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hi all! i won one at an auction and was wondering, how are these supposed to sound like? mine sounds quite dark and bass heavy, which i find wierd considering the fact that most phones during that time might be considered bass light. there's also a slight imbalance between right and left channels... what's bugging me is that they sound quite veiled and even muddy at times. not very detailed too. i guess i was expecting more considering that these were quite expensive when they came out. do they really sound this way or is something wrong with the one i have?

 

[flipflop]

just to elaborate a bit further...
 
my set sounds almost tube like, but quite lacking in terms of detail and instrument separation.  the sound gets easily muffled with more complex tracks, and it just generally sounds like something's not quite right.
 
has anyone tried disassembling a pair? would it have any other electronics inside of the cups other than the drivers themselves? i really didn't spend much on these but i'd hate to have to bust it open unless i'm positive im missing out on something sound-wise.  i think the channel imbalance stems from an issue with the plug, as moving it around in the headphone jack SLIGHTLY improves the output. any help/feedback/information on these would be most appreciated.
 
i've also seen that its electrostatic counterparts (ESP/9 and ESP/10) have issues with the foam in the cups.  does the Dynamic/10 have the same sort of foam inside? cups seem sealed shut. 

 

[flipflop]

ok, so i hooked them up to another amp (Onkyo A917F) and they sound waaayy better. it seems i was having synergy issues with my NAD 304, which seems quite picky when it comes to pairing up with speakers and headphones. it still sounds VERY warm but the switch up sort of opened up the sound, giving way to the detail i was looking for. still not overly impressed but they're definitely more "listenable". i'll probably pop these open one of these days to take a look inside.

 

[Das Mookid]

Thanks for posting your impressions - I am quite fascinated by the different models Koss has offered over the years. 
 
I must admit, I am not familiar with the Dynamic 10, do you have an pics or links to the model? Needless to say, if you do end up popping them open, please grab some shots! 

 

[flipflop]

  Thanks for posting your impressions - I am quite fascinated by the different models Koss has offered over the years. 
 
I must admit, I am not familiar with the Dynamic 10, do you have an pics or links to the model? Needless to say, if you do end up popping them open, please grab some shots! 

 
i'll post some pics soon. they're basically the dynamic/non-electrostatic version of the ESP/10. they have exactly the same housing/chassis, cable, air-filled pads, etc. the only difference, it would seem, are the drivers.
 
i'll probably give them a closer look once i find a disassembly tutorial for the ESP/10.

 

[flipflop]

  Thanks for posting your impressions - I am quite fascinated by the different models Koss has offered over the years. 
 
I must admit, I am not familiar with the Dynamic 10, do you have an pics or links to the model? Needless to say, if you do end up popping them open, please grab some shots! 

 
i'll post some pics soon. they're basically the dynamic/non-electrostatic version of the ESP/10. they have exactly the same housing/chassis, cable, air-filled pads, etc. the only difference, it would seem, are the drivers.
 
i'll probably give them a closer look once i find a disassembly tutorial for the ESP/10.

 

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there's hope after all!
 
i was taking a closer look at these last night when i noticed a small gap between the air-filled vinyl pad and cup. i figured, what the hell, right? i slowly tried working the gap with my hands and... viola! the pads are off (and intact)! it seems the pads have a rather rigid plate built into them to make it seem as if the pads are actually fixed on the cups.  anyway, i then see four screws which seem to hold the entire assembly together.  should i? no, not yet. i'll try putting on a pair of spare velour-like pads i had lying around first.  since the pads were a bit too small, i just sandwiched them between my head and the 'phones. i plugged it in and WOW! night and day! there's the detail i was looking for! as a plus, no more channel imbalance! it seems the air-filled vinyl pads were causing both the imbalance and the muffled/bloated/bassy output! i lost quite a bit of bass but they just sound so much better. i am now VERY happy with them.
 
if anyone else has these, try replacing the pads with velour ones. also, make sure to keep the fabric which covers the driver (or use pads with that fabric in the middle). i tried another set of pads without the fabric in the middle (fully exposing the driver) and it was a bit too harsh and tinny. i'm still experimenting on which pads would best suit these but i'm just so happy that i got a glimpse of this model's potential.  i'm now trying to look for suitable velour pads that actually fit. DT880 pads seem right but i'll have to investigate further. any other Dynamic/10 users out there?

 

[flipflop]

some further observations...
 
1.  it seems that the size of the pads also have an effect.  i tried on another set of velour/felt pads which was a bit bigger (and stiffer) and lost too much bass.  still sounded good though. my best result was with a pad that had an inner diameter of 45mm.
 
2.  i also tried synthetic leather pads that were foam filled. little change over the original pads although they did sound better overall. makes me wonder why they decided to use those air-filled pads in the first place.
 
3.  it would seem that "real" velour would be most ideal to get a good balance across frequencies. my pads are the cheap kind which are only velour-like. lost quite a bit of bass with them. again, still better than the original pads.
 
and some pictures...
 

 

 

 

 

 

 

 

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a final tweak...

i've got a pair of beyerdynamic pads on order so i decided to play around with my pads a bit more.

as i mentioned earlier, the switch from stock to velour/velvet/felt pads drastically reduces the bottom end. it also allows for more leakage, thus the need to turn up the volume. i needed my bass, and i feared the increased volume might damage the drivers. and so, taking a page out of the Grado Modders playbook, i wrapped electrical tape around the pads.... game.. set.. match.





they now sound so much more musical and detailed, which was what i was expecting in the first place. i think this is far as i'll go with this particular piece (until my new pads arrive).

