CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS
Lobby => Headphone Measurements => Topic started by: Marvey on June 15, 2012, 11:10:23 AM
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ratoKOSSter (KSC-75 mod) Frequency Response and CSD Waterfall Plots
(http://www.changstar.com/index.php?action=dlattach;topic=348.0;attach=1330;image)
Compare with KSC75:
(http://www.changstar.com/index.php?action=dlattach;topic=231.0;attach=863;image)
Pre-Measurement Listening Notes:
- they are awesome. mids are awesome
- bass needs for low end, and treble scratchy, but you can't do much about that - limitations of the driver.
- good balance - nice mid-centric headphone - grado-ish eccentricities solved.
- some reverb in the cups at high volume
- could dampen that with stuffing material, but I don't know how that may change the FR
- consider pillow stuffing or wool, cotton never works right, but you may need to change cup size since stuff will effectively increase internal volume
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Marv, thanks for measuring them and your advice as to how one could approach the remaining issues. In the end it is nice to see that your ears did not play tricks on you when working on the phones. I guess one could easily start telling yourself how good they sound just because you wanted them to sound good.
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Ohhh.....I want to listen to these!!! 8)
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Wow. Nice job, Strat!
CSDs don't look offensive at all. Is that dip at 4K on the FR just a backwave?
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Nice job stratomaster. Can I ask what your mods are, or at least just generally what you did?
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Wow. Nice job, Strat!
CSDs don't look offensive at all. Is that dip at 4K on the FR just a backwave?
That would be my guess based on the huge dip....
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Wow. That's a really fine response for a mod on a $15 pair of headphones.
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FYI. 4k dip is a measurement artifact ("bogus" reflection, etc.) You can tell if the dip is legit on the CSD. If it's legit, we will see the dip propagate in time.
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Nice job stratomaster. Can I ask what your mods are, or at least just generally what you did?
Here is the link to the mod page: http://www.head-fi.org/t/611982/the-stratokosster-a-closed-diy-headphone-based-on-the-koss-ksc-75-driver-and-grado-cup-design#post_8415950 (http://www.head-fi.org/t/611982/the-stratokosster-a-closed-diy-headphone-based-on-the-koss-ksc-75-driver-and-grado-cup-design#post_8415950)
Pic shows the measured StratoKOSSters.
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You did achieve very good bass extension, but at the price of overall bass volume. I like what you did better than the stock.
Do you mind if I take it apart to experiment with different internal volumes and stuffing materials? I figure it's the least I can do since you've sent it from so far away.
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Go ahead Marv.
Actually I am already dealing with that on another set of stratoKOSSters, but you are very welcome to apply any changes you find worth trying.
Any input and suggestions on further improvement are much appreciated.
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Wow, these aren't ksc-75's anymore! I was expecting just some damping changes or kramer type drilling.
So you left the driver in it's stock plastic housing, inside the grado cup?
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Yes, the driver is intact, stock, it can be recabled easily, you can remove the plastic grill and replace it with a kind of mesh ...
So there are lots and lots of options. What just amazed me was the synergy the drivers had, to my ears, with CLOSED Gradoesque wood cups. The damping scheme is finetuning, as with the Fostexes.
Another aspect, and I guess an essential one, is the pads. The leather-lined Grado L-cushs gave me the best results. Other, less expensive pleather pads enhanced the bass further, but left it to some degree undefined and bloated.
The pads I sent along with the StratoKOSSters for measurement were my first ones, made of lambskin. The leather is less soft than the ones I am using now, which by giving me a better seal have a positive effect on the bass response. I do not feel I am missing out on the bass volume, the bass has nice extension, is quite well defined and in balance with the mids. But it might be just my ears that tell me so.
Before sending them off to purrin I was wondering if I should enclose some stock Grado L-cushs for a comparison, but then I thought I could not be too bold and ask too much. Now I am quite certain sure that pad choice together with damping adjustments IS the key to further improvement.
Purrin, do you think the dip around 200Hz could be caused by the fact that the cups are not tightly sealed, I mean there are still the holes for the headband and cable that are at least partly open.
