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Measuring Amplifiers - Page 3

post #61 of 1913
6/10/07 at 3:45pm
It's interesting that two different amps from the same manufacturer acheive their claimed ratings so differently, one gets close and the other fails dismally. You would expect the manufacturer to have better quality control over all their products.
Chas, this is where your collection of data and information becomes so important to others. We can all appreciate your methodology now that we can see the data in your printouts. Excellent . . . . . git er dun!
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post #62 of 1913
6/10/07 at 3:48pm
I'd love to see the 'bridged' results!
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post #63 of 1913
6/10/07 at 4:08pm
Yeah, I'll be running my two RL-p18d4's bridged off that 2500...

Love these tests!
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post #64 of 1913
6/10/07 at 4:10pm
Thread Starter 
Here are the 2 ohm results for the EP2500 amplifier rated at 1200 watts/channel 1 KHz at <0.1%THD both channels driven.

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post #65 of 1913
6/10/07 at 4:14pm
Thread Starter 
Here are the 8 & 4 ohm results for the EP2500 amplifier in the bridged mono configuration.

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post #66 of 1913
6/10/07 at 4:26pm
Interesting, does the bridged 4ohm trip the circuit breaker at 20hz?
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post #67 of 1913
6/10/07 at 4:26pm
Thread Starter 
Some comments on testing these amps. Even though the results I got from bench testing these amplifiers do not read like the published specs in the Behringer manual, they will do their rated specifications if tested the way Behringer tests them. I found heat and the circuit breaker located in the amplifier to be the 2 items that caused the amplifiers to fail the tests and not meet the published specs. I almost opened up the 2500 and bypassed the circuit breaker just to see if it would go on or go up in smoke. If I had a room that was temperature controlled to about 70 degrees with heavy duty air handling capabilities (and a duct pointed right at the intake of the amp), the amp would not have gotten so hot, so quick. Even with all that these amplifiers will not run with a sine wave at full power at 1 KHz for more than 5 minutes under any load, 2, 4, 8, or bridged! They are just not made to run like that. On the other hand, if you were to derate the power of the units, they could run all day at rated specs. SO you have to ask yourself....... Did the marketing dept. decide that this amp could do 2500 watts at 4 ohms bridged mono and the engineers said "Not really", but marketing did anyway? I don't know. Considering the money to be spent on them, for home use, they are fantastic.

I will be doing more tests next weekend with some amplifiers from Yuriv so stay tuned for more.

As far as testing a buttkicker... I do not have one or know anyone that does. Augerpro asked about maybe testing his so we shall see. If anyone in Florida would like theirs tested, PM me.

Chuck
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post #68 of 1913
6/10/07 at 4:27pm
Thread Starter 
Quote:
Originally Posted by crackyflipside View Post

Interesting, does the bridged 4ohm trip the circuit breaker at 20hz?

Absolutely The amp would only run for less than 20 seconds in that mode with a pure sine wave!
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post #69 of 1913
6/10/07 at 4:30pm
Thread Starter 
armystud:
This ones for you!

2.34 ohms load
bridged mono EP2500
20 KHz sine wave
52.2 volts RMS
.982% distortion
1,164 watts

Yes, it will run 2 ohms in bridged mono but not very hard or for very long.

Chuck
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post #70 of 1913
6/10/07 at 4:55pm
These tests are very impressive, Chuck. Those Behringers seem to be made from very hardy stuff. They are really amazing values, especially the 2500.

I'd love to see someone do some blind listening tests against some highly regarded home and pro amps.
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post #71 of 1913
6/10/07 at 5:44pm
nice indeed Chuck!!! Very impressive and more impressive in person!!

as soon as I get a chance to breathe, I will stop by and we can get the Crown K2 a little workout on your rig.

well done Sensei!
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post #72 of 1913
6/10/07 at 8:42pm
Quote:
Originally Posted by ssabripo View Post

nice indeed Chuck!!! Very impressive and more impressive in person!!

as soon as I get a chance to breathe, I will stop by and we can get the Crown K2 a little workout on your rig.

well done Sensei!

You mean you are going to let Chuck torture your K2?!?!?




I mean; he was ready to kill an innocent EP2500:

Quote:
Originally Posted by chasw98 View Post

......I almost opened up the 2500 and bypassed the circuit breaker just to see if it would go on or go up in smoke...

