[robar]

You need to see @robar drill which use for 1.5mm vents. Very powerful tool

Do you still using "heavy duty" drill?
This applies to most of us.

Well, I still don't have any other option But I ordered the cheap set of hand drill on aliexpress, so hopefully I'll be able to drill smaller diameters as well in the close future. My smallest bit at the moment is 1.5mm, this is why I use it for everything I would say it's the max diameter that is usable for my purpose, any bigger than this and the regular horseshoe foam wouldn't be able to cover it properly. I guess something around 0.7-1mm should be more ideal for adding vents, it's easier to cover with foam and gives more control. In the meantime, I plan to experiment with enlarging stock vents on the mx500 shell. The 1.5mm drill seems to be ideal for this, I hope it allows me to fine tune the balance in the mids. I also received some cables today, so I'll be able to finish my Qian69 + 19-21 32ohm build soon. I have some ideas to try on the shell before finalizing, but I wanted to wait for the cable so I don't have to open it multiple times.

 

[beanxinh]

This is the PART 2 for 130ohm Beryllium driver but this time I will explain my mod for "medium" cavity size shell.
Previous posts INTRO, PART 1

Before I start, I would like to dedicate this post to Thomas Wilson aka. @HungryPanda, one of the most significant members of this community and a man who loved the good earbud "mods". RIP Thomas.
What is special about this mod? This mod had two revisions (the first one is MMCX) and this is the first time that
I prefer the "no-mmcx" version with a simple rubber "neck". Also, this shape and cavity size make this earbud one of my favorites in terms of comfort and sound reproduction.
For this mod, I choose this shell. I bought silver and black shells without the driver from DIY Earphone Tribe Store, but I think they're sold out. When I use this original model, similar to the YMHFPJ Store model but with 130ohm beryllium driver,
the sound was quite congested, with no spaciousness, so I decided to drill the back hole and install the rivets
but I needed also to remove MMCX socket. The following picture shows all the parts intended for this mod.

To better explain what are the pros and cons of this type of shell with mmcx socket and without, I'll use this illustration.

Blue text represents PROS, red CONS, and BLACK shared opinion or comments.
1. "Concave arc" shape allows a very comfortable fit, personally, this is my favorite
2. The angle between the shell and the neck axis is not 90 degrees with mmcx socket
which is also a major problem when it comes to the "rigid connection" between shell and "neck".
By using a rubber "neck" ("elastic connection") this problem can be avoided even if the angle is not
90 degrees as the cable is easily adjustable even when worn str8-up or over-ear.
3. The existing vent is not sufficient to provide adequate airflow for a large driver.
4. Foam width is optimal.
5. "A-detail" shows no space between the shell and cover, and the connection between shell and driver cover is "light",
means that you can remove the driver very easy which is god for "modding"
and you can always use glue for permanent connection.
6. "B-detail": MMCX the connector that comes bundled with the shell makes a "rigid connection" but after a while,
this connection becomes loose as the screw rests on the curved surface of the shell.
7. I mentioned earlier the problem with a "rigid connection" when not at a 90-degree angle.
This is not a natural position of the hanging cable, and as you can see there is a rotation of the shell
and perfect sealing is lost.
8. Closed back of the shell, small vent, mmcx and screw cause chaotic reflection of the sound waves
and almost non-existing airflow.
9. The point of rotation is pushed by the width of male mmcx shell.
10. Now we have improved airflow which can be controlled by changing the diameter of the rivet hole.
11. The weight distribution, in this case, is better and we have no problem with the drag due to the weight of the cable
and male mmcx shell. Therefore, better sealing is achieved because the highest weight is at the speaker position
I wear them often over-ear but str8-up is also comfortable.
12. In this case point of rotation is closer to the small vent but this not have any effect on airflow.
"C-detail" shows all mod elements. Instead of using knot on cable, I added green and red shrinking tubes to block
the cable pull and mark the left and right sides at the same time.
With this mod, you can easily tune the sound by changing the diameter or partially block rivet hole.

