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[ortho transplant] "Orthosex": SFI into AKG K240 Sextett LP (in progress) - Page 3

post #31 of 50

would some wood in the back help? may help increasing the bass reverberation. it sure work for grados.

or enclosing the driver capsule somehow but not too closed to the driver. or... (I have 2 cups of coffee, bear with me) a grado driver + the ortho in each cup. would be like the ortho-dynamic duo lol

post #32 of 50
Thread Starter 

While the wood idea is fascinating, I have no idea how I could incorporate that into the headphone without some major overhauling. Maybe turn out a rear cup out of wood? Lacking a lathe tough, this probably won't be possible for me.

 

And you know, I briefly thought about trying to make an ortho/dynamic headphone... I do have an SR125 sitting around partially disassembled... but I think I would want a fostex driver for the ortho side. The SFI is treble heavy enough as it is. I would also need a larger frame, hmm... 

post #33 of 50
Thread Starter 

Added eight more pics, and listening notes in the third post.

post #34 of 50

I did the same thing a few years ago with a pair of k240 and a pair of k140, possibly the same ones Don mentions above, not sure mines ended up with him but I know of no one else using the same phones with SFIs.

 

The AKG frames are possibly the worst ever made to use with ortho drivers, space is cramped, they are full of reflections, and they take ages to open and close to test a new damping scheme.

 

I have to admit I knew nothing about ortho damping when I made mines, so part of the awful sound was due to my ignorance, but I'm pretty sure that even now with some experience with orthos I'd never get them to sound even remotely as good as a pair of cheap Yamahas.

 

But they were fun projects, and I'm sure you are enjoying tinkering with SFI drivers too. I even made a pair of desktop speakers with some cardboard and a pair of SFI drivers, when they still were plentiful.

 

Here are awful cellphone pics from my old transplants, the K240

 

akg_hybrid_1.jpg

 

akg_hybrid_3.jpg

 

and K140

 

k140sfi.jpg

 

akg_hybrid_140_1.jpg

 

akg_hybrid_140_3.jpg

 

akg_hybrid_140_4.jpg

 


Edited by ludoo - 9/5/11 at 7:54am
post #35 of 50
Thread Starter 

Was that a regular K240 or a Sextett shell you used? Those pics are handy reference; I see you mounted the driver into the ring gimbal as I did, but it looks as if yours was then mounted directly to the baffle instead of being able to pivot?

 

And yeah, I agree that this frame is a pain to work with. Right now I only have one cup wired up with short test wires, and just hold the rear cup on by hand. I use clip leads to connect to an amp and test from there. Thus all I have to do is unclip the wires and pop off the rear cup to access the guts. 

post #36 of 50
Thread Starter 

So a visit to my parents today and raiding my mom's sewing cabinet yielded some medium density felts and some thin non-breathable packing wrap

 

I've been fiddling with damping the last couple hours, working on the theme of "reflections are bad" and trying to absorb as much as possible. I figure the big surfaces should be covered with a non-porous material, otherwise sound goes through and reflects off the plastic behind it, which is where the packing wrap comes in. I figure blutak/putty might be better, but I'm trying to keep things light.

 

On the back of the rings I put a layer of the packing wrap, then a ring of felt, then the same foam/nylon tube as before. On the back of the baffle I put down micropore tape over all the hard surfaces. In front of the driver, one small disk of felt over the main driver opening, a large disk of felt over the entire baffle, then a large disk of foam on top, all squished down beneath the pad. In the rear cup the side is lined with suede, the rear has a ring of felt then a ring of foam. 

 

Treble is now tuned down to manageable levels, bass response is much improved, and I've still got a relatively flat frequency response.

 

More pics coming later.

post #37 of 50
Thread Starter 

Updated with more pics of the newer damping scheme. 

post #38 of 50
Thread Starter 

Has anyone tried connecting SFI drivers directly to speaker taps? I need to get some more volume out of these to really evaluate them. 

post #39 of 50

Couldn't hurt. Just make sure the grounds are separate and the volume turned down.

post #40 of 50

1. aaah, ludoo - I knew they had been passed on to me but for the life of me , I could not recall from where ( yes it is an age thing ) Good to see that you still follow along ;-)

 

2. SFI and speaker taps = yep, they will be just fine. be careful on how quickly you crank up the volume ..dB

post #41 of 50
Thread Starter 

Argh, I just discovered last night that my receiver (an old HK) has some grounding problem. I've got 600mV offset on the headphone jack ground. Fortunately I only plugged in the SFI and a 600 ohm can so no damage was done. Yikes, and to think I almost plugged in a DT1350. The speaker output also seems to have the same offset, though intermittent. I was intending to hook the SFI up to speaker set B and simply turn off A, but if I turn off A then I get offset in B. If I turn on A, the offset is gone, but then I can't hear the headphone. Grr... so now I have to get a new amp before I can test these out. 

 

(and yes I tried disconnecting speakers A, but that didn't solve things)

 

 

post #42 of 50

Remember, a ss amp that puts 100W into 8 ohms will only put a little more than 6.5W into 120 ohms. Just watch out you don't voltage-clip the amp. Sorry to hear about the HK, but look at it this way: moar amps. Really, can one have too many?

post #43 of 50
Thread Starter 

What's the max power rating of these drivers anyways?

 

Hmm, I wonder if I can rig up a buffered cmoy or somthing with ridiculous gain and see if that works.


Edited by Armaegis - 9/6/11 at 10:35pm
post #44 of 50


Quote:

Originally Posted by Armaegis View Post

Was that a regular K240 or a Sextett shell you used? Those pics are handy reference; I see you mounted the driver into the ring gimbal as I did, but it looks as if yours was then mounted directly to the baffle instead of being able to pivot?


I seem to remember they were a pair of regular K240 with a broken driver, Sextetts were too valuable to butcher. Yes, the driver was mounted to the baffle, first with bluetack then with string glue.

 

Quote:
Originally Posted by dBel84 View Post

1. aaah, ludoo - I knew they had been passed on to me but for the life of me , I could not recall from where ( yes it is an age thing ) Good to see that you still follow along ;-)


Heh, I did not even remember sending it to you, old (well, not really...) age is a common condition it seems. :) And yes, I still follow along from time to time, but as I'm pretty much satisfied with my setup the incentive to experiment and tinker is very low. Just got a butchered pair of old style T20s though, I'll try to resurrect them and might stop by *the* thread to report.

 

post #45 of 50

The T20v1 is currently my second favourite headphone, modded obviously and with O2 pads. I honestly think that the T10 / Early T20 fostex are some of the best  small driver orthos around..dB

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