amp to my bedroom system, which does not have a lot of power. I think it has the potential to actually matter there, unlike my main system where it's likely not going to make a difference (other than adding more blinky lights, which I always welcome!)


Pros -

* Price; Free shipping and below market price due to it being a demo (with no cosmetic damage to the front, some very light scratches where you would expect on the bottom); Even at standard market price, it does not seem overpriced for 200x2 watts

* Weight; Amazing. You could carry a stack of these with no strain

* Power; Plenty for my needs! I suspect more power than most people would need for a normal HT setup

* Good connectivity for consumer use - RCA inputs, binding posts


Cons -

* I was not pleased that I could not plug in my banana plugs in the usual way

* I wish the indicator lights had been a bit easier to read - in the sense that I could not always tell when -10 was lighting up; a minor point as normally I would not worry about them - I wanted to get an idea of how often I was getting within 10 dB of clipping


So we have a very light 200x2 watt amp with sufficient power for many people's needs that can be installed in your rack without pain. For less than $1500, you can power a full 7.1 surround sound setup. I am not really the guy to judge sound being 45 with some hearing damage, but I suspect many people simple won't be able to tell these apart from any other amps.


Some people online thought these were expensive. I am not sure why. Market price for a 200x2 watt amp is at least $250 I believe, so the XLS 1000 does not seem unreasonable.
 

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Quote:
Originally Posted by MichaelJHuman /forum/post/19661373


I was a bit annoyed by the binding posts. There was a plug where I should have been able to insert a banana plug. I was able to insert the plugs in a hole after unscrewing the posts all the way. Odd...the plugs are vertical now, and touch the cabinet, which never seems good. I read something in the manual about safety plugs for Euro use, due to their power connectors there, but I am in the good ole USA!

Michael..

Use an awl and the little plugs pop out. In Europe since their AC plug is similar to a dual banana plug, Semko requires this as to avoid possible safety issues..



Just my $0.02...
 

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Quote:
Originally Posted by M Code /forum/post/19661413


Michael..

Use an awl and the little plugs pop out. In Europe since their AC plug is similar to a dual banana plug, Semko requires this as to avoid possible safety issues..



Just my $0.02...

Yeah, I tried to pry them out. I could not manage it with tools on hand. I had assume it should be possible. Thanks. I had assumed they were for Euro safety but the manual seemed to imply the they would not be there on US models.
 

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Quote:
Originally Posted by dm /forum/post/19633805


Is this the correct math in the consumer vs pro amp story?


PRO:

+ 4 dBu = 20 * log (voltage / .775 V)

voltage = 1.228 Volts


Consumer:

- 10 dBV = 20 * log (voltage / 1V)

voltage = 0.3162 Volts


It would appear that the nominal levels on the consumer gear are lower and may cause issues driving the pro amps to full gain. Although a pro amp driven to even a percentage of it's maximum is probably still alot of power.

The numbers are right, but it's a misapplication of the information. What you cite applies to the fixed level signals like tape in/out levels.


Since the pre out and amp input signal continually varies as you change volume, there isn't really a "reference" level for these signals.


Stop reading non-applicable information and merely browse the Internet and look at the specs of "consumer" power amps. Then, come back and tell me how many have around ~0.316V input sensitivity and how many have ~1.5V input sensitivity.
 

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Quote:
Originally Posted by MichaelJHuman /forum/post/19633830


The standard spec given for receiver line outputs is 1 volt RMS. I read something not long ago which suggests that those numbers may not be reliable. I believe bench tests have often indicated much higher voltage than 1 volt RMS from the pre outs.

The "rated" pre out voltages likely are correct, but they are only correct at the specified input signal voltage. Often the input sensitivity to the receiver or pre/pro is quoted at a low level like 150mV. So, if you have a much hotter signal as is almost certainly the case from a DVD or CD player, the pre out signal level will be correspondingly higher.


For example, my new Marantz AV7005 pre/pro lists the rated output voltage at 1.5V, but this is with input sensitivity/signal level of 200mV. This equates to 17.5dB gain (7.5x voltage multiplier). So, if one had a 0dBFS track from a CD player which is usually about 2V output from the player, the Marantz would theoretically put out 15V but I'd be surprised if it could do that. I'd guess it probably tops out somewhere around 5-6V before clipping the signal. It's possible it could put out more...my old Yamaha C-80 preamp will put out roughly 12.5V before clipping.
 

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The final decision is whether to use this from L/R and my Emo XPA-3 for X/RS/LS. Or the XPA 3 for L/C/R and the Crown for LS/RS.


In either case I will use my Z7 for the rear surrounds.
 

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Quote:
Originally Posted by dm
Well my Panasonic BX500 manual does not list the voltage for the LFE output. So all I know is that I had to boost the signal by approximatley 10dB using the HSU Bass Optimizer box or now that I have the S Convert on that box to get adequate gain out of the amp and my subwoofers.
When you say "adequate gain" what is the reference to determine "adequate gain"? Gain issues are generally relative to other devices in the system so what is "adequate gain" defined with respect to?


Not disputing that you have/had some sort of gain structure problem it's just not clear to me the details behind why, because the Crown's input sensitivity is quite normal regardless of pro amp or consumer amp designation. The Crown guy is misleading (or outright wrong) in his statement that the amp is expecting pro line level input. It just happens to be somewhat coincidental because it's a highly common ballpark number for a great many amps, consumer or pro.
 
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