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[John Roberts {JR}]

Sorry, my bad, that was just the first link that came up on Google, i'm used to ignoring all the advertising rubbish those sort of pages throw up before the download link appears..

Try the below, straight link to the .pdf if you wanted to have a look:
www.lite-works.co.uk/qsc_plx3002.pdf

I'm somewhat curious what that part actually does as the PSU seems to run at 220v natively as far as I could tell ?

Cheers,

matt

Thanks I can read that... without any trolls under the bridge collecting a toll.

It looks pretty much like I thought , either a FW rectified 340V or +/- 170V ...   They use a 50a 600V bridge and stack reservoir caps in series with resistors to force them to share. They are only 200V caps so can't handle the full rectified 240V mains. (Big high voltage caps are large and expensive).

This front end rectifies the mains to make DC, then chops that to send through a small HF transformer to generate the secondary winding voltages.

It does not care where the 340V DC  comes from 1x 340V or 170V+170V.

Pretty much what I expected...

JR

PS: Maybe tomorrow when I'm sober I'll look for the low voltage cut out circuitry. Not now. 

[Jeremy Young]

My reading of that white paper suggests a 10 millisecond ride through time (an actual test measured 18 mS on one particular supply), which seems more plausible and practical.

GTD

Many of you have caught on to my typo.  I will refrain from posting via a phone again, that obviously stirred up more than it should have.  Yes, I meant to say MILLISECONDS!  Holy cow if 10 seconds were real, imagine what the marketing departments would have done with that info! 


Sorry to derail things a bit guys, was strictly unintentional.

[Jeremy Young]

I wrote a long answer this morning but was mostly repeating myself so deleted it.

Hi Matt, welcome to the party. It looks like Bob Lee has graduated from herding cats on the internet.
Not sure what this has to do with audio power amps... there is no 10 second rule when it comes to power amps.  8)I don't recall the rule of thumb but IIRC it was something like +/- 20% of nominal mains voltage (plus some extra something for service in primitive markets).  Things got a little weird when 220/240 countries became 230V countries (a good thing IMO), and there were always markets like out in the OZ outback at the end of a miles long power feed when voltages were crazy low, or at the start of a long power run where they were crazy high, to make it to the end without step up in the middle. The crude switching PS used in front of typical value amps offer no regulation to speak of and no significant drop out protection. You would need capacitors the size of a car battery for 10 seconds of hold up at power, more or less.

JR

I'm used to seeing minimum and maximum operating voltages in the mechanical engineering universe that occupies most of my mind.  (I'm not one, but I have to interpret their work daily).  For example, I know of cooling equipment that will operate down to 94VAC, but NOT 93 (because that would be terrible/sarc).  It just won't turn on below that.  More often, it's the stuff that works on 230v but not 208v that causes grief.  I'm sure there must be defined allowable voltage drop in the NEC as far as the receptacle, but once we start running our own power, where's the threshold? 

Mike, with your Suretest Analyzer, what percentage of voltage drop would indicate a "fail" to you, versus a "pass"?

So I guess I was hunting for a "minimum acceptable voltage" on the spec sheet, so I could compare a DSP versus non-DSP amp, and a linear versus SMPS amp, since I would expect a DSP amp to be more susceptible to brief (in the MILLIseconds, see what I did there?) voltage drop, whereas something "dumb" might still make noise for that moment, albeit clipped.  This seems to be the issue the OP is having, where the amps go into protect under voltage sag. 

The line of thinking (in my head) would then follow to say that perhaps a SMPS would be more resilient to these brief voltage drops.  Different power supply topologies in different amps = different animals.  However, you have stated otherwise so I stand corrected.  I was connecting dots together and likely misinterpreting something along the way so.....I'll go back to lurking. 

Mike, JR et al are the true experts on this forum.  I seem to have gotten lost wandering out of the lounge.  Anyone seen the "you are here" map? lol

[Dan Richardson]

Mike, with your Suretest Analyzer, what percentage of voltage drop would indicate a "fail" to you, versus a "pass"?

So I guess I was hunting for a "minimum acceptable voltage" on the spec sheet, so I could compare a DSP versus non-DSP amp, and a linear versus SMPS amp, since I would expect a DSP amp to be more susceptible to brief (in the MILLIseconds, see what I did there?) voltage drop, whereas something "dumb" might still make noise for that moment, albeit clipped.  This seems to be the issue the OP is having, where the amps go into protect under voltage sag.

In an earlier thread, when I was first having trouble with my PLXs going down at the end of long extension cords, I did some bench testing. Bridged PLX 3002 into a 4 ohm sub, pink noise, just flickering clipping, analog ammeter wildly swinging around 10A, goes to protect at 87v. Idle protect was 75v.

Another post in this thread indicates that they are also sensitive to voltage changes, either positive or negative. I was only testing more-or-less steady states.

[John Roberts {JR}]

I'm used to seeing minimum and maximum operating voltages in the mechanical engineering universe that occupies most of my mind.  (I'm not one, but I have to interpret their work daily).  For example, I know of cooling equipment that will operate down to 94VAC, but NOT 93 (because that would be terrible/sarc).  It just won't turn on below that.  More often, it's the stuff that works on 230v but not 208v that causes grief.  I'm sure there must be defined allowable voltage drop in the NEC as far as the receptacle, but once we start running our own power, where's the threshold? 

Mike, with your Suretest Analyzer, what percentage of voltage drop would indicate a "fail" to you, versus a "pass"?

So I guess I was hunting for a "minimum acceptable voltage" on the spec sheet, so I could compare a DSP versus non-DSP amp, and a linear versus SMPS amp, since I would expect a DSP amp to be more susceptible to brief (in the MILLIseconds, see what I did there?) voltage drop, whereas something "dumb" might still make noise for that moment, albeit clipped.  This seems to be the issue the OP is having, where the amps go into protect under voltage sag. 

Many digital controlled products can reset if power is interrupted even briefly, but this should be benign, unless it happens in the middle of a song.  Waiting for a long boot-up sequence can be upsetting. Better designs can add enough hold up time to ignore very brief interruptions.

The line of thinking (in my head) would then follow to say that perhaps a SMPS would be more resilient to these brief voltage drops.  Different power supply topologies in different amps = different animals.  However, you have stated otherwise so I stand corrected.  I was connecting dots together and likely misinterpreting something along the way so.....I'll go back to lurking. 

Yes, switching PS (or class D amps) introduce a new risk where the control circuitry can get stupid at too low voltage and blow itself up. 

JR

[Dan Richardson]

If you can't fix the power, use a tool you know will couple better with the lower voltage?

Update. I replaced the pair of bridged QSC PLX3002 with a single Peavy IPR2 7500. Same Honda EU3000i generator. Beat it hard all day. No problems. Sounded great.

[g'bye, Dick Rees]

Update. I replaced the pair of bridged QSC PLX3002 with a single Peavy IPR2 7500. Same Honda EU3000i generator. Beat it hard all day. No problems. Sounded great.

Congrats.  Another problem transcended.

[Tim McCulloch]

Congrats.  Another problem transcended.

I just love a happy ending.   

[Scott Holtzman]

I just love a happy ending.   

I love my IPR2 also!

[John Roberts {JR}]

Update. I replaced the pair of bridged QSC PLX3002 with a single Peavy IPR2 7500. Same Honda EU3000i generator. Beat it hard all day. No problems. Sounded great.

Glad it worked out..

Peavey has been messing with class D since before I went there in 1985. They have probably already made all the obvious mistakes, and engineer amps for world power conditions that can be far worse than we encounter.

JR

PS: I just wish I had these modern amps to market back last century when it was my day job.

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