[Ulfar4]

Thanks Wachara for the tip! I ordered from aliexpress (I was not able to find anything here which is reasonable priced) 50ml EELHOE Graphene Car Coating 12H, and it works great! It sounds louder than laundry softener and seems sticks well to the mylar. I checked first with applying it just to one of the phones and it definitely sounds louder.

That is very good price, and it is good that it is working too, I will order one too to try it.

It’s been more than a month now, and I’m happy to report that the graphene coating has been performing very well. I’m really happy with it.

As always, I’m taking a set of headphones with me when traveling. So far this is my favorite set. What is yours?

I am still using this pair for long time, I've tried tried many different headphones over time but in the end I always ended with them.

 

[Christer]

It’s been more than a month now, and I’m happy to report that the graphene coating has been performing very well. I’m really happy with it.

As always, I’m taking a set of headphones with me when traveling. So far this is my favorite set. What is yours?

Hmm these look very similar to my old Jecklin Float electrostats.
The Jecklin Floats still remain one of the three most open sounding and transparent headphones I have ever used.
I still have them ,but they are not working any longer and compared to planars with an open cup they were very transparent but weak in the bass. How deep do these go?
And how do they compare to the latest Stax models?
Cheers CC

 

[chinsettawong]

Hmm these look very similar to my old Jecklin Float electrostats.
The Jecklin Floats still remain one of the three most open sounding and transparent headphones I have ever used.
I still have them ,but they are not working any longer and compared to planars with an open cup they were very transparent but weak in the bass. How deep do these go?
And how do they compare to the latest Stax models?
Cheers CC

That’s exactly where I got the inspiration from. I also have a pair of JF. They sound very nice and relaxed except that they can’t be played off a Stax amp. My version has 0.5 mm spacer and uses Stax bias voltage and thus can be played with any Stax amp. In the picture, the phones are played off Stax D10 and they sound very nice together.

The phones have plenty of bass on my standard. Of course, it’s not as deep and heavy as the ones with proper sealed ear pads. But, for some unknown reasons, I always prefer them to any other headphones.

 

[Christer]

That’s exactly where I got the inspiration from. I also have a pair of JF. They sound very nice and relaxed except that they can’t be played off a Stax amp. My version has 0.5 mm spacer and uses Stax bias voltage and thus can be played with any Stax amp. In the picture, the phones are played off Stax D10 and they sound very nice together.

The phones have plenty of bass on my standard. Of course, it’s not as deep and heavy as the ones with proper sealed ear pads. But, for some unknown reasons, I always prefer them to any other headphones.

Hello and thanks for your rapid response. So how does your build compare with the old original JFs´or modern Staxes?
There is also a German made, "newer" better? Jecklin Float model which I have not heard that looks almost identical to your build.
Is that the one you have?
Or do you also still have an old orginal Jürg Jecklin model?
I stopped using mine when I bought my HD800 which had better bass but are not quite as transparent, which I have used on all my travels to SE Asia including Thailand very frequently until Covid hit.

15 winters usually Nov to May, and really hoping to be able to come again in November 2022.

If so I would really like to hear your model and compare it to my two travel headphones HD800 and HIFIMAN HEKV2 if possible.
Do you build on demand?

Personally I never listen to music while "on the run" only in a quiet hotel room or the condo I used to rent in Phuket for 2-3 months every winter.
And even with my two current headphones I sometimes turned off A/C to avoid disturbing noise.
At home I use my quite transparent ML electrostatic speakers on a daily basis. But I have not used electrostatic headphones for quite a few years now.
I sometimes still miss the amazing openess of my old JF "earspeakers".
Cheers CC

 

[chinsettawong]

I don’t want to say which headphones are better, because everybody has his own preferences. I welcome you to try all my DIY phones when you come to Thailand again next time. Let’s meet up and see for yourself.

If you are handy enough, you should try to make the headphones yourself. Please read through the old posts and you’ll see that the phones aren’t that difficult to make at all. Unfortunately, I can only teach and guide you. I don’t sell my works.

 

[tib8]

