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Power amps: Stereo vs Bridged

Discussion in 'Amps and Cabs [BG]' started by ADuck5150, Sep 2, 2004.

  1. ADuck5150


    Jul 31, 2004
    I'm thinkin about pairing a QSC PLX 1602 with an Eden 210xst. I'm pretty much sold on the Eden, while I'm still up in the air about going the pre/power route. I've noticed that most of you pre/power users run your amp bridged. I was wondering what the perks of running bridged were, besides the volume. It seems that if I were to run stereo, the 500 watts the amp would put out would be a good matchup with the cab I'd be using (4ohms, 450 watts handling). Am I wrong about this?
  2. James Hart

    James Hart

    Feb 1, 2002
    Endorsing Artist: see profile
    one 2x10 cabinet isn't gonna be run stereo, so if you don't bridge, you'll be using 1/2 of your amp.
  3. chucko58


    Jan 17, 2002
    Silicon Valley, CA, USA
    I paid for all my gear myself. Well, me and MasterCard.
    If half of your amp is enough - and at 500 W with an efficient cabinet, it should be! - then go ahead and run one channel. You can always add another cab later.

    There's nothing wrong with bridged mode, it will definitely give you more clean headroom. But you can easily exceed the cab's power rating without even knowing it. Running one channel of the PLX, you will get a clip light when you exceed 500 W, so you at least get an indication that you're pushing the limit.

    If this is your first big power amp, take it easy until you get used to its capabilities.
  4. TheChariot


    Jul 6, 2004
    Boston, MA
    ... which wouldnt really hurt anything, though. I think you'd be fine to run in stereo. Later on you can simply add another 4ohm cab and have 500W per side.

    Another option is to go for the PLX2402... because I would think your cab could handle 700W just fine. This would give you more headroom for the future if/when you add another cab to the equation.

    As for Bridged vs Stereo.... I think a lot has to do with impedances and stress on the amp. Unless you buy a complete piece of crap, then your power amp should be able to run Bridged just fine. Sure... the components are technically stressed a WEE bit more and blah blah blah.... but its nothing serious really.

    However, looking at the power ratings of the PLX series... it would be less stress to run a PLX3402 @ 4ohms stereo and get 1100W... than it would to run a PLX1202 @ 4ohms bridged and get almost the same amount of power.

    It's only as complicated as you want to make it. I really dont think any of it is a big deal unless your playing some big, outdoor gig where you need a FULL 1600W amp and then some; a situation where you'd be pushing your amp hard. Other than that... standard operation isnt much of a concern.
  5. ADuck5150


    Jul 31, 2004
    With the type of music I play, I really don't see how I would need more than 500w, especially since I get PA support 98% of the time. But if I were to add a second 4ohm cab and run stereo, the amp would be running 2 seperate 4-ohm loads, not one 2 ohm? And I'm not too clear on the headroom issue - what constitutes how much headroom you have?
  6. Two four ohm cabs run stereo will create a 4 ohm load on each channel, so you're only running at four ohms...however the same 4 ohm cabs run bridged mono will result in a 2 ohm load on your amp...a situation that you want to stay away from. As for your other question: the more watts you have, the greater your headroom, or potential volume. Now this only goes as far as the number of watts you cab will take, but generally the more wattage you have the better your sound will be, even at low volumes, regardless of your cab's power rating. Your amp will also not need to work as hard to reach full volume.

  7. CrackBass


    Aug 10, 2004
    i definately recommend bridging your amp. i can tell a big difference in the sound when i bridge mine. 4 times the headroom is a great thing to have. even at lower volumes it's like you can hear the extra force behind the notes. besides that, you never want to run a power amp full out. that's when you get distortion, the number one speaker/tweeter killer. i would rather use 500 watts out of 2000 than 500 out of 500. it is so much cleaner. i run a 2000 watt amp (bridged) into a cab rated at 450 watts. i never run out of clean power. 3 years and no blown speakers. the more power the better. the trick is not to use it all. although i would wager more speakers are blown from lack of clean power than an overabundance.
  8. FWIW... it seems to me that running an amp bridged puts a lot of extra strain on it. I've been running my QSC RMX 1850HD in bridged mono, to dump 1800 watts into my Acme B4.. and not only does the amp get quite warm (and makes you sweat your a$$ off when you're standing 3 feet away from it and playing), but even putting out that much wattage, it's quite easy to set the clip lights off during slapping or low B action. :meh: I guess headroom isn't all it's cracked up to be, at least when you're putting it through a current sink like an Acme cab.
  9. CrackBass


