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Post by yellowjeep on Nov 29, 2010 8:29:01 GMT
I snagged a pair (well 2 pair) of SFI 40mm drivers from eBay now I need something to put them in. Here are my ideas so far.
M880s Knock off ESw9 Vintage Pioneer SE-XX.
I am kind of leaning towards vintage as it would be really easy to replace the plastic cups with something made from wood . I need some more ideas.
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Post by UzminiNu on Nov 29, 2010 14:33:52 GMT
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Post by Defecitve Audio Component on Nov 29, 2010 15:13:16 GMT
I haven't made any DIY sfi can myself, but I used to have an SFI headphone (The Eagle orthodynamic). The drivers need some space behind for damping, but not too much space, because then all bass will be lost. Also, there needs to be a bass vent on the back (otherwise bass will be lost), but you might need to experiment there also, because of there is too much ventilation, all bass might be lost because of that too. (the SFI drivers were meant to be tweeters.) To keep bass inside, there needs to be a water tight seal between the cups and the baffle. And sealing pads (for instance leather) are needed. Preferrably with an isolating material inside.
There's also the orthodynamic roundup over there that can give you even more ideas, and also a few weeks of reading :-)
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Post by yellowjeep on Nov 29, 2010 16:29:15 GMT
The idea came from the massive ortho thread. I used the search tool and found references to SFI and have found a few posted for sale (like the one above) but no build threads. I did find one using HD555s with good results but that thread digressed and fizzled.
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Post by UzminiNu on Nov 29, 2010 18:42:37 GMT
any links:?
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Post by yellowjeep on Nov 29, 2010 19:20:24 GMT
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Post by PinkFloyd on Nov 29, 2010 22:09:20 GMT
I've got a pair of Pioneer SE-305 which may be good donors: I have a feeling they may be a bit on the large side to do any justice to the SFI drivers (tweeters) but I may be wrong, I'll certainly give them a go. I think the Kanen KM-880 would be better donors for the SFI drivers... the SE-305 may require a secondary driver ( a different type) to handle the bass and then we would have to fit some type of crossover.... there's plenty of room inside the SE-305, you could even fit a passive bass radiator just to give you a tad more oomph. The SE-305 (as they are) aren't a bad sounding 'phone.... they lack in the bass dept. and sound pretty two dimensional (narrow) but the enclosures definitely have potential. Are you sure the cups are plastic? (I haven't been under the hood yet).... whatever they are, they are covered with pleather coated foam which makes for good anti resonance. The SFI drivers will have to be glued into position (preferably with a non hardening glue) as I can see no other way of fixing them (from the supplied pictures) this is probably preferable, anyway, as you will get a better seal and superior anti resonance properties than a "bolted down" driver.... in fact, a good quality silicone sealant may be even better than a non hardening glue..... there is no internal cabinet "pressure" from a headphone driver so we don't have to bolt these drivers down and treat them as if they are about to enter "space" on the end of a rocket. I will have PLENTY of time, over the next month, to play about with these.... I have downed tools until January (work wise) and will be "pottering" doing the things I have wanted to do for quite some time.... I've got an armoury of different glues, foams, cables, drivers (even some passive ABR radiators 25mm wide ).... I'll keep an eye on this thread and hope to join in as soon as the Kanen and SFI have arrived. Nice thread Yellowjeep Mike.
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Post by UzminiNu on Nov 30, 2010 2:01:14 GMT
thank you for the links yellowjeep :].
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Post by yellowjeep on Nov 30, 2010 2:22:25 GMT
^^^ indeed.
Mike, those are some of the phones I've been thinking about, or the SE20, 30 or 50. Interested to see what you come up with. I'm excited about this project. Did you order the 120 or 32 ohm version?
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Post by yellowjeep on Nov 30, 2010 5:09:07 GMT
KC25 UR20 Hmmmm......
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Post by PinkFloyd on Nov 30, 2010 9:26:13 GMT
^^^ indeed. Mike, those are some of the phones I've been thinking about, or the SE20, 30 or 50. Interested to see what you come up with. I'm excited about this project. Did you order the 120 or 32 ohm version? I ordered the 120 ohm version YJ.
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Post by Deleted on Nov 30, 2010 9:40:51 GMT
I changed my order in a nick of time to 32 Ohm. Since we will all be receiving 4 drivers someone might be interested in trading 2x 120 Ohms for 2x 32 Ohms so you can experiment with both types of drivers.
