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My time with a CA9 and a PLX: I believe Bob AND Jim

Discussion in 'Amps and Cabs [BG]' started by KPO2000, May 11, 2006.

  1. KPO2000

    KPO2000 Supporting Member

    Sep 5, 2001
    I'm not trying to reopen an old debate. I've been following the comparisons between the CA9 and QSC PLX line with interest. Just about everyone has weighed in but I'd never heard of anyone having success heeding QSC Bob's advice to match input sensitivity. I thought I'd present some observations from my recent test. I actually have both a Crest CA9 and QSC PLX 3002 at the moment. In the signal chain I run Sadowsky pre pedal and an Alembic F2B.

    Like many others, I've found that out of the box, they sound very different. Like everyone has said, the CA9 is louder and fuller at like settings as the PLX. But, what I've found is that I can match the tone of the CA9 by adjusting the input levels just a bit. I ran the comparison through two Bergantino HT112s.

    The test (all settings below in the o'clock positions):

    Sadowsky pre pedal (vol, 12:00; treble, 12:00; bass 12:00)
    Alembic F-2B--Channel A (Vol, 12:00; Bass, 12:00; Mid: 5:00; Treble, 10:00)
    CA9 set at 8:00 (one channel)

    = VERY similar tone as QSC PLX 3002 set at the following

    Sadowsky pre pedal (Vol, 5:00--all the way up; Treble, 12:00; Bass 12:00)
    Alembic F-2B ((Vol, 12:00; Bass, 12:00; Mid: 5:00; Treble, 10:00)
    PLX 3002 set at 9 o'clock (one channel)

    I switched between power amps within 30 seconds for an A/B comparision and kept all EQ settings the same with the exception of the Vol control on the Sadowsky pre.

    - I was surprised, but I think QSC Bob may be right. Input gain/sensitivity matters and directly impacts tone and volume. The QSC needs to be hit with a louder signal than the CA9. At first, I was trying to control this by turning up the Alembic F2B preamp, but realized that doing that really changed the tone quite a bit. The Alembic preamp tone really opens up when the volume is cranked up. The Sadowsky volume control seemed more uniform and linear--just louder--having less impact on the tonal characteristic. Maybe all I need is a line driver, instead of the Sadowsky preamp in the signal chain. (I'll see if I can "boost" using the output control on my graphic eq.) Clearly, Jim's proved you can do amazing things with a switch mode amp. Could this be all you need to do? Seems so for me. Maybe I boosted the bass control on my active bass a tad. That's it. Not night and day any longer.

    - The CA9 sounds better "out of the box". It was easier to to get a pleasing, full, punchy tone at lower (average) volume settings on my Alembic and Sadowsky preamp. I didn't need to crank up either preamp.

    - Both the QSC and CA9 are comparably oud and with this adjustment in setting, I'm pretty sure I can reach comparable volume and tone with the QSC as the CA9...without clipping. I matched input sensitivity so that the preamp signal stayed consistent and then increased the power amp volume from there. I think the Bergs would blow before I'd clip these amps.

    - The CA9 is wicked heavy. I have a the QSC in a 6 space SKB rack with power conditioner, graphic EQ, Preamp, and tuner and it's still over 10 lbs lighter than the CA9 in it's own 2 space Gator case.

    I'm not ready to sell the CA9 just yet, but this little comparison was an eye opener for me because at first, like many here, I noticed a significant sonic difference. I much prefer the weight of the QSC rack. It may come down to that.

    Everyone needs to use their own ears and mind their ergonomic needs. I'm eyeing a new IP112 and biding my time with a GK 1001RB-II in the meantime. I like them all. There's no bad or wrong amp for me among these. It comes down to preference and G.A.S.

    Hope this was helpful. I've enjoyed everyone's opinion. I just think that Bob's pt has merit. I experienced it firsthand. YMMV
  2. pickles

    pickles Gold Supporting Member

    Mar 23, 2000
    Ventura, CA
    Try it again with the device controlling the levels *after* the Alembic. With this test, when you cranked up the sadowsky pre, you started hitting the F2B's gain stage harder, which on a tube amp tends to fatten up the sound.

    I'm not saying it invalidates your test at all, and actually if thats all it takes to get the bottom end happening then so be it, thats an easy fix!
  3. KPO2000

    KPO2000 Supporting Member

    Sep 5, 2001
    That's a good point. I should add...I'm not hugely technical when it comes to amps. When I cranked the vol on the F2B though, it sounded more open (chimey) as one would expect in a Fendery sort of way.
  4. inazone


    Apr 20, 2003
    Thats a good post and I agree with you on a few of your points, BUT, I have to add:
    I have a ca9 and a plx 3402, sad pre, into two berg 322's, Ive had these for a few years now. I agree with you up to a point and when you match gains the amps become very close to each other. The big difference, to me,comes when you get the plx close to its limits. The clips LED's glow red on the plx. At this volume the ca9 has more weight to its tone. When I get to the limits of the plx, the ca9 have a few more gears left and is just hitting its stride. At this volume I cant match gains cos the plx simply wont produce no matter what the settings, gains, bass, mids, master, etc.

    I do agree, if you dont need the bone crushing volume of the ca9, you can get the plx to sound good. Its a solid amp.
  5. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    sweet little experiment. :cool:

    truth be told, both power amps are incredible, and deliver more than enough sonic goods for moi.
  6. pickles

    pickles Gold Supporting Member

    Mar 23, 2000
    Ventura, CA
    As much as I am in the camp that they sound different, I still agree with this.
  7. lowmid1

    lowmid1 Supporting Member

    Aug 16, 2002
    Baltimore, MD
    I haven't tried the PLX series but I have a PL236 and a CA-9 and my experience is that the QSC is flatter, has less gain but more power and better features. However, I apparently didn't get one of the "never clips" CA-9's and mine will clip when it runs out of headroom just like any other amp that I have tried. At one time, I firmly believed the heavier is better story but after using both I quickly got past that.
  8. Poon


    May 20, 2003
    Los Angeles, CA

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