ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  
Pages: 1 2 [3] 4 5 6   Go Down

Author Topic: PL380 v IT8000 v 9001 Pro v PLX3402 Smackdown  (Read 32094 times)

Bob Lee (QSC)

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1788
Re: PL380 v IT8000 v 9001 Pro v PLX3402 Smackdown
« Reply #20 on: July 20, 2007, 07:29:26 PM »

The 9001 is class H, but also based on class AB+B (if you disregard the multiple supply rails).

The MA5000VZ is class AB+B, but the VZ power supply could be thought of as similar to a class H concept.
Logged
Bob Lee
Applications Engineer, Tech Services Group QSC Audio
Secretary, Audio Engineering Society
www.linkedin.com/in/qscbob

"If it sounds good, it is good."
 -Duke Ellington

Don Boomer

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1034
Re: PL380 v IT8000 v 9001 Pro v PLX3402 Smackdown
« Reply #21 on: July 20, 2007, 08:54:35 PM »

Langston Holland wrote on Thu, 19 July 2007 15:55

Observations:




Crest 9001


It is interesting that the 20Hz result is higher than the 50Hz result - I repeated both measurements several times to be sure.
index.php/fa/10203/0/




I wonder if you would see the same result  (the difference between 20 Hz and 50Hz if you ran the test say at half power???
Logged
Don Boomer
Wireless Sales Engineer
Line 6, inc.

Langston Holland

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 908
Re: PL380 v IT8000 v 9001 Pro v PLX3402 Smackdown
« Reply #22 on: July 20, 2007, 11:29:26 PM »

Don wrote on Fri, 20 July 2007:

I wonder if you would see the same result  (the difference between 20 Hz and 50Hz if you ran the test say at half power???


Sorry for my ignorance Don, but I don't quite understand about the half power thing. To make a wild guess, I didn't mean to imply that any of the amps produced different gains depending on the frequency they were fed, but that they were capable of different output potentials at the tested frequencies for a single 50ms burst into 4 ohms. At first my speculation was that the lower 50Hz output might be due to the close 60Hz of the 120v line frequency powering the amps. Then I threw this out when I thought about the I-Tech's step-up to 250kHz (or something like that) of the line frequency to do its switching power supply voodoo.

I think JR may have hit on something when he hinted that differing pulse durations at different frequencies might be more appropriate due to the nature of music (I would guess). At 50ms, the 20Hz impulse is exactly 1 wavelength whereas at 50Hz the 50ms pulse is 2.5 wavelengths. Maybe that has something to do with it? I'm clueless. :)

I really don't know what I'm doing, but I'm convinced that my testing of all the amps in the same manner is reasonably revealing of their abilities in comparison _to each other_. I think it would be a big mistake for folks to look at my data and compare it to mfg published specs that were derived in a completely different manner. My purpose in all this was to prove to myself that the PL380 was a good fit for my application (replacing the I-T8000's on lows and subs) and it has proven better than I'd hoped. :)

Edit: I think I get it - I've been testing (probably) at something close to 1/8 power, thus 1/2 power would be driving the amps much harder. But how hard and how to you decide you're at 1/2 power? A certain THD level?
Logged
God bless you and your precious family - Langston

Soundscapes <><

Langston Holland

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 908
Vortex 6 Smackdown
« Reply #23 on: July 21, 2007, 03:44:05 AM »

I've been using the Vortex 6 on the mid/high bandpass on my KF730's for about 1.5 years and have been very pleased with their sound and power for up to 4 boxes per channel in stereo mode. This is a great sounding amp. Thus I didn't bother to test it because I'm not interested in another amp for this application - I just wanted to replace the I-Tech's I use on the lows and subs.

But. Since Dan got me a gig that had something to do with fish and little kids AND I got paid...

Vortex 6

Lights flickered a little with continuous 1kHz 50ms on / 50ms off signal at limiting in both stereo and parallel mode. For something new to do I plugged the amp into a Furman 20 amp PM-PRO Series II surge protector and it tripped within 3 seconds of its meter indicating 20 amps during the continuous test while I was still about a dB shy of full output. Bypassing this unit and plugging the amp directly into the 120v, 20 amp breaker stopped the tripping. Furman needs to use a longer time delay on its breaker for concert work. My Motion Labs RacPac 20 amp breaker never tripped in this testing either.

