[MDR30]

Thanks. Seems all PMB headphones were made in Germany by former Mikrofon-Bau then. Reason I ask is it's important to set down an orthodynamic time-line. After Wharfedales pioneer 1972 headphone it took a few years before PMB, Fostex and Yamaha presented new lines in 1975-1976. Would be interesting to know in which order - should be reports from hifi shows available..

Question is also if ortho loudspeaker tweeters were designed before that.

 

[ballhead]

Is that brown blutak? You also mentioned holes to make the drivers breathe, would be interesting to know where you put them. In my U70, the damping felt was circular, not square, and I think only one each of them. Ear pads look like a perfect solution, not to thick, not airtight, and with a controlled central opening (not too large, causing cavity resonances).

So how do they sound?

 
 

  He made holes on side walls of shell, similar to YH100.
 

that brown thing is polymer clay, but can be blutak or anything easy removable - it's just filler for the holes (for clips and cable), and must be removed after the bafle is fillled with hot glue. breathing holes on the sides, right. old felt doesn't seem right to me (this is felt used for shoe insoles, 7mm), but damping can be done in many ways - and cups are easy removable, no screws, so damping can be tweaked easily. those holes are essential - and with them cups are similar to yamaha's, right. final touches - placed 15mm reflection dots (leather), recabled (24 strands single core copper in silk litz). placed perforated felt diffuser on drivers front side - it was some ringing left, now gone. sound is very nice. everything is clean, fast and detailed from bottom to top. quick test with singen - from about 58hz to 1000 flat, no sharp peaks or dips after that, down from 58 fades gradually to the hell, can hear 20. no dips here too.

 

[Ocellia]

Yes to tweeters (I think).
My Leak 3090 speakers have orthodynamic tweeters.

 

[BucketInABucket]

So the batch of SFI tweeters that I ordered from ebay finally came today. Finally I can complete the project I've been planning and working on for ages.

Spoiler: Picture diary.

Two of the tweeters, took out the other two already.

One of the baffles of the Fidelity headphones.

I cut out the center and most of the sides of the baffle. I also cut out part of the metal baffle the tweeters came in and pushed it in so that it was flush with the outside of the baffle where the pads go and then hot glued the metal tweeter baffle to the plastic headphone baffle. I later sealed the front of the drivers to the baffle too (not shown here).

The cups of the Fidelity headphones. Made of 100% metal but I replaced the strain reliefs with a spare pair I had lying about.

The cable I DiYed for this project. NOS Beldun 26AWG SPC with a Rean jack on the end and heat-shrinking for the Y-split and jack strain relief.

The frankenheadband I made from 2 different headphones. A pair of crappy fender headphones and a pair of crappy other headphones. Took the yokes and curved plastic thing (with the branding sanded off) of the fender headphones and mated it with the headband and padding of the other ones.

Pair of nice ESW9 pads I ordered for this project. Comfy as hell.

Small circle of felt on the bottom of the cup.

Large donut of felt to cover the rest of the cup.

Final donut of felt to attempt to tighten and increase the bass (not very successful).



Glamour shots. Not sure if extremely beautiful or extremely ugly 

Sound impressions: slightly closed in (of course, no venting and it's a small cup), really bass-light (can't think of how to improve this short of cutting out part of the cup which I really don't want to do, any other suggestions will be amazing

) but with the famous ortho mids that I treasure. Treble is a bit rolled-off but it's perfect for my preferences. Overall, not bad for my first frankenortho!

 

[GREQ]

From my light tinkerings with SFI drivers, they can respond well to loose-woven materials, like cotton make-up removal pads.
That may help bring out some more bass.

 

[BucketInABucket]

Ouch, that's something which I don't have. I currently have heavy wool felt, arctic cotton and bamboo, creatology felt, paxmate and dynamat. Guess I have to buy some of those makeup removal pads then.
 
EDIT:
 
In addition, how should I apply those? Thanks mate 

 

[GREQ]

My mods never had any science, I just tried a few things until something sounded good.
But since there is quite a bit more space inside that can, I would first try putting the pad directly against the driver and holding it in place with a ring of open-cell foam. I think a disc of foam may end up over-damping the bass.
I found it too easy to over-damp SFI tweeters, but YMMV. No idea how it will respond inside that enclosure.