Is there any book about air flow and acoustic inside a chamber ? I see there are some books about design speaker so are these the same with earbud ? Thank.

Well, I still don't have any other option But I ordered the cheap set of hand drill on aliexpress, so hopefully I'll be able to drill smaller diameters as well in the close future. My smallest bit at the moment is 1.5mm, this is why I use it for everything I would say it's the max diameter that is usable for my purpose, any bigger than this and the regular horseshoe foam wouldn't be able to cover it properly. I guess something around 0.7-1mm should be more ideal for adding vents, it's easier to cover with foam and gives more control. In the meantime, I plan to experiment with enlarging stock vents on the mx500 shell. The 1.5mm drill seems to be ideal for this, I hope it allows me to fine tune the balance in the mids. I also received some cables today, so I'll be able to finish my Qian69 + 19-21 32ohm build soon. I have some ideas to try on the shell before finalizing, but I wanted to wait for the cable so I don't have to open it multiple times.

I have a small hand drill that can fit drill bit from 0.5 to 3mm bit. There are some drill make from a small 12V motor sold for 10$. I might buy it to make thing easier .

 

[robar]

Is there any book about air flow and acoustic inside a chamber ? I see there are some books about design speaker so are these the same with earbud ? Thank.

I have a small hand drill that can fit drill bit from 0.5 to 3mm bit. There are some drill make from a small 12V motor sold for 10$. I might buy it to make thing easier .

That's great, keep us updated on your build I'm not very familiar with speaker building, but my problem with translating speaker building principles to earbuds is that these devices work in very different contexts. When you make a port on a speaker, the sound waves from the port will directly contribute to the sound, because well, they emit sound in the same room. But the vents on an earbud are directed outwards and not towards your ears, so they have a different role. I think the closest thing to earbuds are open-back headphones. I would assume that you would find much more relevant info by researching that field, there are many headphone diy-ers out there.

 

[Themilkman46290]

I worked in a garage that installed sound systems in cars, we built a lot of boxes, there are a lot of tricks to change sound but some of those tricks work in the opposite way and some work the same. Sound deadening materials reduce some peaks, but depending on the shells and driver they can also remove the "space" from the sound or make the sound too "dark" adding holes can bring up the bass but to many can reduce the bass, stuffing a box with cotton can improve the lows and make it sound more spatious but in earbuds it seems to bring out the highs.
Alot of tuning is just trial and error

 

[furyossa]

Alot of tuning is just trial and error

Exactly, that is the essence of this hobby.

 

[willyboyaudio]

As well as what I think is a Yuin PK1 type bud:
https://www.aliexpress.com/item/ori...25.html?spm=2114.13010208.99999999.267.MKXLvF

Hi guys, I’ve found these drivers in my local marketplace. I can build them for the same price as a pair of Seahf 150 Ohm.
Which one will give better sound? Sound tuning is subjective of course, but which one has better resolution and clarity?
Also, how much would you typically spend on cables and plugs in relation to the drivers cost?
I don’t like braided cables as on the Seahf which is part of the reason why I’m hesitating to get one.
Thanks guys.

 

[willyboyaudio]

I measure by pushing the earbud with foam onto the mic of a Tascam dr-05 field recorder. The diameter of the mic barrel matches the earbud front cover perfectly so I don't need any special adapter. I feed the signal of the Tascam into a Focusrite 2i2 which is then processed by REW. I made a post about this here with pictures a few months ago, I think you can find it.
I'm not familiar with your gear, but I can give some general pointers based on my experience. This is my point of view after a lot of reading and experimenting, but this is a controversial topic so others will have different opinions. So first things first, try to bring the mic and earbud as close as possible, to eliminate any extra stuff which would create unnecessary distortions and resonances (just makes the graph unpredictable and hard to understand). Ideally you don't want anything else just the mic, the earbud and some kind of a platform/surface which lets the earbud front cover to sit in front of the mic. Maybe a small rubber ring or something like that, it depends on the shape of your mic. You need some kind of force that keeps the earbud in position, I use my hands as it's the simplest method and the strength of pushing doesn't really matter in my case, only the alignment. The most important thing is to not make a perfectly sealed environment, the seal should come by compressing the edge of the foam on the earbud front cover. (also, look out for the vents on the shell, don't cover them accidentally). But no matter how you do it, just don't expect perfectly unbiased measurements. My simple and straightforward technique gives pretty consistent and readable results, but it's not free from certain peaks. You definitely have to learn how to read the measurements with a critical eye, and there will be certain amount of guesswork no matter what.