120 Ohm, probably, will need a higher voltage to be driven to the same SPL as the 32 Ohm version.
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Post by PinkFloyd on Nov 30, 2010 10:09:30 GMT
I changed my order in a nick of time to 32 Ohm. Since we will all be receiving 4 drivers someone might be interested in trading 2x 120 Ohms for 2x 32 Ohms so you can experiment with both types of drivers. 120 Ohm, probably, will need a higher voltage to be driven to the same SPL as the 32 Ohm version. I'll do a trade Frans 120 ohm for 32 ohm
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Post by Defecitve Audio Component on Nov 30, 2010 10:25:46 GMT
I tried the SE-205 with a bass-weak orthodynamic driver, and it was indeed to big, too much air inside. But that wasn't SFI. It was a RFT driver. A crossover for bass would in a way ruin the idea of an orthodynamic transducer. The idea is to get the whole frequency range from one driver, including deep bass. Besides, planar bass can sound very nice. I've got a pair of Pioneer SE-305 which may be good donors: I have a feeling they may be a bit on the large side to do any justice to the SFI drivers (tweeters) but I may be wrong, I'll certainly give them a go. I think the Kanen KM-880 would be better donors for the SFI drivers... the SE-305 may require a secondary driver ( a different type) to handle the bass and then we would have to fit some type of crossover.... there's plenty of room inside the SE-305, you could even fit a passive bass radiator just to give you a tad more oomph. The SE-305 (as they are) aren't a bad sounding 'phone.... they lack in the bass dept. and sound pretty two dimensional (narrow) but the enclosures definitely have potential. Are you sure the cups are plastic? (I haven't been under the hood yet).... whatever they are, they are covered with pleather coated foam which makes for good anti resonance. The SFI drivers will have to be glued into position (preferably with a non hardening glue) as I can see no other way of fixing them (from the supplied pictures) this is probably preferable, anyway, as you will get a better seal and superior anti resonance properties than a "bolted down" driver.... in fact, a good quality silicone sealant may be even better than a non hardening glue..... there is no internal cabinet "pressure" from a headphone driver so we don't have to bolt these drivers down and treat them as if they are about to enter "space" on the end of a rocket. I will have PLENTY of time, over the next month, to play about with these.... I have downed tools until January (work wise) and will be "pottering" doing the things I have wanted to do for quite some time.... I've got an armoury of different glues, foams, cables, drivers (even some passive ABR radiators 25mm wide ).... I'll keep an eye on this thread and hope to join in as soon as the Kanen and SFI have arrived. Nice thread Yellowjeep Mike.
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Post by Deleted on Nov 30, 2010 12:58:38 GMT
I changed my order in a nick of time to 32 Ohm. Since we will all be receiving 4 drivers someone might be interested in trading 2x 120 Ohms for 2x 32 Ohms so you can experiment with both types of drivers. 120 Ohm, probably, will need a higher voltage to be driven to the same SPL as the 32 Ohm version. I'll do a trade Frans 120 ohm for 32 ohm Okidoki... settled, Will let you know when mine have arrived.
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Post by yellowjeep on Dec 2, 2010 19:05:33 GMT
Mine should be here tomorrow if USPS is to be believed.
I had a line on a pair of shit sounding but nice looking Sony dr5a head phones for "free" but shipping from the Great White North would be around $30... not worth it to me for a set of cans I'm going to hack up. I have a couple of antique malls in town that may have something worth while.
Hey Claus, I've seen your fantastic wood boxes, any chance you can also turn cups?
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Post by yellowjeep on Dec 7, 2010 1:49:01 GMT
Mine came in today. I don't have a ton of time to mess with them tonight but I did hook one up for a quick listen just holding it up to my ear. The mids are about all I could hear clearly but they were smooooooth, I like it. Not much base as to be expected with it just sitting there but I feel that the potential is there. Can't wait for you guy with loads more experience than I to get yours in. I am interested in your impressions.
