Showing 1 of 310 reviews about:
AlanDixon
43
Mar 19, 2019
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Mine have a faint whine on the left channel. It is intermittent and I can sometimes get it to go away for a bit by moving the cable but it inevitably comes back. Pretty much negates any acoustic advantage the headphones may have had.
metal571
61
Mar 20, 2019
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They have a lifetime warranty so just ask Koss and they'll get you a new pair
CEE_TEE
3477
Apr 2, 2019
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Hey AlanDixon,
Sorry to hear you have an issue...
- Please go to the drop down menu next to your profile pic in the upper right hand corner.
- From the drop down menu > Select Transactions > go to the Koss transaction > at the bottom of the transaction there is "Contact Support".
- Click on that (it's a link) and a ticket will be created for the specific transaction.
(Edited)
coasterpro99
39
Apr 4, 2019
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> upper left hand corner
This may be different on PC and Mobile. The vertical three dot "..." menu in the upper right hand corner if you're in a PC browser. :)
(Edited)
Nottagorilla
56
Apr 16, 2019
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I just received mine, and I have what may be the identical issue. I have alot of experience with both electrostatic speakers & headphones, & have several pairs of each. My experience with my Stax headphones tells me they should be energised CONTINUOUSLY, so I did the same when I received the 95x's. Besides, I also wanted to "burn in" the energiser, so I just left everything on continuously with music playing through it at a perceived 80-85db volume level. On the 3rd day, I noticed a faint whining/whistling noise coming out of the left channel only, which I could hear only when music had stopped playing (in between tracks). Experienced as I am with electrostatic technology "gremlins", I just instinctively gave the earpiece a gentle tap with my index finger, & it immediately stopped! About an hour or two later, the noise returned. One little tap, gone again! It's not the cord, and it's not the Energiser unit. I know it's a bit of leakage from maybe a small bit of foreign matter in between the membrane & one of the stators. If so, with a bit of handling, the offending piece of fluff will eventually move away from the trouble spot & the noise may disappear forever! High humidity also can cause electrostatic leakage noise to be a minor nuisance. OTOH, my 40 year-old Stax SRX-III's have ALWAYS been perfectly reliable & SILENT as far as leakage noise is concerned. But it's older technology, and uses only 160 Volts bias; not the 600 Volts the Koss & post Y2K Stax phones now use! Long story short, if the noise is faint, and you can make it disappear for a while by gently tapping on it, don't freak out right away. Don't use them when humidity is over 80% if possible. Consider only leaving them charge for an hour prior to a listening session instead of leaving things running continuously. And see if the noise doesn't just disappear all by itself after a few weeks. Be patient, you have a lifetime warranty! No other electrostatic headphone has that, THANK YOU KOSS! :)))
DiMora
262
Apr 23, 2019
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Sounds like a nice pair of headphones that whine and whistle and have to be “tapped” to make the noise go away. I’m glad I sold mine immediately due to a lack of bass and construction quality that reminds me of a cheap child’s toy.
prignony
25
May 9, 2019
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Thanks for this piece of information, I have that gremlins on the right chanel, it pop or vibrated badly it come and goes. I even throught to return them but as you said, gentle tap made it goes away. Probably foreign material as you said :)
r33tom
15
Jun 25, 2019
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it is the crappy power supply. replace it with a linear power supply and all whining high pitch sounds will be gone. I had the same issue with my headphones and replacing the power supply with a breeze audio linear power supply fixed the whining issues for me.
Nottagorilla
56
Jun 26, 2019
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No, you may have solved a different problem, not the one we are talking about here. My unit came with a bulky 9V/1Amp LINEAR wall-wart, clearly by size & weight there is a "conventional" power transformer fitted into it. So either Koss uses more than one 9V adapter to supply with this headphone system (which I doubt, but...), or you are talking out of your ass/have no idea what you are talking about. Anyway, short of buying an aftermarket Energiser for Koss (none exists to my knowledge, the other choice is to buy a custom extension cord, a duplicate of the extension cable supplied but with the proprietary Koss plug replaced with the Stax Pro plug, from Fong Audio for $160, to allow use with a Stax Pro Energiser as the 600V polarising voltage & headphone drive requirements are virtually identical...), all the wall-wart does is power an internal DC-DC Converter (a switching power supply!) that takes the 9VDC & turns into the various higher voltages that the amplifier runs on & also the low-current 600VDC that energises the headphone element membranes. So you CAN'T get around the switching power supply built-in to the Energiser/Amplifier itself! The Stax headphones were never designed for portable use so until very recently all their Energiser/Amplifiers had fully linear power supplies. In any event, my experience with the Koss amplifier is that is ALWAYS DEAD SILENT even with volume cranked. NO hiss, NO hum, NADA! The ONLY problem I have had is with the headphone elements VERY RARELY (acted up ONCE a month ago, and used DAILY, & so I have the amp running CONTINUOUSLY to assure full charge/best sound) making dribbling little Electrostatic "farting" or hissy/spitty noises (overwhelmingly the latter), something I'm well used to having owned QUAD & Martin-Logan & Janszen speakers for several decades now. The hissy spitting noises are ALWAYS low enough in level that they go unnoticed until the music stops or is extremely low in level. And a gentle but firm fingertip tap (maximum 3) puts a COMPLETE stop to it for an absolute minimum of 1/2hr. but usually for the rest of a multi-hour listening session & usually the relief lasts well into the next several listening sessions, for that matter.
