[musmecca]

For share

Quite nice! How did you add the gold flake?

 

[mattmatt]

Quite nice! How did you add the gold flake?

I added them in the mold

 

[musmecca]

I added them in the mold

So you put the flake in the mold, THEN poured the red?

 

[mattmatt]

So you put the flake in the mold, THEN poured the red?

Yep!

 

[dhruvmeena96]

Howdy, I've been lurking and have a few questions that I couldn't answer by searching (here, or google.)

Background: mechanical engineer, mid 30's, decent grasp on electrical, got really into cheap chifi iems during the pandemic, then started in on basic mods (mmcx conversions) and in the process gathering tools/components, and working on my soldering skills. So now I have a full fledged aliexpress addiction, and I'm sitting here with some drivers and shells in the mail for diy iem projects.

Not asking for anyone to hold my hand, but pointing me in the right direction on the electrical side especially is greatly appreciated. I think I have, or can obtain, a decent handle on the physical/acoustic damping. But I am also smart enough to know what I don't know, about all the other aspects of this type of project.

Anyway, now for the electrical questions, let's say all are general/hypothetical for now.

1) DIY hybrid iem, 1DD and 1BA in parallel, I assume you can use a low pass inductor on the DD without negative consequence to the BA, true or false? Or do I need an RC low pass on the DD instead? I am generally familiar with the BA inductance and saturation, at least enough to know there are issues and trying to low pass a BA with an inductor is a no-no.

2) Using a single capacitor high pass filter on 2 BAs in parallel, any pitfalls?

3) What is everyone using for crossover design? Downloaded Xsim but can't find any of the common BA driver files (FRD / ZMA files)

4) Not strictly electrical, but has anyone used a knowles SR-32453 for super high frequencies? The graph looks good over 10k, but what really struck me was the fairly stable impedance in that area, not a super sharp increase like you see with most other BAs. At face value it looks way better than say a 30095, which is a very common solution...

5) OK so I lied about these being only electrical questions. Thoughts on a 4x RAF or RAB in series with 2 of the dampers closed, 2 open? Would your thoughts change if there was a dip switch with the option to also put them in 2x2 series/parallel configuration?

6) I have a dayton imm6 set up and can make some reasonable looking graphs for iem comparisons, but I know I still have a lot of work to do on measurements.

7) Yes I know it seems like I'm getting in way over my head. I spent some "real money" on a pair of 10mm planar drivers, so between tweaking those and trying to fix some things I don't like about a few cheaper chifi hybrids, I promise I'll take it slow and do some work on the phsyical/acoustic tuning side. I'm also fine with a guess and check method for more complex multi driver stuff, anything to keep me occupied. Who knows, I might get lucky.

Thanks in advance for any input, I have pretty thick skin so as long as there is a shred of helpful information, just let me know what you really think.

Answer
1) inductor is not possible for new project as SMD inductor have high dcr and normal inductor are quite big.

2) no pitfall, just measure if it's causing dip and then reverse the phase( wiring of the driver causing the dip... Ie the driver with cap)

3)why would xsim have the file for BA parameters?

4)SR is fullrange dynamic replacement driver and is not a tweeter. Actually it's very weak in tweeter. For iem, tweeter is above 5kHz when we talk tweet ability...unlike speakers.

SR is nice mids to uppermids(pinna), but weak treble overall

5)series only increases circuit inductance on driver part, making it smooth sounding. Power distribution is still 1/4 per driver.
Zobel fix impedance rise what amplifier sees otherwise it's super smooth

Now about the cloth damper on back vent, you will average between RAB32033 and RAB32257 on bass

About series parallel, it sounds like single driver but now you are able to hear the difference from single driver on technical front. As driver impedance remains same and driver is on 1/2 V 1/2A pure 1/4 power split.

Sound is not changed, impedance behaviour too.


You can have switch but when doing series parallel and Series only switch.

You might need two pcb

As series will be

Series wiring on pcb + zobel


And for series parallel would be

Series parallel + zobel + resistor( to match upto series resistance value)


Because once you switch, the loudness of series parallel might shock your eardrum


6) pls get 711 from AliExpress. Dayton sucks bad

7) planar..... @Xymordos will help

 

[Wgibson]

@dhruvmeena96 thank you for the thorough response, some of it will take me time to process, but I think covers everything.

Just a few clarifications:

3) crossovers - so is there any software that can simulate, or you just manually calculate based on impedance at the frequency you want to cross at? Then how would you check the total impedance of multiple drivers? My first thought was to build an excel sheet and learn as I create it, but I was hoping something already existed.

4) Yes the SR6438 I agree does not look good for highs, but the SR32453 still shows more than100db up to 17k or so. Does this not work in reality?

I need to learn about the Zobel circuits but there is plenty of info available there.

4 driver 2x2 series/parallel I got a functional result with 3 switches, I will have to see if zobel still works with that.

None of the aliexpress 711 setups have a clear enough description to know what I am actually buying :/

Edit: on a fundamental level, I don't see why fully capable loudspeaker design software like Xsim couldn't just be applied "wrong enough" to use it with BA and smaller DD drivers, if the appropriate driver files were created. You should be able to get a good electrical simulation, and a very rough starting point for frequency response, before considering any acoustic damping.