 

[BucketInABucket]

Should I leave my existing felt mods in place? I have a feeling that it will overdamp the driver but gotta make sure.

 

[ballhead]

you will not have any bass, till the cups are completely closed. and make couple of holes in the earpads.
one small hole at the center is enough, if you make something like this turbine.

 

[ballhead]

well, or you can make vents in the baffle

 

[c61746961]

Ouch, that's something which I don't have. I currently have heavy wool felt, arctic cotton and bamboo, creatology felt, paxmate and dynamat. Guess I have to buy some of those makeup removal pads then.

EDIT:

 
In addition, how should I apply those? Thanks mate 

Nice cups!

In my experience, bigger cup volume = more bass, you don't NEED to make a bass port, but it will enhance the sub-bass response and equalize the pressure inside the cup so that the diaphragm doesn't bend when the temperature changes. However, acoustic treatment != driver damping, the foams, overly dense felts, wool, makeup pads, etc. are mostly used to absorb the backwave produced by the planar driver, so, what I would do is pick a reasonable material for damping (arctic cotton, regular felt), applied directly to the back side of the driver, followed by a very breathable and stiff material (creatology hardened felt, or my personal favorite, a piece cut from non-scratching dish scrubber, only the fiber part) to prevent easily suffocating the driver with the rest of the materials, then varying quantities of your absorbing material of choice. I have had good results with high-density latex foam (the kind that make up applying pads use, google 'makeup wedges' to know what they look like), or medium density open-cell polyurethane foam, but not very good results with cotton. Play with the quantity, use the least you need, you could also line the inside of the cup with sticky felt or some other material to prevent high-frequency reflections, too, but be careful if using paxmate since it's very thick and the cup volume is quickly diminished.

 

[BucketInABucket]

  you will not have any bass, till the cups are completely closed. and make couple of holes in the earpads.
one small hole at the center is enough, if you make something like this turbine.

I don't want to make any holes in the cups, sorry.

  well, or you can make vents in the baffle

Much better thanks, I'll drill a few holes into the baffle tonight and put a felt donut under the pads.
 

Nice cups!

In my experience, bigger cup volume = more bass, you don't NEED to make a bass port, but it will enhance the sub-bass response and equalize the pressure inside the cup so that the diaphragm doesn't bend when the temperature changes. However, acoustic treatment != driver damping, the foams, overly dense felts, wool, makeup pads, etc. are mostly used to absorb the backwave produced by the planar driver, so, what I would do is pick a reasonable material for damping (arctic cotton, regular felt), applied directly to the back side of the driver, followed by a very breathable and stiff material (creatology hardened felt, or my personal favorite, a piece cut from non-scratching dish scrubber, only the fiber part) to prevent easily suffocating the driver with the rest of the materials, then varying quantities of your absorbing material of choice. I have had good results with high-density latex foam (the kind that make up applying pads use, google 'makeup wedges' to know what they look like), or medium density open-cell polyurethane foam, but not very good results with cotton. Play with the quantity, use the least you need, you could also line the inside of the cup with sticky felt or some other material to prevent high-frequency reflections, too, but be careful if using paxmate since it's very thick and the cup volume is quickly diminished.

So I replaced the wool donut with arctic cotton today, unsealed the driver from the baffle and made a small hole in the pads. I'm going to reseal the driver later today along with drilling the above holes as I suspect that it's the main reason why the bass quantity hasn't really changed. I don't have any access to open-cell foam at the moment so I have to improvise with what I currently have.

 

[MuZo2]

Another solution is to use felt ring in between baffle and cup , if you donot need holes. This way the driver can breathe.

 

[BucketInABucket]

  Another solution is to use felt ring in between baffle and cup , if you donot need holes. This way the driver can breathe.

You mean a ring of felt on the point where the cup touches the baffle?

 

[MuZo2]

Yes, you might need bigger screws.