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Ohhh.....I want to listen to these!!! 8)
LFF, you are very welcome to have purrin send them to you. It would be very interesting to read your impressions and have you try some of your damping skills on them. They are very easy to work on, since the drivers can easily be popped in and out, there are no screws etc.
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.....I can testify that a slower low end rolloff is achieved by closing the driver.....those 2 graphs are quite dissimilar no?
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FYI, I have made the differences visible. And I am sure damping the interior and/or completely sealing the cups can flatten out the bass response from 100 - 250hz further. It's kind of hard when you can't check the effect of changes without having access to measuring equipment. Because changes will certainly effect the mids and higher frequencies too. And when there is something I especially like about the Stratos then it is the mids and the, to my ears, nice balance.
I am working with SinGen and trying to even out the response. What sending the StratoKOSSters in for measurement did was helping me see that in fact you can plot your own curve when working with tools like SinGen. Actually I learned that I can trust my ears, because the measurements mainly correlated to what I was hearing when using SinGen.
On the whole, I think the closed KOSS are little gems, for all their cheapness and flimsy looks. I would be more than happy if people tried the mod out themselves. I think it is a rewarding experience.
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I wonder if the pads are not affecting things more than the cups? Maybe some pad tweek could swing the graph back in the other direction. Maybe realworld phones sound best when have a little emphasis on the graphs in the low mids like the stock 75. A dip there seems to be problematic at least. But like you say, now you know where to focus/listen/tweek to at least getting looking flatter.........and i still wonder about that 4k drop off?
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Pads do play an important part in the mod.
Purrin said he would try out damping variations and I am looking forward to reading about any changes that he comes up with.
As I said, I do think there is much you can do to play around with the response (playing around with damping and cup volume, sealing or opening up the cups with some kind of bass venting ...). The problem is, it does not help (especially in this forum) if I do it and say now the curve should be dead flat or something, when there is no measurement or objective data ;-) to make people see what I am hearing.
As a matter of fact, at the moment it is just me and purrin, who both see the graph and know how the headphones (this specific prototype, with this wood, cup diameter, cup depth, damping scheme and leather pads) sound. I guess at the moment only purrin can comment what he believes (from listening to the headphones) contributes to the dips around 200hz and 4k and if they are sonically malign or not. I do not have enough knowledge of interpreting graphs and plots to comment and speculate on those issues.
The StratoKOSSters I sent in are a prototype, I was not really dead careful assembling them, didn't bother to recable them etc. I just wanted to see the measurements to find out if I was on the right track with what I was trying to achieve and show others how dramatic a change it would be to put the KOSS into cups like the ones I used. I have been trying to mod Grados and Symphones Magnums, but doing those I have never come up with changes as huge as with this mod. And to my ears the modded phones sound better than stock. But then again, that may very well be just me. And I know that others might quite probably disagree.
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Going to try foam tonight. Had to get out to buy some over the weekend. Sorry it's taking me so long. It was Father's Day in USA this Sunday.
I do like the modded version better. It corrects the treble issues which I find are most harmful and presents the midrange properly. The 4k dip is a measurement artifact as can be seen in the CSD (the dip does not propagate in time)
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No prob, I am in no hurry.
The dip from 100 to 300hz kind of reminds me of the Beyer T70 dip. I was thinking that it may well be that it is not really harmful, since it does not bring the system out of balance and might give the sonic impression that the bass extension is even better without an overwhelming mid-bass hump that dominates the bass response.
Anyway, it should be possible to deal with it. As a matter of fact, I have a low profile cup version and a PS1000 clone version as well. Neither of those has this dip, could very well be that I was a little sloppy with the damping. In my other systems I have the cups lined with acoustic foam and I am using a damping "sandwich" of a thin disc of open cell foam, fibrefill in between and another disc of open cell foam facing the back of the driver.
I am curious as to what you will find out.
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I now pronounce stratoKOSSter v1.5 the best sub $20 dollar headphone mod EVAR!!!!! Stay tuned for details. Incredibly neutral sounding.
