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grado sr60i cup tuning

post #1 of 36
Thread Starter 


Mainly inspired by thelostmidrange I decided to do my own experiments on cup tuning.  this thread is not meant to give be all end all opinions.  it is intended to be more of a journal of my fwj exploits.  
all comments are welcome and the interest in my jorney is appreciated.
for the sake of conserving funds i'm doing the tunings on a set of grado sr60i.
first off, I wanted to test out a certain cup geometry ive been thinking about.  the theory is to create a convex shaped opening, meaning the chamber will be slightly flared out as you go from the driver to the face of the cup.
i don't really have any scientific basis for it but i've heard that paralell walls and standing vibrations are not good.
I also figure that it will help channel the vibrational soundwaves in the air away from the driver.
to test this i started by liberating one of the drivers from the plastic housing.  then i turned my first prototype of my concept out of some crappy pine bed i had lying around in my garage.  
I compared the stock plastic vs the wood cup with mono recordings of purple haze and some gerry mulligan. 
I thought the sr60i sounded pretty decent but when i heard it with a fwj it was amazing how crappy the stock plastic sounded.  
to describe the effect i would have to say the plastic made the sound feel veiled and canned in.  the sound out of the pine cup had much more space around each instrument.  the highs really felt much more aired out. It felt like finally being able to stretch after sitting in a car for an extended ammount of time. 
 with the stock plastic i also noticed a strange sort of echo like distortion in the mid and high range.  the pine cup pretty much pointed it out to me.  
also, with having more air between the instruments, the bass felt less flabby and muddled in complicated passages.
the pine cup also has a much more natural decay and timbre (if thats the right term) of the high hat.
I was definitely amazed.  I went out and bought some real wood to continue my experiments.
i picked up some zebrawood and genuine mahogany.  unfortunately i totaly forgot to make sure they were dried so the zebrawood i have will probably be unworkable for another year or two.  but luckily the genuine mahogany was dry enough to work with (probably kiln dried).
I then made a few cups to test a couple variables.  first i wanted to test the difference in tone in the woods.  I turned 3 cups out of the mahogany.  1 was similar to the pine but with a slightly different outside design.  
the design i made still had a few variables that needed to be worked out but the overall shapes were similar enough for me for now.  
The other two cups i left in a rough form with a straight chamber with paralell walls.  the variable i wanted to test with these was length so i cut one to 1 3/4" way above thelostmidrange's harmonic length.  The other was cut to 1 1/4" which is about the length that thelostmidrange had the most luck with.
testing was done with mono recordings of jimi hendrix, frank zappa, and gerry mulligan
testing results...
flared mahog cup sounded very similar to the pine.  The mahog to my ears was a bit better though.  i would say total it was about a 1-2 percent improvement in overall sound.  
to give that number some reference i would say that my grado sr60i's are about a 10-15 percent improvement in overall sound compared to my dt 770 pro80's. 
 the difference between stock and fwj grados is about an overall increase of about 5-10 percent in sound quality. 
once again these percentages are not any kind of basis for what these headphones really sound like. i would like you to think of it as a reference for my statements in overall sound improvement as per my tastes.
The mahogany to my ears has a much more pleasant soundstage.  the instrumental seperation is increased and each sound fits in its spot very well.  the pine, although it did open up the overall soundstage, has a strange sort of blended squashed effect to the sounds.  they feel like they mush over each other instead of sitting in their seats.  the highs are a bit higher on the mahogany but it isn't any more tiring because of the increased feeling of air around them. also the snap and decay of the hi hat is a bit more natural with the mahogany.
i then tested the harmonic length theory.  first i put on the 1 3/4" straight chambered rough formed cup.
it felt like i went almost all the way back to the stock plastic.  that tin can effect was back in full force.  thick sludgy highs.  strange sort of mid range echo and distortion.  flabby and less impactful bass.  total probably about 1 percent better than stock plastic.
i then compared the two straight chambered different length cups to each other.
the shorter 1 1/4" cup sounded about 3 percent to 5 percent better than the 1 3/4 cup
the tin can effect was reduced dramatically.  the low end was still a bit flabby but much more impactful than the longer cup.
so far, in my opinion the flared design is the biggest factor in sound improvement.  
I hope the improvement in sound isnt just placebo caused by my ego...  it would be nice if someone else could try the flared cup design to see if they get similar improvements in sound.  or maybe this was always known and just not commonly done because it minimizes the ammount of the shiny beautiful face grain.  overall though i think its worth it.
pretty lengthy beginning,  thanks for reading.  
what i'm working on right now is testing the difference between thicknesses of the walls.  the variables i'm testing are the size of bead on the end of the cup and also the wall thickness at the cove for the gimbals.
testing with shellac finishing (inside and out), and different woods (figured koa, figured curly walnut, tiger maple, cocobolo, zebrawood, bocote) comming soon !! atsmile.gif
post #2 of 36

