Hi there, have you come up with an ideal configuration of crossover(s) and drivers that you can recommend?
Multiple balanced armature speaker systems with crossover networks - Page 2
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Thanks for starting this resource, Moz-Art! I too am interested in learning more about BA applications and appropriate crossover networks so I've been reading about it a bit myself, but your links to Knowles documentation is definitely helpful. I know Sonion has some documentation on their site about each unit as well, but they are much more difficult to acquire (I asked their customer support specifically about the AcuPass 1723 and there is a minimum of 1000 units per order) so I'll be sticking to Knowles units for now. Another alternative to Mouser is Digikey, and the prices are pretty much identical so whichever gives you the better shipping price
Unfortunately, proper artificial ear measurement tools are extremely expensive, I recall Rin's write-up on the IEC 60318 stating that each unit was roughly $3k! I suspect the other options like the GRAS RA0045 (or 43AG ear simulator) and B&K 4157 are similar...and after reading about what goes into them, rightfully so. Now, I've definitely seen some DIY alternatives out there but it's hard to say just how accurate (rather, how much less accurate) they will be. I guess one option would be to make friends with an audiologist or hearing-aid technician and see if they would be willing to measure your units - that could be a practical way to get accurate measurements without breaking the bank haha. I think at first I will go the route of attempting a fairly simple DIY measurement rig of some sort (still researching if it's worth the effort) using some software compensation and then subjective impressions from myself and others. I'm interested to see your findings though! I have come across some other potentially useful resources:
I think for starters I am planning on trying a design using GQ-30783 (so just a two way crossover config at first) and then go from there, just due to availability and ease of use. The GQ series seems to implement a similar design as Sonion's AcuPass but I'm not sure if they have a similar type of low-pass filter implemented in already. I guess an alternative is to acquire a used TDK BA200 and cannibalize the drivers from there (I really love the BA200) but it's a shame nobody sells Sonion units in lower quantities. I would say judging by the measurements they are fairly similar in topology though. My other current IEM, the InEar SD-3, does utilizes the GQ-30783 in conjunction with an additional woofer (possibly a Sonion driver) but I believe it is still a two way crossover. I really like what these types of units mean for designers...primarily for simplicity in construction but also because it seems like a good base to start with if you're adding more in. What do you think?
I've been sifting through some threads here on DIY CIEM, as piotrus-g and a few other well-known DIY'ers have posted some really useful information and this one has quite a bit:
I'll share any additional findings I come across
In the US - so far I've only contacted Sonion US but I know they have a few EU distributors...do you happen to know which might have low minimums?
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Just came across this thread while looking into making my own custom IEMs.
Great info Moz, thanks - did you write the Instructables piece also?
Anyhooooo... if you're after Sonion drivers in small numbers, Colsan Microlectronics (http://www.colsanmicro.com/) in the UK will sell you as few as you like, though the per-unit price is significantly higher than buying 25+.
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It's been a while since my last post and this is mostly cause I've been very busy at work and because I spent a long time choosing the right speaker combination. I've ordered a rang of speakers and they arrived in the mail last week. Next week I start building my crossover network.
To test the frequency respons of the setup, I've contacted a few university's and found one that had the ear simulator and was able to convince them to use it a couple of times. Because I don't assemble the in ears myself, I contacted a local lab specialised in hearing aids, they can recreate my setup over and over because they can test the frequency response in a special box (not ear simulator) to match my reference pair. They can also test that the left and right monitor has the same response.
I'll try to post some pictures soon!