(http://www.changstar.com/index.php?action=dlattach;topic=348.0;attach=1359;image)
Changes to mods:
- Removed cotton stuff and replaced with medium density packing foam
- Placed drivers to rest on top of the cup (with pads resting on top to keep them in pad) as opposed to pushing the drivers inside.
These are it. Incredible sounding!!!
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CSDs. First set of L+R are original. Second set of L+R are mods.
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I KNEW IT, my other sets tell me the same!
Marv, thanks again for carrying out the measurements. I guess people will understand now that I called these little gems.
I know people will call it blasphemy, but since I developed the StratoKOSSters I have very rarely given my Symphones Magnums and HE-500's any head time.
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I'm listening to these over the TH900s right now :-) Way more neutral. Will post pix of what I did.
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Slow cap for you both. That's a very impressive mod of the KSC75. I really want to scrounge together the parts to put one together myself.
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I am extremely delighted, because now people (myself included and those who are open to measurements) have objective proof. I knew from the moment I put my hands on the open wood shells and thus closed them that I was onto something. When I modded the Grados, I also knew, but only that I could not change much for the better.
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I now pronounce stratoKOSSter v1.5 the best sub $20 dollar headphone mod EVAR!!!!! Stay tuned for details. Incredibly neutral sounding.
(http://www.changstar.com/index.php?action=dlattach;topic=348.0;attach=1359;image)
Changes to mods:
- Removed cotton stuff and replaced with medium density packing foam
- Placed drivers to rest on top of the cup (with pads resting on top to keep them in pad) as opposed to pushing the drivers inside.
These are it. Incredible sounding!!!
I need to hear these!!! :P
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Pix.
- Driver resting on top of cup (rather than being stuffed inside.) Closer to ears - more bass. Increased volume inside cups, less direct refraction and reflection off side walls = no dip at 200Hz.
- Foam stuffed inside cups. Works better than cotton to absorb reverb. May want to try memory foam for greater effectiveness.
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Pix.
- Driver resting on top. Closer to ears - more bass. Increase volume inside cups = no dip.
- Foam stuffed inside cups. Works better than cotton to absorb reverb. May want to try memory foam for greater effectiveness.
LOL!!!
I should show you my SFI mod....
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looks like we're all on the same page ;)
Nice work!
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One thing that is absolutely essential is the pads.
Purrin, if you happened to have any (Grado) foam pads lying around, or if you could get hold of cheap pleather headset pads that fit the cup diameter, you could also highlight that.
I tested those and my ears told me that it is exactly the pads I used that give the best response.
PS: Marv, consider these StratoKOSSters yours. I planned from the start to give them to you as a little thank you present from one audio enthusiast to another for your being ready to do the measuring. I would never think of doing this if the Stratos were crap, now I can let you have those with a clear conscience and glee in my heart.
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Wow, nice work guys! That is incredibly impressive for a 20 dollar phone.
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Tried the regular bowl and TTVJ flat pads. Your pads by far were the best. It wasn't even close.
Woohoo! Yay! Thank you for the gift!
I can post results on HF? This is too good not to let others know about.
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Wow, nice work guys! That is incredibly impressive for a 20 dollar phone.
You have no idea how surprised I am. The stock cable is so short than I am bending my head toward the amp in order to listen to it while I am typing. Very uncomfortable with my head tilted 15 degrees, but you guys know how much a priority I put on something that's well behaved in terms of FR.
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You have no idea how surprised I am. The stock cable is so short than I am bending my head toward the amp in order to listen to it while I am typing. Very uncomfortable with my head tilted 15 degrees, but you guys know how much a priority I put on something that's well behaved in terms of FR.
Doesn't sound so bad. Just type in italics 8)
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I can post results on HF? This is too good not to let others know about.
I was about to ask you to do so, but please post the results in my thread on Head-fi, where I introduced the mod and also provided a picture tutorial for making the pads.
Link to Head-Fi thread: http://www.head-fi.org/t/611982/the-stratokosster-a-closed-diy-headphone-based-on-the-koss-ksc-75-driver-and-grado-cup-design#post_8415950 (http://www.head-fi.org/t/611982/the-stratokosster-a-closed-diy-headphone-based-on-the-koss-ksc-75-driver-and-grado-cup-design#post_8415950)
I have already recabled all my other Stratos, I just sent in these with the stock cable to point out that the cable is of no importance for the sound just for comfort and fancy looks
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Awesome work, guys!