Very interesting.

I like the looks of the trumpet shape, though I must admit they remind me of the cartoon character Shrek.



post #3 of 36

How are you doing the a/b's? Are you using one driver in each of two different cups or listening to the pair of drivers in each different set of cups?  there was variability in the magnum drivers to such an extent I couldn't even do the one driver method because any heard difference was likely the drivers mismatches sounds, and not the intended variable I was listening to. Some/alot of my findings may even be null and void for that reason since I discoverd driver variability rather late in the game. Don't know if grado drivers would vary as much though, so it may be possible to do it that way. You can check by making two cups identical and listen to each individually in both ears with one driver in each (one at a time, back and forth) to see if you pickup any differences. If not, you are in a much better postition than I was with magnums, because you could then proceed with using one driver for one variable cup and the other for the other, using the one ear method. Alot more accurate because they are relatively instant comparisons. The only other option if drivers vary, is to listen to the set in one set of variable cups and then swap them out into the next. This time lag is a big variable that requires a zenlike mental state so you don't 'lose' what you heard while swapping them into the 2nd set you are comparing them too......make sense?  


The angled inner wall I would think would be a change easily heard compared to straight walls. May be cool, maybe not but that is such a critical variable I can't imagine it not haveing some affect one way or another. 


Pine is too soft/light/ as you know and i'm guessing you are starting with it for ease of manufacture to test some of these variables that don't involve the wood itself, like the above inner wall. Which may be fine, but just be aware that wood may not sound great no matter what, just something to keep in mind.


The length of 1 1/8 may even be a better one to use than 1.25, especially if you use a nice crisp clean end treatment where the sound 'exit's the end of the cup. I think the length is dependent on the driver physics but nevertheless, longer lengths may be useful in 'cheating' physics to help some of the woods in areas they lack. Not that i'd recommend that route, instead i'd search for woods that have the fewest 'problems' and stick with them for all experiements. But mahogany for example, seemed to benefit from the longer length a bit to fill out its lower mids, but using the wrong length to achieve a benefit still doesn't feel right to me, so I just stopped using that wood.


Of the list of woods you have as of now, you may want to spend the most time with tiger maple (it should be less dense and heavy than standard 'rock' maple but depends on what country you are in and such. 2nd, Walnut, unlike most hardwoods, is ring porous instead of diffuse porous so it is an oddball in its cell geometry if in fact that matters. ( That just means the open pores inside the wood are only around the rings and then it's a large section of no-pore wood until the next ring. alot of softwoods are ring-porous too.........)  I suspect it does matter though, and so spent little time with walnut which otherwise is a nice candidate due to it's workability and middle dense characteristics. I personally wouldn't use walnut or cocobolo


too bad that zebrawood is 'green' since that is one of the few good candidates for sound chambers ime. especially compared to cocobolo. Although coco is a 'wower' in terms of sonic impact, for me it was way unatural, and natural sound was my guiding principle. If 'wow' sound is your guide, that would be a good one to work with. Who knows maybe the right geometry and finish could save it's negative characteristics and use it's wow affect to yield natural sound somehow.


the sr60 driver you may find wants a different cup than another driver. So doing all experiments with it may tell you something about something but it is working as an invisible hand in guiding this whole process and the cups you end up with may be suitible to it, but not other drivers. But one has to choose some drivers so it is what it is. That driver , at least in the stock grado 60's80's I had was soft and un-trebly, so it may work well with denser woods that may tend to 'harden' and brighten the sound.


