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PLX Bridgers: you might want to try this out.

Discussion in 'Amps and Cabs [BG]' started by lo-freq, Aug 17, 2003.


  1. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    Let me give you a caveat right up front, I am running my PLX1602 with the Clip Limiter set to 'Off'.
    This is not really recommended for the general bass playing populace, you can fry some good speakers in a heartbeat.
    I don't play at high decibel levels and I don't slap/pop (not live yet, anyway). Even so, I still keep a very close eye on my level indicator lights.
    The clip limiting is not supposed to be audible [according to Bob (QSC) Lee].

    The settings listed below will show CL on (cause I know some of you speed readers will skip/miss some of the details of this post and it's better to err on the side of caution.

    Below are excerpts from another TB thread (Thanks again, Big String for the info).

    --------

    OK. I'm bridged with no filters, so here's my switch settings:
    01 right
    02 left
    03 right (position shouldn't matter?)
    04 left
    05 left
    06 left
    07 right
    08 right (position shouldn't matter?)
    09 left
    10 right

    Pervieced results from switching from "Parallel" to "Stereo" while in "Bridged" mode on PLX1602 playing at two different clubs over the weekend: took a little more tone tweaking, but to my ears (& with my SR5) a good-sized step in the right direction toward to my ideal tone.

    Less stuffed-up sounding (more open & effortless), more naturally musical sounding and organic (that's organic, not orgasmic, but not far off).

    --------

    If anyone else tries this, I would appreciate hearing your feedback.

    [Maybe I'm just psycho-ceramic.]

    :bassist:
     
  2. Bravo LoFreq
    Glad it made a difference for you. That is what this site is all about. Sharing information and learning. Made some great aquaintances too. I wish it had spell check though...

    I'm gonna keep on experimenting with the Bridge thing, but I still feel I need a more powerful amp for Bridge and Stereo/Parallel modes. I'm gonna order a Bergantino NV610 very soon. Won't that be interesting :D
     
  3. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    Two questions for you. First, you are saying that switching from parallel to stereo was an improvement, right? Second, did you try both parallel and stereo modes in both clubs, or parallel in one club and stereo in the other? And if you did the latter, how do you know how much of the change was from the amp setting, and how much was from the room differences?

    Okay, that was three questions, but you get my point. :D

    Thanks, Tom.
     
  4. thank you
     
  5. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    Q1: right.

    Q2: both clubs are regular venues we have played (one of them only twice before and the other probably eight times), so I am familiar with their individual acoustics' effect on my system's sound. Up until this past weekend I'd used the bridged/parallel settings exclusively, so I can confidently attribute the sonic improvement to the switch to bridged/stereo.

    Doesn't make any sense to me. If the only change is input impedence, how could it have that much of an impact on the sound (especially with an active bass--seems like it might make more of a difference with a passive bass)?

    Anyway, it definitely sounds much better to me. Maybe Bob Lee would have some helpful input (or maybe I've just flipped out).

    Either way, I'm a happy camper.

    :bassist:
     
  6. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    Interesting. Now I have two experiments to perform, the "crank the gain on the PLX and back off on the preamp final gain" experiment and the "parallel/stereo" comparison.

    Thanks for sharing the knowledge and experiences!

    Tom.
     
  7. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    Se nada.

    Maybe you need a PL236?

    I'd sure like to hear a NV610, good luck.
     
  8. Phat Ham

    Phat Ham

    Feb 13, 2000
    DC
    The bass doesn't have anything to do with it (unless you are plugging your bass directly into the power amp). The preamp has a certain output impedance, and if the input impedance on the power amp is too low it will load the preamp. The same thing happens when the input impedance on the preamp is too low and you load the pickups on a bass. By switching the power amp from parallel to stereo you increase the input impedance on the power amp, which in turn means there is less current drawn from the preamp. This increases performance because the preamp doesn't have to try to deliver more current than it is capable of.
     
  9. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    Yeah, I guess I had a brain fart on the type of bass interacting with a change in power amp input impedance.

    Thanks for the input.

    I use a Demeter VTBP-201S preamp. Are tube preamps more or less affected by impedance changes than SS pre's?
    Just curious.
     
  10. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    This thread has languished awhile.

    Maybe someone could answer the last question (above) for me.
     
  11. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Tube preamps tend to have higher output impedances than SS (but there may be exceptions), which would make them more sensitive to amp input impedances.
     
  12. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    Thanks, Bob!
     
  13. Hey Lo Freq
    How's going? Sounds like that little ditty helped you some. I also liked it better and noticed the same thing as you slightly less conjested. I re-read my intial post that you quoted and it seemed slightly confusing after I read what I wrote down, but it is acuate. That information BTW came directly from Bob Lee when he happened to mention it while I was grilling for fine details one time. Yep, in Bridged mode if you keep the 4-5-6 to the left on the stereo marked side it is better to me. Only if you run your signal to another power source/amp would you NEED to swith those dips to the right/parallel. As you know I also own a 201s and now feel my QSC2402 is plenty of power and sounds great through my NV610. I also use the WWU with both my cab rigs. life is good!
     
  14. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    Got an off-topic question for you BigS, tonally, how does the Dem 201S + PLX compare to the WW Ultra (at similar volume levels)?

    [BTW: My band is doing a 10,000 sqft venue gig in Feb. I'll be running with no PA support. Should be interesting. Will be the hardest I've ever pushed my rig. I definitely think I'll turn on the clip limiter for that gig, just in case.]
     
  15. DEVILMAN

    DEVILMAN

    Nov 24, 2001
    New York,NY
    Did anyone try/notice a difference when switching from parallel to stereo in a non-bridged situation(2 outs from pre to both inputs on QSC compared to 1 out from pre to power amp) to power 2 seperate speaker cabs?



    ~S~
     
  16. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    That's probably one for Bob (QSC) Lee.
    I've never had a need to run mine any other way than bridged.
     
  17. DEVILMAN

    DEVILMAN

    Nov 24, 2001
    New York,NY
    BTW, I'm using an Eden Navigator pre. I was just wondering if the output impedence of the pre in stereo vs. parallel would effect the overall tone coming from the QSC?



    ~S~

    PS: I run all my filters & clip eliminators on
     
  18. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    I also use a Navigator with a PLX series amp, and I have connected them in nearly every conceivable way. My typical connection is in "stereo", though I am sending the same signal to each channel. However, on numerous occassions, I have also used just one connection from the Navigator and let the signal carry across the inputs on the PLX 3002. I cannot hear a tonal difference (at least not a significant one) between these methods.

    FWIW, I do not use the Eden's limiter, though I do use the compressor (though it's setup so that it doesn't kick in very much of the time). Also, I run the hottest signal that I can without clipping out of the Navigator, and I use the gain on the PLX 3002 for overall volume. I know that several others prefer to run their amps wide open, and back off on the preamp gain, but I have found the first method to work better for me.

    Later, Tom.
     
  19. DEVILMAN

    DEVILMAN

    Nov 24, 2001
    New York,NY
    I've been sitting here doing a comparo for a bit now & haven't noticed much of a difference either. I run my gain at 10:00 & my master between 9:00-12:00(max) & let my QSC control the overall volume to each cab.

    I thought the impedence change(if any?) with the switch from stereo to parallel might give a different result on the overall output/sound.

    It seems even if there is a variance, it has no effect in a non-bridged situation.

    Oh well, it's worth a shot to always try & tap into more sound from your gear. Thanks guys!

    ~S~
     
  20. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    If you mean operating in parallel-input mode with one cable from one preamp output versus feeding both channels using a Y cable from one preamp output, then no, there won't be any difference.