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(http://www.reactiongifs.com/wp-content/gallery/yes/3517jvp.gif)
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I though about trying something like this myself before but I always figured that the plastic frame (which the diaphragm is actually mounted to so it's not to easy to get rid of or cut away) would hold it back too much. I guess I was wrong though.
I'm going to have to try this sometime.
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I was about to ask you to do so, but please post the results in my thread on Head-fi, where I introduced the mod and also provided a picture tutorial for making the pads.
Link to Head-Fi thread: http://www.head-fi.org/t/611982/the-stratokosster-a-closed-diy-headphone-based-on-the-koss-ksc-75-driver-and-grado-cup-design#post_8415950 (http://www.head-fi.org/t/611982/the-stratokosster-a-closed-diy-headphone-based-on-the-koss-ksc-75-driver-and-grado-cup-design#post_8415950)
I have already recabled all my other Stratos, I just sent in these with the stock cable to point out that the cable is of no importance for the sound just for comfort and fancy looks
Will do. I'll write a funny review similar to the HD700 one with comparisons to comparable headphones, SR-80, KSC35, HD700, etc.
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Looking forward to that review ;-)
Anyway, I guess the work that the two of us did on these Stratos just reflects what responsible audio companies should do. Based on inspiration and subjective listening, putting prototypes to objective tests, learning from them and using acquired knowledge and inspiration again to tweek the system in order to finally achieve an awsome sounding product.
There is no need for fancy looks, posh BS and invention of awe-inspiring technological terms when something just sounds right. Yet, what we see too often, especially on HF, is people who are trying to make people believe a mediocre headphone is a flagship and thus assisting audio companies trying to reach into people's pockets. But then again it might not be the companies' fault alone. There is also the army of people who buy such headphones getting on crusades for the headphone they have been talked into spending 1 or 2k on while this headphone has obvious limitations or deficiencies. Their arguments get even more heated when they are faced with objective data or reviews of people who no longer want to be taken for fools.
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Yes!
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Really nice and very encouraging mod. Thanks for sharing.
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Looking forward to that review ;-)
Anyway, I guess the work that the two of us did on these Stratos just reflects what responsible audio companies should do. Based on inspiration and subjective listening, putting prototypes to objective tests, learning from them and using acquired knowledge and inspiration again to tweek the system in order to finally achieve an awsome sounding product.
There is no need for fancy looks, posh BS and invention of awe-inspiring technological terms when something just sounds right. Yet, what we see too often, especially on HF, is people who are trying to make people believe a mediocre headphone is a flagship and thus assisting audio companies trying to reach into people's pockets. But then again it might not be the companies' fault alone. There is also the army of people who buy such headphones getting on crusades for the headphone they have been talked into spending 1 or 2k on while this headphone has obvious limitations or deficiencies. Their arguments get even more heated when they are faced with objective data or reviews of people who no longer want to be taken for fools.
Indeed! :)
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you are going to listen and help me on it. then i can translate your comments so people won't be as pissed.
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LOL at "translation"
LFF: these headphones blow donkey chunks
Translation: the sonic presentation and signature do not particularly mesh with my audio priorities
LFF: the engineer of this headphone should be murdered with a rusty screwdriver
Translation: this headphone could have benefited from further research
LFF: The StratoKOSSter SHITS ALL OVER YOUR 1K HEADPHONES
Translation: The StratoKOSSter exhibits some fine qualities that enable it to punch above its price class
EDIT: Looking forward to the review as well!
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LOL, if you could have seen us edit in real time on GoogleDocs for that HD700 review...
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Stratocaster, will you be updating the thread on HF to reflect the changes purrin made? Very impressive work!
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Stratocaster, will you be updating the thread on HF to reflect the changes purrin made? Very impressive work!
I will edit the initial post and include measurements (if I get purrin`s ok to use them) as well as updated modding info.
Might have time over the weekend.
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Go right ahead. I'm tied up with work and a few more measurements.
