[jerg]

'Ello Head-fiers,
 
I wanted a pair of good workout clip-on headphones, and after much digging here I (like many probably) grabbed a pair of Koss Ksc75 from ebay for around $20 all included. The packaging seems completely genuine but...
 
The sound it produced is suspicious, the treble is surprisingly clear but not painful, the mids are fine, but the bass is problematic on both sides. Whenever I crank the source (I tried a laptop source, a sony stereo source, and a sony walkman source) to an appreciable volume, the base and vocal in songs with beats start becoming severely distorted; it sounds like a cross between cricket-chirping and metallic oscillations. This really kills the sound fidelity and makes it unbearable to listen to.
 
Regardless, I later committed and applied the Kramer mod on with success, overall the sound DID improve but the distortion was still there. It seems to be a driver problem.
 
Has anyone else owning a Ksc75 experienced this phenomenon? If so, is it remediable or do I have to return it for another one?
 
Currently I'm burning it in with some beat-heavy songs, hopefully that'll reduce the chirping distortions but if not, I'm at a loss.
 
 
Thanks!

 

[jerg]

Bump,
 
An update, I've checked all the preliminary factors - no hair in diaphragm or outer padding, no dent on the diaphragm, I really can't think of much else to try. Someone has to have an answer here right (I mean there's a gazillion Ksc75 threads, everyone has a pair)?

 

[Uncle Erik]

I think your headphones are fine. However, you are driving the amp in the player into clipping. Clipping is when the amp runs out of power, especially when a large amount of power is demanded in the low end. What you're describing sounds like a textbook case of clipping. You might want to think about a portable amp for a little more output.

When there's a problem with a driver, it shows up in one of two ways almost every time. First, is physical damage to the driver, like a tear or a separation of the voicecoil from the cone. If there was a tear, you'd hear it at every volume level. If the voicecoil separated, it would either be dead or you'd hear it buzzing against the cone. The other way drivers fail is an internal short. The insulation on the wires in the voicecoil is a thin enamel coating. If the voicecoil heats up too much (either too much power or DC offset, usually) then the enamel melts and causes the voicecoil to short out. When this happens, you hear nothing.

Anyhow, head over to the portable amp forum and take a look. There's something for any budget and you can even build your own CMoy for about $20.

 

[jerg]

Quote:

I think your headphones are fine. However, you are driving the amp in the player into clipping. Clipping is when the amp runs out of power, especially when a large amount of power is demanded in the low end. What you're describing sounds like a textbook case of clipping. You might want to think about a portable amp for a little more output.

When there's a problem with a driver, it shows up in one of two ways almost every time. First, is physical damage to the driver, like a tear or a separation of the voicecoil from the cone. If there was a tear, you'd hear it at every volume level. If the voicecoil separated, it would either be dead or you'd hear it buzzing against the cone. The other way drivers fail is an internal short. The insulation on the wires in the voicecoil is a thin enamel coating. If the voicecoil heats up too much (either too much power or DC offset, usually) then the enamel melts and causes the voicecoil to short out. When this happens, you hear nothing.

Anyhow, head over to the portable amp forum and take a look. There's something for any budget and you can even build your own CMoy for about $20.

Thanks for the insight about amp, however, after some searching on headfi, it seems Ksc75s are very easily driven and literally no one mentioned about bass distortion due to lack of source power output. It seems to be an inherent problem on my specific pair of cans. 
 
Maybe I should take the whole thing apart and see if there's something stuck in there? The odd thing was as soon as I listened to it after unpackaging, the problem resided in both headphone speakers. The chance of a defect occurring in both sides is unlikely unless the entire batch of Ksc75s they were producing at the time were screwed up.
 
Thanks.
 
 
 
 
 
quick update:
 
After dissecting the thing, I found that the chirping sound comes from the fragile metallic diaphragm, it seems to rattle abnormally whenever there's strong bass/beats in the music source, causing the metallic chirping. If I carefully press on the diaphragm while the music is playing, that rattling/chirping stops. Perhaps I should do some sort of mod to fix up the diaphragms in the headphone speakers?

 

[az2123]

This happened to me before. This means that the metallic diaphragm is dented (I was trying out some mods...). Nothing you can really do except use your lifetime warranty to get a replacement from Koss.

 

[jerg]

The problem continues... I sent it back to Koss and just today got a new pair in my mail. After unboxing it enthusiastically and plugging it in, I notice the same problem still? The new set still has that vocal/bass distortion at mid-high volumes!!!!
 
