The directivity of a dome tweeter is basically dictated by it's diameter.
IE - all one inch tweeters have similar directivity.
The only real exception to this rule is if the diaphragm material is "lossy" enough that it no longer behaves like a rigid piston. (IE : soft dome tweeters)
That is only half true, the shape/height of the dome is quite significant. The Bliesma drivers also incorporate variable thickness membranes which introduce differences too.
You only have to look at Hificompass's measurements of the different Bliesma 1" domes to see they are quite different while having the same diameter.
Yes, absolutely, I'd second that. I did some ABEC/AKABAK-simulations with different dome-heights and could reproduce the wide dispersion of the Blisma tweeters related to the special dome-shape. Will post the simus if I find them...
Beside that, I could see that concave tweeters (like Focal or Accuton) gerally show wide dispersion pattern.
Not sure, if very wide dispersion necessarily fits with application in wavegides though.
Edit: Found some simulations on that issue here.
Unfortunately, the Peerless DA32TX00-08 is no longer available to the DIY market.
Well, people seemed to like its little a 1" brother best...but it was a tempting driver to try first order slope... the large domed front plate was problematic due to its diameter for c to c spacing and high XO cut-off.
Peefeless is a strange company... The more they have good product which is often, the more those products are rapidly NLA or come with buying minimum quantity. Which is odd as the diy market is ceftainly its best advertiser in a sorta of win win relation as better priced than many brand at equal quality.
Peefeless is a strange company... The more they have good product which is often, the more those products are rapidly NLA or come with buying minimum quantity. Which is odd as the diy market is ceftainly its best advertiser in a sorta of win win relation as better priced than many brand at equal quality.
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https://www.somasonus.net/peerless-vifa-ot19nc00-04
For a USD$17 tweeter it's quite good... No 6" WG, only 6.5", but with a steep filter, you might hit 1kHz.
Hello everyone!
I'm planning a 3-way project with two SS 18WU/8741T00 woofers in parallel, the SS 12MU/4731T00 midrange and the Bliesma T25B-6 tweeter (I´ve attached a picture of the project). It will be an active system and I´ll use the DEQX HDP4 as a pre/crossover, so the phase problems should be resolved because this device achieves the time alignment between drivers. So my question for those of you with experience with the Bliesma T25B-6 is if you would recommend using a waveguide, or do you think it is not necessary. If you recommend a waveguide, I would appreciate it if you could tell me which of the multiple models made for 3D (I´ve seen some nice WG by Augerpro, Soma Sonus, Hificompass,...) is the one that has reported the best results for the T25B-6, or better asked, which WG do you think would match in the best way to this system?. Thank you very much for your opinions.
Best wishes.
I'm planning a 3-way project with two SS 18WU/8741T00 woofers in parallel, the SS 12MU/4731T00 midrange and the Bliesma T25B-6 tweeter (I´ve attached a picture of the project). It will be an active system and I´ll use the DEQX HDP4 as a pre/crossover, so the phase problems should be resolved because this device achieves the time alignment between drivers. So my question for those of you with experience with the Bliesma T25B-6 is if you would recommend using a waveguide, or do you think it is not necessary. If you recommend a waveguide, I would appreciate it if you could tell me which of the multiple models made for 3D (I´ve seen some nice WG by Augerpro, Soma Sonus, Hificompass,...) is the one that has reported the best results for the T25B-6, or better asked, which WG do you think would match in the best way to this system?. Thank you very much for your opinions.
Best wishes.
If I used a non-waveguided tweeter, it would be in a cabinet similar to yours with the big round corners. That said, a waveguide will make your life easier when developing a crossover for sure. I think my 5" might be a bit too deep for perfect time alignment (I still need to verify these AC depths). But I recently designed a 4" that is intended to to match to the MW13TX for a center channel. You can try it out but I warn you I haven't measured it yet, it might not perform as well as all the others I've done for the T25B. You should measure it first before you route holes in a beautiful cabinet.