you are at the beginning of this science so any small finding if it is real, is worthwile, don't bite off more than you can chew is my advice. meaning, watch out for your personal bias. The listener is always the biggest variable unfortunately.

post #4 of 36
Thread Starter 

i'm doing the A/B like you stated, with each driver in a different cup.  I was thinking about the driver variance so after i make an opinion i switch the cups to the opposite driver to see if the differences still stand.  although i think i may notice a difference between each driver,  it feels like the difference is so small that the characteristics of the cups affect the sound much more than the driver variance.  I would say that overall the difference between the drivers is about a fourth of a percent.  barely distinguishable to me.  the difference feels mostly in the vibe and feel of the sound rather than any sort of technical aspect that i can point out.



you really hit the nail on the head when you mentioned the benefit of instant a/b  i find that i need to switch back and fourth at least 5 or 6 times before i start being able to pick out the specific differences.  at first what hits me is the overall feel and nature of the headphone.  what i mean by nature is the certain feel one headphone has over another.  The nature to me is mostly determined by frequency response and soundstaging.  after i establish what one headphone feels like, i can then more deeply pick out certain differences in instruments,  cymbals usually come first, then bass, then snare, then bass drum.  for me, the last place i find differences is in the mid range.  the mid range is a very different beast in my ears compared to highs and lows.  where tightness and crispness are very easily distinguishable as good or bad in the bass and highs,  the mids, i feel are more up to interpretation of how an instrument should sound.  of course there are things that are more easily noted like crunch and presence but those alone are not enough to fully judge a mid section.  i mostly judge the mid section based on what I think a certain instrument should sound like, meaning does it feel as if i was playing the instrument.  i feel this is where the tonality and timbre of a headphone lies.  not easy to qualitatively assess and definitely not a science.  


for me, the experiments with the sr60i will tell me just how far i can push a headphone to be "tuned" to my liking.  meaning if i can tune 60i's i'm sure i can get similar or better results from custom tuning to different drivers.


I must admit, i do enjoy the wow factor in headphones, but for long term enjoyment wow always wears off and the decision of weather or not i like the headphones relies mostly on preservation of tonality, timbre and musicality. maybe not necessarily neutrality tho.  I don't mind color in my sound but what i do mind is when the color interferes with the listening experience, like when bass is overemphasized it tends to get flabby and boomy; overall uncontrolled.


the softness you describe in your 60/80 drivers may be due to the straight walls.  it seems to me that the standing vibrations damp out the highs.  they feel canned in, and mushed with the rest of the music so that it makes the highs sound more recessed.  i definitely notice a big difference in the presence and air of the highs when i switch the cups to the flared out version.


I used the pine because I just had it lying around.  definitely it isn't the best wood but i was surprised by how small the difference was between the mahogany and the pine.  overall i would say there was about a 1-3 percent improvement with mahogany vs the pine, but from coned to straight walls i felt there was about a 7-12 percent difference.  i thought the wood would make more of a difference, especially since one is known for being a tonewood and one is completely not suited for tonality.  Though the difference is overall small, so far the presentation of the sounds and instruments is what seems to really be different between the woods.


 the zebrawood i tried drying in my microwave sounds as expected, a bit more splash and crispness to the high end and a bit more tightness in the low end as well (compared to the mahogany).  overall 1-2 percent difference, and not all of the changes were improvements.  i think it didn't sound as good because of the way i dried it.  maybe it wasnt fully dried.  i did buy some more zebrawood and its on the way (kiln dried)  it will be interesting to see what the moisture content does to the sound.


overall these findings led me to believe that the most important factor so far, isnt the wood type but the shape.  although definitely each wood does have its own sound characteristics, the amount of difference between the woods that i have tried is something that is more felt than heard.



i can also see how it would be easy to overwhelm ones self.  so many variables to test and only a limited amount of wood and funds.  i'm just trying to take it one step at a time.  i am going to try shorter and longer lengths for the coned cups to see if it makes a difference.  the two variables i have to deal with are the angles of the cone created by a ratio of length to the diameter of the opening.  I also want to try to vary the wall thickness on a few cups to see how much it affects the sound.


