How to I use 2 additional qsc 500 watt power amps to push 6 jbl225x (4) ohm cabinets. I am running unbalanced stereo. Thanks, William

You would want an amp at least the wattage of the speakers, I would go double the wattage, say 800 watts and fuse speaker so as not to blow them. This way you have power to spare if you upgrade.
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You should NOT drive the amplifier into the clipping mode continuously. There is a possibility that you have fried your speakers or that they are the real problem. You haven't told us what you were driving, however this amp will deliver 450 Watts per side RMS at 8 ohms which means your speakers have to be rated at least that much RMS power for continuous. When speaker voice coils fry, they can wipe out amplifiers. Let us know what speakers you are using and how they are configured. This amp is going to be expensive to repair I can tell by looking at the schematic: Here is the schematic:

http://elektrotanya.com/qsc_plx2502.pdf/download.html

Scroll down to "get manual" and click to download it. IGNORE other download links.

This amp has circuits to boost the power supplies to the amps to handle the peaks. It is rather complex but the schematics are complete and have good explanations... some of the best I have seen. There are going to be a lot of destroyed components and great care has to be used after repair to "cold start" the unit to make sure nothing else is bad or it will blow up again. Most people do NOT have trouble with the QSC amps... so do tell me what speakers you are using and how they are configured so we can verify the design is correct. This amp is rated for 8 ohms so USUALLY only ONE speaker can be connected per side... and finding an 8 ohm speaker that can take 450 watts continuous RMS isn't easy. People fall for the advertising claiming "Peak" and "Program" power which are FAKE advertising... ONLY use continuous RMS power when sizing amps and speakers. There are MANY ways to cook out equipment... One is to boost the bass or the treble way up. Another is to NOT use balanced interconnect lines between mixers and your amps. Yet another is to NOT power ALL interconnected equipment from a single receptacle or power conditioning module. Please describe your setup further so I can help you more!

You can do that but your subs will have to be monsters or you will blow them out as bridged mode will drive 2400 watts RMS into 4 ohms. Many speakers are rated in peak or program power... these are FAKE specifications. with this amp in bridged mode each of two identical speakers would have to be rated at 2400 watts program or about 3600 watts peak each to survive... When rating speakers and amps ALWAYS compare RMS values... and for safety use an amp of 80% of the RMS rating of the connected speaker or speaker system.

when using amps,, you can't go by the number of the amp to determine what wattage the unit puts out, after checking on this amp,, the white marks that your seeing on the cable, is probably just some of the thermal paste that you apply to any heatsink or CPU ,, nothing to worry about, now as far as the wattage,, here is what they say about that amp, so there is a difference between the 4 and 8 ohm set ups
The Markbass Little Mark 250 bass amp head is a high-quality bass amplifier with a solid-state preamp and an analog power amp. The Little Mark 250 delivers 250W of power into a 4 ohm cabinet, or 150W into an 8 ohm cabinet. This Little Mark has a 4-band EQ, Markbass' VLE (Vintage Loudspeaker Emulator) and VPF (Variable Pre-shape Filter) filters, as well as both Gain and Master volume controls. The front panel accepts both a passive or active bass 1/4" input, as well as a balanced XLR input for acoustic bass pickup systems or a microphone. On the rear panel you'll find a Neutrik Speakon combo jack output that accepts both Speakon or 1/4" speaker cable as well as a second 1/4" speaker out jack. You'll also find a balanced XLR out, unbalanced tuner out so you can tune as you play without passing your signal through pedals, and a Send and Return Effect loop which saves you from losing your signal if one of your pedals dies or a cable in the chain gives out.

This makes no sense... 32 Watts and 12.8 volts... something to do with this speaker that is rated at 500 Watts???

If you are trying to calculate something for a car amp you don't understand how they work... that is the only thing I can think given the 12.8 volt thing you stated. Most high power car amps BOOST the incoming battery voltage up with a switching power supply. For instance, they might boost to 48 volts and that applied to a 4 ohm speaker would be 12 amps PEAK maximums. BUT the RMS power is one half that or about 288 Watts in round figures before considering losses.

Many car amps are designed to run with 2 ohm speakers... JUST SO THEY CAN CLAIM massive power values in their ads so you will buy them!

The JBL EON 305's are 8 ohm speakers. The PMP5000 wi;; produce 400 Watts per side into a 4 ohm load (600 Watts peak). Into your 8 ohm speakers, the peak current will be halved while the voltage remains the same so you ACTUAL power per side is 200 Watts. It is hard to know how much you expect to get out of the amp. This power would fill a venue of at least 2000 sq ft. If you need more sound, try borrowing another 8 ohm speaker for each side and parallel them with the EON's as a test. That will double the power and add 3 Db more of sound. Your main slider should be around unity typically. This amp is a class D switching type (very efficient) and runs on +/- 70 volt rails. giving about 45 volts RMS output. At 4 ohms, this is just over 10 amps giving 450 Watts... at 8 ohms this is around 5 amps or 225 Watts.


Please read my tip on Fixya about the ground hazard of channel A when using 1/4 inch cables out of the PMP units... essentially the BARREL of the connector from channel "A" is the HOT,... NOT the tip of the PLUG. Ground the barrel IN ANY WAY AND YOU FRY CHANNEL "A" AMP !!!

150 watts should be easily handled by four Peavey speakers in the connection you described.. If the Peavey's are 8 ohms, then your total load was 8 ohms for the series/parallel arrangement which is well within the 2 ohm drive capability of the Crate according to specs.

I question if you really mean the speakers were in series? This requires a special cable to do this. Now if you mean they were "daisy chained" like the amp went to one speaker and another cable connected that speaker to another, then you REALLY had ALL speakers in parallel electrically which would be at the 2 ohm low limit of the amp... In either case, with only 1/4 of the 150 Watts to each, the speakers should NOT have been damaged. The amp MAY have been damaged. Try each speaker individually at a REASONABLE level to test.

If you plug into the effects loop out jack,OFTEN the connection to the internal power amp is broken so you might have to arrange a special cable as a wye to go back into the power amp as well as your external amp. In any case pwere ALL interconnected amps, etc from the same power source/receptacle for system safety.

Use a SPEAKER RATED cable which will have good quality 1/4 inch jacks. Go from a speaker out on the head to one of the jacks provided on the speaker cabinet. NOTE: some newer speaker cabinets use SPEAKON connectors and if those are provided, they are more secure than 1/4 inch plugs/jacks.

PLEASE loop the speaker cables through a handle of the cabinet at each end to avoid them being yanked out while hot as the amplifier can be damaged if it happens.

OBSERVE the maximum load. If the amp says 4 ohms minimum, put no more than two 8 ohm cabinets on the amp as two 8 ohms parallel to 4 ohms.

DO NOT use an instrument cable.

that depends on your speakers, not the mixer. the amp should be matched to the speakers, in watts and in ohmage. for example, 400 watt, 8 ohm speakers should get an amp that runs at 350-500 watts at 8 ohms.

If you add 8 ohm speakers in parallel then you would be running the amps into a 4 ohm load ...which will overheat and possibly damage them ...... if you wire series then the amps would be loaded to 16 ohms ...which would be ok ..but you will only develop 70 % of the total output power
IE a 100watt would be down to 70 watts
much better to add some seperate powered speakers