[musmecca]

Any one have a preferred method for applying lacquer / shellac to the inside of the shell that allows the coating to fully cure out? No matter what product i use (Egger, Lack3, NanoScreen, L-1, detax, etc) the inside doesnt cure out in the same way as the outside. Ive even tried it in a nitrogen environment and submerged in glycerine. i even bought the Thermosoft curing agent, OxyStop, to see if that would help… nada. If I could coat the inside of the shell the waxed impression wouldnt have to be SOOO perfect…..

I Use laq 3 as it cures superfast....I dip the entire empty shell. With laq 3, glycerin isn't necessary. I've seen many who ignore the inside of the shell, but a smooth outside with an unfinished interior yields poor results.

 

[stegeoc]

I did some experimenting with my UM3X and RAB drivers and things got a bit more complicated than I expected and I got a bit lost.

First off, I got my mic so measured the driver sets separately and together and played around with various resistances to use. I wanted to use dip switches to keep options open but in the end I struggled to even fit the drivers in the shells so I went with a mix I thought was working (an 82R resistor in series with UM3X).

However, when I listened in stereo something was seriously wrong in the midrange and the treble was harsh. The frequency response curve looked ok, but there was a massive lack of clarity, possibly phase related, I don’t know. I tried a few things, including the driver sets on their own, and various dampers and nothing really worked or seemed to help me track down the problem.

Eventually, I added a high pass to the UM3X and it actually sounds quite good now, so I may leave it like that. Any thoughts what may have gone wrong, and if my solution is workable? To my ears and limited listening (shells are not fully put together) it sounds ok.

Thanks!

Circuit that didn't sound right:

Rescued circuit?

Frequency response of latest configuration. Ignore specifics of graph, this is the first time using the mic

 

[mattmatt]

How exactly is this done, I'm curious

What exactly? There are a ton of things played here.

 

[Xymordos]

RAU-34832-B148 Balanced Armature Supertweeter

Knowles has advanced the state-of-the for in-ear acoustics with the release of its “supertweeter”. This new balanced armature offers much improved output with the ability to reach an ultra-high frequency of 40kHz, making it ideal for in-ear monitors (IEMs) and true wireless stereo (TWS) earphones.

https://seltech-international.com/wp-content/uploads/2022/05/receiver-datasheet-rau-34832-b148-1.pdf

I wonder how it compares to the SWFK hmm...

 

[Wgibson]

Impedance looks very interesting, whole thing kinda looks like a 30095 shifted right a few kHz. Easy way to earn a hi-res sticker I guess.

 

[dhruvmeena96]

Just a quick question on the philosophy of the MASMs. Is the general idea that you are adding full range drivers to a module that already has a complete sound signature, in order to enhance or fill out the sound?

It seems a bit counter intuitive that this would improve detail as having different drivers playing the same frequencies, possiblly slightly out of phase, doesn't sound like it would. Is the design very specific to overcome this, or does it generally not matter?
Thanks!

Depends on your point of comparison and perspective. If your comparing response and circuitry to that of loud speakers, while the fundamental elements are similar, the proximity to the source changes the game entirely. The only REAL time electrical phase comes into play is charging up a parallel capacitor. Outside of the occasional Zobel (which doesnt effect electrical phase) Ive never used a parallel capacitor. Then there’s acoustic phase, which is part of tuning process, and polarity. Driver selection is imperative to a good build. Doubling up on drivers (ie turning a 5 driver set into a 10 driver) wouldnt necessarily effect soundstage, but you get more headroom and much less THD across different source impedances.

Answers
1- any preassembled driver in MASM series like GQ, HE etc are all in phase crossed
2- a fullrange rab is generally added to fill up the uppermid range dip due to wonky crossover response
3- that fullrange is always slightly lower dB, so it doesn't effect the main driver in regions like bass and mids by significant degree
4- zobel is added so integration is easier and drivers dont start reacting to each other impedance and turn it into a wonky sound
5- MASM was designed so its easier to make and people can learn things... its about learning impedance, decombing response with peak and dip adjustment, how tube resonances work, the change in resonance main peak....increasing length of RAB tube will lower the frequency(the hertz) and this way, you can adjust where RAB peak lands

actual problems tbh are
fullrange driver harmonic distortion and intermodulation distortion
and its not teaching you crossover and how to work with it


its just a quick iem


also
Finale series was made just as an experiment of damperless sound and it sounds good.......

 

[Wgibson]

@stegeoc try to keep the frequency response flat from 250hz to at least 1.5khz, then increase to a peak between 2-3khz, above thst is really personal preference. Too loud at 1khz will sound bad every time.

 

[stegeoc]

@stegeoc try to keep the frequency response flat from 250hz to at least 1.5khz, then increase to a peak between 2-3khz, above thst is really personal preference. Too loud at 1khz will sound bad every time.

Thanks for the tip, I'd pretty much written this experiment off and may end up trying to salvage what I can from it instead of finishing it. It sounds better than the first attempt but something is still not quite right. Unfortunately since I took that measurement, I've developed a problem with my mic and everything is measuring a lack of bass now (including very bassy iems). I may have damaged something when I pulled the coupler off and the end piece of the mic came off with it. It went back on easily enough (and seems air tight) but I can;t get the measurements to show properly, so will hold off any more exploratory work until I fix it

 

[Wgibson]

KZ ZS5 are on aliexpress now for $11-12 USD, good price for metal shells

Edit: Not metal, but look nice and there is room in the nozzle for EST's so...

 

[stegeoc]

For those of you using 3D prints, what type of filament do you use and is there anything special about the printers you use?

I was shocked to see that there are printers available very cheaply now, some cheaper than a bottle of resin!

 

[Mr.HiAudio]

what type of filament

im using a PLA and PETG

https://www.head-fi.org/threads/earbuds-round-up.441400/page-3876#post-16616239

 

[stegeoc]

im using a PLA and PETG

https://www.head-fi.org/threads/earbuds-round-up.441400/page-3876#post-16616239

PETG sounds interesting. Is ok for customs too? I presume you use 1.75mm?

I don't know anything about 3D printing, but seeing the prices are now so low has perked my interest

 

[swtnate]

PETG sounds interesting. Is ok for customs too? I presume you use 1.75mm?

I don't know anything about 3D printing, but seeing the prices are now so low has perked my interest

You may be able to get some good universals using filament, the industry standard in audiology is resin printing. On an industrial scale you’re looking at either DLP or laser SLA. Theres potential for some of these resins to be successfully used using LCD maskedSLA (MSLA). However, there is no current standard established or certified to be fully compatible using an LCD SLA style printer. All that said, there are people on this board that report successful prints using many different processes.

 

[Aldo40]

Liquid resin printing is the best choice and between 300-400 euros now we have high quality monochrome 4K printers.
Wire printers are not very recommended in iem-ciem the wire is much bigger and the finish coarser.
In liquid resin we work in 0.05 in much finer precision than the wire

 

[stegeoc]

Ahah! I knew there was a catch somewhere! Liquid resin printers seem about the cost/trouble I was thinking originally and probably not going to happen for me.

I am very tempted to give PETG a try though, given the relatively low cost. After a bit of sanding and lack 3 the results may well be better than my poor attempts using the traditional methods. It also opens up a lot more options finish wise...

I appreciate that resin printers probably give you that perfect look right out the printer, but a bit of sanding post-print doesn't sound like the end of the world. Has anyone tried this with customs?