Topic: RD's T50RP mod v0.5 (Read 6578 times)

Marvey · « **Reply #30 on:** March 20, 2012, 08:59:01 PM »

Quote from: rhythmdevils on March 20, 2012, 08:43:15 PM

I'm pretty sure the stock cable is causing or at least contributing to, the 10k peak. Any way to check this Purrin by comparing stock cable to Vmoda cable?

If not, I'll send both cables next time :-)

I've measured cables - they all measure they same. Cable differences are only detectable by humans as of now.

dBel84 · « **Reply #31 on:** March 20, 2012, 11:15:58 PM »

Quote from: purrin on March 20, 2012, 08:59:01 PM

I've measured cables - they all measure they same.

this must be O2 artifactual

..dB

gurubhai · « **Reply #32 on:** April 01, 2012, 03:13:28 PM »

Quote from: dBel84 on March 06, 2012, 03:00:19 AM

Greetings all. I guess it only appropriate that my first post be ortho related AND to give a heartfelt "well-done" to the 2 of you. I spent many hours playing with the T50RPmkII way back and felt I had achieved a relatively smooth response from about 100Hz up, but it rolled off pretty steeply below 100 and with the plethora of options, it just never found a place in routine use. It would be very interesting to see what it might have measured like.

I shall borrow this from Don since I feel the exact same way & had a similar T50RP experience.

Quote from: dbel84

To clarify differential damping - ( and wualt does not "approve" of the theory ) , with some of the center pinned drivers, the diaphragm does not present a uniform wave front and thus the idea is to "differentially" damp different 'radii' of the driver so as to achieve adequate damping without killing the bass. I think it might apply to some of the tensioned drivers too as some of them are pleated to allow for the opposite wave motion of a center pinned driver. ( picture a butterfly flapping its wings as opposed to a trampoline with someone bouncing on it) - this really needs animation as my analogy sux but hopefully you get the idea. One of the best examples of the latter is the LCD2v1, it is technically the best driver I have ever seen.

Quote from: purrin on March 05, 2012, 10:47:31 PM

I couldn't do what you asked because I just had to even out the FR. The diaphragm should have equal pressure at all parts, otherwise you get wierd standing waves.

I have a different take on 'differential damping' theory. I don't think that the observed phenomenon has anything to do with driver itself.
my hypothesis is that the effect occurs because of how the Yamaha cups are designed.Most of them are elevated in center.
If you place a full circular felt layer directly behind the driver, the foam(assuming uniform thickness) spring pushing it would result in unequal pressure being applied on different zones of driver. The central part would receive more pressure than peripheral parts and that is probably why people find the 'donut' to work better.
Basically what I am saying is that its critical that you must provide uniform pressure over the damping layer to get the best results.
Its easier said than done though !

regal · « **Reply #33 on:** April 08, 2012, 04:25:32 AM »

I am black sheep grado guy, I know they don't measure worth a damn but they do electric guitar like no other (at least I think.) The way I used to see things is the rythm section will always suck comparing headphones to speakers so why bother.

But I decided to pick up a pair of the Fostex T50RP. Seem to have a well engineered driver in a made for production japanese style enclosure that needs improved
.
I am way behind the curve as far as "modding" these.

In stock form I was impressed with the strings, the upper notes of the electric guitar didn't "pop" out to my liking, but damn if the vibration and reverb wasn't natural, and the rhythm section was amazing for a headphone.

This is my second day with them. I damped the outer cup by layering adhesive craft art foam inside. This seemed to really help with bring out the mids.

Then I put a small amount of poly fill inside, first listen the mids improved but the upper vocals got grainy and the rythm section was hurt.

I know nothing about ortho drivers and want to seal around the driver but not sure if I should touch any of the printed copper (the part that looks like a pcb on an acetate.)

A local woodworker is sending me a pair of wood cups.

Fun little project, lot less stressful than working on 400V tube amps. And tubes aren't a great choice to drive these Orthos, so I am using an O2.

These Fostex headphones seem to have potential to out do magnums/grados with the guitar seem to be clearer with less unnatural distortion.

I'm not a speaker guy so I would be grateful of any hints folks could point me to on the web on the best way to get these to have good upper mids and maintain that incredible rhythm.

Marvey · « **Reply #34 on:** April 08, 2012, 04:38:45 AM »

Try material that will absorb the backwave that is not polyfill. Polyfill will effectively expand the internal volume leading to an overall reduction in bass. The small size of the fostex driver really puts an restriction on maximum internal volume.

Don't seal the driver completely. While I personally don't like messing with the "gauze" behind the driver, others have used various other less porous materials. RD used a coffee filter and pokes holes in them. Search around for the measurements and pix of his pair. EDIT: Doh! I'm not sure if I actually posted those though.

rhythmdevils · « **Reply #35 on:** April 08, 2012, 05:12:08 AM »

I'm going to write up a big tutorial and guide in a week or 2 that will hopefully make it a lot easier. I'm just waiting on Tyll to measure my T50rp and send them back so I can try one last idea...

RexAeterna · « **Reply #36 on:** April 08, 2012, 10:39:01 PM »

i use fiberglass usually all the time for complete absorption. there is different densities of fiberglass though. i think one i use is r-30 and i used r-30 for room acoustics as well since i got it cheap and it was 9'' thick so i had lot to work with. if you get less dense of fiberglass,it's fine as well but might need to use a bit more depending what for. for headphones it should still only take a little. i used about 1'' to 1 3/4-1/2'' thick compressed in the cups to help kill the low frequencies resonance and used polyfill for everything else but your gonna probably gonna wanna experiment though for best results. that's all i used for the cups myself.

i took care front of the driver as well since planers are dipole and found the akg 240 studios' thick foam disc to work wonders for them. i stuffed the 240 foam disc in the shure 840 pads and fluffed out the pads a bit by putting cotton underneath to help the pads seal better and made it more comfy for me.

Author Topic: RD's T50RP mod v0.5 (Read 6578 times)

Marvey

Re: RD's T50RP mod v0.5

dBel84

Re: RD's T50RP mod v0.5

gurubhai

Re: RD's T50RP mod v0.5

regal

Re: RD's T50RP mod v0.5

Marvey

Re: RD's T50RP mod v0.5

rhythmdevils

Re: RD's T50RP mod v0.5

RexAeterna

Re: RD's T50RP mod v0.5

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Author Topic: RD's T50RP mod v0.5 (Read 6578 times)

regal