[AudioCats]

more impression on KSC55 drivers with 1g acousta-stuf stuffing:
* good bass, goes deep and has solid impact. Actually a little too bassy at times (and this is coming from a self-proclaimed bass-head

)
* voice can "bite" at times, slightly sharper than I'd like.... but I suppose I shouldn't expect too much from $15 drivers.
* very engaging. Can keep on listening for a couple of hours at a time ( with stock phone I can do 3~4 songs, maybe)
* The detail is good but not great. However I don't feel the details lacking unless I know something "should be there".
Overall, sounds pretty ok for everyday work use.
 
Lets call this mod level, "driver-transplant-only and no output cap upgrade", the Level-1.....
 
Level-1:
* driver transplant only, leave the output caps alone. Very easy mod, without the risk of overheating the circuit board and lifting the pads (guess how I know).
* new drivers should have high sensitivity and >30 ohm impedance (for deeper bass than stock).
* recommended drivers: start with with the Koss KTXpro/KSC55 drives and see how you like the sound, if you want more warmth and less brightness, go for Sportapro drivers; for more brightness and less bass, go for KSC75 drivers. These Koss drivers are 60 ohms.
* add some acoustic stuffing to kill echo,
 
Tools and parts:
*screw drivers and soldering iron.
* drivers:
start with drivers from Koss KTXpro1 ($14) https://www.amazon.com/Koss-KTXPRO1-Titanium-Portable-Headphones/dp/B00007056H
* acoustic stuffing: a few grams of acousta-stuf, or some foam, or some cotton balls, or , as has been suggested, some cotton pads. 1 gram of acousta-stuf per ear cup is working ok for me.

 

[AudioCats]

  My mind is too old for all the school work

 and don't feel like doing a spreadsheet 

no need for a spreadsheet, just use the online 1st-order crossover calculator and plug in the #'s...
 
By the way, do you think Grado sr60 have the same driver as sr125?

 

[DavidA]

 
Quote:

 
no need for a spreadsheet, just use the online 1st-order crossover calculator and plug in the #'s...
 
By the way, do you think Grado sr60 have the same driver as sr125?

probably, but I think the SR-125 drivers are better matched and are probably better FR measuring
 
You want to try a pair of SR-80i drivers?  $20/pair, has sorbothane on the driver magnet, opened 3 vent holes
Also have a pair of PX-100ii drivers, $35/pair, sorbothane on driver magnet

spares, just never had the time to find wood cups for them

 

[AudioCats]

 
It will be fun to try those in the SkullCandy, for sure!
 
PM'ed.

 

[Sonic Defender]

 

 
It will be fun to try those in the SkullCandy, for sure!
 
PM'ed.

Nice, looking forward to your findings Dr. Frankenstein!

 

[AudioCats]

(updated 2/12/2017)
 
Level-2 (Koss driver transplant, plus output cap upgrade).
 
Output cap upgrade: The main limitation is the available space. The gap between board and the cup wall is 8mm, so a direct replacement to the stock caps can not be taller than that. Oversized caps can be placed elsewhere in the cup as well, of course, but it might take up too much room and cause noticeable acoustic difference between L/R.
 
possible upgrade caps:
 
Panasonic OS-CON 330uf/6.3v, 6.3mm diameter x 5.9mm tall (the same size as stock caps --> a direct replacement). The leakage current spec is a bit high at 0.42mA;  $1.3
http://www.mouser.com/search/ProductDetail.aspx?r=667%2d6SVPC330M
 
Nichicon Muse bi-polar 330uf/6.3v, the size is 10mm diameter x 16mm long, it is slightly oversized, not a direct replacement. Leakage current spec 0.063mA;  $0.7 each
http://www.mouser.com/ProductDetail/Nichicon/UES0J331MPM/?qs=sGAEpiMZZMtZ1n0r9vR22e0BBN1kF1oicpHfHnmAsZ8%3d
 
I don't really like the Muse bi-polars as signal caps (though their KZ line is really good for power supply). I will use OS-CON for my tests.
 
Drivers: will try drivers from Koss KSC55/KTXpro1 (60 ohms, titanium coated diaphragm) or Koss KSC35/Sportapro/R10 (60 ohms, non-coated diaphragm).
 