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StratoKOSSter V2
I have been using Koss KSC-35 drivers instead of KSC-75 drivers for the V2. While the midrange and lower frequencies remain pretty much as they were, the higher frequencies are a tad smoother and cleaner sounding than compared with the 75 drivers.
As for the damping, the foam should not fill the whole cup. If it presses against the drivers, the Stratos sound a little thin. When there is a kind of air cushion between drivers and foam, they perform best with the most balanced sound.
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Have measured some other stratocasters...
(http://i837.photobucket.com/albums/zz296/solderdude/all6_zpsec8a6e40.jpg)
For those interested in the results they can be found here:
http://www.mediafire.com/view/6axk75y6svpu1x7/Stratocaster_woodies.pdf (http://www.mediafire.com/view/6axk75y6svpu1x7/Stratocaster_woodies.pdf)
It should be noted that they aren't finished 'products' and have been measured to see where they need more improvements.
For headphone tuning exclusively by ear the results are already quite good.
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Aside from the channel imbalance (fixable, I reckon), the T50RP + Alpha pads has terrific performance with almost no shelving, very impressive!
May I ask what kind of foam/felt sits in front of the Fostex drivers?, it seems to tame the 10 KHz peak to a good degree.
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In this particular case the secret ingredient isn't the foam in front of the driver but rather the damping behind it in conjunction with Dan's Alpha pads.
(http://i837.photobucket.com/albums/zz296/solderdude/t50rpalphanofoam_zps4857e75d.png) (http://s837.photobucket.com/user/solderdude/media/t50rpalphanofoam_zps4857e75d.png.html)
With and without foam...
A clue is found in the plot below.
I mounted an Alpha pad on my modified T50RP (just some damping in the cups and white medical felt in front and rear of the driver)
(http://i837.photobucket.com/albums/zz296/solderdude/alphavs940_zps57097780.png) (http://s837.photobucket.com/user/solderdude/media/alphavs940_zps57097780.png.html)
As you can see the Alpha pads are filling in the hole and remove the peak (but add that sharp dip)
Alpha pads are compared to SRH-940 velour pads in this case.
I can feel the next question popping up... How do the 940 pads compare to HM5 pads ?
(http://i837.photobucket.com/albums/zz296/solderdude/hf5vs940_zps4e02fa0f.png) (http://s837.photobucket.com/user/solderdude/media/hf5vs940_zps4e02fa0f.png.html)
there you are :D
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I guess it is more than just the damping and the alpha pads, there are many variables that create the sound. The ebony T50RPs are different from the Kerelian birch T50s in so far as the internal cup dimensions are different (the ebony cups are significantly deeper), as well as the white damping paper behind the driver has been removed from the ebony drivers and replaced by T50RP damping paper. I tried the alpha pads and the same damping in the Karelian cups, yet the sound was significantly worse than with the ebony set.
There may be driver variances, damping material/amount differences, cup dimensions, cup materials, pads .... It is combination of all that and maybe a lot more that creates the result. There is simply no standard modding approach, results and suggestions by others may help you or not. You have to work on each set of headphones/drivers more or less differently and trust your ears and/or measurements.
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There is simply no standard modding approach, results and suggestions by others may help you or not. You have to work on each set of headphones/drivers more or less differently and trust your ears and/or measurements.
Judging from the results on the Alpha padded T50RP it appears you can get great results with mods even without the guidance of measurements.
These do make life of a modder easier when you are aiming for balance and flat frequency response.
Given that these mods were all mechanical/acoustical the results are excellent.
but to get back on topic:
I have been using Koss KSC-35 drivers instead of KSC-75 drivers for the V2. While the midrange and lower frequencies remain pretty much as they were, the higher frequencies are a tad smoother and cleaner sounding than compared with the 75 drivers.
That's what my measurements (and ears) tell me as well.
(http://diyaudioheaven.files.wordpress.com/2014/01/portapro-bl-75-green-35-pur.png?w=921&h=615)
green = KSC75 (old)
purple = KSC35 (old)
blue = PortaPro (recent)
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I think stratocaster reverted back to the KSC75 drivers in his latest builds.