combo mod, horn volume control

Discussion in 'Amps and Cabs [BG]' started by brock29609, Sep 18, 2003.

  1. brock29609

    brock29609 4 strings, 2 wheels

    May 11, 2003
    Greenville, SC
    How hard would it be to make this modification to my SWR WM 15? I want a dial that will let me control the volume of my horn separately from the 15. I'd like to keep the horn one, but tone it down a little.

    What parts would I need?

    Also, how much would I benefit by replacing the horn with a better one? Maybe that would make it less harsh and I wouldn't need the dial. Anyone have a recommendation for a replacement horn?
  2. BruceWane


    Oct 31, 2002
    Houston, TX
    The item you want to control tweeter volume is called an L-pad. They come in different impedance and wattage ratings. Get an 8 ohm L-pad for an 8 ohm tweeter, and you may as well get the highest wattage rating available because they're not very expensive anyway. An 8 ohm 100 watt L-pad from is about 6 or 7 bucks.

    As far as replacing the tweeter, I've used the Peerless #811647 and I like it a lot. Almost all bass cabs use compression tweeters, which are widely known to be harsh sounding. Audiophiles avoid them entirely. Manufacturers use them because they are cheap and loud. Soft dome tweeters (also called "textile dome" or "silk dome") sound a whole lot nicer. Much more natural. The problem with them is that they generally aren't very loud - a typical musical instrument speaker will drown it out. The Peerless tweeter is a little different. It's a soft dome, but it's horn loaded to boost it's efficiency (to 99db) so it will work well with most M.I. speaker systems. It handles 100 watts, which is more than the compression tweeters in most bass cabs, so there shouldn't be any problem there.

    HOWEVER - a big part of integrating a tweeter into a speaker system is using the proper crossover. I'd bet that the current tweeter you've got uses a simple 1st order low cut design - which is simply a capacitor wired in line with the tweeter. This only gives you a 6db per octave roll off, so they have to use a fairly high crossover point to keep from having frequencies below the tweeters operating range hit it and damage it. It's probably crossed over around 5K. Which leaves a fairly large "hole" between where the woofer loses high end and the tweeter takes it up, in a frequency range that is fairly critical to good, articulate sound. Ever notice how in almost all bass cabs with a tweeter, you can hear the woofer and tweeter separately no matter what you do? It never seems like a single, solid sound. That is exactly what you get from an improperly designed tweeter and crossover scheme.

    SO.........yes you can try replacing your tweeter, and it probably will be somewhat of an improvement. But you won't really get all you can out of it unless you also replace the crossover. That Peerless tweeter runs about $25, and a decent 2-way crossover can be had from for about $20. They use a 2nd order design (12db per octave). I prefer a 3rd order for tweeters (18db per octave), but still, a 2nd order is a big improvemnt over a 1st order. I'd cross this particular tweeter over at 2.5K

    Total to do this whole thing would be about $60-$65, so I don't know how much money you'd want to put into that cab................