I'm thinking of using the T34A specifically because of the super-wide dispersion. My next thought was to pair it with a 4" instead of 6.5" because 1) I'm going to include at least one 10" per side in this build and 2) I might not even need a waveguide in that case. It looks like the aluminum Purifi 4" has next to no beaming around 1500. Same with the T34A. The T34A has low and diminishing distortion in that range. Both will be far from their breakup regions.
The big snag is that the 4" has wayyyyy less sensitivity than the tweeter, (perhaps this calls for putting two 4"s in instead of one 6.5... but now this is starting to sound silly) but other than that, what am I missing? Would there still be a benefit to a WG? I'm very comfortable with 3D printing (currently printing a coffee table in 16 parts as I type this, plan to 3D print the entire cabinet for this proposed speaker) but keeping the overall design simple is a benefit either way.
The big snag is that the 4" has wayyyyy less sensitivity than the tweeter, (perhaps this calls for putting two 4"s in instead of one 6.5... but now this is starting to sound silly) but other than that, what am I missing? Would there still be a benefit to a WG? I'm very comfortable with 3D printing (currently printing a coffee table in 16 parts as I type this, plan to 3D print the entire cabinet for this proposed speaker) but keeping the overall design simple is a benefit either way.
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We did this combination in a project with active crossover (so the sensitivity of the 4" was no problem) - but it always remaind the "weak" link (but sounded very good). Have a look into PHL 5" drivers! They have a very small footprint, you can get close to the tweeter and radiation should be fine. Good sensitivity and always low THD with PHL.
btw - the owner of the project just recently changed the midrange to M74 paper version. Will have to talk to him about the differences.
btw - the owner of the project just recently changed the midrange to M74 paper version. Will have to talk to him about the differences.
I already recommended PHL for this usecase - definitely better a the 8NMB420.
I started with the Beyma 8P300Fe/N (what a name
) for my project but Beyma changed the surround for a more stiff version without noticing or changing the datasheet. What changed the whole chassis in a direction I didn't like and of course I don't like manufactureres to just fu? around with their chassis cause they can't source the right parts.After many many trials I finally landed at a very similar chassis again ... some projects have strange twists
kemmler3D
Usually in a loudspeaker, the woofer section is the lowest sensitivity (mainly because the baffle step loss), so if the 4" midrange have enough sensitivity for your woofer, than you just need to pad down the much more sensitive tweeter and done. However these Purifi drivers have quite low sensitivity, they clearly traded high efficiency for more low frequency extension but a dedicated midrange driver don't necessarily need to produce low bass.
If you need higher sensitivity midrange driver, check this for example:
https://www.bcspeakers.com/en/products/lf-driver/5-0/8/5mdn38-8
Anyway a good waveguide is always beneficial, even for the T34 for more even off axis response, even at higher frequencies, not just down low around the crossover point.
Usually in a loudspeaker, the woofer section is the lowest sensitivity (mainly because the baffle step loss), so if the 4" midrange have enough sensitivity for your woofer, than you just need to pad down the much more sensitive tweeter and done. However these Purifi drivers have quite low sensitivity, they clearly traded high efficiency for more low frequency extension but a dedicated midrange driver don't necessarily need to produce low bass.
If you need higher sensitivity midrange driver, check this for example:
https://www.bcspeakers.com/en/products/lf-driver/5-0/8/5mdn38-8
Anyway a good waveguide is always beneficial, even for the T34 for more even off axis response, even at higher frequencies, not just down low around the crossover point.
The waveguides as designed by @fluid arrived from the printer today. They look great and the fit is perfect with the T34A's!
In the mean time the plan for a 2-way has changed into a 3-way: T34A tweeter, Satori MW13TX mid, Satori WO24P woofer. The MW13TX has a wide dispersion at 1300hz, much wider than the MW19TX. And because it's smaller than the MW19TX, the tweeter can be positioned closer (somewhere between 1/4 and 1/2 wavelength distance).
As soon as the cabinet is ready, I will post my listening impressions and measurements.
In the mean time the plan for a 2-way has changed into a 3-way: T34A tweeter, Satori MW13TX mid, Satori WO24P woofer. The MW13TX has a wide dispersion at 1300hz, much wider than the MW19TX. And because it's smaller than the MW19TX, the tweeter can be positioned closer (somewhere between 1/4 and 1/2 wavelength distance).
As soon as the cabinet is ready, I will post my listening impressions and measurements.
They look really nice and it seems like I didn't screw anything up
That would be great, it is always nice to see a real comparison to the simulated one.
Following with interest. How hard was it to get the grille off without damaging the dome? Looks like a really nice fit. One of the benefits of sintering-style printing, I guess. My printer can get accurate results too... on the 8th try.
Not so hard. I've followed the instructions from others. Mount the tweeter on a large piece of wood. With a heatgun on 80 degrees celsius the glue becomes soft quickly. Then you can gradually remove the grille. Use wooden sticks only. Be very careful with metal tools because of the driver's powerful magnet.
80° is already a lot - there is also the glue for the surround in this area which we don't want to get weak.
I always remove the grid of the T25s just with force - works fine. Schould also work for the bigger ones, had a look at the M74 but will not remove the grid completely for now, just lifted one "edge" easy.
I always remove the grid of the T25s just with force - works fine. Schould also work for the bigger ones, had a look at the M74 but will not remove the grid completely for now, just lifted one "edge" easy.
According to Stanislav 100 degrees for 5 minutes is no issue but 120 degrees for more than 30 mins can cause demagnetization.
Hificompass used a copper foil heat shield to concentrate the heat only at the grid glue line which seems like a reasonable option particularly if you don't have a low temperature heat gun.
That's good to know - cause I plan to route the front plate of the M74 and it will get hot.
My methode is easy, save and quick but hey, useing a heat gun is always fun.
Well, the famous ATC SM75-150(S) mid dome have an Fs of 320Hz and is crossed at 375Hz. Just an example.
So I think a 240Hz Fs and 400Hz crossing is manageable.
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Interesting. I always thought that it was a good rule of thumb, to keep an octave away from FS and breakup's - hence the likings of broad-band drivers for midrange. But if it works... I'm game 👍
Breakups is a good idea - but it largely depends on the filters. As rule of thumb you should not see any long decay after filtering, the you are fine.
At FS there often is some sort of long decay, after all it's a resonance. But with tweeters/domes this is not always the case or it's just minimal so you can go close with the corner frequency. Just keep an eye on it.
On the contrary: most domes, whether mids or tweeters, are more vulnerable near Fo than most cone drivers, which are as rule a bit more sturdy in their construction: surround plus spider, whereas most domes are only suspended by their integral surround. That is the logic between the "octave away" rule of thumb. Because of its double suspension the ATC is an exception.
I always have a close look at which frequency H3/K3 starts to rise at higher level. That's normally a sign for the limits of a tweeter/midrange.
Newer constructions are pretty good in this regard, like B&C DE360 driver or Bliesma T25x tweeter. they have a high resonance frequency but can be driven quite close to it. I'm not nice to these speakers but up to now they take it fine
In older/simpler designs third harmonics rise way earlier - an added backchamber alone doesn't make a tweeter you can use at low frequencies ...
