Measuring Amplifiers - Page 25 - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #721 of 1917 Old 05-15-2008, 12:22 PM
AVS Special Member
 
thylantyr's Avatar
 
Join Date: May 2004
Posts: 3,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
Where are all the fanboys that don't approve of the 'rms test method'. Come out of your closet





Spy pics of the *new* Crown XTI-6000




The storm was gone, but dark clouds still hung around
The perfect setting for things to come......

thylantyr is offline  
Sponsored Links
Advertisement
 
post #722 of 1917 Old 05-15-2008, 12:42 PM
AVS Special Member
 
Ricci's Avatar
 
Join Date: Mar 2007
Location: Louisville KY
Posts: 5,128
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 39 Post(s)
Liked: 240
Wow. I seriously hope that something is wrong with that particular unit cause that is one shoddy performance. We would all be ragging on it any way if it had done 200watts per channel at 20hz into 4ohms just because it would still be so far off.

Makes the EP2500 look like a HAUS and an even better value now.
Ricci is offline  
post #723 of 1917 Old 05-15-2008, 01:39 PM
Advanced Member
 
geoffstgermaine's Avatar
 
Join Date: Jan 2007
Location: Winnipeg, Canada
Posts: 504
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
I've been checking Crown's website waiting for their response. I have an XTI2000, but if the specs are this far off I will be getting a different amplifier. If nothing is wrong with the amp then the performance is pathetic and the specs are fabrications.
geoffstgermaine is offline  
post #724 of 1917 Old 05-15-2008, 01:52 PM
AVS Special Member
 
exojam's Avatar
 
Join Date: Dec 2004
Location: MA
Posts: 2,553
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 28
I am not holding out to much hope for Crown to look at my thread (I do really hope they prove me wrong though). If there is nothing soon I may see if Chuck will mind me trying to copy over his data showing just how bad it did and than see if they respond.
exojam is offline  
post #725 of 1917 Old 05-15-2008, 01:54 PM
AVS Special Member
 
TheEAR's Avatar
 
Join Date: Nov 2006
Location: Montreal,CANADA
Posts: 3,464
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by thylantyr View Post

Where are all the fanboys that don't approve of the 'rms test method'. Come out of your closet





Spy pics of the *new* Crown XTI-6000


Stop insulting that bird Thylantyr !

Placing Clown with big bird in the same class will result in a lawsuit from the bird !

90W into a 4 Ohm load at 20hz! WOW I am ...floored.

I sent them an email,they better respond. I hope they to not try to hide in the sand.And the failed 2 Ohm stereo tests! They have two black eyes and a broken nose now...

Ask yourself mortal , do you have as much displacement as me ? The answer is no unless you have a Windmere fan sub.
TheEAR is offline  
post #726 of 1917 Old 05-15-2008, 01:55 PM
AVS Special Member
 
TheEAR's Avatar
 
Join Date: Nov 2006
Location: Montreal,CANADA
Posts: 3,464
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by geoffstgermaine View Post

I've been checking Crown's website waiting for their response. I have an XTI2000, but if the specs are this far off I will be getting a different amplifier. If nothing is wrong with the amp then the performance is pathetic and the specs are fabrications.

I am with you on that one,I have THREE Crown XTi amps(1000,2000 and the 4000) .They have some answering to do.

I would ask any Crown XTi owner to send Crown an email with the ling to this thread,like I did.


...90 F watts...!!!

Ask yourself mortal , do you have as much displacement as me ? The answer is no unless you have a Windmere fan sub.
TheEAR is offline  
post #727 of 1917 Old 05-15-2008, 01:58 PM
AVS Special Member
 
thylantyr's Avatar
 
Join Date: May 2004
Posts: 3,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
* Imagine if you do a low AC line test, the scores are much less.

* Crown said it's class AB+B, [not class H].

* There was suspicion of it having a tracking power supply
due to some comments made by others but unverified
and then looking deeper into this, it didn't appear so.

* Chuck's test reveal it must be a simple class AB+B
with a simple SMPS, and the heatsink design won't support
high power if it's a straight class AB+B when doing sine
wave tests.

There were many little clues that lead me to believe something was fishy.

Another clue.
http://www.crownaudio.com/amps.htm

According to this, the XTI isn't recommended for cinema,
yet the lowby XLS's are

Lets face the facts, Crown has been going downhill after
Harmon snatched them up.

Quote:


Acquired by Harman International in March of 2000, Crown has continued to move forward, producing numerous innovative designs .........



http://www.crownaudio.com/history.htm

I-Tech series is nice.

Macro-Tech I-series is a stupid marketing name for an I-Tech 'lite'.

XLS and Xs is not a Crown design.

Crown said XTI is based off the cheap CE1000/2000 design,
a known turkey in the proaudio world. [CE4000 = different animal].

Clues.. clues... clues...