This is ridiculous...Maybe the newer production lines of Ksc75s are all pumping out defective cans?

 

[renegg]

That is very strange, I just received my second pair of KSC-75 after the first one died in an attempt to re-cable 

 and neither have that chirping sound you are describing or at least nothing that sound's strange to me. Maybe you should contact Koss directly and describe what you are hearing from the headphones. 

 

[jerg]

Quote:

That is very strange, I just received my second pair of KSC-75 after the first one died in an attempt to re-cable 

 and neither have that chirping sound you are describing or at least nothing that sound's strange to me. Maybe you should contact Koss directly and describe what you are hearing from the headphones. 

It's hard to describe...sort of a metallic buzzing/chirping which distorts the vocals whenever some bass comes in a song. Most of the time it is in the background, but for some songs it's very very obvious.
 
And yes, I'll be sure to send em an inquiry concerning this.

 

[Amatsu]

Have you tried with different songs? Maybe they are badly encoded or produced. Also, does it happen in both sides? I have the hair problem very often with the KSC75 and the effects are similar, but it's just only on one side.

 

[jerg]

Quote:

Have you tried with different songs? Maybe they are badly encoded or produced. Also, does it happen in both sides? I have the hair problem very often with the KSC75 and the effects are similar, but it's just only on one side.

Yeah I've tried different songs and music, the distortion is only apparent for hip-pop / techno / pop / some rock songs, basically ones with constant strong bass and vocals it will distort. 
 
The old pair I had had strong distortion in both sides, this new one has a little distortion in its left, and pretty strong distortion in the right one.
 
Oh I've tried examining everything, taken the whole thing apart and checked the diaphrams carefully, clean as a whistle and no damage at all (in both the old and the new pairs), the distortion is just as strong if I listen with it with no foam nor lid. It seems to be the diaphram's problem - e.g. I tried a small strip of scotch tape on the diaphram kind of restraining it from over-vibrating, the distortion stops but the bass output gets cut by half, so that's no go.

 

[jerg]

Is no one else with a recently purchased / warranty-returned Ksc-75 having similar issues?
 
I found out that a friend bought a pair a few months back too, and I asked to try it yesterday and it has the exact same bass/vocal distortion issue, which was why he basically had it in a drawer collecting dust.
 
So so far 3 separate new Ksc75s fresh out of package with the same distortion issue, god it's annoying, eespecially because I love the sound! (when there's no distortion lol)!
 
 
 
edit:
 
A bit OT but, I also tried listening to the sound of a PortaPro from someone I know, it really isn't to my preference...trebles are just too muddy to uncover all the nuances.

 

[Cristian69]

Hi Jerg,
I have the same "chirping" problem you described on both two pairs of KSC-75 just bought.
 
One I have broken trying to find out from where it was coming...the second pair I'm going to burn in night and day for some time...I'm really curious to see if it goes away.
 
Strange...and really a pity as they are wondeful cans in absoute terms (I even find the mid-high resolution half way from a standard hedphone and my AKG 702..).
 
I noticed your posts about this subject are old, have you any further uptade on this? (did you give up the KSC 75 maybe?)
 
Bye

 

[jerg]

Quote:

Hi Jerg,
I have the same "chirping" problem you described on both two pairs of KSC-75 just bought.
 
One I have broken trying to find out from where it was coming...the second pair I'm going to burn in night and day for some time...I'm really curious to see if it goes away.
 
Strange...and really a pity as they are wondeful cans in absoute terms (I even find the mid-high resolution half way from a standard hedphone and my AKG 702..).
 
I noticed your posts about this subject are old, have you any further uptade on this? (did you give up the KSC 75 maybe?)
 
Bye

Lol quite the necro-bump there, this was one of my very first posts on HF I think. Basically KSC75s have small drivers which means they can't handle power too well (i.e. bass-heavy music at loud volumes), hence bass distortion gets out of control at loud volumes. It's not a fault of the headphones so much as a physical limitation.

 

[Cristian69]

Thank you for your reply. It must be like you say indeed, even if still I find strange the KSC can produce the "chirp" even on low volume sometimes, while other times they can handle deep and powerful bass... Bye

 

[Timoteew]

Hi all,

This is quite some time later, but this is one of the only mentions of this "chirping" problem I have come across. I too experience this, particularly when the KSC75 tries to reproduce the sound of clarinets and saxophones. If you turn the driver around and listen to the rear of the earpiece the effect is more pronounced - it's almost as if this undesirable sound is leaking into the ear, whereas most of the time it isn't discernible. Unbelievable sounding cans otherwise though.