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PLX 3402 to hopefully cure Acme headroom woes

Discussion in 'Amps and Cabs [BG]' started by mrpackerguy, Dec 29, 2005.


  1. mrpackerguy

    mrpackerguy Supporting Member

    Jul 3, 2004
    Madison, Wisconsin
    I've got a used evilbay QSC PLX 3402 (1100W per channel) on the way to replace my Yamaha p5000s (750W per channel). The idea is that my headroom woes will be cured. Currently I'm running the Yamaha with a Kern IP777 going into that, then two Acme Low B2 2x10 four ohm cabs running out of the Yamaha.

    The Acmes are notoriously inefficient, and the 3402 should breathe some new life into the Kern and the Acmes. If not, I'll be very disappointed.

    The mint Yammy with orig box, packaging and manual will be listed below in the GFS forum before too long.
     
  2. DEVILMAN

    DEVILMAN

    Nov 24, 2001
    New York,NY
    With the Kern & Acme's, why didn't you just go with a Crest CA9 or Crown?

    ~S~

    PS: There was a WHOLE thread on this a day ago...
     
  3. I hope that works for you. One thing you should do is take your power amp and preamp and play through some other speakers just as a reference point. I used a couple of B2's for a while, and was reasonable happy with the sound. However, when I did an A/B with my old BagEnd sd15 and Sd15x that I still had, they were so much louder and punchier (by a magnitude of 3 or 4) that the Acme's went up for sale the next day. It you put 750 watts into a Berg or Epifani, you could knock a herd of elephants over!

    Just a thought since I see quite a few Acme users constantly upgrading to quite ridiculous power levels to make these speakers work in a moderately loud live setting... and since I went through that myself quite a while ago :)
     
  4. tombowlus

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

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    +1 I've had better results with my Acme's using conventional power supply-based amps, like the CA9.

    Tom.
     
  5. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    What will probably make more difference than the extra power is the QSC's low-cut filters. Try both 30 and 50Hz - I find 50Hz works best for live use indoors, as the room gain usual adds more extreme lows than you want (creating boom and mud). I run a PLX 3002 into my Low-B2s and one cab with one channel into it is plenty for practices and small gigs with my fairly rock band, whilst the pair together covers everything else. The 50Hz filter adds a lot of headroom, punch and clarity, and the limiters are very transparent so you get another 3dB or so for nothing.

    If the rig isn't loud enough with that much power behind it you're doing something wrong with your EQ. Get the right sound from your bass and the Acmes will make it plenty loud enough. Have a bass that relies on cab colouration to cut through the mix and you may struggle.

    Enjoy the new amp!

    Alex
     
  6. DEVILMAN

    DEVILMAN

    Nov 24, 2001
    New York,NY
    Tom B,

    When's the 1st edition of "Gear Whores Gone Wild" video being released?...LMAO!!!

    ~S~
     
  7. tombowlus

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

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    That is good advice, and a nice feature of the PLX series.

    Tom.
     
  8. jokerjkny

    jokerjkny

    Jan 19, 2002
    NY / NJ / PA
    lol,

    but yea, i'd think the sheer massive volume from QSC would cure something. if not that tumor... ;)
     
  9. jokerjkny

    jokerjkny

    Jan 19, 2002
    NY / NJ / PA
    +1

    if you're in an especially loud setting, and dont quite have a semi parametric EQ handy, using Acmes in ear scathing settings will be rather frustrating.

    a nice dose of the Epifani should cure that in the evening. :)
     
  10. mrpackerguy

    mrpackerguy Supporting Member

    Jul 3, 2004
    Madison, Wisconsin
    I considered both the Crest and Crown, but went for the weight factor and the fact that my first amp was a QSC RMX series which I enjoyed very much.

    Also, my understanding of the specs on the Crest and Crown is that it takes a little more effort to run them in parallel mode, i.e. jumper or y-cables vs. the QSC's DIP switches. Also, price was somewhat of a factor as was the fact I run speakon cables. The Crest and Crown for about the same wattage run at or near $1000. I was able to get the like-new QSC PLX 3402 for $825 delivered. So I think I saved a few bucks and a few pounds.