The storm was gone, but dark clouds still hung around
The perfect setting for things to come......

thylantyr is offline  
post #728 of 1917 Old 05-15-2008, 01:59 PM
AVS Special Member
 
exojam's Avatar
 
Join Date: Dec 2004
Location: MA
Posts: 2,553
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 28
I am not sure if you guys with the Crowns are registered on their forum but below is the link to my thread I started about this if you want to add anything.

http://www.crownaudio.com/forums/ind...showtopic=2438
exojam is offline  
post #729 of 1917 Old 05-15-2008, 02:08 PM
AVS Special Member
 
thylantyr's Avatar
 
Join Date: May 2004
Posts: 3,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
Quote:
Originally Posted by exojam View Post

I am not sure if you guys with the Crowns are registered on their forum but below is the link to my thread I started about this if you want to add anything.

http://www.crownaudio.com/forums/ind...showtopic=2438


Chuck's tests are meanginless to them because pro audio
amplifiers are usually not tested the same way.

They may laugh at you for not reading the specs.

For example, look at the XTI datasheet.
http://www.crownaudio.com/pdf/amps/139472.pdf

* The power scores don't have the word continous nor
any mention of 'RMS'.

* Specific to XTI-1000, the disclaimer that the 2 ohms/ch
or 4 ohms bridge mode is not rated for 100v versions.

* Power rating @ 1khz only [no 20hz or 20khz rating].



The storm was gone, but dark clouds still hung around
The perfect setting for things to come......

thylantyr is offline  
post #730 of 1917 Old 05-15-2008, 02:17 PM
AVS Special Member
 
exojam's Avatar
 
Join Date: Dec 2004
Location: MA
Posts: 2,553
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 28
Well hopefully they would not laugh to much when Chucks test shows 100+ watt difference at their spec.
exojam is offline  
post #731 of 1917 Old 05-15-2008, 02:43 PM
AVS Special Member
 
TheEAR's Avatar
 
Join Date: Nov 2006
Location: Montreal,CANADA
Posts: 3,464
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by exojam View Post

Well hopefully they would not laugh to much when Chucks test shows 100+ watt difference at their spec.

I joined the Crown forum. I seriously hope they answer. Right now I am fuming.

90W this is not even a cold turkey, it is a stuffed roach.

Ask yourself mortal , do you have as much displacement as me ? The answer is no unless you have a Windmere fan sub.
TheEAR is offline  
post #732 of 1917 Old 05-15-2008, 03:11 PM
AVS Special Member
 
michael hurd's Avatar
 
Join Date: Nov 2007
Location: 49th parallel
Posts: 2,122
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked: 31
I look forward to the retest and also the bridged test. I have a feeling that the price for used QSC's are going to go through the roof.

"You take the blue pill - the story ends, you wake up in your bed and believe whatever you want to believe. You take the red pill - you stay in Wonderland and I show you how deep the rabbit-hole goes."
michael hurd is online now  
post #733 of 1917 Old 05-15-2008, 03:19 PM
AVS Special Member
 
thylantyr's Avatar
 
Join Date: May 2004
Posts: 3,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
Forget the Crown Forum..




If you want some excitement, post on the PSW forum.
http://srforums.prosoundweb.com/index.php/f/2/0/

This will rattle the cage



The storm was gone, but dark clouds still hung around
The perfect setting for things to come......

thylantyr is offline  
post #734 of 1917 Old 05-15-2008, 03:23 PM
AVS Special Member
 
thylantyr's Avatar
 
Join Date: May 2004
Posts: 3,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
Maybe Chuck mistaken a Crown XTI for this ?

Canon Digital Rebel XTi







The storm was gone, but dark clouds still hung around
The perfect setting for things to come......

thylantyr is offline  
post #735 of 1917 Old 05-15-2008, 04:02 PM
Senior Member
 
anidabi's Avatar
 
Join Date: Jun 2007
Location: Finland
Posts: 200
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Those numbers are really strange indeed. If the amp is not defective, I have to admit that the xti series is umbelievable.

But that is not the most disturbing thing I have noticed now that this gigantic noise has risen because of this new test. What disturbs me the most is that, even people who have several different amps, good and bad, couldn't distinguish the horrible amplifiers from the good ones with their ears? Now that the amp has been tested and you have the numbers, all of the sudden everybody gets angry and starst yelling everywhere. It's like the audio hobby for some people is to watch all sorts of tests all day long and brag about ther ├╝ber systems and gadgets. I tend to use my ears time to time, when comparing different systems. Not just watch some test data and numbers all year around.

90w in subwoofer application is something that everybody should have been able to hear with their ears, and not just blindly believe the high price and ultimate marketing bul****. Even I did notice the huge leap towards better sound when moving from 350w plate amp to 2kW pro amp. The difference was just something that you have to be a deaf people if not be able to tell the difference.