One question I have is do you have the skills to design the crossover? Would be a shame to spend all that money on great drivers and have subpar performance if you don't know how to do the most important part. I only ask, because when I see someone mention using an active XO, it's usually because they know nothing about design and mistakenly believe that going active will solve their lack of skills.
Some details on intended crossover points might help.
One question I have is do you have the skills to design the crossover? Would be a shame to spend all that money on great drivers and have subpar performance if you don't know how to do the most important part. I only ask, because when I see someone mention using an active XO, it's usually because they know nothing about design and mistakenly believe that going active will solve their lack of skills.
Some details on intended crossover points might help.
Thank you very much for your answer, augerpro.
Actually I am not an expert in the design of passive crossovers, that facet is done by my partner in the project. However, I do consider that I have mastered the functionalities of the DEQX, which seems to me to be one of the most advanced digital filters nowadays. We've even experimented with 2-way loudspeakers alternating passive designs with premium components with the DEQX's active filtering, and the DEQX's performance has often come out on top. What I stand out the most about its use is the possibility of solving the problem of time alignment of the drivers at the stroke of a pen, which is usually a headache in the design of passive crossovers. The plan is to cut at 300Hz/2500Hz with a slope of 96dB/octave (I´ve attached a simulation image)
Regarding the waveguides for the T25b-6, what do you consider to be the model that has revealed the best measurement results to date? Thank you very much for sharing that 4" model, but I prefer to choose from already tested models to implement that WG to the final design.
Best.
Actually I am not an expert in the design of passive crossovers, that facet is done by my partner in the project. However, I do consider that I have mastered the functionalities of the DEQX, which seems to me to be one of the most advanced digital filters nowadays. We've even experimented with 2-way loudspeakers alternating passive designs with premium components with the DEQX's active filtering, and the DEQX's performance has often come out on top. What I stand out the most about its use is the possibility of solving the problem of time alignment of the drivers at the stroke of a pen, which is usually a headache in the design of passive crossovers. The plan is to cut at 300Hz/2500Hz with a slope of 96dB/octave (I´ve attached a simulation image)
Regarding the waveguides for the T25b-6, what do you consider to be the model that has revealed the best measurement results to date? Thank you very much for sharing that 4" model, but I prefer to choose from already tested models to implement that WG to the final design.
Best.
I'll be measuring the 4" (actually 4.5" now that I look at it again) over the Christmas break if you can hold off until then. Otherwise I would suggest the 5" but it might be too deep for the 12cm mid.
There really is no best. The measure similarly, the main difference being more directivity to a lower frequency, as the waveguide gets bigger.
There really is no best. The measure similarly, the main difference being more directivity to a lower frequency, as the waveguide gets bigger.
These are my initial measurements of the Bliesma T34A tweeter with @fluid 's shallow waveguide in my new 3-way.
Measurements are made with the driver and waveguide in the cabinet. Measured at a distance of 60cm. A few DSP filters were applied to get a reasonably flat response.
I'm not really sure what to conclude from the measurements. The waveguide seems to do something up to 5k hz. But after that it narrows again. At 20k hz there is only 9 db difference between on-axis and 60 degrees. That seems similar to HifiCompass' measurements of the T34A driver without waveguide.
And how much of it could be caused by diffraction?
This is how the baffle of the (unfinished) cabinet looks like:
Measurements are made with the driver and waveguide in the cabinet. Measured at a distance of 60cm. A few DSP filters were applied to get a reasonably flat response.
I'm not really sure what to conclude from the measurements. The waveguide seems to do something up to 5k hz. But after that it narrows again. At 20k hz there is only 9 db difference between on-axis and 60 degrees. That seems similar to HifiCompass' measurements of the T34A driver without waveguide.
And how much of it could be caused by diffraction?
This is how the baffle of the (unfinished) cabinet looks like:
Crossover point I have in mind is 1,3k hz with a 24db slope. The MW13TX mid has a wide dispersion until at least 1,3k to 1,5k hz.