The way i see it is that it's a process.  i'm not trying to get to the end in just a few leaps.  i don't even think there really will be an end so much as a place where i will stop and enjoy what i have accomplished. the key is learning and trying to find the truth, whatever that may be.


some koa arrived today, i will be posting some more experimental results toward the latter part of the week.


(edit for clarity) >.<

Edited by MrHee - 3/19/12 at 12:56pm
post #5 of 36
Thread Starter 

@BGRoberts  ...you're totally right. haha. they do look like shreks ears now that u mention it.  i was wondering why i felt like ive seen the shape before :P


@thelostMIDrange i will definitely try the 1 1/8"  i'm going to use the larger rough shaped mahog cup and cut it down to compare the straight chambered at those lengths. and then ill try to cone one of them out and do another listening session.  i think the reason why you are finding that the shorter ones sound better is that more of the soundwaves can travel directly out of the cup as you cut lengths off.  the only problem i see with my thinking is that at shorter lengths some of the qualities of the wood might be lost due to having less area to soak up soundwaves.   i'm also wondering that if neutrality is the goal wouldn't it be best to have no chamber at all? maybe something like an ear pad that can work as a baffle and a holder for the driver.  i say this because when i put the uncupped drivers to my ears they sound pretty damn clean haha.



edit: just to clarify, neutrality isn't my overall sound goal.

Edited by MrHee - 3/19/12 at 1:28pm
post #6 of 36

hond mahog is not all that different a wood than pine so the little difference in sound is not a total surprise. Try mahog and cocobolo back to back for a more apparant difference in wood.


interesting about the slanted walls. that may be a good variable to spend some more time on once you get a handle on what woods you like with the 60



post #7 of 36
Thread Starter 

i didn't know they were that similar.  i just got some walnut and koa.  the zebrawood, cocobolo and bocote are still on the way.  


i'll try to do a thorough comparison of all the woods.  coco and mahog will be the first i do

post #8 of 36
Thread Starter 

couple more impressions.  


i cut down the larger of the rough mahogany cups to 1 1/8".  like thelostmidrange found, the highs really do open up compared to the other lengths of straight walled cups.  much more accurate and much less of the tin can feel.  although, as i search deeper through the differences, i find that the sound does still feel a bit boxed in.  the highs are very accurate but as you go to the mids and the lows they get more and more recessed.  the mids and lows do feel tighter as a result of being farther back.


i compared the straight walled rough mahog cup to the semi finished thicker walled coned 1 7/16" mahogany cup and another mahogany cup of the same length but thinner walls and no bead on the end of the cup.


the thinner walled cup had a warmer sound.  the bass was very present but also kind of flabby.  also the thinner walled cup had some strange resonances around the mid and lower mid range.  the bass presence also affects the highs by making them sound more laid back and warmer.


with the thicker walled coned mahog cup i still noticed a bit of the distortion and looseness of the bass as with the thinner walled coned cup but it was much tighter.  the mid range felt completely natural without that strange echo distortion of the thinner walled cup.


compared with the 1 1/8th length cup, the thicker walled mahog cup was almost identical on the high end.  the 1 1/8th high end was a little bit more in your face and crisp. but the difference was in the mid and low ranges.  the mid range on the 1/ 1/8th cup was definitely recessed compared to the coned mahog cup.  the bass is also a bit recessed.  but although the bass is a bit recessed, it is a little bit sharper and more punchy compared to the coned cup. 


the coned cup lacked  tightness in the upper bass compared to the straight wall.  overall i'm still going to stick with the coned design.  i may vary the angle of the cone to see if it has any more affect on tightness and mid range presence.




coned wall=more even response in mid section and bass compared to straight.  open airy highs. less punch in bass compared to straight

straight wall 1/ 1/8" =  open and slightly more forward highs. massively recessed midrange and slightly recessed bass.  accurate and slightly more punchy bass

thin wall= mid range and low end vibrational distortion.  bloom?  warmer highs.  

new hypothesi 

the thicker the wall is the less of the wood is able to color the sound.