 

[Wgibson]

Unfortunately, I reviewed the zobel circuit theory and my conclusion is that I should consider cracking open all my single DD iems and adding a zobel if there is room...

 

[dhruvmeena96]

@dhruvmeena96 thank you for the thorough response, some of it will take me time to process, but I think covers everything.

Just a few clarifications:

3) crossovers - so is there any software that can simulate, or you just manually calculate based on impedance at the frequency you want to cross at? Then how would you check the total impedance of multiple drivers? My first thought was to build an excel sheet and learn as I create it, but I was hoping something already existed.

4) Yes the SR6438 I agree does not look good for highs, but the SR32453 still shows more than100db up to 17k or so. Does this not work in reality?

I need to learn about the Zobel circuits but there is plenty of info available there.

4 driver 2x2 series/parallel I got a functional result with 3 switches, I will have to see if zobel still works with that.

None of the aliexpress 711 setups have a clear enough description to know what I am actually buying :/

Edit: on a fundamental level, I don't see why fully capable loudspeaker design software like Xsim couldn't just be applied "wrong enough" to use it with BA and smaller DD drivers, if the appropriate driver files were created. You should be able to get a good electrical simulation, and a very rough starting point for frequency response, before considering any acoustic damping.

3) there are many software, but i feel they are useless kind of, because after a while, you are used to crossover on BA so much after some experience, that you can blindly select cap for specific driver and it comes out correct. why do i say that is because impedance issue of BA makes it very hard to set up on software. and merging them with cross doesnt settle all issue related to electric transfer function on impedance and electrical phase. if you zobel every driver and then use software, then its a different story but you then need Le or Inductance value of the BA voice coil. and using softwares first adds up to difficulty first. i would say, understand build first, some iem impedance and issues related to BA. then build some, slowly, then once you confident with your crossover , to make things more complex and advanced, use software

but then thats me, everybody learn things differently

4) Treble amount is relative to its bass and mids
second, see the Brochure datasheet instead of pro engineer for 711 graph, and see the damped response one
plus in tube, you have tube resonance and cancellation node points with acoustic gain till specific length and then acoustic losses

so it doesnt come out as 100dB always. plus having a wbfk crossed very high(like 100nF) always helps gain some treble back in SR

SR is generally uppermid pinna focused, mildly warm, low distortion BA. Its not for tweet application

and when seeing driver FR, dont see its dB at specific frequency but the frequency graph as whole

 

[dhruvmeena96]

Unfortunately, I reviewed the zobel circuit theory and my conclusion is that I should consider cracking open all my single DD iems and adding a zobel if there is room...

DD is generally flat in impedance for iem
sad

 

[Zitrust]

Need some help mate I have a plan to custom my own iem using Knowles ED-33357+ CI22955

But I don't know where to find ED-33357 seller

Thanks

 

[piotrus-g]

Need some help mate I have a plan to custom my own iem using Knowles ED-33357+ CI22955

But I don't know where to find ED-33357 seller

Thanks

The MOQ on this driver is 100pcs, you won't be able to buy it otherwise.

 

[dhruvmeena96]

ED33357 is improved ED29689 in sound department I feel. Pinna is at 3kHz instead of 2kHz which makes it better for ear gain

The MOQ on this driver is 100pcs, you won't be able to buy it otherwise.

@piotrus-g sensei is back
Now gib us some good open source build teacher/sensei(whoever get anime meme)

Meanwhile I am trying FED26792 single driver. The MOQ issue always gets me down.

Nobody builds iem here(i mean india not the group) for fun, so can't even group buy

And shipping from india is very much done for
For now(covid)

 

[dhruvmeena96]

i have edited the post above
i just skipped something and was writing in speech format

here meant india and not the homemade iem group(i was re reading the posts and i felt that the message can have wrong interpretation)

 

[gregeagle]

Did a nice 4-way and wanted to share for those of interest!
I think (my ears.... I do not have a measuring system) it sounds pretty balanced with a good load of bass! the friend I made it for is quite happy with it calling it HIFI?! What you guys thinks about it?? Somebody wants to redo it and measure it??

Sonion 33AJ007 10ohm series, 2ID 16mm, red damper
Knowles 29689 3,3uf Series, Zobel 10ohm/20uf
RAF fullrange
1 tube shared for 29689/RAF 10mm 2ID, green damper

 

[dhruvmeena96]

Did a nice 4-way and wanted to share for those of interest!
I think (my ears.... I do not have a measuring system) it sounds pretty balanced with a good load of bass! the friend I made it for is quite happy with it calling it HIFI?! What you guys thinks about it?? Somebody wants to redo it and measure it??

Sonion 33AJ007 10ohm series, 2ID 16mm, red damper
Knowles 29689 3,3uf Series, Zobel 10ohm/20uf
RAF fullrange
1 tube shared for 29689/RAF 10mm 2ID, green damper

Where do you put zobel
Zobel is always after driver

Driver zobel crossover

And where is the RAF zobel mate

Easiest driver to zobel out

Just asking so if we can improve it together