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my crazy 4x10 cab experiment (car subs)

Discussion in 'Amps and Cabs [BG]' started by gaffster, Feb 18, 2006.

  1. gaffster


    Jan 20, 2006

    So, hmm myself being an electrical engineer (presently designing some of the new avionics for Boeing's new "787 dreamliner") I hate to do anything normal when it comes to electronics. So I wanted to amplify the line out of my Roland db500 practice amp for MAX LOUDNESS. I am not a speaker expert, nor are my ears. I picked up unloaded cab for 50 bucks. A while back I went on ebay and found some cheap car woofers the kids love so much:

    2 of these for Pyle pw-1058us 30$
    # 10" Blue Color Woofer Cone
    # Ultra High Performance/High Power
    # 50 oz. Bumped & Vented Magnet Structure
    # 2" Kapton Bobbin Voice Coil
    # 300 Watts RMS/600 Watts Peak Power
    # SPL 1W/1M: 90dB
    # Diameter: 10 1/8"
    # Frequency Response: 25Hz-2.8kHz
    # Mounting Depth: 3.75"
    # Impedance: 4 Ohms

    And 2 of these Polk Audio GNX104 for 25$

    # Frequency Response: 18hz-400hz
    # Peak Power Handling: 400 watts
    # Continuous Power Handling: 175 watts
    # Nominal Impedance: 4 ohms
    # Sensitivity (SPL at 1 watt/1 meter): 93db

    They had good SPL ratings and tons-opower and I figured they are cheap because they are practically commodities. epecially at closeout deals.

    I wired the two 8 OHM speakers in parallel for a 600 WRMS bass channel and the two 4's in series for 350 WRMS sub channel (seperate jack) Total watts = 950RMS, 2KW peak.

    This cab is the loudest/deepest 4x10 I have ever heard.
    I found that if I just use the two 2.8KHz bass speakers, the subs act as passive radiators and give a beautifull warm sound to the cab. I am pleased with the outcome and let me just say my i am very glad my house sits on 1.5 acres.
  2. Please PLEASE post a sound clip! P L E A S E !!!
    I love this stuff- all you ever read around here is BOUTIQUE this CUSTOM that VINTAGE me bum. I think players should be more open minded, have more confidence in their own choices, experiment more and ditch the brand snobbery. We shoudn't be dictated to by large companys nor buckle under social mores or peer pressure! BLURRRT! Rant over!
    seriously though i was considering this sort of thing myself and id love to hear sound clips. A-b comparisons would be really interesting!
    looks Punk too:bassist: ! good luck fella
  3. draginon


    Oct 4, 2004

    clips man. All you need is a good tweeter and that thing would probably rock. Think about putting some into productions and selling them. I might want to check one out in the future if you do
  4. ardorx


    Sep 23, 2004
    Sugar Land, TX
    and how many people said there's no way it would work.
  5. Wouldn't the sensitivity in that be INCREDIBLY low that it would sound like poo 10 feet away?
  6. To be clear there's a VERY LARGE difference between anybody saying it won't work (read you can't put those woofers in that cabinet) versus saying it won't work WELL.

    Car audio woofers are designed to cover low frequencies only. Typically they are well suited to 50-150hz ranges, nothing above, and often nothing lower, although rarely a car audio setup will actually produce sub-lows. I noticed that the high frequency on your blue coned drivers is in the khz range. Is that at -10dB? -12dB? What's the useable high end and how much do the drivers start beaming above 200hz?

    The biggest issue in comparing car audio woofers to professional audio woofers is sensitivity. At 90 or 93dB at 1W/1M, these will NOT get loud enough for gigging even with 4 of them. They will not cover anything above maybe 500hz, despite their "frequency range" ratings, since we don't know anything about whether these drivers are -3dB or -10dB or anything else at those points.

