Best 15inch/38cm woofer units?

[thin bLue]

You can go for 2-way with 15 inch, something like Geddes did.
Disadvantage is that the beaming will be very high, but it will get you a very nice directivity when combined with a 12-15 inch horn.

Yes! JBL Style WG with compression driver is also great design!

 

[thin bLue]

With the right driver, a 3-way can be built with a very small back volume for the mid cone driver. This is interesting because small is easier to build, and box resonances of a small a mid chamber are going to be high in frequency, even up to 1kHz, which is easier to mitigate probably. Very low Vas, low Qts drives that'd work for this best are going to be higher sensitivity, so better match for something like a 15" woofer. Also such drivers have high Fs, in theory this might be good for excursion limiting effect from the sealed response, higher resonance and roll-of also works better for a passive crossover. (With the right sealed response could be even just one cap, and a notch filter to flatten the impedance.) On a similar note, one 15" that has been mentioned has Vas of 400l, that's some difference compared to 110l of something like a B&C driver, I mean smaller is easer to build.
If you have the mid and tweeter time aligned (by using a waveguide for example) and you're able to get nice curves from a passive crossover, using DSP crossover would be more convoluted in comparison. You can have passive LPF on the low, and passive HPF on the mid and high and use separate amp channels for them. Sensitivity could be matched either way with simple line-level attenuation before the amp, and DSP could be used upstream for additional tweaking.

Beauty of sealed box with hybrid x-overs. YES YES YES!

 

[earik]

I've followed ASR for awhile without posting anything, but just saw this thread and wanted to chime in. There's actually a pair of Bliesma M74s making their way to me through customs right now.

Anyway, some comments for you, @thin bLue :

1) The only reason you'd want to use the T34 tweeter is if you were going passive and wanted to match the 97db sensitivity of the dome. But with a 3" dome, you really are going to want to cross higher rather than lower, so you'd be better off with the smaller T25. If you're going active, the sensitivity mismatch won't matter, and a smaller tweeter lets you get the center-to-center spacing closer.

2) You can use the M74 down to 600hz or so with a steep crossover, so you need a hand-off here to a woofer that can play cleanly up to that same level. This means you can't really use anything larger than a 10" without having to worry about weird issues in the crossover range. I think the 8" Purifi that you've chosen would probably be great here. I built a Purifi-based 4-way as my pandemic project, and those Purifi's are *amazing*. (I really, really want them to come out with a 10".)

3) That W38 is an odd bird. I really want to like it, but every time I look at it, I get mad at scan speak. Too expensive, and it rolls off way too high. When I've modeled it, I always end up having to pair it with a subwoofer. So although it's bigger than the 8" Purifi, they both are going to roll off right around the same place. But the 15" can't play as high, so you aren't going to be able to get it up to where the M74 needs to hand off. So in that case, you sort of have to ask yourself if you'd be better off just going 3-way with the 8" (or multiple 8's?). The Bliesmas are both sealed, so you don't need separate chambers for them, so your entire box size would be based on the Purifi.

4) If you drop the 38we, and still want to do a 4-way, then I'd either just add a couple 8" purifis, or look into adding a subwoofer. I used a 13" Scanspeak sub in my Purifi build for the lowest couple of octaves, and unlike the 38we, those can go really low. If you go sealed with a little boost, the sub is only going to need 1-1.5 cubic feet, so it won't make your tower too gigantic.

Hope that helps. Please post some pics if you get started on the project.

Thx,

E

 

[thin bLue]

I've followed ASR for awhile without posting anything, but just saw this thread and wanted to chime in. There's actually a pair of Bliesma M74s making their way to me through customs right now.

Anyway, some comments for you, @thin bLue :

1) The only reason you'd want to use the T34 tweeter is if you were going passive and wanted to match the 97db sensitivity of the dome. But with a 3" dome, you really are going to want to cross higher rather than lower, so you'd be better off with the smaller T25. If you're going active, the sensitivity mismatch won't matter, and a smaller tweeter lets you get the center-to-center spacing closer.

2) You can use the M74 down to 600hz or so with a steep crossover, so you need a hand-off here to a woofer that can play cleanly up to that same level. This means you can't really use anything larger than a 10" without having to worry about weird issues in the crossover range. I think the 8" Purifi that you've chosen would probably be great here. I built a Purifi-based 4-way as my pandemic project, and those Purifi's are *amazing*. (I really, really want them to come out with a 10".)

3) That W38 is an odd bird. I really want to like it, but every time I look at it, I get mad at scan speak. Too expensive, and it rolls off way too high. When I've modeled it, I always end up having to pair it with a subwoofer. So although it's bigger than the 8" Purifi, they both are going to roll off right around the same place. But the 15" can't play as high, so you aren't going to be able to get it up to where the M74 needs to hand off. So in that case, you sort of have to ask yourself if you'd be better off just going 3-way with the 8" (or multiple 8's?). The Bliesmas are both sealed, so you don't need separate chambers for them, so your entire box size would be based on the Purifi.

4) If you drop the 38we, and still want to do a 4-way, then I'd either just add a couple 8" purifis, or look into adding a subwoofer. I used a 13" Scanspeak sub in my Purifi build for the lowest couple of octaves, and unlike the 38we, those can go really low. If you go sealed with a little boost, the sub is only going to need 1-1.5 cubic feet, so it won't make your tower too gigantic.

Hope that helps. Please post some pics if you get started on the project.

Thx,

E

Thanks for the comment!

I've heard Purifi started preparing 10" for next year 2023! that would be fantastic for you(& me xD).

BTW, Purifi announced new 8 ohm 8" has Cu voice coil with great measures, check this link out!

https://www.diyaudio.com/community/attachments/ptt8-0x08-nab-02-data-sheet-0-95-pdf.1076991/

 

[earik]

I've heard Purifi started preparing 10" for next year 2023! that would be fantastic for you(& me xD).

Whoa! Ok, I'm totally going to watch for that!!

 

[Frank207be]

For a similar mixed stereo/HT LCR in-wall project I'm also looking at:
Bliesma T34B
2x Purifi PTT6.5M08-NFA-01
I already bought the 15" woofers (6x PHL 6201MNd)
I'll use the Hypex FA253 (or FA503?) (and of course a 2nd order passive HPF to protect the Bliesma as gy-k confirmed)
Speakers will be MTM for LR and TMM for the Center where the speakers form a triangle.
All boxes will be sealed with Q=0.5 and crossover points will be 200Hz and 1500Hz.