No, that's completely random, I just don't bother at this point. I said it's loud because it sounds substantially louder at about the same level as I typically use. But it may be the frequency response.
Yeah ok, understandable, you've published quite many measurements recently and even done fast it's quite much work.
Any chance you could emasure ND3T in the smaller A400G2?
Any chance you could emasure ND3T in the smaller A400G2?
I don't have that waveguide assembled yet. It should lose a bit of sensitivity towards the low end as the beamwidth will be a bit wider there, i.e. the DI lower.
As I understand the acoustic vent mentioned is ePTFE, that is microporous PTFE. Searching for this, there are ePTFE or sintered PTFE films from other manufacturers as well, but to be able to buy some of it seems rather hopeless to me right now.
There's also PTFE coated glass fiber fabric in porous versions, I'm extrapolating here from the basic idea that there should be a PTFE surface to reflect high frequencies, but it should be also breathable to some extent to let sound through, IF that's the basic idea.
Or maybe Teflon coated breathable fabric that is used for outdoor gear, but can't really imagine what a piece of fabric covering the mid outlet would do. Like, wouldn't it want to move as a second membrane? Same with painters masking tape. On similar note for something that would seem like a closed surface to the eye, there's also PVC coated polyester fabric, I guess breathability could depend on the thickness of the plastic coating, light coating being not airtight?
Interesting you post this now. I have a pair of Beyma 750ti that I have been thinking about doing this with. I was going to ask about this here but see incredibly little done with 2" compression drivers.
Is there a particular reason you tried this 2" driver or did you have it lying around?
No, no particular reason. I had a good experience with D2500TiNd, and the 2-inches were for a fairly good price in a local sale.
I considered CP750Ti, it could also work well.
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Selenium D2500TiNd, A520G2 / 25-STD-2
It's not a very good match even for the STD-2. The driver has a very large exit angle (altough the exit is short) and is also a tiny bit smaller than 1".
This just calls for a special adapter.
It's not a very good match even for the STD-2. The driver has a very large exit angle (altough the exit is short) and is also a tiny bit smaller than 1".
This just calls for a special adapter.
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I'm working on a small, complete loudspeaker kit. This is the waveguide (28cm), to be used togeter with a passive cardioid midrange -
This is measured with the DF10.171K, it will probably stay.
Polar map normalized @ 10 deg.
The raw polars (0 - 80 / 10):
The original simulation:
This is measured with the DF10.171K, it will probably stay.
Polar map normalized @ 10 deg.
The raw polars (0 - 80 / 10):
The original simulation:
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So far I'm pretty happy with the results. I made a new damped rear chamber for the driver -
BTW, don't waste time with this, it doesn't make any difference 🙂
BTW, don't waste time with this, it doesn't make any difference 🙂
0 - 10 - 20 - 30 deg (the same format as with the Gen2 measurements):
- I'm pretty sure that the whole middle band could be optimized to basically flat, but without a complete model of the driver, this is only a dream...
- I'm pretty sure that the whole middle band could be optimized to basically flat, but without a complete model of the driver, this is only a dream...
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Found out there are filter membrane discs available on Amazon for pretty low cost, from PTFE, nylon, paper, with specified pore sizes, like 0.45um 0.22um. I guess nylon might be more interesting as it's a stronger material. If anyone happens to have a hole in his WG and wants to try to patch it and see what it does. (Also there are lots of different types of Whatman paper filters, specified thickness, air flow rate. My first guess would be that thick/stiffer is better.)
This article mentions the usage of Nomex fabric in a large scale acoustic installation to reflect higher frequencies https://fabricarchitecturemag.com/2012/05/24/hearing-fabric-2/
Attachments
At first sight it seems micro slit absorber discs/plates wouldn't be too hard to design and print for a custom back chamber for a HF driver. See figure 4.1 on page 61 in the following thesis: Sound absorption mechanisms in perforated plates https://pure.tue.nl/ws/portalfiles/portal/290366693/20230331_Aulitto_hf.pdf
Like printing it watertight and cutting the slit (b) with a hobby knife, something like that.
Like printing it watertight and cutting the slit (b) with a hobby knife, something like that.
^ thanks!
Coincidentally, that photo was taken in a hotel bar in your lovely city!
Coincidentally, that photo was taken in a hotel bar in your lovely city!