Revive a 15+tweet cab

[mixamatchi]

A friend gave me a SWR Son Of Bertha 15+tweet cab, after he discovered it really did nothing for his sound in combination w/ his Hartke 4-10. He didn't care for it alone either, so I became the lucky recipient. Turns out, it's not really my flavor either. My regular rig is a fEarful 15/6. I like a modern, and very "mid-forward" tone from my rig.
After reading on this cab, I found that the tweet is crossed over @ 5khz. No way that 15" is making it that high. Leaves a significant hole in the upper mid. What to do? I found a 5" mid driver made by Goldwood(PN GM/85-8), that goes as high as 15khz, and as low as 500khz. It's a closed back driver, so no need for a separate chamber. I removed the Fostex tweet, and had to make only a small notch to clear the terminals of the new mid, and it dropped right into the existing hole. I added a Dayton 2khz 2-way pre fab crossover and it sounds great.
The Fostex tweets are very common, and I figured someone else might not abandon a perfectly good cab, with this easy mod. Only cost $47.03 with shipping.

[Steve Dallman]

I gig with two repurposed 12" with a piezo, pretty ancient PV cabinets. I replaced the 12's with 375 watt 12's from MCM Electronics, and the piezos with 6 1/2" sealed back Pyle midranges and used 800Hz crossovers from Parts Express. I originally sealed the ports as the low end was subwoofer extreme. But the first gig with the sealed cabinets (small place, and I was RIGHT in front of the vertical stack) the bass sounded great where I was standing, but a bit thin from the audience. I opened the bottom cabinet port for the next gig there, and it was perfect.

I'm really enjoying these speakers with my PF500. I look forward to gigs even more knowing what this rig sounds like. It's a pure joy to play. I originally tried these cabinets with only a highpass on the midranges, but the spike around 2k in the woofer was a problem. Adding the lowpass did the trick. The midranges I used are only 93dB efficiency and the high end is around 6k, but I've been using tweeters since the late 70's, and these are working just fine. I'm liking the no-tweeter tones.

I've got other repurposed cabinets that I really love.

[mixamatchi]

Yup. A little thought, and chance, can fix up a not so great cab. I know it should all be better engineered. I chose based on the specs, and I got lucky. I don't know the T/S parameters of the 15" driver in the cab, but it is surely a beautifully made driver. The 2khz crossover was cheap, and seemed like a good bet. The original circuit had the 15 running full range, with the tweet high passed @ 5khz. It sounds wonderful in the upper mid now, and there is no yucky sound coming from the 15 trying to make 2-5khz. Probably just was absent. The driver I used has pretty high sensitivity, @ 96db. It's definitely not as zippy as the 18sound 6 in my fEarful, but pleasant and present. Much less harsh than a horn.