Impressions, Level-2-KSC55 (output capacitors changed to Sanyo OS-CON, drivers changed to  KSC55 drivers).
* sound is a little more clear than Level-1-KSC55.
* No sibilance, no bite. This is surprising as I was expecting this combination too be too bright, but the actual result is actually pretty good.
* Less bass quantity than Level-1-KSC55, but a little cleaner. Still plenty of bass to go around. Good bass impact.
* mid range is a little more recessed than Level-1-KSC55.
* sound stage slightly more open.

 

[AudioCats]

so far there might be three levels of mods. Going up one level --> cost on mod parts approximately doubles.
 
Level-1: driver replaced with Koss 60 ohm, parts cost ~$15
Level-2: driver replaced with Koss SportaPro drivers, and output cap replaced with Sanyo OS-CON. Parts cost ~ $25+$5=$30
Level-3: driver replaced with Grado/Senn/Beyer drivers, output cap replaced with Sanyo OS-CON. Parts cost ~$65+$5=$70
 
 
 
 

....To be continued...

 

[aeromojito]

You can use this calculator or any crossover calculator

 

[AudioCats]

Found a video on Bluedio T2s disassembly, looks like there is a lot less circuitry inside. I doubt it has a headphone amp section.
https://www.youtube.com/watch?v=_t74mCEhSjo
 
Looks like picking the SkullCandy Hesh over Bluedio H was actually a good decision.

 

[AudioCats]

Finished a Level-3 mod. 
560uf OS-CON output caps, Beyer DT770/32 ohm drivers. 1 gram Acousta-stuf in the cup to deal with echo.
Lets call it a Level-3-770
 
Some impressions, Level-3-770 (comparing to Level-1-KSC55)
* doesn't play as loud. Sound level is maybe 3 clicks lower. Still plenty loud enough.
* much cleaner sound with much better detail/clarity than Level-1 (in comparison, Level-1-KSC55 sounds congested with a thick cloud of haze in the background).
* less bass quantity and impact than level-1-ksc55, the bass is slightly lighter than my liking (am a bass-head after all

). much better bass texture though.
* smooth mids and highs, no bites, no sibilance. Mids more recessed than the level-1-KSC55.
* presentation is much more layback than the Level-1-KSC55.
** for rock listening in high volume, the Leve-1-KSC55 is actually more engaging, the sound is "dirtier" but it "rocks" better.  In comparison, a Level-3-770 is more like a high resolution back ground listening setup,  very enjoyable even at mid / low volume (there is no need to turn it up, all the details are already there).
 
** Level-2-KSC55 lays somewhere in between, it has the layer of haze in the background but not very noticeable unless compared directly to the Level-3-770;
 
The comparison above is done with Bluetooth connection.
 
When connected using a cable to an iBasso DX90, the Level-3-770 really scales, sounds much better than running bluetooth. The Level-1-KSC55, on the other hand, doesn't improve much. ==> I think the limitation of this bluetooth board has been reached, Beyer 770 drivers are over-kill for it.

 

[AudioCats]

Battery info: the battery bracket (40mm x 30mm)  is a bit larger than the installed battery. So there is the option of upgrading to a higher capacity battery if one needs longer play time.
 
So how does the modded SkullCandy compare with other current Bluetooth phones? I got a chance to listen to a pair of Bose QuietComfort35 today, here is a little comparison review:
* Bose is way more comfy, the oval pads easily go over my ears, pads are soft with very little pressure; in comparison the SkullCandy's pads are border-line too small, I have to kind of "stuff" my ears into them, and a bit harder.
* Bose has active noise canceling, therefore provides a more quiet "listening environment".
* Bose has good detail (not great but I didn't feel missing anything), sound is balanced and more open; Level-3-770 has smaller stage, and a more recessed mid range.
* Bose has more bass, and bass quality is quite good.
* The only thing I didn't quite like, with the Bose, was the mids, especially the voice range. The voice sounded a bit "grainy", as if chopped into pieces then put back together.
** The Bose really impresses for the first 5 minutes or so, I quite liked the sound. The longer I listened, though, the more I noticed the "graininess", I suspect it has something to do with the noise cancelling system actively doing something in the back ground. This voice problem reminded me the Senn HD555, the 555 was quite enjoyable but I sold it after about a month due to the "graininess".
** in contrast, the longer I listen to the Level-3-770, the more I get used to the sound. The L-3-770 does seem to be more detailed as well.
Overall, Id' say they more or less broken even in SQ, but I like the Bose's comfort factor a lot, for long term wearing (>3hr a day) I'd say the Bose wins hands down.
 