r33tom
15
Jun 26, 2019
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Show me the specification from koss that it is a linear power supply. I don't make assumptions just based on weight and size. The aftermarket 9V 1A linear power supply I got weighs 500grams and is bigger than the koss energizer so either the koss power supply is not linear or it is using the cheapest transformer you can get to keep costs down.
I also trust my ears that it fixed the consistent whining I was getting on the left channel every time I use it.
Anyway you don't have to take my word for it, I am just sharing what I and many others on headfi experienced by upgrading the power supply.
Nottagorilla
56
Jun 26, 2019
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I've been designing & fixing all manner of (mostly) audio equipment for 40 years. I'm not your garden-variety audiophoole ignoramus with an outsized opinion. Since I understand circuit theory, implementation & technology I don't need to void my warranty by sawing open sonically-welded $20 wall-warts to know whether there is an actual power transformer in it. Mine is clearly both too large & too heavy for the 9VA rating to be a switcher, which otherwise weigh about 1/5th what this one does for the same rating. Your ignorance of electronics in general makes this easy & simple observation beyond you. Likewise Koss mentions a 600VDC polarising voltage to the Electrostatic membranes, and that the amplifier can deliver peak voltages in excess of 2000VAC(!). Even a first year technician knows that to get these voltages from a 9VDC wall-wart requires a DC-DC switch-mode converter! So I don't need to open the Energiser box to figure that out. Also those high drive voltages are beyond most bipolar transistor output devices; my ears confirm the tell-tale "MOSFET Mist". I've also worked on "upgrading" the Stax 007t Energiser so I am also confident that the Koss circuit is likely virtually identical in topology (just sub the 6CG7's for MOSFET's). I also went to the trouble of looking up your Breeze PSU. Another in an endless stream of cheap trash boxes..
Do you use the 15W or 25W model? Or do you have the faintest clue? Did you SPECIFICALLY request the PSU be set for the CORRECT 9VDC or not? I think the factory default is 12VDC, with the potential to slowly melt down the Energiser over time & void your lifetime warranty if you were stupid enough to be honest with Koss about your mucking about! I know how to open a Breeze PSU & set the EXACT output voltage. Do YOU even have the ability to measure it?? Also, the Breeze has a regulated output. Meaning it has a whole bunch of feedback circuitry in it that the unregulated linear wall-wart does not. This means that it will have a correspondingly "electronic" sound signature that more than likely will degrade the sound of the Energiser. Listen carefully! Finally, audio chat rooms are an absolutely fantastic place for know-nothing idiots to share their know-nothing idiot opinions. Add the tendency to bullshit & otherwise talk out of their asses to brag to their unknown audience (so they are ultimately completely unaccountable to it), excuse me for being utterly unimpressed by "herd consensus". Granted, if the herd is large enough speaking with the same voice, the advice is at least worth investigating further. And the Breeze has that almost magical virtue: it's very cheap for what it "appears" to offer. However, the Breeze has another characteristically "quality": it's specifications are both extremely vague & equally lacking! ANY respectable power supply should have specs for the following: Line Regulation, Load Regulation, No Load & Full Load ripple (noise), and CONTINUOUS output current (not the momentary peak current rating which is the ONLY spec Breeze gives besides the output voltages!). Breeze also claims VA (wattage) ratings for the power transformer that are IDENTICAL to the circuit output wattage, a sure sign of COMPLETE BULLSHIT since this is A THEORICAL & PRACTICAL IMPOSSIBILITY. They claim to have it both ways here, so I'm sure they achieve neither! Fortunately for you, the power consumption of the Koss system is substantially below 9VA/watts, so even if you bought a 15W rated Breeze it SHOULD manage the less-than 5 watts peak the Energiser will ever demand from it. Please let us know if it is still working 3 months from now (or 3 weeks, for that matter). And I'm SURE it has CE electrical approval, so you can be reasonably assured that even when (not "if" ☣☣☣) it burns up it doesn't take the rest of your home with it. CAVEAT EMPTOR!!!