I do have SDX15 sonosub tuned to 15Hz.
anidabi is offline  
post #736 of 1917 Old 05-15-2008, 04:24 PM
AVS Special Member
 
thylantyr's Avatar
 
Join Date: May 2004
Posts: 3,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
Quote:
Originally Posted by anidabi View Post

What disturbs me the most is that, even people who have several different amps, good and bad, couldn't distinguish the horrible amplifiers from the good ones with their ears? Now that the amp has been tested and you have the numbers, all of the sudden everybody gets angry and starst yelling everywhere.

Who are these people ?
Which amplifiers are those?

This sounds more like a hypothetical situation.

Here's my take on this. Most people in DIY home audio
have not experienced the more powerful amplifiers. Their
point of reference is low, but it works for them, until they
experience something better.

How many people meet all these requirements, raise your hand.

* You own a Crown XTI-1000
* It's driving your subwoofers @ 4 ohms/ch.
* You are playing a sine wave, not music.



The storm was gone, but dark clouds still hung around
The perfect setting for things to come......

thylantyr is offline  
post #737 of 1917 Old 05-15-2008, 04:33 PM
AVS Special Member
 
Willd's Avatar
 
Join Date: Jan 2003
Location: Charlotte, NC
Posts: 5,647
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:


Here's my take on this. Most people in DIY home audio
have not experienced the more powerful amplifiers. Their
point of reference is low, but it works for them, until they
experience something better.

Yep. I had no perspective when I began with my BKA. Then I moved up to the XS900. Now its easy to tell the difference.
Willd is offline  
post #738 of 1917 Old 05-15-2008, 05:45 PM
AVS Special Member
 
TheEAR's Avatar
 
Join Date: Nov 2006
Location: Montreal,CANADA
Posts: 3,464
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by thylantyr View Post

Maybe Chuck mistaken a Crown XTI for this ?

Canon Digital Rebel XTi





The Canon XTi has more output at 20Hz into a 4 Ohm load !

Ask yourself mortal , do you have as much displacement as me ? The answer is no unless you have a Windmere fan sub.
TheEAR is offline  
post #739 of 1917 Old 05-15-2008, 05:46 PM
AVS Addicted Member
 
penngray's Avatar
 
Join Date: Feb 2006
Location: Florida
Posts: 26,779
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
exojam, remember your post....

Quote:


Penn,

Your friends may not have heard a difference, but could you? I know going from a Buttkicker to the XTi100 was a vast change for me at least.

If chuck's tests are remotely accurate I would say "Vast change" for you was simply the well know placebo effect.

I know I have placed TWO identical amps, speaker sets in front of people and then I told them set A was $2K and Set B was $500.....I think you guys know the answer to which set they like Outside of placebo drugs, audio is the only place where placebo has such a huge presence.

It is not "open-minded" to reject knowledge - Bob Lee
penngray is offline  
post #740 of 1917 Old 05-15-2008, 05:50 PM
AVS Addicted Member
 
penngray's Avatar
 
Join Date: Feb 2006
Location: Florida
Posts: 26,779
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
On deck for testing...Im sending one of my SC-1250 amps too Chuck after I use it this weekend

Cant wait to see 4 Ohms.....400 WATTS!!!!!!

It is not "open-minded" to reject knowledge - Bob Lee
penngray is offline  
post #741 of 1917 Old 05-15-2008, 05:51 PM
Senior Member
 
LINEARX's Avatar
 
Join Date: May 2007
Location: Pottsboro, Texas
Posts: 323
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
This is when the suspense is deafening . . . . . . just like the power of the Crown amp was supposed to be.
LINEARX is offline  
post #742 of 1917 Old 05-15-2008, 06:03 PM
Senior Member
 
LINEARX's Avatar
 
Join Date: May 2007
Location: Pottsboro, Texas
Posts: 323
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
The inside of my XTi 4000 has more . . . . . stuff. More capacitors and 16 transistors vs 12 for the XTi 1000. It DOES look like the same circuit board as the XTi 1000.
I also notice that on the Crown website they have added a "20 msec Burst" power rating to their wattage stats for the Itech amps. Maybe the consumer pressure to tell the approximate truth is getting to the manufacturers? Nawwwwwww.
LINEARX is offline  
post #743 of 1917 Old 05-15-2008, 06:33 PM - Thread Starter
AVS Special Member
 
chasw98's Avatar
 
Join Date: Dec 2004
Location: Margate, FL
Posts: 1,085
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Very precisely and carefully I made another set of 4 ohm measurements at 1,000 Hz, 200 Hz, 100 Hz, 50 Hz, 25 Hz, and 20 Hz. All readings were taken with a THD set between 0.475% and 0.5%. Just in case you are wondering how this is done behind the curtain, I have included 2 photos of the analyzer set at THD and then at voltage while testing at 20 Hz.

