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Bridging a PLX 3402 into a pair of Acme B4's

Discussion in 'Amps and Cabs [BG]' started by Mo'Phat, May 5, 2004.

  1. I did a search and found many Acme/Plx threads, but none that really addressed the following question:

    I've got a QSC PLX3402 which can put 3400 watts into a bridged 4 ohm load, or 2200 watts into a bridged 8 ohm load. Stereo, it puts 1100 watts into 4 ohms per side.

    Would it be more intelligent of me to get 4 ohm Acme Low B-4 cabinets or 8 ohm? I'll probably play half of my shows with just one cabinet. I've seen on Talkbass that 1000 watts is the minimum that should be considered for an Acme 4x10, so 1100 watts/side is just over the minimum, whereas 1700 watts (1/2 of 3400) might really make these cabinets sing...loudly.

    If I got the 4 ohm cabinets and then ran bridged from the power amp (thus having a 2 ohm load), would I incur the wrath of God? More importantly, would I damage my power amp or speakers?

    Any advice from PLX bridgers, Acme afficianados, or crackpot philosophers will be welcomed. Thanks.
  2. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    I'm using a PLX 3002 into a pair of B2s. Unfortunately I bought 4 ohm cabs (5 years ago) and ran them in stereo with my Mackie M1400, so when I wanted to add headroom (and reduce weight) I had to go with a big amp for stereo operation instead of a smaller bridged one. They get 900W each and can be cranked seriously loud. It's amazing what one B2 will do with 900W behind it!

    Go for 8 ohm cabs and bridge the amp into them - they will love it! Use the 30Hz filters and clip limiters. And be judicious with your cranking of the bass knob (the one on my Aguilar OBP-3 is particularly potent) - though you'll hear the speakers distorting (exceeding Xmax) long before they break (exceed Xmech).

  3. I thank you for that. I do really want to throw 3400 watts at the audience, but I just needed some backup.

    Thanks for backin' me up, man.
  4. What about 1 8 ohm and 1 4 ohm. That way you could take the 4 ohm on single cab gigs, and take 2 cabs on other gigs?

    PS the PLX series amps seem to love low ohm loads from what I have seen
  5. geshel


    Oct 2, 2001
    You still wouldn't want to bridge the PLX into the two combined cabs (at 2.67 ohms).
  6. inazone


    Apr 20, 2003
    The guys at epifani told me that two 8ohms 410 cabs with a bridged plx 3402 would work great. I would think it would work well with the acmes too. I currently run a plx 3402, 1100 watts a side @ 4ohms into two bergantino 322s and have no problems.
  7. Thanks for the tips, everybody. I don't want to get two different ohmage cabs. Either 2 4's or 2 8's, and I'm fairly sold on the 8's. When I use both, bridged, there's 1700 watts per, and if I just use one, bridged, there's 2200 watts.

    There's room for head.
  8. My next step is to get another 4 ohm B-4 (to go w/the one I already have) and a PLX 3402 and run stereo. IMO 1100 watts into each cab will be plenty loud for me. With the doubling of surface area it should push a max SPL around 129db. Two 8 ohm B-4s w/1700 watts each are going to come in at 131db.

    Honestly, at these volume levels I don't think 2db is going to make much of a difference. Both set-ups will pretty much sound identicle. If you've already got a 4 ohm cabinet I would suggest just getting another and save yourself a few bucks. Either way though it's going to be one serious asskickin rig!
  9. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    well, when you're demo'ing your rig with your Low B, i'll be sure to call up FEMA and the National Guard for your area... :p

    but yea, dual 8 ohm, and you'll truly live up to your TB name. ;)

    btw, what bass & preamp you got goin' on?
  10. Thanks joker and GPB...I've been checking your past Acme related posts and find your words extremely valuable.

    Strangely enough, I don't play a 5 or 6 with any regularity. My only 6, a Carvin BB-76 with piezos, is my 2nd backup. I'm just not as comfortable with it, and since stage presence is such a big part of my live shows, I can't be staring at the fretboard and worrying about whether my thumb hits the E or B. Besides that, I've got a 10 month old son, who thinks I don't need to practice and I should be spending time on the floor watching Baby Mozart and changing poopy diapers.

    My main basses switch between a '92 Warwick Dolphin w/ 18v EMG's and a stock 2003 Stingray w/ 3 band EQ and maple board.

    I'm running a Sansamp RBI through a Joe Meek compressor and BBE 462. Crystal clear TONE with plenty of oomph.

    Do either of you guys think adding an EQ (either graphic or parametric) helps when working with Acme's?

    Lastly, I don't own any of them yet...I'm in the process of liquidating all my Mesa gear (400+, 2x15 and 4x10) in order to get the Acme's.

    ps. I should add that I have been dreaming for weeks about a Bolt-on Warwick Thumb 5 with wide string spacing. BassCentral's got one for $1200...
  11. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    I'd go with 8 ohm Acmes...

    Assuming that you're buying your cabinets new...a word of warning. Make sure that you break the woofers in before you play bass through them loudly. Acme woofers are notorious for getting creases in the cones if they are hit with too much power before they're broken in.

