My TD15M system so far….


  • Participant
    Scholl on #331

    High all,

    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!


    Participant
    Scholl on #3917

    WE had a rainy day Sunday so I cleaned out the bassment some and setup the big system.

    Tha Speakers:

    TD15S in 6 cubic foot tunded to 27hz via 6″ by 11″ port.

    Good old JBL 2118J midrange with passive third order to a BMS 4538 driver on a B&C ME10 horn for a sweet combo.

    The gear:

    Adcom 500II preamp

    Machland 400hz xover

    Crown PL4 on the midshighs

    AB President 900 on the 15s. These woofers need to be activly crossed over and run with the most robust amp possible. Once the cone starts to move more than a few mm some amps will just shut down. Both amps peak at about the same volume depending on the music.

    Dynamics are scary.


    Member
    simon5 on #3918

    Simple but nice looking setup ! 8)


    Participant
    Scholl on #3919

    Thanks,

    Simple, effective and great HI-FI. Parts quality is the key. Anyway I’ll reiterate the two key points with using the TD15S…Active crossovers and amps tha can control the cone. The M can be used with small tube amps crossed passive at 1500hz, the S like unfettered current.

    The S is a good ballance of Hoffman’s Iron Law, 30hz in 6 cubic foot at 93db is about as good as it gets.

    Later


    Participant
    Scholl on #3920

    Hi guys,

    Wanted to add that I swapped out the BMSME10 for an old Fostex 850T tweeter for a massive upgrade in the highs. The DE250ME10 is and excellent tweeter combo for three ways but the BMS didn’t cut it in this combo.

    Later

    Scott


    Participant
    stryke on #3921

    All compression drivers on a waveguide will take a good amount of EQ. You have to compensate for the directivity of the horn that gives the rising response as you go lower in frequency until the cutoff. What did you use for EQ for the DE250 and ME10 combo? Did you EQ it flat on axis, or off axis?

    John


    Participant
    Scholl on #3922

    Hi,

    I’ve struggled with EQing CD horns for a few years with little luck getting a proper ballance. I don’t like those convoluted crossover messes that Altec and JBL used in the 70s etc. I respect those engineers back then but the sound just isn’t for me. Them one day a came across an article in French where the designer used the DE250 with the RCF 100 horn and he used a third order crossover with a very small first capacitor. So looking at the crossover from the amp to the speaker he used a 2.2uf cap to a 1mh choke to ground them an 22uf cap to a resistor then driver. I don’t use his exact network ( i use an l-pad)but this works very well for about 1600hz and would be and excellent combo for a 15M two way. My favorite horn driver to date and I use it with a 12″ two way awsome sound stage and nice tone.

    http://francis.audio2.pagesperso-orange.fr/Filtre_Passif_15MI100_DE250.pdf

    But you asked about the ME10. Here’s a link to a measurement using a DE10 and a cap http://www.zaphaudio.com/tidbits/B&C-DE10-ME10-FR-singlecaps.gif Unfortuneatly he missed the piont with drivers and horns. This works for low watt amp fans only. The DE250ME10 with a 3-4 uf cap works well here too but frequencies in the mid hunderds can be heard with this crossover. I simply added the 1mh choke and 22uf cap here too to supress those mid hundreds nasties. But since I wanted this combo to cross to the the 2118 I went back to the 2.2uf first cap and it makes a 3K crossover with this combo.

    So..the short answer is that I EQ on axis starting with a small cap to knock down the low frequency hump, loosly using other peoples measurements and experiements to support this. I do use a ratshack spl meter with a Panasonic element to sweep the driver to make sure I have the smoothest integration I can get with my tools on hand. I use recordings with guitars that use single coil pickups or Gretsch (they sound like single coils) and Rockabilly like Southern Culture on the SKids, Jeff Beck and the Big Time Playboys, Johnny A, The Reverand Horten Heat, James Hunter, a few Bonn Scott vocals all at about 110DB to make sure there’s no brain darts, gurgle, glareblare etc. I like to be able to listen like that for a while and walk away with clear hearing which means good integration and low distortion. If I get annoyed it goes on Ebay.

    B&C had a resource guide on thier site that had a crossover for the DE250ME45 that used a similar crossover to what I use. I can’t download that today, give them an email next week for that guide.

    My main thing is imaging, the CD horn does a great job.

    Another link

    http://www.cinetson.org/phpBB3/haut-rendement-f3/4eme-vie-des-lasagnettes-t31578.html

    Have a great weekend!!

    Scott

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