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High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place. |
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High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place. |
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In Reply to: RE: Alternative to the EV ST350 horn tweeter on EV Sentry IV-A's posted by Geary Lyons on October 29, 2013 at 14:18:28:
Geary
The X36 is a Constant K crossover, the main feature of which is a low insertion loss, and secondary to this is the use of two identical value inductors: 0.727 mH (see the X36 EDS for more, if it's still up on the EV site). Constant K's are seldom seen now except in line level stuff, but EV championed them back in the 70's, which always seemed odd to me due to the fact that the T350 (107 dB) and 1823/1824 (105+ dB) mids had to be padded down to mate with even high efficiency direct radiators in boxes. Anyway, the three parallel inductors in the 6K XO for the ST350 start to make sense in the light of this. The sensitivity of the ST350 is listed in the EDS as 101 dB with the aforementioned EQ circuit used, and the use of 3 paralleled inductors was most likely an attempt to maintain as low a DCR as possible to maximize sensitivity, without having to source a single low DCR (and thus heavier wire) choke of the necessary value.
I did'nt take the 6K XO seriously in fig. 6 due to the fact that you would realistically need active boosting in the area between the 1823M and ST350 to make it work, but it 's a stand alone XO for the 1823M and ST350 none the less, which slipped by me. You can use one of the online calcs I linked to design your own 6K XO for the ST350, and then design a notch filter to pull down the ST350 mid hump centering around 2.5K Hz., and see what you get for comparison. As Paul Joppa's post notes: the XO, the accompanying EQ , and non-flat response of the CD horn ST350 are all a working unit. You would have to try the EQ circuit with a Butterworth and see how it performs, but I would'nt expect any drastic departures from what I've seen.
For the easiest way to go, just combine the X36 with the EQ circuit already discussed. You'd need just 2 caps, 2 coils and a few resistors from Parts Express, and then see how you like it. You can probably even run the ST350 wide open with no L-pad. Note Inmate's post from a few days ago concerning matching the coverage pattern of horn drivers. The ST350 is probably a better match to the ST120 mid in this regard than many others. I love the Fostex alnico horn tweeters, but they have been criticized by some for being a bit beamy. You may run into problems however in a small room (or a rectangular room with the Sentrys on the short wall) with reflections off the side walls from a mid horn with a wide horizontal coverage pattern like that, resulting in smearing of the stereo image, but you don't seem to be complaining about that so far.
I moved on from my X36's (and X8's) some years ago after measuring the response of my 1823's and T350's with no crossover. First order 500/2500 Hz parallel seemed the obvious way to go, and later first order series crossovers. That's perhaps a bigger can of worms than you wanted to open though.
Paul
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Follow Ups
- RE: Alternative to the EV ST350 horn tweeter on EV Sentry IV-A's - Paul Eizik 10/29/1320:33:54 10/29/13 (2)
- RE: Alternative to the EV ST350 horn tweeter on EV Sentry IV-A's - Geary Lyons 23:01:17 10/29/13 (1)
- RE: Sounds like a good plan! - Paul Eizik 16:51:39 10/30/13 (0)
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