Congratulations! Please share how they sound to you.
1. 800Vpp so did you apply +-400V to the membranes? 1.2mm with such voltage will sound quiet. But if you double these 400 to +-800, you will see a huge difference. Going to 0.6mm though even with +- 400v will stick membrane to the stator especially with such low stretching (108Hrz). Remember it's not like normal design with one membrane which experience equal force from both stators in idle. These 2 membranes are attracted to each other with 800V electrical force, so they are always bended in the middle and closer to the stator, hence I used in my latest design dual middle stator bended like this )( . With a straight stator my experience with 0.6 mm spacers, 140 Hrz and +- 630V is that one of the membranes sticks after 5 mins to the stator. So 1.2mm is good if you want stability with +-800. And by the way distance is definitely not a linear factor - in fact it is quadratic to the e-force - (k x Q1 x Q2) / d^2. The reason you did not hear a difference is in my opinion, that membranes are stuck to the stator, discharged and of course very quiet. With 1.2mm distance and 400V it cannot be loud. Even normal design with 1.2mm spacers will be quiet (see p.3)
2. 2u mylar is in my opinion too thick for this configuration - that's one of the reason for the big bass - heavier membranes. You can try to stretch the membrane a bit more, to remove the bass, but with me this did not work - my current stretching is 170 Hrz and bass is almost the same as with 120Hrz. My opinion is that ear sealing plays much more role for the bass than stretching. I guess the only solution is to make the area smaller (which is good from esthetic point of view) and to order 1um Mylar. I love bass, so it's not that bad for me, I made some equalization to make it flat and it became a bit poor.
3. As for the loudness, ignoring the smaller space (because of the constant attraction in my design), +-400V (800V) and 800Vpp (single) should be equal to single 400V and 400Vpp (800 differential) in normal design. Assume stator is at +400V then one membrane sees 0V the other 800V. Now with normal design one stator is at -400 the other is +400, membrane is at +400. Again - one side is 0V, the other is 800, so it's the same es-force. And this is the main flow of single stator design - you have to double either the output of the amp or both biases to get the same level. I can't explain how you got such huge 20dB difference (my guess is the spacers are not the same thickness), I don't have much experience with a single membrane, but as I mentioned, I'm with +-630V now and about 580Vpp (single ended) and it's quite loud, my normal listening is at half volume. It's still quieter than a dynamic phones at the same source level, but still loud enough. If I go to high volumes my wife starts complaining - she can hear the phones pretty loud standing 2m away . I see now how you are going in my steps - I used to have +-300V biases and yes it was quiet, but +-630 made a huge difference. Stretching is also a nightmare - you have to stretch 4 membranes in about the same frequency (better - slightly different) and glue them and check after that again and match them by pairs. The smaller space between center of membrane and stator also plays some role in the loudness. And if this is not enough you can always go for a higher biases (increasing amp output is not easy), by doubling the power rails voltage of your amp.
4. Highs - something is wrong with your setup - I have measured 30kHz there without any problem. This design also has theoretically almost 0 capacitance (only cable capacitance), so it shouldn't have any problems with high frequencies. May be you have somewhere high load capacitance to the output of the amp? By the way hum and crosstalk of channels is removed with small capacitors (NO MORE than 10nF, considering about 3MOhm biasing resistors) AFTER the biasing resistors on both +- biases to gnd. PLEASE be careful - biases become now very unpleasant - 10nF although not lethal is not pleasant to discharge through you. If you can - put 20Mohm and 1nF. And before anyone starts to blame me - I saw original STAX amp schematic with 10nF capacitors after the resistors. Just make sure you never touch naked wires, membranes is ok to touch you won't even feel the voltage. The best is to put the caps inside the phone frames, but that would require a gnd wire to run to the phone, which is inconvenient and adds additional capacitance.
5. The highs will surely go much higher when you close the back of the phones, this should also happen with normal design or any open baffle design, but that's not a solution at all. Electrostats don't tolerate closed volume (except at your ear), they must be opened at the back. You can put a very transparent grill at the back, that would not disturb the sound waves in any way.

PS. Just remembered something. I have an ellipse design - 100x70mm AA. Used the same amp and biases. The spacers are 0.6 and membranes stuck to the stator all the time. I made some additional spacers on a 3D printer - 0.2mm (single layer) and now membranes are stable with about 0.8-0.85 mm. I think, that the shape affects also stability, because the shorter 70mm distance of the ellipse equals to a circle with 70mm diameter, but the area is much bigger. I can tell these ellipses sound the same as my 90mm circles - may be a bit louder in the mids-highs. This could be also because my circles have these thin foam inside the earpads.

Ikos 98,
Thank you for your advises, and sorry for the late feedback - I had no time to work on this project util last night.
With some heating I increased stretching to about 160Hz, then I tried to remove one of the spacers -> you were right: 0.6mm is not enough: at 'large' volume the membranes touched the stator, so I went back to 1.2mm.
Then I changed back to use again the bias power supply instead of the amplifier's power rails.
When I increased the voltage, it started 'popping' noises = arcing, so I replaced the metal screws with plastic ones (in the single membrane version metal screws were working fine, but here both membranes touching a bit the screws - this is not good!).
Probably this was the point when they started to sound well! (not like if the sound would come out of a bucket)

Also I tested again, and the loudness now do increase as I turn the bias setter pot (I can set between +-240V .. +-750V).
So with everything on the max the volume is just fine for normal listening, but I still miss that I can not increase the volume a bit sometimes.
Not much time left for testing, but my first impression compared to the classic version is that is has a bit warmer sound and a bit even more impactfull bass.
Then I accidentally made a few holes in one of the membranes, so I went to sleep.

