25 SEPT 2010

The orginal goal for this project was big volume from a small box. (Shticks on steroids) The Bravox woofers looked promising and were certainly cheap enough. I already had the Vifas on the shelf and liked them in the ARLOS. In keeping with the buyout theme, I chose the Peerless mid because it was the right size, had great power handing and I never heard a Peerless Nomex I didn't like. Despite my goal of creating a headbanger special, I just can't bring myself to using complete crap.

I used 1/2" baltic birch for the cabinet. The mid chamber (inside dimensions) is 8.5" high X 2.5" deep X 7.25" wide. I also used a 1" deep, X 7.25 X 7.75" long slot port that exits at the bottom rear of the box. (Figure your own net volume, I used a lot of 1/4" internally).All drivers are surface mounted. The mid chamber is lined with 1/2 inch sonic barrier and stuffed with dacron. The areas below the woofers & behind the mid chamber have some scrap foam and dacron batting

After upgrading a lot of my measurement gear, it took me 3 hours to get a set I thought I could trust for design. (I did find out that part of the issue was using a TAmp for power, one of probes got fried too.) I used a splice of nearfield and far field for the woofers (wired in parallel). I'm not going to show you those, they only make sense to me.

The crossover design turned out to be a real PITA. Though the pair of Bravox could be called 6 ohm, I had a difficult time keeping the impedance up. This is always a challenge with 3 ways. I originally had planned on full 6db of baffle step (these woofers should handle 200 watts before excursion issues set in). But I couldn't find an easy way to keep the impedance reasonable without a ton of extra crossover parts. So the final version has about 3dB (based on my experiments with tone controls on my preamp). The version shown below is where I decided to stop tweaking. Crossover points at 480 & 2600 Hz. I used 20ga air cores throughout to boost the impedance a bit and keep the parts count down. It's definitely a 4 ohm design, wimpy amps need not apply. My APA-150 had no problem driving these to ear bleed level.

For the mid padding, I actually used a pair of 5.6 ohm resistors (though I found no heat problem) and 3.7 ohms on the XT tweeter. If you want a bit more recessed mids, you could bump it up to 2.7 or even 3. Of course, you'll need to adjust tweeter padding. If you want to use a 1.5 mH laminate core in the mid circuit, then bump the 1.5 ohm to 2.0 or 2.4.

Overall, this is a very capable full range box in a footprint not much bigger than the Shticks. While the bass does reach into the 30's, it's too clean and articulate for a headbanger box. (Though you definitely could ratchet up the bass if need be). Presentation is a bit forward. The Peerless is capable of clear articulate midrange and gobs of power. The Vifa BC is a great $12 tweeter, not the ultimate reach of the pricier models, and a bit twitchy to pad. I think the XT is a step up in clarity. If you intend to run these at earbleed levels, consider more padding. It get's a bit raspy when pushed very hard. Overall, a very clean, rich design for not a lot of money or floor space. I would have no problem keeping these and listening to them on a regular basis.

I think the Shticks are a bit more refined and detailed. The Braptor will definitely play louder with ease, and I would guess sensitivity is in the 85-86 db range. If you want to play with the box size and tuning, I think you can get a bit more thump.

Wiring Note: The lug markings on these drivers are not clear or consistent so: For the BC tweeter + goes to the negative (unmarked) lug. For the XT tweeter + goes to the small lug (It has two sizes) For the Bravox + to the Large Lug For the Mid + to the Large Lug