    Thanks for the advice on the filters.
     
  11. tombowlus

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

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    Nope. A flick of a switch is all it takes on either my PLX 3002 or my CA9 to run in parallel or in bridged mono.

    Well, I was able to buy one of my "like new" CA9's for $325, but that was an unusually good deal. They should be easy to find for $500-600, though.

    But I'm just playing Devil's advocate. Enjoy that 3402! :)
     
  12. mrpackerguy

    mrpackerguy Supporting Member

    Jul 3, 2004
    Madison, Wisconsin
    So in order to be sure I don't fry the woofers on the Acme, am I going to want to go heavier on the power amp gain or the Kern premp gain?
     
  13. jokerjkny

    jokerjkny

    Jan 19, 2002
    NY / NJ / PA
    i keep the gain close to 80%, just below any extraneous hiss or noise appears, and then use the kern for overall volume control.
     
  14. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    Don't wanna be a wet blanket, but I'm not 100% sure that the PLX will solve your problem. It might, and if it does, great, but I don't think it's necessarily a slam dunk. You've probably already considered this, but is it possible you're expecting too much output out of those little 2-10s? A cab reaches a point where it just won't put out any more, regardless of how much power you throw at it. In that situation, a bigger amp won't solve the problem. I'm not saying this is going to be the case for you, but it's worth bearing in mind. I just remember, when I was buying my Acmes, hearing Andy Lewis gripe about people thinking they could just run any old amount of power into his cabs, then being shocked when they fried components. He even wrote something to that effect in the manual.
     
  15. mrpackerguy

    mrpackerguy Supporting Member

    Jul 3, 2004
    Madison, Wisconsin
    That's an excellent point I hadn't really considered. One thing I just did was to engage the 50hz filter on my Yamaha. I could tell right away it had more punch and less boominess and, I'm embarrassed to say, it seemed like a little more volume. In fact, I cut the Yammy back to about 60% and ran the Kern a little more full out. I really liked the tone, a little more bite.

    I'll A/B the 3402 with the Yamaha before deciding what to do. I can probably sell the Yammy for around $500, so I'm really only out about $325 if I keep the PLX. Otherwise the PLX will be turned around for quick sale.

    At what level do I run into danger with the PLX as to potentially frying the Acme's? As stated above, pushing the PLX full and using the Kern for volume control seems counter intuitive.
     
  16. Steve

    Steve

    Aug 10, 2001
    I have a couple B2's and a B4 that I use pretty regulary with a PLX 2402. I've used just about every combination I can think of at one time or another.

    I think you'll be fine. Use the low cut filters. They make a significant difference.
     
  17. The PLX should do very nicely with the low-cut filters as suggested. Just remember to ease up on any slappin' or poppin'. With that much juice you do have the potential to crease the cones.
     
  18. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    For live playing, you should not have noise issues with the preamp (as long as the Kern's tubes are OK) or power amp.
    Since any added tone should come from either your playing style, your bass' settings, and your preamp, just experiment until you dial in the tone (or tones) that make you smile the most. :bassist:

    [Like dial in the tone you want using the Kern's gain/tone and set the overall volume with the PLX.]
     
  19. jokerjkny

    jokerjkny

    Jan 19, 2002
    NY / NJ / PA
    FYI, on the Kern front,

    i'm pretty sure given the fendery topology, a setting of:

    treb = 2
    mids = 10
    bass = 2

    is the "neutral, flat" setting.
     
  20. mrpackerguy

    mrpackerguy Supporting Member

    Jul 3, 2004
    Madison, Wisconsin
    With my ASAT I've got the Kern at about 10:00 bass, 2:00 trble and 3:00 mid, bright switch engaged, deep switch off and that's with very mild treble and bass cut on the ASAT