(Edited by moderator AlexPk)
Nottagorilla
56
Jun 27, 2019
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My experience with the hissy/spitty low-level leakage noise is that it more or less went away all on its own after 3 weeks or so of near-continuous use. It only acted up a grand total if ONCE thereafter; I have the system powered up now continuously & summer humidity is here (a mere 75%RH at this moment) and...not a single "fart" in a month now. What I suspect happened here is that this is an initial break-in gremlin. And that instead of contacting Koss (who may well have just sent you a new one for $25 to cover shipping, as is their policy) you (not unjustifiably) kind of panicked & did one of the few things that you felt you had the power to do. So you jumped to a hypothesis/conclusion about the wall-wart, replaced it with this shiny chinese regulated Breeze thingy, and the problem simultaneously disappears (which is my point!), so you assume, as perhaps did some others in a headhifi forum, that the Breeze "solved" the problem. I think TIME solved the problem, & your purchasing this questionable-quality Breeze POS just happened to coincide with the break-in timeline for the problem to sort itself out all by itself, leading you to a false conclusion both as to the actual nature of the issue & it's solution. Why don't you reconnect the stock wall-wart & see if the problem returns? I'll bet it doesn't! You can also see at least one other poster in this forum tried my "tapping" advice & found it equally definitive! Also with no further comments about the problem returning, much less getting worse! Electrostatic drivers are "tweaky" things, kind of like valves (vacuum tubes). They don't necessarily work as predictably "right out of box" as inferior technologies do, so they are things that aren't for the "faint of heart". The other side of the coin is that their behaviour, whilst a bit "different", shouldn't be so flakey & unreliable as to leave owners' in a continuous state of bewilderment and/or anxiety as to what will happen every new day they turn things on to have a listen! Then, clearly, the product is "unfinished", a prototype perhaps, and the prospective owner should at least be warned that they are "Beta Testers"!! I heard my first ESP/950's back in 1994, so they are NOT prototypes! As well Koss has a LOOONG history of making Electrostatic headphones; these aren't my first Koss Electrostatic phones, I also own a perfectly functional (if ergonomically highly flawed, they weigh a TON!) 1970-vintage pair of closed-back ESP6's! Only Stax, AND KOSS, have a proven track-record for making reliable & durable Electrostatic headphones. NO ONE ELSE! Other companies tried their hand at it & failed, like Numark & PWB, whose phones I either once owned or still do in broken & unrepairable condition. For that reason, I also advise caution to rich fools who might dive into the latest multi-kilobuck offerings from either HiFiMan or Mr. Speakers (never mind Shure in-ears). If the power supply WAS the source of the whining hiss, then it would be there CONSTANTLY, not just very occasionally. It would also be COMPLETELY unresponsive to any poking or prodding of the earcups, or jiggling of the headphone cable itself. You walked yourself into the unnecessary purchase of a cheap & flashy regulated power supply that you almost certainly don't need, at the same time risking your "golden" lifetime warranty! You should at least contact Koss to discuss your problem(s), and get their blessings about using the Breeze or any other "flavour of the minute" power supply.
Scoop_ESP9
0
Dec 16, 2019
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I'd be curious to compare them with my ESP9s'. I have two pairs that both required extensive restoration inc. breadboarding of one energizer. A simple voltage multiplier through a 22M resistor (x2) generates the polarising voltage. The other energizer looks the same on the outside but houses a different circuit. It did not require attention so only the drivers were rebuilt. They both sound fantastic though there is a very small subjective difference noted in a side by side comparison.
ESP9 Audio is of course fed from the speaker outputs of an amplifier.
They can be driven ear splittingly loud without any distress - except perhaps to the wearer. I'd be interested to know the maximum acoustic levels available from the E90's audio stage.
As for an external PSU, I have neat leather case which houses a 12v 7AH battery. Adding a 7809 regulator would be easy. The voltage range (as published) for the 'wall wart' is 120 - 220v. The nominal 230v mains in the UK can easily exceed 240vrms where I live.
When I see the ESP95x listed new on ebay for under £300 I'm tempted. I would hate to be disappointed and there is nowhere I know of the UK able to demo them.
Scoop_ESP9
0
Dec 16, 2019
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I've never needed to claim replacement headphones from Koss. I have pair of PRO4AAs purchased new in 1971 for £28.00 (about $90 USD at the time) which was a lot of money 48 years ago. They do sound markedly better than later versions of the PRO4AA though fall well short of the same generation ESP9 as you'd expect. I did request six replacement cushions from a uk agent. They were gratefully received free of charge, but they don't fit (heating them in the oven won't stretch them enough) and front/back markings are reversed.
The ESP9s have the same cup size. I have two pairs of ESP9s bought on ebay 'spares or repair' so a claim on the warranty would hardly be fair, and they can't be replaced anyway. Repairing them was surprisingly easy, though absolute cleanliness is needed when handling the electrostatic drive units. Restoring the first pair went so well, I sought another pair to restore. The end results easily justify the efforts!
970EVO
11
Mar 10, 2020
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damn it. I had the same problem and a single tap make the noise go away
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