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SR60-Mod - Page 95  

post #1411 of 5003
Thread Starter 

THE FORMULA

 

More and more as I try to dig myself out of a woodworker's apprenticeship (if that), I become a keen admirer of the carpenter's craft of cutting things in such a way that it all clicks together like Leggo in a kind of a tongue-and-groove fashion.  Matching the tight tolerances between the lip of the plastic inner and the limited room for rotation within the C clamps, I've found it challenging, if not frustrating, to end up with such thin dimensions, especially when working with the most beloved wood.  Even with a drill press, which is far less wasteful of the wood than a lathe, I can't help but regret the loss of such fine wood and the resulting fragility of shells that might otherwise be as solid as a rock if allowed a greater thickness.  The space between a 2" plastic lip and a 2 3/8" outer face is just that: 3/8".  That's not much.  Where possible, I've sometimes widened the outer face to 2 1/2" but that leads to less up-and-down rotation, though it has - indeed - made for sturdier shells.

 

Photo on 2011-02-15 at 20.21 #2.jpg

 

My solution has been to use a triple-cut strategy, one that produces a groove for the plastic in-between upper and lower (or outer and inner) walls or layers of wood that brace the plastic rather than simply slipping over it.  Where the groove stops, the integrity of the wood remains untouched and a thicker outer face makes for a stronger shell, particularly where durability counts. 

 

Photo on 2011-02-15 at 20.21 #3.jpg

 

That was with regard to the outer wood "slip-on" designed to fit the standard plastic inner.  Redesigning that inner chamber, however, to remake it as a wooden housing, has produced some interesting results.  I'm not done yet, but I truly believe that the integration of wood - front and back - will make for a much more responsive shell overall.  I'm beginning to see it as a three-stage mechanism whose full integration is necessary to really "get what you paid for."  If I may be so bold as to say it, "glue" is the devil.  Why would anybody want to put something rubbery in a dynamic shell?  Why unnecessarily dampen the very mechanism you're using to augment the driver?  That would be like throwing a sock in a saxophone.  Glue may be necessary where the parts do not fit together on their own, but why aren't they fitting together on their own?  Isn't this a cheat?  Can you really cheat acoustics?

 

Photo on 2011-02-15 at 20.22 #2.jpg

 

The next step has been to redesign the plastic inner to be a wood inner, one that would extend the shell to the mouth of the driver.  The benefit of using such a shell, particularly with a tongue-and-groove arrangement, is that - whatever wood "does," it could start doing it at the driver, and where the force of the driver is greatest.  Fitting together in this tongue-and-groove arrangement, there would be more than just a lengthening of the driver (without distancers or horn-like rear chambers).  The interlocking of the front and rear driver walls would reinforce the walls (for durability) and double the contact surface.  

 

Photo on 2011-02-15 at 20.23.jpg

 

To make the front "inner" fit the outer rear chamber, I had to cut an outer wall of 2 1/4" with an inner wall of 1 7/8".  But to create a cradle where the driver could be placed, I had to limit the depth of the 1 7/8" cut  and plow through the rest of the ring at 1 5/8".   

 

Photo on 2011-02-15 at 20.23 #3.jpg

 

The result is an integrated pair that fit together "as snug as a bug in a rug."  

 

Photo on 2011-02-15 at 22.38.jpg

 

This old, broken driver is one I use for reference purposes.  It doesn't fit as tightly as I'd like - in terms of width - but the depth is right.  I could cut inner circle at 1 3/4" (thickening the space up by 1/8") but when I've done that in the past, I've found it too tight.  I might order a hole saw at 1 13/16, which would probably tighten up the slack.  As much as possible, I'd like there to be no shimming material - whether it's glue, rubber or anything else that would damp or deaden the transmission of vibrations from the driver to the walls of the shells.  To the extent that the shells are to be an extension of the drivers, I want that contact to be as pure as possible.  

