BillFitzmaurice.info

Finally getting around to hopefully maybe building my speakers. I purchased a bunch of Sony closeout drivers back in 2011 (dang, where did the past 9 years go?) along with a bunch of tweeters to build some TLAH's. Fortunately, the specs are still available for the Sony's (https://www.parts-express.com/sony-5-1- ... r--299-012). If I remember correctly, there weren't data sheets for the tweeters, but they were generic enough to make them work (again, I'm remembering back 9 years). I believe there were a bunch of people that got in on that deal, so can someone comment on what crossovers I'd need for the TLAH's? I apologize for my delayed question, and appreciate any feedback. I've attached pictures of the tweeters, if that helps.

Looks like they were tweeters from Apex Jr from DIY audio (had to do some digging). Looks like the link to the frequency graph is no longer around.....is it possible to still figure out how to use this combination?

Plans recommend Goldwood GT-302, so I'd try to match those within 10% like we do with all other drivers (8 ohm, 3/8-1/2" dome, 2.5" diameter max frame). I don't think the tweet specs are as critical as mids and lows since the crossover will tame them. So if it fits that criteria I'd say you're good.

Thank you for the feedback. I guess I should clarify, these were both speakers that were determined to be acceptable for use on the SLA/TLAH's nearly 9 years ago (yeah, I'm a slacker)....I'm just trying to piece together information to get the correct # of speakers and the crossover. Thank you all for your patience while I learn and figure things out.

Looks like the the Apex Jr has the following specs:

Sensitivity = 90db/1watt @1 meter
Lowest crossover point used by others in a line array: 4300hz (seems most cross over at 6000Hz, though)

So, if I'm doing my math right (iffy), I get that I would want 8 (2 in parallel, 4 in series) Apex Jr tweeters and 9 Sonys (3 in series, 3 in parallel)?

Sony's:

Eff. Gain = 10 log 9 = 9.54 dB
Total Imp. = 1 / (1/24 + 1/24 + 1/24) = 8 ohms
Sen. Gain = 10 log (8/8) = 0 dB
Sensitivity = 85.3 + 9.54 - 0 = 94.84 dB

Apex Jr:

Eff. Gain = 10 log 8 = 9.03 dB
Total Imp. = 1 / (1/16 + 1/16 + 1/16 + 1/16) = 4 ohms
Sen. Gain = 10 log (8/4) = 3.01 dB
Sensitivity = 90 + 9.03 - 3.01 = 96.02 dB

Is 1.18 dB close enough?

Those are likely close enough to the recommended tweeters to use the same number and crossover.

You responded while I was typing out the math. Does my logic seem right as far as the number of tweeters? I remember there is a ratio of tweeter line to woofer line in length, but I don't remember what it is.

EDIT: OK, looks like the tweeter line should be no less than 80% of the woofer line.

You want the tweeter line to be close to the same height as the midbass line so that they'll have similar dispersion in the crossover region.

I don't think 8 tweeters would be tall enough at 2" - 3" spacing to get anywhere near 80% of the line height of the base line. I could wire 12 tweeters as 6 sets of 2 and get the same sensitivity, but it would be 2.67 ohms. Is that going to be a problem for the receiver? I don't know how that works.

2.67 ohms is probably too low, as few receivers are even 4 ohm rated. Worry less about the sensitivity, more about the impedance.

Gotcha, so I gather there isn't a way to check all the boxes perfectly with this speaker combo? Can't have 80%+ line height, close to same sensitivity and proper ohm rating (8-12ish?) So if I had to check the correct boxes, 80% line height and proper ohm rating are more important than close to the same sensitivity? Thank you again for your patience and help. I was away from the game for so long, I'm kinda having to re-learn some probably pretty fundamental stuff. Makes it somewhat tough there is a nearly 5 dB SPL difference apiece in the 2 speakers. 12 speakers gets at about 6 ohms and 99 dB....still bad?

I haven't done the math but are you comparing sensitivity per watt? Or per volt? It makes a major difference.

Short answer, I don't know, but I believe it's per watt. I'm basing my math off this post: viewtopic.php?p=202944#p202944 and this post: viewtopic.php?p=232529#p232529 that is using the Apex Jr tweeters as well (don't have much else to go off of for the specs). For the Sonys, I'm getting the info from the spec sheet at Parts Express (https://www.parts-express.com/sony-5-1- ... uctDetails). I'll admit, I'm very green at this....but trying to understand.

If it's 90dB at 2.83v that's 2 watts, not one watt. I'd wire them for 6 ohms and if it turns out the tweeter line is too bright you can always pad them down later.

Gotcha. So that would be 12 speakers 3 and 4, that would put us right at 6 ohms. I didn't know about padding, but that is good to know I can tame those down a bit if necessary. Thank you for the feedback.