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Author Topic: adavantage?  (Read 17779 times)

Nathan Short

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Re: adavantage?
« Reply #10 on: February 16, 2010, 10:29:14 pm »

The powersoft k10dsp actually let's the end user set the mains current limit within the dsp.  Can be a lifesaver in a difficult situation.   Unfortunately the test was done off of a heavy duty 20 amp plug on a 30 amp circuit off the mains panel in the shop. I did not feel comfortable wiring the amp into a bigger circuit and the k10dsp went back before the new distro arrived or I would gave taken the powersoft tests much much further. I had an old hearty 3600vz drawing 44 amps for a few minutes before getting scared!  That was neat to measure  
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AIS Chicago--System Designer

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Elliot Thompson

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Re: adavantage?
« Reply #11 on: February 16, 2010, 11:25:49 pm »

The old Crown’s were known for being current hogs. I really believe many never understood the amount of current those amplifiers will draw (based on the high current limit setting) and, assumed the size of the power cable was means of decoration. If I remember correctly, the MA 3600 current limit is 90 amperes.

Amplifiers that fall within the K10 range, really shine on voltage ranging from 200V on wards. If the United States offered 240 volts, as a standard Crown & QSC would have more than likely not be at a stand still on how much power they could offer to their customers.

Best Regards,
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Nathan Short

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Re: adavantage?
« Reply #12 on: February 17, 2010, 02:20:13 am »

Now if only we could put tiny little ZPM's inside them.....

Zero point modules, come on science!
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AIS Chicago--System Designer

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Matt F Castle

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Re: adavantage?
« Reply #13 on: February 18, 2010, 10:42:04 am »

Interested in any more info on what you found with the PLX3602, any likly hood of that happerning in a realy world usage situation?

Cheers

matt
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Nathan Short

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Re: adavantage?
« Reply #14 on: February 18, 2010, 02:19:27 pm »

My guess would be absolutely ,  keyboard or synth music, feedback near 15K which is very likely would be devastating to tweeters, low feedback near 30hz might be bad in a DJ situation.

I have had a few instances over the years where I had a properly limited system and for some unknown reason during some hip hop nights I had 1 or two subs basically blown right out of the basket, and leads ripped off without any other damage,  a quick burst of near 70-80v at 30hz would absolutely be a culprit.  As no coils were burned and just leads ripped out.

Who knows maybe Bob Lee could shed some light?

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Matt F Castle

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Re: adavantage?
« Reply #15 on: February 18, 2010, 06:42:58 pm »

What sort of input was causing this to happen?  I would like to think QSC test these things fairly well and you were doing somthing faily out of the ordinary for what you describe to happen?

Cheers

Matt (interested as I have a few 3602's)
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Nathan Short

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Re: adavantage?
« Reply #16 on: February 19, 2010, 12:08:57 am »

Hey grab an oscillator and find out. Turns out the new ones I just go do exibot this behavior.  Let me ask a few EEs and and designers then get back to you.
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Bob Lee (QSC)

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Re: adavantage?
« Reply #17 on: February 19, 2010, 05:24:57 pm »

Nathan Short wrote on Mon, 15 February 2010 14:58

The most interesting thing was finding a flaw in the PLX3602 that at 30Hz and 15K  channel 2 would behave normally and channel 1 would try and put out 81v!!!  Danger Danger!  and the amp would go into overdrive and try and pull 33amps from the wall.


What were you testing, and how?

What does "go into overdrive" mean?

And what is an RMX2402?
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Bob Lee
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Nathan Short

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Re: adavantage?
« Reply #18 on: February 19, 2010, 11:20:33 pm »

Sorry Bob, it seems you have not read the thread.

I have been in the process of torture testing about 4 OEM amps, and a couple of prototypes from new companies.  Included with these tests I had a pile of QSC  new and old, the new ones slated for an install in NYC coming up.  Some rebuilt RMX2450's, damn input pots are one of the only flaws with that amp,  always failing.  Thank god for my pile of replacements, and a good ol can of Caig labs deoxit and pro gold to protect them when they go into installs with any humidity in the air.

My apologies on saying 2402  when I meant Rmx2450.  

A slew of tests were run on all amps into two types of dummy load, various passive loudspeakers, and a couple of huge port assisted hybrid horn loaded 18's with 5in voice coils and a lot of abuse room.

Overdrive is what I would call when the amp in question, the PLX3602's fan kicked into high speed, and the meter showed that it was pulling a ridiculous amount of current I have never seen that amp draw before.  But granted this is the first time I have torture tested that amp other than the near 100 units I have put in my medium budget DJ rigs over the past 5 years or so since it came out and replaced the older plx model.

The current meter/distro unit I was using I cant actually say, Signed the NDA already.  But needless to say it is ridiculously accurate, and is the same unit that protects every server farm on nearly every US military server farm.

I don't know if it is just the batch I just received, but I also found one other amp that did this,  an A/B Bipolar Mosfet Hybrid,  channel one was more than double the voltage at 15Khz but not 30hz. Current draw went up a bit, but the 3602's took the prize for jumping to 33amps and 81v.
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AIS Chicago--System Designer

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Matt F Castle

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Re: adavantage?
« Reply #19 on: February 20, 2010, 01:36:05 pm »

It would be helpful if you could actually tell us how you achieved this happening, what were your test conditions, what were you putting in to the amp etc?!

I would like to think QSC do fairly comprehensive testing on there products and the condition you describe was not as a result of the amp being connected to a normal speaker and just driven with a test tone or normal program music with an amount of the frequency's you mention? and this something that will happen consistently with a *normal* use input??

Cheers

matt
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