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[John Roberts {JR}]

Scott Hibbard wrote on Mon, 02 April 2007 15:52

Nate, I noticed a damping factor of only 200 on the PL380. Is that a typo???? The mighty 6.0 has a damping factor MUCH higher (2k if I recall correctly). Hoping it's a typo.  If it's not, it would have the lowest damping factor of any PL, PL2 or PL3.  Let me check with QSC... ScottH

Without lecturing about how good 200:1 actually is, I suspect in a class D design with an big honking output filter to convert the PWM back to continuous audio, that's a respectable number considering the engineering tradeoffs involved.

The downside to publishing specs is seeing how people draw curious conclusions from apple to orange comparisons. The short answer is a damping factor of 200 is more than adequate. I'm too lazy to write a long answer at the moment.

JR

[Scott Hibbard]

John,

Let me save you the typing and post a message from Bob Lee in this regard.

"...The PL 380 is a class D amp, which requires a passive low-pass filter on the output to integrate the switching pulses back into a reconstructed audio signal. This filter increases the output impedance by a small amount of impedance."

I didn't mean to imply a low damping factor was bad, it was simply an observation when comparing AB's, H's and D's - maybe unfairly so on my part.  (I also failed to remember at the time of posting that the PL 6.0 is a class H amp - totally different animal)

With MAP prices posted per John, these should sell pretty well.  I just placed an order for (6) PLX 2502's otherwise had I known these were coming I might have changed that order to (4) PL340's.  Oh well!

ScottH

[John Roberts {JR}]

Scott Hibbard wrote on Mon, 02 April 2007 20:14

John, Let me save you the typing and post a message from Bob Lee in this regard. "...The PL 380 is a class D amp, which requires a passive low-pass filter on the output to integrate the switching pulses back into a reconstructed audio signal. This filter increases the output impedance by a small amount of impedance." I didn't mean to imply a low damping factor was bad, it was simply an observation when comparing AB's, H's and D's - maybe unfairly so on my part.  (I also failed to remember at the time of posting that the PL 6.0 is a class H amp - totally different animal) With MAP prices posted per John, these should sell pretty well.  I just placed an order for (6) PLX 2502's otherwise had I known these were coming I might have changed that order to (4) PL340's.  Oh well! ScottH

Ok, not to beat a dead horse, but a DF of 200 is not "low", it only seems low on paper in  comparison to some other amps that deliver silly high DF for mostly marketing purposes and/or to mitigate another company's misguided marketing Sometimes it's easier to join them than un-learn a factoid once it's gained traction with consumers (like slew rate, etc).

I was involved in that dance for a while and tweaking an amplifier to deliver silly DF numbers can involve things like heavier duty relay contacts, heavy gauge internal point to point wiring, etc. I even had one high DF amp that could only be dialed in for high DF with one or the other of the output connectors not both (but that was a DF in the thousands).

DF in modern solid state amps is a non-issue. If a salesman tries to convince you otherwise put a hand on your wallet for safety and back out of the store.

JR

[Kent Clasen]

From talking with QSC at NSCA they should be available soon.  From what I heard, a VERY well known touring company had significant input on this amplifier.  Also, the testing that QSC puts their amps through before they release them is very stringent, from what I have heard (not fact), many popular amps by other mfgs. will not pass their list of tests that these PL3 amps pass.

PL6.0/9.0 are really fine amps.  I think these amps will perform well, esp. considering cost.  PL3 amps are built to order in Costa Mesa by their mostly automated assembly process=cost savings, 4.0/6.0/9.0 were hand made=very expensive.  Time will tell...

From this months System Contractor News:  

http://systemscontractor.com/articles/publish/article_1467.s html

Here is Pat telling us about the original 9.0 (I think, this was many, many years ago...I am very young and wearing the white shirt/bad haircut) I laughed hard when I saw this    

[Paul Bell]

Yeah, I'm using the 9.0 to drive a pair of the BASSMAXX Z5000 cabinets, one 2 Ohm cabinet per amp channel.

Yes, at 4 Ohms bridged or 2 Ohms stereo, the 9.0/6.0 was rated at 1KHz. However, at 4 Ohms stereo or 8 Ohms stereo or bridged, they rate them at 20Hz to 20KHz.

All the ratings of the PL3 amps are at 1KHz.

[Kent Clasen]

Nathan Lehouillier wrote on Mon, 02 April 2007 07:58

The PL3's don't look all that great on paper. I am a little concerned about the way the PL3's are   rated. It's one thing if my pants burst but my amp's should just Rock. I love all my QSC's but I think QSC should take a mulligan on the burst thing and come back with some real #'s. I would like to see a PL-384. Give me a sub amp I can use. 4000W at 4ohms than burst power will be just fine. Nate KDS&L

From looking at their web site, it looks like only the PL380 at 2 ohms was rated with Burst Mode testing.  Obviously the 380 is not intended to be a 9.0.

In looking at other bigger amps, it seems that about 1/2 the other mfgs rate their amps in this category at 1kHz.  Maybe they are just trying to appease all the people that just look at watts/per channel, I dunno.  I would like to see 20-20kHz AND 1kHz ratings.
   
PowerLight 3 Power Amplifiers
Watts at Clipping
    Watts per channel
Model    8 ohms    4 ohms    2 ohms
PL325    500    850    1250
PL340    800    1250    2000
PL380    1500    2500    4000*
EIA 1 kHz 1% THD
* Burst mode testing required due to AC service current limitations

[Nathan Lehouillier]

My question is why is the 380 limited by input
current. Doesn't the 9.0 live on a 30A 120V?
With class D the 380 should be fine with the
same 30A. So what is the problem?

Nate KDS&L

[Jason Joseph]

If I was to understand correctly QSC is still waiting for the Nuetrik Powercon 30amp connectors to be certified so maybe that is the reason for the preliminary numbers... I own a Powerlight 6.0 II currently but knowing what these amps look like they can put down on paper and knowing the companies fine reputation I am eager to see what they can do in the real world...