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post #73 of 1913
6/11/07 at 1:03am
Thanks a ton chuck, I was planning on using it as 2ohms per channel in a bi-amped config, this confirms that the amp cannot be used effectively bridged for low impedance wiring.
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post #74 of 1913
6/11/07 at 5:50am
Thread Starter 
Quote:
Originally Posted by crackyflipside View Post

You mean you are going to let Chuck torture your K2?!?!?




I mean; he was ready to kill an innocent EP2500:




I am a certified, factory trained Crown Technician.





And I stayed at a Holiday Inn last night!
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post #75 of 1913
6/11/07 at 5:52am
Thread Starter 
Quote:
Originally Posted by armystud0911 View Post

Thanks a ton chuck, I was planning on using it as 2ohms per channel in a bi-amped config, this confirms that the amp cannot be used effectively bridged for low impedance wiring.

2 ohms per channel - OK
2 ohms bridged mono - NOT OK
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post #76 of 1913
6/11/07 at 5:58am
Thanks a TON for spending a lot of your time testing these amps. I know everyone here really appreciates it.
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post #77 of 1913
6/11/07 at 7:45am
Quote:
Originally Posted by armystud0911 View Post

Thanks a ton chuck, I was planning on using it as 2ohms per channel in a bi-amped config, this confirms that the amp cannot be used effectively bridged for low impedance wiring.

This should not come as a big surprise to anybody since the manual clearly warns: "CAUTION: 2-ohm loads should never be applied when in mono-bridged mode."
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post #78 of 1913
6/11/07 at 8:32am
This is a great thread . Thanks for the tests Chasw98, I know this is alot of work.

Here are the amps I think would be of the most interest, that I'm sure most would like to see tested if possible.

Buttkicker
ED LT1300 plate amp
Crown XTI4000 & CE4000
QSC RMX2450 & any of the PL series, new or old( mostly the 3.6 though)

Maybe some will be willing to send their amp to Chasw98 for testing If he would be willing to do it.
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post #79 of 1913
6/11/07 at 8:38am
Quote:
Originally Posted by Ricci View Post

This is a great thread . Thanks for the tests Chasw98, I know this is alot of work.

Here are the amps I think would be of the most interest, that I'm sure most would like to see tested if possible.

Buttkicker
ED LT1300 plate amp
Crown XTI4000 & CE4000
QSC RMX2450 & any of the PL series, new or old( mostly the 3.6 though)

Maybe some will be willing to send their amp to Chasw98 for testing If he would be willing to do it.

Look at the bink test, he tested CE4000 and some of the PL's.
http://home.pacbell.net/lordpk/bink/bink.jpg

No need to reinvent the wheel.

EP2500 is a clone of RMX2450, I'd expect similar numbers within 10%.

Crown XTI4000 would be the really nice one to test since it's a new line
from Crown. Who's going to fork over one. hehehehe

Crown XLS version D would be nice as it has a new look inside, looks a little
better than prior version {A thru C}.
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post #80 of 1913
6/11/07 at 1:18pm
Quote:
Originally Posted by mojomike View Post

This should not come as a big surprise to anybody since the manual clearly warns: "CAUTION: 2-ohm loads should never be applied when in mono-bridged mode."

That doesn't necessarily mean a thing, Thylantir is running a 0.8ohm bridged mode on his PLX amps, thats 0.4ohms per channel and its only rated for 2ohms per channel, you can often times cheat the specs if you use an amp for a different app.
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post #81 of 1913
6/11/07 at 1:39pm
Thread Starter 
Quote:
Originally Posted by armystud0911 View Post

That doesn't necessarily mean a thing, Thylantir is running a 0.8ohm bridged mode on his PLX amps, thats 0.4ohms per channel and its only rated for 2ohms per channel, you can often times cheat the specs if you use an amp for a different app.

armystud talked about running high frequency devices in a 2 ohm configuration, I believe. It is probably possible and safe to do this with the EP2500 in bridged mono mode. I would not try and push several hundred watts out of the configuration, but to drive some tweeters in active configuration would probably not damage the amp. I would be very careful at first, though.