This accident on the other hand gave me good reason to try the 1um mylar you recommended for membranes (which I did not use at the first place because it is so easy to break them).

My long term goal with these is to integrate the amp onto the headphone (except of course the power supply).
(if we get rid of the cable capacitance, smaller currents can be used and the heating of the amp hopefully decreased enough to be dissipated on the headphone frame...)
To do this I'll try to increase stretching even more - it would be really nice to use only 0.6mm gap and less voltages (or higher volume).

I'll report my findings.

 

[lkos98]

Ikos 98,
Thank you for your advises, and sorry for the late feedback - I had no time to work on this project util last night.
With some heating I increased stretching to about 160Hz, then I tried to remove one of the spacers -> you were right: 0.6mm is not enough: at 'large' volume the membranes touched the stator, so I went back to 1.2mm.
Then I changed back to use again the bias power supply instead of the amplifier's power rails.
When I increased the voltage, it started 'popping' noises = arcing, so I replaced the metal screws with plastic ones (in the single membrane version metal screws were working fine, but here both membranes touching a bit the screws - this is not good!).
Probably this was the point when they started to sound well! (not like if the sound would come out of a bucket)

Also I tested again, and the loudness now do increase as I turn the bias setter pot (I can set between +-240V .. +-750V).
So with everything on the max the volume is just fine for normal listening, but I still miss that I can not increase the volume a bit sometimes.
Not much time left for testing, but my first impression compared to the classic version is that is has a bit warmer sound and a bit even more impactfull bass.
Then I accidentally made a few holes in one of the membranes, so I went to sleep.

This accident on the other hand gave me good reason to try the 1um mylar you recommended for membranes (which I did not use at the first place because it is so easy to break them).

My long term goal with these is to integrate the amp onto the headphone (except of course the power supply).
(if we get rid of the cable capacitance, smaller currents can be used and the heating of the amp hopefully decreased enough to be dissipated on the headphone frame...)
To do this I'll try to increase stretching even more - it would be really nice to use only 0.6mm gap and less voltages (or higher volume).

I'll report my findings.

Great, please share if there's difference in the bass after changing to 1um. I'm unable to find anywhere 1um mylar - the seller no longer sends to my country.
0.6mm won't work with big areas. On my ovals 100x70 with about 180Hrz FAR, I'm using a flat stator and ~0.85 mm spacers and still if I listen for very long time and high volume some membrane may stick to the stator, but it's really rare.
Using plastic bolts is good, but to find small size is not easy, so I use metal bolts M3 with heat-shrink tubes on them, (the holes are actually 4mm, so neither of the membrane, stator or frame is touching the metal and I don't have this sparking noises anymore.

 

[chinsettawong]

M3 nylon screws are easy to find. Try ebay!

 

[tib8]

Great, please share if there's difference in the bass after changing to 1um. I'm unable to find anywhere 1um mylar - the seller no longer sends to my country.
0.6mm won't work with big areas. On my ovals 100x70 with about 180Hrz FAR, I'm using a flat stator and ~0.85 mm spacers and still if I listen for very long time and high volume some membrane may stick to the stator, but it's really rare.
Using plastic bolts is good, but to find small size is not easy, so I use metal bolts M3 with heat-shrink tubes on them, (the holes are actually 4mm, so neither of the membrane, stator or frame is touching the metal and I don't have this sparking noises anymore.

I have replaced the membranes on the broken side with 1um mylar.
I had to decrease somewhat the bias voltage because at +-750V no mater how I stretched this 1um, it sticks to the stator.
Otherwise I hear no difference compared to the 2um (but I did not heard any difference with my older headphones either) - so next time I likely switch back to 2um.

Now I plan to measure and compare this and the old one, because it seems to me that the lower half of the spectrum is too loud (or the upper half is weak?)
I need to know what is happening exactly: is it the resonance of the "box" created by the two membranes, or my amp has problem with highs?
Other than this issue I really like the stability of this construction!

 

[chinsettawong]

I have replaced the membranes on the broken side with 1um mylar.
I had to decrease somewhat the bias voltage because at +-750V no mater how I stretched this 1um, it sticks to the stator.
Otherwise I hear no difference compared to the 2um (but I did not heard any difference with my older headphones either) - so next time I likely switch back to 2um.

Now I plan to measure and compare this and the old one, because it seems to me that the lower half of the spectrum is too loud (or the upper half is weak?)
I need to know what is happening exactly: is it the resonance of the "box" created by the two membranes, or my amp has problem with highs?
Other than this issue I really like the stability of this construction!

How do you stretch the diaphragm? Are you using a stretcher?