Distortion set point.



Voltage reading after setting distortion at 20 Hz.



The results of the measurements with all pertinent data.



If you look carefully the power really appears to drop at 20 Hz.

Chuck
chasw98 is offline  
post #744 of 1917 Old 05-15-2008, 06:46 PM
Advanced Member
 
2100's Avatar
 
Join Date: Mar 2008
Location: Singapore
Posts: 729
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by thylantyr View Post

If you want some excitement, post on the PSW forum.
http://srforums.prosoundweb.com/index.php/f/2/0/

That's a big bag of worms. I still remember the really expensive linearray Adamson cabinets being put down by users in the review section and punches literally flew. But the "officials" from Adamson did come in. If you wanna get a response, THIS IS IT!

But we'll prob get laughed at.

Why not someone try the XTi1000 or XTi2000 with a 4-ohm know sub (as close to 4ohms impedance at 20Hz), whack some 20Hz tones at 0.25m nearfield, and post the SPLs? There is indeed a noticeable difference in dB between 90W and 500W.
2100 is offline  
post #745 of 1917 Old 05-15-2008, 06:46 PM
AVS Special Member
 
Willd's Avatar
 
Join Date: Jan 2003
Location: Charlotte, NC
Posts: 5,647
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Thanks a lot fireanimal for sending your amp to Chuck!

Bizarre how the amp drops in output from 50Hz to 20Hz.

On an semi-related note, has anyone seen these amps?

http://www.audiolines.com/Samson-PG2...p-p-21076.html

http://www.audiolines.com/Samson-PG3...p-p-21077.html

They look like they could be good values...
Willd is offline  
post #746 of 1917 Old 05-15-2008, 06:54 PM
AVS Special Member
 
exojam's Avatar
 
Join Date: Dec 2004
Location: MA
Posts: 2,553
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 28
Penn,

Since you quoted what I had stated, I will say it again with the same conviction. Going from the Buttkicker to the XTi was a vast improvement to me. Just because it (the XTi) seems to be weaker than advertised does not negate the difference I hear between those amps.

Also, just because of these tests does not mean I want to all of a sudden throw it away. I would just like to hear what Crown says about it if anything. I am happy with it and it will stay in my system. If you want to come on up to Boston and help me change them in and out you can tell me if you hear a difference between them in my setup.
exojam is offline  
post #747 of 1917 Old 05-15-2008, 06:54 PM
AVS Special Member
 
thylantyr's Avatar
 
Join Date: May 2004
Posts: 3,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
I also notice that on the Crown website they have added a "20 sec Burst" power rating to their wattage stats for the Itech amps.

20 seconds is way too generous. It's much less than that. hehe



The storm was gone, but dark clouds still hung around
The perfect setting for things to come......

thylantyr is offline  
post #748 of 1917 Old 05-15-2008, 07:02 PM
AVS Special Member
 
thylantyr's Avatar
 
Join Date: May 2004
Posts: 3,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
Quote:
Originally Posted by exojam View Post

Penn,

Since you quoted what I had stated, I will say it again with the same conviction. Going from the Buttkicker to the XTi was a vast improvement to me. Just because it (the XTi) seems to be weaker than advertised does not negate the difference I hear between those amps.

Also, just because of these tests does not mean I want to all of a sudden throw it away. I would just like to hear what Crown says about it if anything. I am happy with it and it will stay in my system. If you want to come on up to Boston and help me change them in and out you can tell me if you hear a difference between them in my setup.

The scores seem to indicate some funny business, perhaps audible from
lets say 35hz on down. Lets say 35hz - 100hz the output difference is still
inaudible. You would have to do a precise test in the 20hz range to see
what happens when you play music vs. tones. Maybe the amplifier can burp
higher voltage but chokes on sustain.



The storm was gone, but dark clouds still hung around
The perfect setting for things to come......

thylantyr is offline  
post #749 of 1917 Old 05-15-2008, 07:05 PM
AVS Special Member
 
thylantyr's Avatar
 
Join Date: May 2004
Posts: 3,887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
Has the DSP been zeroed out for testing ?



The storm was gone, but dark clouds still hung around
The perfect setting for things to come......

thylantyr is offline  
post #750 of 1917 Old 05-15-2008, 07:11 PM
Member
 
cluelessngr's Avatar
 
Join Date: Feb 2008
Posts: 81
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
How much below 50hz output is needed in pro-audio ( I am picturing a 4 piece band playing on a stage in some mediumsized bar)? Looks like this is a good/mediocre PA amp but a lousy LFE sub amp. Difference between this and the Dayton was the Dayton claimed to be a Sub amp and their specs reflected this. However misleading, Crown never really stated it would do anything specific output wise other that at 1 khz correct?
cluelessngr is offline  
Reply DIY Speakers and Subs

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off