Chuck
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post #82 of 1913
6/11/07 at 1:41pm
Yeah, after seeing what they can do with 2ohms per channel at 1Khz, I will stick with that, if I start bridging stuff, it will be after I get a PLX amp.
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post #83 of 1913
6/14/07 at 11:02am
I am running my EP2500 2-Ohm bridged and i can say that it works and i think you may get a hair more power from bridged then a single channel, but it gets hot and draws a ton of power. But it will survive as long as you make sure not to let it get too hot from consistent high use.

i will be changing it back to one channel as i would rather not risk it.

Thanks allot for the tests!
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post #84 of 1913
6/14/07 at 9:04pm
Well, the way I see it, that just isn't a cost effective way to go, I could power each cabinet with an EP2500 or with two EP2500's, two of them would give me a hair more power but would be far less efficient and more abusive on the amps.
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post #85 of 1913
6/14/07 at 9:28pm
Cool stuff Chuck. That is quite a nice looking test rig.
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post #86 of 1913
6/14/07 at 9:29pm
Why odd?
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post #87 of 1913
6/15/07 at 6:01am
How did you come up with this resistance load device? What do engineering firms use to do this? You are the coolest guy I "know" Chuck. If not for the hurrricanes I'd have to move down there to watch all the smoke and sawdust that pours out of your shop. Also, how long are you holding these amps at each level to perform your measurements?
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post #88 of 1913
6/15/07 at 12:06pm
Thread Starter 
Quote:
Originally Posted by jvgillow View Post

Cool stuff Chuck. That is quite a nice looking test rig.

Thanks, Jeremy! Bring an amp by next you're down this way.

Quote:
Originally Posted by price3 View Post

How did you come up with this resistance load device? What do engineering firms use to do this? You are the coolest guy I "know" Chuck. If not for the hurrricanes I'd have to move down there to watch all the smoke and sawdust that pours out of your shop. Also, how long are you holding these amps at each level to perform your measurements?

I got the idea from some links thylantr sent me to for some pro audio guys. Actually back in the old days you would use Dale RH250 non-inductive wirewound resistors. A 250 watt, 8 ohm resistor would cost about $100.00 each. Buy 4 of them and you could easily test 4, 8, aand 16 ohm capabilities. But remember the biggest amp back then was a Phase Linear 700. I will have to say I saw a 10,000 watt, sea water cooled load bank at the Crown factory when I went there for training. It had a room all by itself!

How long am I holding these amps at power? Well, these amps won't take steady state sine wave testing at their published limits very long. At the higher wattages and lower impedances, maybe 30 seconds. At high power and 8 ohms, they will run almost all day at full power into a load at any frequency.

I will have some more amps tested this weekend if Yuri comes by, otherwise I will sneak into ssabripo's house and steal his amp to try out!

Chuck
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post #89 of 1913
6/15/07 at 12:51pm
Chuck,

First of all, thank you for doing these tests.

Have you considered taking some peak/burst output tests? I mean 30 second steady sine wave is not a very common event in real program material. I know you're trying to test whether manufacturer's specs are true or not, but IMO it would be beneficial to try to "replicate" the real program material too. 20 ms burst is pretty commonly used to test the peak output. That way you wouldn't also have any heat problems.

Just a suggestion.
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post #90 of 1913
6/15/07 at 12:59pm
A while ago on the pro forum, they were talking about loads. Bink was using some
resistive network that was used to brake trains as they use a DC motor. lol
He also had some huge tank with elements.

One guy posted this picture;
http://home.pacbell.net/lordpk/load/...ent_Load-1.jpg

Three element load.

I went to home depot to look at the water heater elements and I found a
5kw one. It's resistance value was some obscure number. To allow me to
get 2 - 4 ohms, etc., you need more so you can series and paralell this obscure
resistance value into the desired resistance range.

I needed seven to do this. 35kw rated
http://home.pacbell.net/lordpk/load/...ent_Load-5.jpg

This also helps keep a stable load as each element doesn't get very hot so the
resistance is stable.

Chucks is eight element.
http://home.pacbell.net/lordpk/load/...ent_Load-1.jpg

It's about $100 to DIY.

I'm not sure what the inductance is on these elements as I only did low frequency
tests. If it has significant inductance, your high frequency test can be erroneous.
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