Thanks, gerG for putting them up so fast, and for your listening equipment, your testing equipment, your measuring equipment, your music... what can i say, i'm indebted to the man!
this is the first, base, mod for the gradoes. the frequency response does NOT tell the full story, though!
i used 1/4" popular wood and cut a donut, then mounted gerG's beyer dt831 pads on them to see what differences, if any, showed up.
i have been finding myself pushing-in on the bottom of the grado driver enclosure to get a more "fuller" sound, otherwise it sounds too tinny. i found that if i played with the pad placement and pushed it in "just right" it would produce 'acceptable' sound. but the soundstage was too wide, too thin. (right now, push in the bottom or front side of your headphones without covering the outer shell (should it be the open type). use just 1 finger. did the sound change?
so then i started bending the band IN to put more pressure on the enclosure to get a fuller sound. unfortunately this caused physical ear lobe pain. my ears hurt for two days. but it did sound better.
the problem with the 1/4" poplar wood is that it's too thick and the band can not be adjusted up and down far enough; the bottom plastic blocks (L/R) will only come down so far and then stop (it hits the pad). i will be moving on to 1/16" aluminum in the next few days and that should resolve that problem. of course i'll have to wrap the outer edge of the aluminum so that it doesn't cut into the pads, but if glued, rubber should suffice. heck, you could probably glue 1/16" rubber on the top and bottom and then you'll have no problem with the beyer pads (from being destroyed).
now on to the sound - totally different! you can actually listen to them now. bass? check. mids? check. highs? check. *** now when i press on the front or the bottom of the case the sound does NOT change whats-so-ever! *** (did you do the finger pressure check as i suggested?). the tinniness was gone. there's bass to mid bass now, the harshness is gone. much sweeter. but i know that there's room for improvement. so i'll be waiting for those aiwa ak100's. one pair is gonna be taken apart for parts. i originally wanted the ak100's because of the band - it looks like it puts clamping pressure (pushes the bottom in) in the correct place. this alone should give a much fuller sound. (i was working on the mod before the ak100's went on sale for $19.95).
and yes, i wanted to paint the outer wood miata red, and put blue felt on the inside.
and those pieces of wood are one piece (although i broke one at 2am this morning). i pushed a square peg through a round hole.
4 "C" aluminum pieces (to make an "O") will probably work. i wonder what the smallest rivet size is? i will probably use the same trick to get the grado can to go into a 2" hole.
for those of you who want to use the beyer pads in their own mods, the inner hole is 2" and the outer hole is 3 & 15/16". this is why i asked if there was a difference in size between the dt990 and dt831 pads. it's just different materials on the outside.
Notorious, I did the senn yellow pads (1495 pads?) and forget it - it's not worth the trouble. junk. do the head-wize sock mod instead. you'll probably get better results. or just glue a piece of velour on the outside of the bowl pads. the velour should cost you about $2 for a square yard at a fabric store. a can of glue-in-a-can should cost you about $3. this is what i originally was going to do. but i still kept pressing the bowls in to get better sound. and i kept moving the pad off my earlobe so that my ear lobe would not hurt. but then the transducer was touching my ear. and this gave a very harsh sound.
so this idea came to me... nice pics, gerG. thanks.