Not sure if this should be an disappointment to me. After installing Beyer drivers (which are already over-kill for the SkullCandy's electronics), the mod only reached to the SQ level of "over-rated, over-priced" Bose QC phones... where does the Bose QC stand, in the world of Bluetooth phones?

 

[AudioCats]

Level-3-PX   (with Senn PX-100ii drivers)
* output caps changed to 560uf/6.3v OS-CON
* Sennheiser PX-100ii drivers (32ohm)
 
This mod requires a lot of stuffing material. With 1 gram of Acousta-stuf, the sound was boom, boom, boom, boomy. Change to 2g, still boomy. Change to 3 grams per cup (at this point the cups are firmly packed with stuffing), the bass is still very strong, border-line boomy (overpowering at times). I don't think it is realistic to pack more stuffing into the cups so I called it good enough. Sound is very warm, soft and layback, certainly not fatiguing. But the extra bass muddles the sound a bit.
 
These drivers came from DavidA,  with sorbathane pads. Add sorbathane pads on top of driver magnet, the sound cleaned up a bit, the best stuffing amount seems to be around 2.5 grams of Acousta-stuf per cup (bass got too flat with 3 grams of stuffing). The problem at this point is the bass, it is strong and fat but kind of "flat" (instead of the more natural "fat and round"), I don't know if it is the fabled "bass fart". I ended up removing sorbathane pads and went back to bare driver with 3g stuffing.
 

 
 
Sound has good enough detail, and is cleaner than the L-2-KSC55, but the sound level is much lower than both the L-3-770 and L-2-KSC55, and there is noticeable distortion at the max volume setting. I suspect the headphone amp section doesn't quite have enough juice to properly handle these PX drivers.
 
Good for low volume back ground music listening (can still feel the bass at low volume).

 

[DavidA]

The PX-100ii drivers don't get too loud before some distortion, since my normal listening level is not very loud (65-72db) the distortion was never a problem but I think one other member did some measurements and found that they do have a bit more distortion than either Ypsilon, Nhoord or Magnum drivers.
 
You might want to try dynamat on the magnets, found it to work better on my 225i drivers than the sorbothane.
 
Try sealing some of the vent holes, I tried it since even in a open cup the bass was too much with some pairs of the PX-100ii drivers (the not so good ones that went in the trash), seemed to help but the over all tone of the driver was not good to begin with.

 

[AudioCats]

L-1-KSC35
 
Got my 3rd pair of SkullCandy and swapped the drivers with some KSC35 driver (60 ohm non-coated Koss).  Left the stock output caps alone. Added 1.5 grams of Acousta-stuf per cup.
 
The L-1-KSC35 has more noticeable distortion than the level-3 stuff (of course). it has less "haze" than L-1-KSC55, if my memory is good, but bass doesn't feel to be stronger. Voice is a bit smoother than the L-1-KSC55, for sure, no glare/bite.
 
I probably should have moved slowly so I could have both Level-1's at the same time to do a quick A/B instead of relying on memory. But it is too late now, I am not installing the stock caps back into the L-3 phones. I'd say for Level-1 the KSC55 and KSC35 drivers are both viable, pick the one that is easiest to get at your location.....

 

[AudioCats]

  The PX-100ii drivers don't get too loud before some distortion, since my normal listening level is not very loud (65-72db) the distortion was never a problem but I think one other member did some measurements and found that they do have a bit more distortion than either Ypsilon, Nhoord or Magnum drivers.
 
You might want to try dynamat on the magnets, found it to work better on my 225i drivers than the sorbothane.
 
Try sealing some of the vent holes, I tried it since even in a open cup the bass was too much with some pairs of the PX-100ii drivers (the not so good ones that went in the trash), seemed to help but the over all tone of the driver was not good to begin with.

 
Thanks for the info.  I will try blocking a few vent holes first and see how it goes. If the bass quantity can get knocked down a little more, I think the L-3-PX might be a good basshead setup.