    The point is that there's more than simply bolting speakers into a box involved in designing and building a *good* speaker cabinet. As a practicing engineer, you should have an appreciation for this process not being as simple as that. It's not a matter of "can I bolt these speakers in this box?" It's a matter of designing the box to suit the T/S parameters of the driver and to suit your tastes and design goals. I'm also surprised that in your electrical engineering studies you've never covered enough to even know basic audio concepts such as the logarithmic nature of power and sound intensity, or the subject of sensitivity.

    I don't mean to be bashing you at all, and it's always fun to experiment, but I think you need to actually compare this to a good professional-grade bass cabinet and see what's missing. Also, as an electrical engineer, you should have the knowledge to do some simple calculations that'll tell you why car audio stuff doesn't really work out.
  7. seamonkey


    Aug 6, 2004
    Since very few manufacturers actually publish any specs with charts on their cabinets - maybe just tossing 4x10" in a cabinet does give the same or better response.

    I have a feeling the majority of cabinets are just speakers tossed in a box. They might have been "designed" at some point in their history, but the original speakers no longer available and the manufacturer just tosses in whatever they can get with similar specs. Similar may only be the power rating.
  8. I tend to agree. If you play around with WinISD, the enclosure sizes are impossibly large to get a proper alignment with most instrument speakers (unless you have roadies, of course).

    Given that manufacturers publish little in the way of measured specs for their products, I'm also of the opinion that the design of many of these enclosures is basically "suck it and see", and many of the currently-fashionable "slot ports" look far too big to me for the driver(s)/enclosure size, although I'm not a speaker designer.

    The potential problems I see with the OP's enclosure are

    . Very low efficiency compared with "dedicated" bass cabs;
    . Very limited frequency response, which could be overcome with a tweeter, at additional cost; and
    . Potential damage to the woofers because the roll surrounds may not be sturdy enough to stand up to the attack and dynamics of notes from a bass guitar at gig volumes (although they're fine for "music" within their power ratings).

    The idea of having a passive radiator is interesting, and it's been used on and off in hifi enclosures, but rarely in instrument cabs (Mesa Walkabout, an Ampeg combo, and some old Yamaha gear, from memory).
  9. gaffster


    Jan 20, 2006
    I selected these for their good range. These sound bright, probably the BW was spec'd +/-3dB, not sure. Im not so hot on lots of highs these days. I think alot of these bass tweeters sound harsh and crappy. I prefer the mid highs of drivers with bright strings to a typical finger-noise amlifying tweeter. I like it when you feel bass as well as hear it. Plus my db500 has a loud tweeter. It annoys me.

    Efficiency is not an issue for me, I have a KW RMS amp. Many musical instrument speakers have less efficiency than these. These Lower frequencies also carry better and in a more omni pattern. This sucker wakes up my PC (moves the mouse).

    I had a Hartke 2x10 (pro?, maybe, maybe not) with the aluminum cones...and it was just OK. After 20 years of designing electronics professionally, let me just say this.. There is a reason most projects invest in rapid prototypes. You can analyse things to death, but bad or impartial data (aka the real world) just gets you a bad analysis. "Just bolting a speaker into a cab" pretty much tells me everything I need to know.:hyper:
    I try and make a clip, but the limiting factor will be the microphone.
  10. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    If you put four autosound tens into a box and hit them with enough watts they won't be any worse than most of the 4x10cabs out there. Sensitivity isn't that much of an issue, being true woofers these are no worse than the average pro-sound driver below 100 Hz, and better than most. Pro-sound drivers tend to be rated at the frequency of their maximum sensitivity, which means precious little if that's 2.5 kHz. Where these drivers would come up short is in the midrange, but with adequate EQ they'd suffice. What this exercise really points out isn't how good a cabinet you can create using autosound drivers, but how poor the average commercial 4x10 is when something as basic as this is comparable.
    Exactly. It doesn't take a degree in audio engineering to come up with a box that's better than 'just OK', and just OK is a good description of most of what's available.
  11. Petebass


    Dec 22, 2002
    QLD Australia
    Is the cab sealed? If so, there's not a hell of a lot of engineering involved.

    Personally I wouldn't build a cab with no mids or highs, but that's just me. If that's what gaffster likes to hear when he plays bass, than so be it.