So treat the earbud measurements more like a relative comparison, if the setup is consistent then you can compare different tunings perfectly. Choose a baseline, like your favorite earbud and use it as a point of reference. I can redo measurements weeks and months apart and the graphs will match. But don't expect it to be perfectly compatible with any other kind of measurements. You can make educated guesses and compensate in head or even make some rough adjustments in the software, but it becomes speculative.

(edit) By the way, how do you mean that mx500 is too small for your ears? It becomes loose because it doesn't go deep enough, or the diameter is small? There are many shells that have more concave neck than mx500, so they reach deeper thus improving fit. I never had problem with the diameter itself, maybe you can still buy rubber rings that go below the foam, but I would try other shells as well.

Hi robar, well noted with many thanks on the measurements technique. I will try that and adopt that for the equipment that I have.
Regarding the MX500 shell, they are too small for me in terms of diameter. I put a rubber ring around it (Sabia V7, which has the same shell) and with foam they fit snuggly and provides good seal.

BTW I gave away the modded Monk+ to a workmate. He said he was impressed with the clarity. So that was a project well-done, in my book. Thank you all for your assistance and input.

 

[WoodyLuvr]

Curious, what is the hardest to drive (lowest sensitivity and/or highest impedance) earbud driver currently available on the market now?

 

[furyossa]

Curious, what is the hardest to drive (lowest sensitivity and/or highest impedance) earbud driver currently available on the market now?

Diy 600ohm beryllium driver also there is Toneking 600ohm

 

[willyboyaudio]

@robar @subwoof3r
Friends, I think I’ve also found your favorite drivers in the local marketplace. Is this the 19-21 driver? The markings look similar.
I read a few pages back that @robar simply put them in MX500 shells with standard horseshoe foam on the shell. How is the sound in this configuration? Thanks!

 

[robar]

Here's a new 14.8mm speaker at CKLewis, I think I've seen this in other stores for much more money before. Now it's only 3.9usd. Has anyone tried it? Seems like a decent one, and I would like to build something usable with my 14.8mm shell for a long time. https://www.aliexpress.com/item/4000930280442.html

@robar @subwoof3r
Friends, I think I’ve also found your favorite drivers in the local marketplace. Is this the 19-21 driver? The markings look similar.
I read a few pages back that @robar simply put them in MX500 shells with standard horseshoe foam on the shell. How is the sound in this configuration? Thanks!

Wow that looks the same. There are a few variations on aliexpress that are only different by the color of the marking, so we can't be 100% sure which variant is it, but my favorite ones are red too. In my experience, this speaker sounds great in any configuration haha. It depends on the exact type of shell, horseshoe and the quality of snapping (if you don't use glue). If the cover sits loosely than it will sound different, usually flatter and warmer. I cherry picked the best fitting regular black shells because I don't have glue. It sounds slightly v shaped (just a touch, with a bit extra presence on upper mids) with tight deep punchy bass. It gives the feeling of large closed headphones. I ordered my 5th pair a few days ago lol, I got scared from the rising shipping costs. For about 3.75usd, it's a steal, best all rounder I've found so far.

I would be pretty interested in the steel mesh version, also there is a titanium variation which has purple marking, sadly NSC wants almost 3usd for the shipping so I skipped it so far.