 

This is completely at odds with loudspeaker design, where speaker cabinets are essentially garbage cans for back-wave resonance, acoustic containment systems in conjunction with a baffle.  On the other hand, loudspeakers have dedicated woofers (and self-contained tweeters and midrange domes).  They have to do something about all that bass resonance (with cabinets that are as stiff as possible but also as absorbent as possible).  The 40mm Mylar drivers in Grados, like those of many headphones, are wide-range drivers with no special emphasis on bass.  The beyerdynamic DT770 has a thick gel added to its drivers, which no-doubt helps with the bass and helps retard cone breakup, but Grados rely on the wood shells to amplify the thump of its bass.  I like this approach because it doesn't compromise the treble by adding mass to the driver.  The driver, proper, is allowed to act like a tweeter while the shell is allowed to assume double duty as a "woofer."  How odd, yet effective.

 

There's a third stage I want to add to this process, and that's the creation of a cap or topper.  The front grill can be more than just a protective enclosure.  It can be a brace that pushes against the outer ring of the driver, holding it firm so that its vibrations don't go to waste.  A tight, snug, fit - front, back and all around - will reduce driver rattling and ringing while pushing more energy into the shells.  That will be the subject of a future project.

post #1412 of 5003
Quote:
Originally Posted by sml1226 View Post



Quote:
Originally Posted by Big Bill View Post

Anyone want to go "halfsies" on a set of 60's with me so we can "split" the drivers, or does anyone have an extra driver they would be willing to sell me???




If you want the driver only, wouldn't the iGrado be a better choice? It's supposedly the exact same driver and it's quite a bit cheaper.


Aren't they all supposedly the "same" driver? I mean come on there is probably a difference.

post #1413 of 5003
Thread Starter 

 

Originally Posted by Big Bill View Post

LOL!!!    biggrin.gif

 

Well, I just tried the "electrical tape" method a few moments ago and guess what happened? That's right, the voice coil glue let go of the Mylar and as a result the driver "buzzes" as the coil "bangs" into it. triportsad.gif

 

Originally Posted by Big Bill View Post

Anyone want to go "halfsies" on a set of 60's with me so we can "split" the drivers, or does anyone have an extra driver they would be willing to sell me???


Before you go there, and since you feel your driver is shot anyway, I'd like you to try something.  I know this will feel like sticking your finger into your own eye but (as gently as you can) push the coil back in.  To do this, you will have to touch the diaphragm.  Just push into it.  Don't be squeamish.  It's for a good cause.

post #1414 of 5003
Quote:
Originally Posted by Danthrax View Post




Aren't they all supposedly the "same" driver? I mean come on there is probably a difference.


Yeah, I know what you mean... but this time Grado actually said it's the same driver used in the SR-60 tongue.gif
post #1415 of 5003



 

Quote:
Originally Posted by Bilavideo View Post

 

 


Before you go there, and since you feel your driver is shot anyway, I'd like you to try something.  I know this will feel like sticking your finger into your own eye but (as gently as you can) push the coil back in.  To do this, you will have to touch the diaphragm.  Just push into it.  Don't be squeamish.  It's for a good cause.



Hello Bill, the Mylar diaphragm pulled loose from the voice coil glue. Since it was shot anyway I cut the diaphragm at its edge with a scalpel and used Krazy Glue to resecure the coil to the diaphragm. I then Krazy Glued the diaphragm back to the drivers "basket".


Edited by Big Bill - 2/17/11 at 4:00pm
post #1416 of 5003
Quote:
Originally Posted by Big Bill View Post



 



Hello Bill, the voice coil never left its magnetic gap "seat". What did happen is that the Mylar diaphragm pulled loose from the voice coil glue. Since it was shot anyway I cut the diaphragm at its edge with a scalpel and used Krazy Glue to resecure the coil to the diaphragm. I then Krazy Glued the diaphragm back to the drivers "basket". I'm waiting for the glue to set and will report back with a progress report in just a few moments. Regardless of the outcome, I'd still like to find a replacement driver. One from a I-60 would be fine with me. 


