Bargin Pro Amplifier

Discussion in 'Home Theater Projects' started by Rob Formica, Mar 19, 2003.

  1. Rob Formica

    Rob Formica Stunt Coordinator

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    Just thought I’d give you guys a heads up on the JBL amps on liquidation... the prices are incredible (and include shipping) and would make great sub amps as they are bridgeable... but there are catches:

    The amplifiers in question are JBL MPC200 (200Wx2 @8ohms 143$ shipping included) and MPC300 (300Wx2 @8ohms 193$ shipping included), which were originally manufactured by QSC and are the same as the QSC-CX4 and QSC-CX6. They are unfortunately 220V units for the export market but can easily be rewired for 120V as they are internally equipped to handle both 120V and 220V. I posted the question on the QSC tech forum at

    http://www.qscaudio.com/cgi-bin/ulti...c;f=2;t=000006

    JBL is liquidating these amps directly at their Tent Sale as Harmon now sells (owns) Crown amps. They have about 90units left... as well as two slightly higher end (but still 220V) MPA275 and MPA750. I don't know if the MPA series can be as easily rewired though.

    The link is:

    http://www.jblpro.com/Tent_Sale/sale_items.htm

    The other catch is that the sale is for US mailing addresses only, which could be a pain in the butt for us Canadians. I hope this can be of some use to someone...

    I've ordered a MPC200 but haven't received it and tried the voltage mod yet. If it all works out, these are a steal.

    Later...
    Rob.
     
  2. David Lorenzo

    David Lorenzo Stunt Coordinator

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    Thanks for the info Rob.

    I can't seem to find the CX4 and CX6 on QSC's site, but found 2 that are similar in power, the CX302 and 502. Are these similar to the JBL amps? If it is, this really is a great deal.

    edit: Nevermind I should have clicked the "info" text on JBL's site before asking. :b
     
  3. Rob Formica

    Rob Formica Stunt Coordinator

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    Someone brought it to my attention, but the amps have 225W is into 4ohms x 2 channels not 8ohms, sorry about the typo… [​IMG]

    These are all discontinued models, but the info is still on both their sites... The JBL literature is available at:

    http://www.jblpro.com/pages/electronics/mpcamps.htm

    And the equivalent QSC CX4:

    http://www.qscaudio.com/support/libr...s/pdfs/cx4.pdf

    Actually QSC keeps most of the product info (CX4, CX6, etc...) online at: http://www.qscaudio.com/support/prod...literature.htm

    I did verify with JBL about whether they are 230V units and the fact that the brochure mentions they are not configurable... they responded:

    "Hi Rob You can change the units to 120V!!! Do you have a Fax # I do not have the mod in a pdf sorry..."

    I also have the fax (which I can scan and post) about the modification... ironically it's a QSC document for the CX4 and CX6, but he (JBL) explained that they are basically the same model. I haven't tried the modification yet, but it's basically moving 2 connectors and a new power cable. I can let you guys know how it works out.

    The way I see it, it's an economical option to the QSC RMX850 with slightly less power.

    Later...
    Rob
     
  4. Tracy_L

    Tracy_L Stunt Coordinator

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    Just to throw a little meat into your comparison, I shopped around for a couple of days on the net to find a best price of $269 shipped on the RMX850. I can get (according to QSC) 600 watts bridged mono. Can't wait to get my IB config built to give it a ride..... :b
     
  5. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    It's a bit of a slippery slope. For $299 shipped, you can get the Crown XLS402, which does 800 watts into 8 ohms bridged, and 1140 watts into 4 ohms bridged. So an extra 30 clams buys you 200 more watts at 8 ohms and 310 more watts at 4 ohms. [​IMG]
     
  6. Robert_Gaither

    Robert_Gaither Screenwriter

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    I was wondering, does the mod require a soldering iron?
     
  7. Rob Formica

    Rob Formica Stunt Coordinator

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    Since i haven't received my unit yet, i'm not sure what connector was used (clip, screw, solder, etc...) and the techinical drawings just show two connectors have to change places. There is also the wall plug to be changed

    It should resemble most other QSC PCB connectors... anyone know?
     
  8. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I wonder how Pro Audio amps sound when powering standard home theater loudspeakers.
     
  9. ThomasW

    ThomasW Cinematographer

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    Chris

    Digital switching amps especially low buck ones, can do weird things to the waveforms above 350Hz. So IMO their use should be limited to subs.