 

[willyboyaudio]

Here's a new 14.8mm speaker at CKLewis, I think I've seen this in other stores for much more money before. Now it's only 3.9usd. Has anyone tried it? Seems like a decent one, and I would like to build something usable with my 14.8mm shell for a long time. https://www.aliexpress.com/item/4000930280442.html


Wow that looks the same. There are a few variations on aliexpress that are only different by the color of the marking, so we can't be 100% sure which variant is it, but my favorite ones are red too. In my experience, this speaker sounds great in any configuration haha. It depends on the exact type of shell, horseshoe and the quality of snapping (if you don't use glue). If the cover sits loosely than it will sound different, usually flatter and warmer. I cherry picked the best fitting regular black shells because I don't have glue. It sounds slightly v shaped (just a touch, with a bit extra presence on upper mids) with tight deep punchy bass. It gives the feeling of large closed headphones. I ordered my 5th pair a few days ago lol, I got scared from the rising shipping costs. For about 3.75usd, it's a steal, best all rounder I've found so far.

I would be pretty interested in the steel mesh version, also there is a titanium variation which has purple marking, sadly NSC wants almost 3usd for the shipping so I skipped it so far.

I am excited already. Interestingly the seller’s description mentions ‘bass’ and ‘sound stage’ - sounds about right, no?
I’ve also read carefully your post about the different MX500 shells, and now I’m optimistic I can get the better one.
Does cable matter much in your experience?
Many thanks.

P.S. I looked carefully the seller’s photo and it matches the one below. The two dimples on the solder pad is unique, not many (at least not all) drivers have those.

 

[robar]

I am excited already. Interestingly the seller’s description mentions ‘bass’ and ‘sound stage’ - sounds about right, no?
I’ve also read carefully your post about the different MX500 shells, and now I’m optimistic I can get the better one.
Does cable matter much in your experience?
Many thanks.

P.S. I looked carefully the seller’s photo and it matches the one below. The two dimples on the solder pad is unique, not many (at least not all) drivers have those.

I think this is it, at NSC it's called "heavy bass" There is a "balanced" and a "clear" version as well with different colored dots, but I haven't tried those. I'm not an expert at cables, I only use cheap ones from aliexpress. What I can say is that as long as the cable is not very thick, it shouldn't really matter much in my opinion. The snapping and the positioning of the tuning foam does.You can go down the rabbit hole of cables if you want, I'm not interested personally. For me it's more of a functional and decorative aspect, I won't pay a fortune for some minor theoretical improvement. (but again, I have no experience with those high-end cables)

By the way I received two cables a few days ago, here's a quick impression:

I had high hopes with this one, but it is really disappointing. Maybe I got a lemon who knows. It's very stiff and thick, plus it makes very annoying stethoscope effect if I touch it. (the stiff cable transmits vibrations too much) I wouldn't recommend it at all for earbuds, maybe it's ok for headphones or something. The knot is so big that the speaker can't fit in many shells, and I think this is one of the few instances where the knot actually has a noticeable impact on sound. https://www.aliexpress.com/item/4000449129490.html?

I really like this one, it looks great and it's pretty soft. I can totally recommend this one. https://www.aliexpress.com/item/32818428493.html

 

[furyossa]

Does cable matter much in your experience?

Most of these drivers lacking detail in the treble, so silver-plated copper is a good choice or a bit expensive pure silver cable. If you prefer warm sound, pure copper
is a way to go. Of course, purity of copper is also an important factor but then the price is a little higher.

 

[assassin10000]

B40 uses a larger pk style shell/driver than the typical yuin pk shell.

I sold a b40 to someone that needed to replace a yuin pk1 housing that was damaged, and the driver/cover would not fit. The housing was too large.

@robar if you still have those b40 shells laying around, have you tried to see if a 15.4mm driver fits them? Looks like the b40 has a pk shaped shell, but doesn't use 14.8mm drivers like the other pk shells.

So you may be able to use your favorite driver on them .