Parallel mode on this amp is not as simple as it is on the QSC and many others. Not only are the inputs wyed together internally, but the two channel outputs are as well. Thus when the Vortex 6 is run in parallel mode both channels are working together and the thing can drive loads at half the impedance of what each channel is capable of on its own in stereo mode. I ran all the tests in both modes and got the exact same results with the amp in stereo driving two 4 ohm resistive loads or parallel driving one 2 ohm resistive load.

The three LED's per channel on this amp from left to right are Power, Signal, and Clip. The first two are obvious, but the "Clip" LED is a 3 color deal that goes from green to yellow to red. Thus it never really indicates clipping until it's red, which for me took some getting used to. The limiter works very nicely and pulls the sine wave down quickly without visible distortion of the waveform. The moment the "Clip" LED turns yellow, limiting begins. If you increase the input signal quickly you can get the LED to very briefly turn red and then it jumps right back to yellow as the output signal is reduced - very nice. A final note is that in parallel mode the "Clip" LED on channel "A" alone indicates limiting and clipping, channel "B" only lights up green when driven hard. I have noticed that this amp is sensitive to overvoltage such as can occur when operating with gennys. The thing goes into protect mode around 128v or so if I remember and mutes its output. When the voltage is reduced, there is a nice ramp-up in volume as it comes back online, but I really think 120v audio gear should work up to 130v without issue.

The amp is quite efficient in transferring its heat as running this thing hard into limiting for a while and then muting the input signal resulted in the fan spinning down and turning off pretty quickly. Even at full speed the fan is not all that loud.

The sine waves looked very good at all frequencies.

Continuous loop of 1kHz sine 50ms on / 50ms off produced 74v RMS at the onset of limiting. Single 50ms sine bursts yielded the following with both channels driven to the onset of limiting.

index.php/fa/10226/0/

Edit: Grammar and minor rounding error on Vortex 6 at 20kHz - changed from 34dBW to 35dBW.
Logged
God bless you and your precious family - Langston

Soundscapes <><

RYAN LOUDMUSIC JENKINS

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2639
Re: Vortex 6 Smackdown
« Reply #24 on: July 21, 2007, 11:45:12 PM »

Hey Langston,

Regarding the Vortex 6.  Did you have the clip limiter and speaker protection engaged during your testing or just the speaker protection.

I think this is a VERY important consideration because with the clip limiter on it will not let the amp drive to more than 1% THD.  Thus the output measurements would not be completley accurate with it on.  They even mention in the manual on page 19 that to get the absolute most output from this amp for low and sub frequencies that the speaker protection circuit should be dis-engaged.  This could definately be the reason behind the lower measured output levels in your chart.  The very sophisticated computer control inside these amps makes me think that they may be difficult to get a truely accurate output measurement from but I may be wrong.  I haven't attempted to measure them in any way.

Keep in mind that this circuit actually lowers the signal level  rather than lowering the output level or limiting the output level and when used in conjunction with the clip limiter will prevent the amp from having more than 1% THD.

Also, the mains over voltage detection circuit will turn the amplifier off if the voltage is above 134 Volts.  I run off of generators all the time and I always adjust them to be approx 123-125 volts.  I have run these amps several times off of a 20 amp circuit into 4 ohms per load an never tripped a breaker.  

I have only seen the little red LED flicker a couple times and only for a very brief moment.
Logged
Ryan Jenkins
"Two days until the end of when I don't know what to think.  Three days until I start the cycle all over again!"

Please visit my website at http://www.murphygirl.com

Langston Holland

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 908
Re: Vortex 6 Smackdown
« Reply #25 on: July 22, 2007, 12:50:26 AM »

Yep, I had the limiter and speaker protection on, effectively putting this amp on a level playing field with the others which also had their limiters engaged. I don't give a rip how Camco's engineers designed the function of their limiters and I think it's risky to disengage any amp's limiters and rely entirely on your loudspeaker processor. What if your amp runs out of steam before you expect it to due to the specific load you feed it, the ambient temperature, low and/or fluctuating supply voltages, etc? Do you really think you can predict all that and program it into your processor to squeeze every clean volt out of your amp without endangering drivers? Not me. I want a backup that actually senses distortion on the output of the amp.