 

[Ulfar4]

Does anyone have tip where to buy good earpads? I am looking for oval angled sheepskin earpads but I had no luck with finding any. Round types are easy obtainable, but the situation is much worse with oval ones with bigger dimensions.

 

[lkos98]

Does anyone have tip where to buy good earpads? I am looking for oval angled sheepskin earpads but I had no luck with finding any. Round types are easy obtainable, but the situation is much worse with oval ones with bigger dimensions.

I have bought from ebay or aliexpress few years ago, but not angled and cheap artificial leather. They were not very big either, but covered my whole ear. I guess you won't like them. Otherwise give me a hint, I'll look through my orders.

Edit:
Just out of curiosity I browsed and found these:
https://www.aliexpress.com/item/400...616541212174365180e8329!10000014548379220!sea
With this price they don't look to me a genuine leather, but still.... Otherwise found a lot other sheepskin leather, but not angled.

 

[lkos98]

I have replaced the membranes on the broken side with 1um mylar.
I had to decrease somewhat the bias voltage because at +-750V no mater how I stretched this 1um, it sticks to the stator.
Otherwise I hear no difference compared to the 2um (but I did not heard any difference with my older headphones either) - so next time I likely switch back to 2um.

Now I plan to measure and compare this and the old one, because it seems to me that the lower half of the spectrum is too loud (or the upper half is weak?)
I need to know what is happening exactly: is it the resonance of the "box" created by the two membranes, or my amp has problem with highs?
Other than this issue I really like the stability of this construction!

Yeah they tend to boost the low bass, but from 200-300 hrz up they are pretty flat. Since with my inear 22mm active area the bass roll off starting from around 150Hrz, I guess active area has the most impact on those. I remember I made some 76-80mm some time ago and the bass there was not enough for my taste. Also if you can avoid stretching with heat - my experience is that it decreases the elasticity of the mylar and after some time membranes are loose again.
Where did you find 1um mylar delivered to Europe? Please share if you can. Thanks.

 

[tib8]

Yeah they tend to boost the low bass, but from 200-300 hrz up they are pretty flat. Since with my inear 22mm active area the bass roll off starting from around 150Hrz, I guess active area has the most impact on those. I remember I made some 76-80mm some time ago and the bass there was not enough for my taste. Also if you can avoid stretching with heat - my experience is that it decreases the elasticity of the mylar and after some time membranes are loose again.
Where did you find 1um mylar delivered to Europe? Please share if you can. Thanks.

This is my only source, I ordered 1, 2, 5um from here:
https://www.freeflightsupplies.co.uk/index.php/products/lightweight-covering-materials
Unfortunately it is far from wrinkle free condition, but with stretching, relatively fine...

I also finished the measurement. Both of my amps (the old symmetric and the new single ended) are perfectly flat in the first 20kHz, I checked this on my scope, so they make no difference.

I attached some freq. response from my 'classic' single membrane, the new '2 membrane' and my HD58x.
The high frequency part should be ignored, but it is clearly visible that the HD58x (also my HD555) and the Classic are all 'flat' (except that bump around 6kHz, which is likely due to the poor measurement setup). On the other hand the 2Membrance has way too many mid and bass compared to the highs (my ears tell the same).

I also compared the 1 and 2um mylar (not very reliable measurement) but seems that 1um has even more bass!

So I hope, I can solve the stability issues of my classic, when the graphene arrives from china, because it is still by far the best sounding headphone from these (and from anything I have heard - only my brothers HD800 is comparable: its bass is not that good, but the spatial resolution is better - I'll likely build a new amp to improve on that...).

 

[lkos98]

This is my only source, I ordered 1, 2, 5um from here:
https://www.freeflightsupplies.co.uk/index.php/products/lightweight-covering-materials
Unfortunately it is far from wrinkle free condition, but with stretching, relatively fine...

I also finished the measurement. Both of my amps (the old symmetric and the new single ended) are perfectly flat in the first 20kHz, I checked this on my scope, so they make no difference.

I attached some freq. response from my 'classic' single membrane, the new '2 membrane' and my HD58x.
The high frequency part should be ignored, but it is clearly visible that the HD58x (also my HD555) and the Classic are all 'flat' (except that bump around 6kHz, which is likely due to the poor measurement setup). On the other hand the 2Membrance has way too many mid and bass compared to the highs (my ears tell the same).

I also compared the 1 and 2um mylar (not very reliable measurement) but seems that 1um has even more bass!

So I hope, I can solve the stability issues of my classic, when the graphene arrives from china, because it is still by far the best sounding headphone from these (and from anything I have heard - only my brothers HD800 is comparable: its bass is not that good, but the spatial resolution is better - I'll likely build a new amp to improve on that...).

Thanks. I will try to make some new measurements to see how close are yours to mine. Unfortunately my mic setup is not very good, so I don't know how reliable it is.