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Post by Deleted on Dec 8, 2010 15:51:34 GMT
For SALE !! 2* 32 Ohm tweeters ! (2 I will keep for myself) Now on more serious note. The drivers arrived today. The efficiency is quite low which is not a real problem because a bit more voltageand a low output impedance and this is cured. They were listed as tweeters and that's exactly what they are. Just like most tweeters can play even the lower midrange but only at a low SPL (headphone levels) this one is no exception. Around 150 Hz there is the well known resonance peak though merely a few dB. The problems are below that point (as usual, speaker builders know this all too well). This can partly be solved by active compensation or creating a resonance in the housing. This last option, however, creates uncontroled = bloated undefined bass. I can tell you the mids and overall SQ is actually quite good. Surprisingly good even, no peak in the highs very balanced. not a trace of harshness and wonderfull mids. All sounding very natural. For what it's worth, as my hearing seems to be seriously impared so I am told Alas below 150 Hz the drop off is enormous. so NO bass at all... maybe just becoming near acceptable with a equaliser below 100Hz at + 10 to +12dB settings. This, however, serious limits the max SPL before clipping starts in. This is not due to my amps not being able to drive a 32 Ohm load full power at 10 Ohm output resistance but limitations of the membrane being tnot able at this point in time. At low to normal listening levels this is no problem, there will simply be no bass extension (which I love) Other thaen that when you listen to it for a while it sounds excellent. I do experience listening fatique.. Aside from the lack of bass it betters the HD681 easily. (no suprise there) Perhaps loosening them up on a heater with 50 HZ on it will make them behave better in the bottom. Defenitely usesless without active compensation for my taste. a pity really because they sound pretty good from 150 Hz and up. Maybe I will continue making something of it in the future with a dedicated amp that is compensated for the losses. Maybe some experiments with other housings and/or pads Also do take into account they came in from the cold and have less then 2 hours on them at this point. but wait.... look for my post 58 page 3
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FauDrei
Been here a while!
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Post by FauDrei on Dec 9, 2010 13:13:40 GMT
I can tell you the mids and overall SQ is actually quite good. Surprisingly good even, no peak in the highs very balanced. not a trace of harshness and wonderfull mids. All sounding very natural. Welcome to the Ortho club.
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Post by PinkFloyd on Dec 9, 2010 14:37:52 GMT
Just as I thought Frans ^^^^ they are after all "tweeters" so there ISN'T going to be any bass is there?.... what we need here is a driver to handle the bass and the SFI to handle the rest of the range... in this case the pioneer SE-305 would be excellent donors as there is plenty of room inside to fit two drivers... I may be talking BS here but if we roll the "bass" driver off at around 150Hz and let the SFI do it's thing we won't be far off the mark?
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Post by PinkFloyd on Dec 9, 2010 14:39:16 GMT
I can tell you the mids and overall SQ is actually quite good. Surprisingly good even, no peak in the highs very balanced. not a trace of harshness and wonderfull mids. All sounding very natural. Welcome to the Ortho club. Yeh, the "bass free" ortho club There's bass Jim, but not as we know it
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Post by Deleted on Dec 9, 2010 15:08:59 GMT
Yeh, the "bass free" ortho club There's bass Jim, but not as we know it ;D Your suggestion with a crossover and 2 drivers is possible indeed. Don't know the pioneer but if it has good bass this might be a very good idea to start with. The efficiency of the SFI driver is much lower but the Pioneer SPL can probably be lowered without too much problems. This way you can still drive the thing with a normal HP amp. a passive crossover must be designed for it and the construction of driver placement could be difficult. Less difficult if you can tell me the (approximate) difference in SPL (fiddle around with an equaliser ?) and the impedance of the Pioneer. crossover at around 150 Hz ? Don't know how efficient the 120 Ohm versions are gonna be...especially compared to the Pioneer. Currently my drivers are in a (semi open) DT990 housing with Beyer pads. I closed off the housing and NO difference at all, concerning bass levels that is. 1 hour ago I designed an (opamp) filter which should compensate the deficiencies exactly as I think I heard them (a slight resonance peak around 150Hz and considerable roll of from 100Hz down). don't know HOW it will sound and you would have to use this extra box in front of the amp specifically for this headphone. This is a pain... to say the least not to mention the amount of parts extra in the signal line. For myself I am simply gonna build this in a dedicated HP amp, saves parts, and the HP connected directlty onto it. a lot of hassle and still you don't get HD681/HD250/HD25 type of bass. Just doing it for the fun of getting them to sound the way I like it. They do have VERY nice mids and highs.
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Post by yellowjeep on Dec 9, 2010 17:52:05 GMT
Looking forward to your amp design. FWIW the consensus on the other forum seemed to be that small and shallow ported supra aural cups seemed to provide the best LF response. And then there is the whole bit about dampening.
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Post by Deleted on Dec 9, 2010 18:09:40 GMT
Didn't try the supra aural. Very possible this will improve LF response. Personally I prefer circumaural so that's where I started. Don't have supra-aural pads lying around (well, KSC75 pads they might even fit directly) Will give that a go when I have the time. I will try small sized pads too on the Beyer and see if this improves things.. it should. Will read the thread, maybe there'll be some clues there.
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Post by yellowjeep on Dec 9, 2010 18:56:18 GMT
That thread is 15k posts , I'd recommend the search tool. I am the same way. I much prefer circumaural but as this is just a for fun project I'm willing to try anything. Thats why those Kanen 880 seem appalling, to me at least. Anybody else have theirs yet? If I'm not mistaken I think Claus has a pair of the cheap woodies so I'm really interested it his findings.
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