length might have something to do with bass punch but also probably lowers bass presence as the chamber becomes smaller


Edited by MrHee - 3/27/12 at 4:34pm
post #9 of 36
Thread Starter 

i just did a comparison between the 1 1/8" straight wall to the 1 1/4 straight wall.  



shorter length = airy and clean highs and more presence, cleaner bass but less bass and mids

 longer = more bass more mids more low end distortion, tin can highs

post #10 of 36

I still think some of the differences you may be hearing are the variation of the two drivers themselves. Have you been able to really listen to each in THE SAME cups yet? Not in the same cup, but each in the same wood/geometry cups so that you can verify the drivers are 99% the same in character and volume? from my experience, the drivers themselves will vary so when you are a/b'ing them only one each, it's hard to know how much is the cup difference (whichever variable it may be you may be investigating at the time) or the variance of driver to driver. I had a set once that was drastically different in both volume and character. So just a heads up as something to really make sure you've figured out so that you can be confident the differences you are hearing are from the cup variables. I'm sure you are hearing differences though.

post #11 of 36
Thread Starter 

I tried switching them between cups after i make a solid distinction between the two sounds.  i came up with the same results the two or three times i did it but i did sense a difference between the drivers.  but because i haven't really picked out a difference between the drivers, i feel that i have unduly overlooked it.  i'll try to pay more attention and switch the drivers to opposite cups more often.  

edit: i'll also be making the roughed out mahogany into identical pairs to test the drivers directly... and of course ill be switching them also just in case theres any cup variance too.

Edited by MrHee - 3/28/12 at 1:35am
post #12 of 36

If the 2 cups are made from the same board, I don't think there would be any difference. I wouldn't worry about that.......so it sounds like you have not made a full set (pair) of any particular cup yet. If so, that would be the thing to do so that you can then a/b each driver directly to itself and see right away how similar/dis-similar they are. That is key imo.

post #13 of 36

btw, as you do the driver a/b, it will be obvious very quickly if there are differences between them. I'd say, If you struggle to identify any, then it's safe to assume there aren't any real differences.............And volume differences matter because volume makes things sound 'better' sometimes. And increased treble makes things seem 'louder'. Just a couple things to watch out for.......It would be great if your set is perfectly matched because then you can keep on just making one cup for each variable you are interested in and do real time a/b's which is the most powerful way to hear differences. I bet they are different though and it doesn't take much to be significant since the variables you are investigating are sometimes quite subtle and there would be no way to know if it's the driver as being responsible for what you are hearing.

post #14 of 36

btw 2. It may seem ridiculous, But when I compare anything, I try and look at the same place in the room for each . I find that what I'm looking at at any given time affects how I feel about things. This is a way to help reduce you as a variable.


Also, fwiw, I just got a new set of koss ksc75's and am comparing them to my other identical set of ksc75's which has about 50 hours and there is a slight variation. And these are identical in every way of course since they are mass produced. So either there is driver variation here too, or it's a break in phenomenon. It feels like a break in thing. But either way, the difference here is quite a bit less (and really just in treble energy), than what I heard in general with different mags which could vary in actual character of sound. These 2 sets of koss have the same character. And they are great ! love these phones.

Edited by thelostMIDrange - 3/28/12 at 3:06pm
post #15 of 36
Originally Posted by thelostMIDrange View Post

btw 2. It may seem ridiculous, But when I compare anything, I try and look at the same place in the room for each . I find that what I'm looking at at any given time affects how I feel about things. This is a way to help reduce you as a variable.


Also, fwiw, I just got a new set of koss ksc75's and am comparing them to my other identical set of ksc75's which has about 50 hours and there is a slight variation. And these are identical in every way of course since they are mass produced. So either there is driver variation here too, or it's a break in phenomenon. It feels like a break in thing. But either way, the difference here is quite a bit less (and really just in treble energy), than what I heard in general with different mags which could vary in actual character of sound. These 2 sets of koss have the same character. And they are great ! love these phones.

have you listened to any portapros midrange? I like them over the KSC75's, I also like them quarter modded( just cut a quarter size hole in the earpad). I think the kramer mod makes too little of a difference to be really worthwhile, but you could try it out too. 

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