The amp would certainly produce more than my measured power levels by disabling the limiter and allowing it to chop off the top the sine waves. So would the others. You'll notice that Camco's literature says this thing is good for about 2,400 watts with a 1kHz sine, which is pretty close to what I measured.

I would choose a class D amp for sub duty.
Logged
God bless you and your precious family - Langston

Soundscapes <><

RYAN LOUDMUSIC JENKINS

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2639
Re: Vortex 6 Smackdown
« Reply #26 on: July 22, 2007, 09:59:17 AM »

I agree with you about using the circuit.  I use it even on my subs and lows.  I would imagine that Nexo's processors probably do take everything into account but for a regular guy, like myself to try to set his processor and expect it to be perfect for all applications is naive.

I was just curious as to how you had the settings because they do appear to work a little differently than others.  Of course Camco does not let the user have the limiter without the speaekr protection.  That would be interesting to se if that changed anything.
Logged
Ryan Jenkins
"Two days until the end of when I don't know what to think.  Three days until I start the cycle all over again!"

Please visit my website at http://www.murphygirl.com

Langston Holland

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 908
Re: Vortex 6 Smackdown
« Reply #27 on: July 22, 2007, 10:18:20 AM »

Ryan wrote on Sun, 22 July 2007:

...but for a regular guy, like myself to try to set his processor and expect it to be perfect for all applications is naive.


The more I learn about this stuff, the less impressed I am with myself. A long time ago I thought I was all that and a warehouse full of Pringles. I am impressed with your posts - you're one of the fastest learners on the forum. :)

Before that:

I would imagine that Nexo's processors probably do take everything into account...


I'll bet you a nickel that Nexo recommends that the Camco's have the limiter engaged even though they have intimate knowledge of their loudspeakers. I would be interesting to have some feedback from a Nexo/Camco user on that.
Logged
God bless you and your precious family - Langston

Soundscapes <><

Dan Brown

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1450
    • http://www.reachcomm.net
Re: Vortex 6 Smackdown
« Reply #28 on: July 22, 2007, 03:01:29 PM »

Langston Holland wrote on Sun, 22 July 2007 09:18

Ryan

I would imagine that Nexo's processors probably do take everything into account...


I'll bet you a nickel that Nexo recommends that the Camco's have the limiter engaged even though they have intimate knowledge of their loudspeakers. I would be interesting to have some feedback from a Nexo/Camco user on that.


Um, as far as I know Nexo recomends to not have any limiters set on the amps.  This would only change the signal after the processor which I KNOW they DO NOT recomend.  I have my Vortex6's set to off on the amps themselves.  You need to make sure you have the processor set right as wells as having the sense lines hooked up from the amp.  If you do that correctly you should be in good shape with you Nexo rig.

sincerely,
db

[edit - Langston, I think you owe Ryan a nickel]
[edit - fixed quote]
Logged

Langston Holland

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 908
Re: Vortex 6 Smackdown
« Reply #29 on: July 22, 2007, 06:03:19 PM »

That's pretty fancy. I didn't know the Nexo processor used sense lines at the output of the amps - one step away from a high quality active loudspeaker. Engaging the amp's limiters would result in a nonlinear sense line measurement near peak output, thus confusing the processor. To a smaller extent, the "speaker protect" switch position on the back of the Vortex 6 apparently reduces gain slightly to minimize clipping as it steps between the 3 rails of its class H design. It would be interesting to find out if Nexo recommends that this feature be bypassed as well.

Bet you a nickel the sense lines enable the processor to clamp down on excessive distortion from the amp as well as over voltage to the driven bandpass. :)
Logged
God bless you and your precious family - Langston

Soundscapes <><
Pages: 1 2 [3] 4 5 6   Go Up
 

Site Hosted By Ashdown Technologies, Inc.

Page created in 0.031 seconds with 18 queries.