 

[Das Mookid]

Very nice, thanks for the pics! I am not surprised that the velour required abit of sealing to keep the profile intact. It's a shame Koss don't carry replacement pads for them...

 

[flipflop]

Very nice, thanks for the pics! I am not surprised that the velour required abit of sealing to keep the profile intact. It's a shame Koss don't carry replacement pads for them...

 
yes, and a shame too that they used the air-filled vinyl pads in the first place.  aside from severely messing up the sound, i found them very uncomfortable.
 
it seems to me that the Dynamic/10 was an afterthought... sort of like "hey, let's pop in these dynamic drivers in the ESP/10 housing and sell 'em."  i'm still very surprised at how good these sound now. i bet they would sound even better in the hands of a more experienced modder. 

 

[Das Mookid]

   
yes, and a shame too that they used the air-filled vinyl pads in the first place.  aside from severely messing up the sound, i found them very uncomfortable.
 
it seems to me that the Dynamic/10 was an afterthought... sort of like "hey, let's pop in these dynamic drivers in the ESP/10 housing and sell 'em."  i'm still very surprised at how good these sound now. i bet they would sound even better in the hands of a more experienced modder. 

 
I do wonder if the stock pads would have sounded better and been more comfy when new, the foam generally is a victim of degradation over time. . . Koss are definitely hit and miss on comfort, but I am increasingly of the opinion that their stock seal and clamp are quite deliberately designed for the headphone.
 
I suspect you are right regarding the origins of these following the ESP/10. I would think it was a manufacturing strategy to sub in the more popular dynamic elements as the ESP10's were going out of production perhaps. That said, I can't track down a year of release for these, so I suppose that the possibility exists that the ESP/10 reuses this cans enclosure rather than the opposite.   

 

[flipflop]

   
I do wonder if the stock pads would have sounded better and been more comfy when new, the foam generally is a victim of degradation over time. . . Koss are definitely hit and miss on comfort, but I am increasingly of the opinion that their stock seal and clamp are quite deliberately designed for the headphone.
 
I suspect you are right regarding the origins of these following the ESP/10. I would think it was a manufacturing strategy to sub in the more popular dynamic elements as the ESP10's were going out of production perhaps. That said, I can't track down a year of release for these, so I suppose that the possibility exists that the ESP/10 reuses this cans enclosure rather than the opposite.   

 
the stock pads are air-filled vinyl pads. no foam in them. i suspect these pads were quite similar to the pads of the ESP/9, which were liquid filled as far as i know.
 
i found a website which provides some basic information about them...
 
http://20cheaddatebase.web.fc2.com/koss/DYNAMIC10.html
 
the translation sometimes acts up so i'll attach a screenshot as well.  these were released in 1977 and discontinued around 1980.
 

 
also found a short article from Billboard magazine: https://books.google.com.ph/books?id=S0UEAAAAMBAJ&pg=PT32&lpg=PT32&dq=koss+dynamic+10+billboard&source=bl&ots=iorLXS3zZI&sig=YCZqQn6NDEP7-V4NqEnTvuRF_5c&hl=en&sa=X&ved=0ahUKEwj_t_nPrpfOAhUBkJQKHdEHDpsQ6AEIIDAA#v=onepage&q=koss%20dynamic%2010%20billboard&f=false
 

 
the article highlights the release of the ESP/10 and briefly (one sentence) mentions the release of a "dynamic version" (at $85).
 
spent a little more time listening to them yesterday and am really liking the sound.  it seems too that they sound best with instrumental jazz and funk from the same era.  they don't sound as good with more modern music. "PYT" (Michael Jackson) sounds GREAT on these. also noticed that there's A LOT of sound leakage.  the whole headphone resonates. i can hear them from across the room! the cups i think are made from steel/aluminum. i'll consider damping them in the near future and see what happens. i haven't really modded any other headphones aside from Kramer modding my PortaPro and KSC75, and have yet to research on the possible benefits/effects of damping sealed headphones.  just hope i don't damage them in the process...
 
UPDATE
i haven't opened these up yet but i'm planning to:
1.  line the insides with Dynamat or similar to isolate the drivers from the cups
2.  apply a second layer of felt/acoustic foam/fiber fill to absorb backspeaker resonance
 
what effects can i expect from these "mods"? i'm basically "winging it" here. no science involved.

 

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opened them up! here's how they look like inside...
 

 
to open them up, just undo the four screws.... voila! no small parts or clips to worry about.
 

 
just as i suspected, absolutely no damping material on the inside of the cup just plastic and what appears to be aluminum.
 

 
the driver.  what's weird is that it seems to be riveted (plastic) to its own housing.  absolutely no way of going much further without the risk of completely damaging the entire thing.  my guess is that this particular driver was designed as an all-in-one, that is, a driver plus housing in one.  the white plastic material is acoustically "dead" (ie. no sound when you tap on it) and underneath that translucent plastic disc at the center is what appears to be a cork disc.  it seems that the people at Koss figured that with this particular design, they'll be able to pop it in just about any form of housing/cup.
 
(update)
i put a dynamat disc on the aluminum part of the cup and a smaller one on the translucent disc behind the driver.  while it addressed the resonance with the cup, it sucked out almost all the lower frequencies.  i then removed the dynamat from behind the driver (still keeping dynamat on the aluminum part of the cup) and it sounded way better.  had to shift back to my aftermarket leatherette pads though in order to get back some of the lower frequencies.  i am definitely sticking with this setup for now.

 

[Das Mookid]

Thanks for the great pics, as well as for the interesting insight into the driver design. Given the modular nature of the driver and integrated casing, I wonder if this was used in any other Koss cans over the years.
 
In any case, it sounds like you have a setup with the pads that works well and lets these sing again - enjoy!