    You can do this by playing recorded music through them for a few hours at a reasonable volume or by playing bass through them at moderate volume. Be sure to ask Andy about the best method to break them in.

    A friend of mine didn't know about breaking them in and creased all 4 woofers in his pair of B2s...cost him $200 to replace them. Andy says it's a fairly regular occurance...some customers replace their woofers every couple of months... Personally, I would never tolerate that nonsense, but they must play loud and low...

    A pair of B4s with that much power would be too much fun!!!!

  12. I think we'd both say "yes" to getting a parametric EQ. The Acmes push out so much low end that being able to adjust the Q points with a parametric would come in really handy for those rooms where you're either too boomy or when you're having trouble being heard. I can usually tweek my graphic enough to get me by in the more difficult rooms but I personally would really like a parametric. I'm pretty sure Joker already uses one.
  13. I'm going with the 8's. I think it will give me all the flexibility and headroom I need. I already have the order form filled out and will be faxing to Andy today... :D :bassist: :hyper:

    Billy: I've already read the 37 pages of results that come up when I search 'Acme' and got the low-down on breaking the speakers in. It's like breaking an engine on a new car in. What, ceremoniously speaking, should I break them in with? I'll probably play 3 or 4 cd's through them at ever-increasing volumes and intensity...hmmm..

    1. Dave Matthews Band: Crash
    2. Rush: Test for Echo
    3. Living Colour: Stain
    4. Rage against the Machine: Evil Empire

    cool down with Stanley Clarke's School Days.

    I would have a freaking conniption fit if I creased any of the speakers.

    Guy: I was thinking about This Alesis EQ, which is a programmable Graphic, or This Presonus EQ, which is parametric. I've got 1/2 rack space to work with...Do you have any other suggestions?
  14. Lonnybass

    Lonnybass Supporting Member

    Jul 19, 2000
    San Diego
    Endorsing Artist: Pedulla Basses
    Lonnybass here (2 x B2s + Stewart World 2.1 pushing lots a' watts!). Sounds like you're on the right track.

    Regarding the equalizer, a parametric is HIGHLY recommended. I use an Aphex 4 band rack parametric which is EXTREMELY useful for fine tuning. As you probably know by now, what you put in is what you get out of an Acme, and you're going to have re-think your entire approach to EQ. In many situations with these boxes, it's better to CUT precise frequencies than boost them. Especially on the low end. I'll tell you what, in almost 2 years of playing with my 1800 watt Acme setup, I haven't gotten a single complaint that the low end is too muddy or rumbly. That's the benefit of a parametric EQ in this application - you can still get good, clean punchy bass without it being unpleasant.

    My friend Billy from LZ is right on the money about a careful break-in period. As for what to play through them, try to find a few CDs that have a consistent "sound" or intensity level so you can put a disc on and not have to worry about a thrashy wailing overdriven guitar section or anything like that. It doesn't have to be "loud" - as long as you get the cones moving for a while you should be fine. As Billy mentioned, I learned this lesson the hard way! :)

  15. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    what gizzard and loony said... :cool:

    btw, pickup a few more basscentric solo CD's from guys like Vic, Johnny Pat, Mikey Man, etc.

    it'd be like they were personally breaking in your speakers for you. :smug: :D
  16. The order has been placed!!

    Suggestions for Parametric EQ's anybody? 1/2 rackspace only please. Leaning toward the Presonus, but that Alesis Graphic looks really cool with all the lights 'n stuff. What's more important, really? ;)

    Thanks so much to everybody for all the tips and advice. I know I made the right decision for me, and the whole U.S. of freakin' A!!!

    At dawn on the 21st day, look to the West, and you shall hear me.
  17. Lonnybass

    Lonnybass Supporting Member

    Jul 19, 2000
    San Diego
    Endorsing Artist: Pedulla Basses
    At dawn on the 21st day, look to the West, and you shall hear me.[/QUOTE]

    Hopefully we WON'T be hearing you on that day...because you're going to break in your speakers first before you "turn it up." :cool: Right?

  18. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL

    congrats, Mo!

    hope you have many great, not to mention, LOUD gigs in the future.

    btw, the Raven Labs True Blue looks interesting, but never tried it.
  19. Yes, Lonny...After I break them in. Those will be some of the longest hours of my life. Maybe not quite on par with the 24 hours of labor my wife went through for our son, but long.

    Other than just playing cd's through them, I've got a keyboard which I can rig to play a sustained chord for a few hours. I'm thinking F#dimSus4 or maybe DminAdd13 for a little dissonance. :smug: Good or bad idea?

    Thanks again for the input, and I'll look into the True Blue, Joker. I got an insight into how small an operation Acme really is, because after I placed my order, Andy emailed me and said he needed to, 'look around the shop to see if he had enough speakers.' I don't know why, but that made me smile. I may not be getting a one-of-a-kind thing, but I'll feel unique in my corner of the world. ps, He has enough, but just barely. whew!
  20. Ask Andy about that, I think he uses a single tone. BTW, my vote for a CD for breaking in the cab is Edgar Meyer playing the Bach Cello Suites. It sounds like the voice of God coming through my Acme 2x10. :D