I’ve been on a much needed vacation from work this week and made the time to refine my TD15M based system. Here’s the latest description and pixs.
The 15Ms are in a max flat BR for about 7 cubic foot but tuned a little low at 35hz. I used 10 ply oak faced plywood. I’d still like to tune to 40hz to get that extra 2-3db lift at 50hz but the 6” port tube I chose is still too small. I recommend building the port from scratch and going at least 6”h by 8”w by 7”d for the higher tuning or using two 6″ ports. If you want to go 6th order assisted alignment then one 6” Parts Express port will work but it’s too small for the higher tuning. I measure a true 45hz 3db down point in reference to 100hz outside. As can be seen, I used simple but effective bracing and Black Hole treatment on bigger panels. I don’t know if the Black Hole did much but it was free and didn’t take up much space. There are 4 adjustable spikes on the bottom to spike them into the concrete floor. I use Carol 3 by 16 rubber insulated wire from the woofer to the jack with white and green together for pos and black alone for neg.
The mids are the JBL 2118J I talk about a lot. Crossed are 550 with a 24uf cap and 2mh coil. The 15 has a 3.3mh coil and 70 uf cap. Outside measurements show a nice smooth response over the entire band of both drivers.
Tweeters are the B&C DE250 on the cheapo ME10 horn with only 5 Parts Express .47 uf tinfoil caps in parallel and an LPad for crossover. If I think I’m going to be pushing more than 100 watts into the system I’ll add a 1mh choke like B&C does for the 8” two way kit they describe on their site. At first I really liked the DE250s but soon became fatigued (like listening to the early Focal tweeters which sound great at first listen but after 15 minutes they lost their sparkle for pain) and switched back to the Altec 902s, but once I went to the tinfoil caps the fatigue disappeared and now they are very open, dynamic and very realistic. A killer combination! I said it before, I’ll say it again, get a pair of these horns!
I also use a baffle step correction filter in front of the midtweeter connection. This steps the response down a bit from mid to high for a nicer balance in the room.
I also use a Parts Express Titanic 12 but adjusted so that’s it’s barely heard. I don’t use any electric EQ outside of what comes with the Titanic. I could down tune the box and EQ the low end to eliminate the sub.
How does it sound? Awesome!!! This is a very dynamic system. The hit is sharp and fast and sounds like it’s coming from the instrument in the sound stage and not the speakers. At first listen it might sound a bit thin but after a minute I notice that’s just the speed of the attack and lack of bloat. I listened to late 50s jazz recorded in true stereo and drums and bass are very articulate, horns have bite but don’t overwhelm, reads are excellent. I switched to 00s ACDC and guitars are detailed and full, snare hits and cymbals are “in the room” not the speaker. Johnny Cash vocals are just unbelievable. “Vocals from the “Brother where art thou” sound track are distinct, deliberate and dimensional. Each singer is easily picked out and followed. Vocal inflections are distinct on any decent recording.
Enough bull shit, here’s the pix!