    Note that high end designs, Bel Canto or Spectron for example, are a different breed of animial.
     
  10. Bill Fagal

    Bill Fagal Stunt Coordinator

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    Hey Rob

    I'd certainly appreciate it if you'd post the mod diagram. I just snapped up an MPC300.

    Thanks,

    Bill
     
  11. Rob Formica

    Rob Formica Stunt Coordinator

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    For those who would like this info, I will be posting both the MPC200 and MPC300 sometime this coming week... stay tuned...

    Rob
     
  12. Rob Formica

    Rob Formica Stunt Coordinator

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  13. David Lorenzo

    David Lorenzo Stunt Coordinator

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    Thanks for the info Rob. Have you listened to them yet? How loud is the fan?

    P.S. I think the term you were looking for is "Printed Circuit Board".
     
  14. Rob Formica

    Rob Formica Stunt Coordinator

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    thanks david... i knew it didn't sound right.... i corrected it... [​IMG]

    As for the fan, i still don't know as i haven't received mine yet. It'll take my MPC200 at least an additional week vs most people, since i'm in Canada and had it shipped to a friend. Oh well, "good things come to those who wait..." let's hope it's true...

    later...
     
  15. Al Garay

    Al Garay Stunt Coordinator

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    It's probably not a big deal to replace the fan.

    I wonder if the MPC300 will work with the AV15? Anyone know? MPC300 claims 900Watts bridged into 4 ohm. There are no specs into 2 ohm.

    Al
     
  16. Bill Fagal

    Bill Fagal Stunt Coordinator

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    I can't think of very many pro amps that are happy with a 2-ohm load in bridge mode...

    Bill
     
  17. Bill Fagal

    Bill Fagal Stunt Coordinator

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    Just got my MPC 300 (QSC CX6) yesterday. They shipped it in only its basic box, no other boxing/cushioning. I hope it's all right. Popped the hood--no visible damage inside/out. It looks/feels pretty bullet-proof. Pretty heavy sucker--felt like maybe 45lbs--mostly the huge tranny. I'll try to make time to do the 120V conversion this weekend.

    For those who were wondering, fan swapping looks like it would be a breeze (pun intended). It's just a standard muffin unit that plugs into prongs on the PCB.

    Bill
     
  18. Al Garay

    Al Garay Stunt Coordinator

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    Let us know how it sounds? What drivers are you using? And what are you using for a crossover?

    thanks,

    Al

    I'm hoping that the MPC300 will have no problem driving an AV15 subwoofer. I would still need to buy a crossover which raises the price ($190 for mpc300 + about $100 for electronic crossover to a level where I might keep looking for a 500Watt plate amp.)
     
  19. Bill Fagal

    Bill Fagal Stunt Coordinator

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    This is an amp without a cause until I decide which way I want to go with my bass system--either an IB or twin ELF boxes. Can't even test it until I perform the 120V conversion.

    Were I in your shoes, I'd go for one of these + a prosound electronic XO. Not only is there more power, IMHO there's a bunch more flexibility. The MPC gives you two channels so you can drive any 2 loads from 2 to 8ohms, and single loads in bridge mode from 4 to 8ohms. Add a pro XO and you've got the potential to fully bi- or tri-amp a 2-channel system. If you don't have bi/tri-amping ambitions, I'll bet there are some on this forum who'd help you figure out how to breadboard a simple electronic XO from scratch.

    If your application is a single AV15, the MPC specs seem like it would be just the thing. Dual 2ohm VCs, right? Well, the MPC has a switch on the back for parallel mode, where one input signal feeds to both channels. Wire a channel to each VC, and you've got a full 900 watts on tap.

    (Of course, I say all this as theory, without having yet heard my amp!)

    BTW, as I read the MPC literature, I got a little worried because it mentions a subsonic filter, but doesn't give the corner freq. I was hoping it wasn't at 20Hz! Well, I just got confirmation from the QSC tech forum that the MPC amps have a third-order subsonic filter at 8Hz. Whew! That's low enough, I'd say.

    Bill
     
  20. Al Garay

    Al Garay Stunt Coordinator

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    Thanks for the advice. I am interested in active amplification. Are there particular prosound electronic crossovers that you are thinking about that are good value?

    Al
     

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