I would have tried to heat the old glue first... good luck though.

post #1417 of 5003

I'm hear to report that my "Krazy Glue" driver rebuild with its new patented  "Krazy Glue" surround (TM) is a roaring success! biggrin.gif

 

 

 

close up IMG_5094.JPG


Edited by Big Bill - 2/17/11 at 4:00pm
post #1418 of 5003
Quote:
Originally Posted by Danthrax View Post




I would have tried to heat the old glue first... good luck though.



Good idea Danthrax.

post #1419 of 5003

Ingenious! Not wasting any soundwave energy I see
 

Quote:
Originally Posted by Bilavideo View Post

 

 

The result is an integrated pair that fit together "as snug as a bug in a rug."  

 

Photo on 2011-02-15 at 22.38.jpg

 

 


 

post #1420 of 5003
Quote:
Originally Posted by sharkz View Post

Quote:


The lucky devil lives in Florida, he likely grew it on a bush outside. Heh.
 

Al, what size hole saws did you use. Your cups have much thicker walls than I got using 2" ID and 2.5"OD saws, or at least they look like they do. I like the look of the thicker walls but am curious how you still fit the driver in its plastic housing inside. Or if the outer ring is thicker, how that fit in the gimbals. Using my sizes, my cups barely have any room to rotate in the gimbals and one wrap of the driver housing with electrical tape keeps it very firmly in place in the cup.

Hi Sharkz,

 

the way I did it was suggested by Bill (and he just posted it) I used a 2" partially to get an inner lip so that the plastic portion could slide in while still retaining a thicker outside wall.  I think I used a 1 3/8 all the way through and the shell is 2 1/2.

 

Hopefully this helps.  Bill has all the pictures to explain this way better than I can.

 

Cheers,

Al

 

post #1421 of 5003

I've had my SR60's for a couple of months now. They were my first real pair of headphones and I thought they sounded amazing right off the bat. Then I found this thread and after reading through every single page, I decided to mod my pair. First just the quarter mod as I was too scared to do anything else. It made such a difference that I gathered up the courage to take these things apart. First vented 5 holes, then went back in and vented 10 and added blutack to the driver and the button. WOW what a difference! Guess there was only one step left, replacing the screen. I finally got around to home depot for some machine screws and some mesh. I just finished the replacing the grill and adding some set screws. These cans opened up so much! I was no expecting such a big difference. Still too scared to try to liberate the drivers and make custom cups. I probably will eventually make either custom wood cups or milled aluminum ones. But for now I am VERY pleased. Thanks Guys!!!

 

Obligatory pics:

 

P2121_15-02-11.jpgP2123_15-02-11.jpg

post #1422 of 5003

Well excitement got the better of me and I decided to go for it and fully liberate the driver.  I went ahead and made the outer shell out of jatoba and made the inner shell out of purple heart.  Once again Bill strikes again with the knowledge to make this happen! Thanks! What do you guys think? I took a quick shot and noticed the glue... That has been rectified.

IMG_0339.JPG

post #1423 of 5003
Thread Starter 

Once again, Al, you've done something that completely takes my breath away.

 

Originally Posted by Alchieng View Post

Well excitement got the better of me and I decided to go for it and fully liberate the driver.  I went ahead and made the outer shell out of jatoba and made the inner shell out of purple heart.  Once again Bill strikes again with the knowledge to make this happen! Thanks! What do you guys think? I took a quick shot and noticed the glue... That has been rectified.

IMG_0339.JPG

post #1424 of 5003

that's beautiful work man.

post #1425 of 5003

Looks great guys. Too bad that purpleheart is hidden away where it won't be seen. I seriously must be the only one without access to reasonably priced and beautiful woods like these. Although I guess I can't complain about my sources of cheap mahogany.

 

Al, thanks for the information. Might have to try to make a slip case for mine like that (where I can slide my driver in). I like the way the thicker ring looks (more RS like). I still need to get to make my cups. Lots of other stuff and projects going on, not getting any better either, going to look at a car tonight!

 

Last try for this. Has anyone here upgraded a JMoney headband or just has a spare Beyer band they want to get rid of? I refuse to pay Beyers ridiculous shipping (maybe I am a jerk) and just want to try a pad out. Apparently no one has an extra or one they want to get rid of now and I would really like to try one out.

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