    Aug 10, 2004
    the goal is not to clip your amp. my point is that if you are clipping running 1800 watts at x volume, unbridged you would be throwing out 10 times the distortion at the same volume. definately a speaker killer.
    just a tip, try turning the bass down a bit and see if you can't get a little louder without clipping.
  10. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Be careful running 1600 watts of bridged amp into a 450-watt cab. Headroom is cool for sure, but one whack of the ol' B string (assuming you have one) could blow even the Eden speakers to teeny, tiny little microscopic smithereens.
  11. thejohnkim


    Sep 30, 2003
    i use that same cab, and it can get nice, loud, and full sounding with even 350 watts (large room with high ceilings, crowd of 300+ no pa support), so I think that 500 watts into the cab may be perfectly sufficient for you in most cases.

    but if you want to be safe you could always get a 8ohm and bridge the plx into that, and you'll ahve the option of adding another 8ohm 210xst later on if you need more volume.
  12. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Running one side of stereo (500Ws) is way enough imo, and it will cause less strain to your amp. Remember, when you run 4 ohms bridged, that means both channels are driven at 2 Ohms...
    If you run just one channel, then
    - you can add another cab later for the other channel
    - you'll have enogh power, anyway
    - the amp will heat up less - and stay good longer

    If you want more power, get a bigger amp - but unless you're playing stadiums without PA, that should do it
  13. Ditto the suggestion for a PLX 2402 or higher. You get the better output circuitry starting with the 2402 model. I own a pair of PLX3002, and a PLX1202. The only difference is price and power... weight and size stays the same. So do the heat sink sizes... my PLX1202 is better suited to a 2-ohm load than my PLX3002.

    Good words about bridging and a 4-ohm load. Yes indeed, both channels are running at 2 ohms... why put all this strain (read: heat) on your amp for no good reason?

    The RMX 1850HD is specifically designed to run at 2-ohm loads, because it has more heat sink area. The player above says his gets good and hot when bridging a 4 ohm load (2 per channel), so the heat load on a PLX will be worse.
  14. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    To a certain extent, more power is better but at some point it becomes meaningless. In the case of the Eden cab, running 500 watts, one side of the power amp will work fine. You can alway's 'donate' the other side of your amp to monitors or key's or just turn that channel down ...

    I don't require as much power as you do so I'm running a Crown CE1000, 275 at 8 ohms, 4 (and change) at 4 ohm, 900 bridghed into 8 and 1100 bridged into 4. I regularly run just one side into either 8 or 4 ohms. Once in a great while, like if I feel the need to be evicted from the neghborhood, I'll run one at 8 and the other at 4 ... with fairly efficient cab's it get's ridiculously loud.
  15. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    DFW, Texas
    I wish I had chosen the screenname 'MaxHeadroom'.

    If you use it carefully and judiciously, headroom while playing bass is a very good thing.
    You should get better dynamics in your sound (more lively and detailed).

    The stress on your amp should not be significant. You have a relatively efficient cab (as opposed to an Acme). The amp will be just loafing along.

    The risk is mostly based on your playing style. Listen to your cab attentively; it will let you know about the onset of stress. Approach volume increases slowly and take into account how hard you might play at different times. If you slap alot and your technique lacks finesse, you should be more careful and would probably be better off going to 'parallel' or 'stereo' mode and make sure the clip limiter is turned on.

    The suggestion regarding more powerful amps is a good one if you can afford it. The more power, the better... :bassist: