"KOSS HV High Velocity Series"

Discussion in 'Headphones' started by luvmusik, Oct 22, 2014.

  1. ChopperChas

    ChopperChas Super Member

    Durham, NC
    I bought the realistic LV-1's for parts, but they turned out to be fully operational when I got them, and I hate to take apart a working headphone if it's not necessary. They just have a very different sound to them. The realistic version has less metal -- the driver cups are all plastic, instead of a mix of metal and plastic. Maybe that's why they sound different. Or maybe it's the wiring, maybe one of them is a little corroded or something. I dunno, I just know I like the HV/1's sound significantly more... full. Like there's more there, like it's bigger and wider than the LV-1.



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  2. luvmusik

    luvmusik HOORAY !...ELECTRICITY !

    So many factors can affect the sound, especially housing & pads if drivers are the same.

    Stick with HV/1 if you like those, they are very nice sounding, I like them.

    I think you got a bad set of RS/Realistic LV-10 however, because they do sound very close to HV/1 if both they & Koss are mint, I have both here & thoroughly A-B tested them; nearly identical result, both my sets are mint.

    The RS/Realistic model is LV-10 (TEN) by the way; no problem, we all have mistyped like anyone else.

    I greatly disliked the HV/2A set; the only model in the HV line to avoid completely; would not recommend it; however, it's never wise to rely only on hearing only 1 sample of a used headphone, judgement is best when hearing 2 or more of the same model to confirm attributes. The HV/2A set I got may possibly have had problems, it produces audio fully competently, just doesn't sound very good & much different than all other Koss/RS/Realistic HV line models.

    As it sounded different than the others, I did not purse a 2nd sample; I like the classic sound signature of the others & even have a duplicate of one model, beside having both LV-10 & HV/1.

    I also did not buy Realistic Pro-60 as felt it would be redundant to my Koss HV/X which sounds very good. So, I did acquire the whole HV-line although not Pro-60 due to not needing that duplicated. The line consists of 6 distinct models & I also have that 1 duplicate, forget which one it is without looking. The "LC" models are simply the same hp as their model # is, but adds a level-control (LC), one of mine is an LC model.

    If your LV-10 set was advertised for parts, possibly the original owner heard something he didn't like in them, thus selling not as 1st quality, but for parts, just a guess.
  3. ChopperChas

    ChopperChas Super Member

    Durham, NC
    So, the LV-10 has a new cord. Would that matter? It is definitely brighter and has less bass than the HV/1A. The measurements are about the same, but the new cord has much smaller diameter wire than the original cord. Would that make a difference?

    left: 156 ohm (measured from tip to ground)
    right: 162 ohm (measured from ring to ground)

    left: 154 ohm (measured from tip to ground)
    right 152 ohm (measured from ring to ground)

  4. luvmusik

    luvmusik HOORAY !...ELECTRICITY !

    Yes, if the cord is either bad or too thin gauge wire, it can affect & worsen the sound. Corrosion, as you mentioned can affect also if it's really eating away or barely connecting.

    If the unit doesn't have the original factory cord, it was modded. On these, the original factory cord should be fine if the cord is working.

    The compromised sound can be due to anything in the electrical pathway inside the cups too, either as a damaged or defective part. It could also be diaphragm seperation has occurred too.

    If you think the sound is the same in the L & R cups, then the cable & wires leading to the cups may be bad.

    But, if that set was modded, maybe something else was done inside also. Is their any dampening or muffling material inside the cups that maybe should not be there, if modded by 1st owner ? Some foam or scrim cloth could have deteriorated inside and fell toward blocking the open vents; if so, just clean that out. Maybe they were modded to block them from outside venting, as if someone wanted more isolation - which would ruin the sound intended for this design.

    Also possible some part inside may have been replaced with the wrong-spec part too.

    Have read your post on the other thread about Koss HV/1LC restoration. Did you open up your Realistic LV-10 yet ? Interesting to see if they were modded; a very popular different RS model, which has a planar driver is always modded all the time by guys for better results.

    The bass of the LV-10 and HV/1 should sound the same, or be really super close to each other; wondering if the drivers are blown, or it was modded with dampening.

    May want to try the easiest repair 1st, possibly a better cord, (if that is not the factory cord now); if it is the factory cord and it looks intact throughout without repairs or cuts in it, then you would need to open them up if really wanting them to sound better as they should, or to diagnose the problem.

    Pretty much out of ideas until really finding where & what is compromised; then if fixing is worth it, or better to find another mint used unit if wanted. Either way may appeal to you, depends on what needs to be fixed; fixing may cost more than a mint used set - these sell very reasonably on ebay. If so, be sure to ask all the pertinent questions there before buying, so seller can inform if they are really mint & sound is perfect, just simply an older but fine working headphone.
  5. luvmusik

    luvmusik HOORAY !...ELECTRICITY !

    Forgot to mention...since earpads can really change headphone sound...are you using the correct Koss earpads (same Realistic) for the LV-10 ? If it is another brand pad that looks identical, it may be OK, but if really different than stock pads are on, I would replace with Koss pads.

    Koss still sells them direct from their site for only $5 a pair.
  6. luvmusik

    luvmusik HOORAY !...ELECTRICITY !

    Here's some other info...

    your measurements look good, the nominal impedence for this driver is known to be 151.4 ohms.

    often the voice coil leads get loose on HV models, but repairing them is very tricky, usually ends up wrecking them.

    depending on the HV model, the diaphragm & voice coil are integrally part of the baffle & frame, so trying to remove driver often tears & seperates driver.

    the Koss cable stock form has a high impedence & better cables can be made from wire, or another cable can be used instead if the Koss cable seems defective. But also, The mint HV sets sound fine with the supplied Koss factory stock cable when cable & headphones are in mint used condition.

    Lastly, check the mispelled thread on Head-Fi, titled Koss HV/A1 (mispelled as A1 instead of correct 1A). HV/1A is the closest model to HV/1 and likewise LV-10, so much good info is in the short HF thread. At least Two of the members posting on links found inside that thread are very knowledgeable; certain folks you really get to know. BigElCat's restoration project is linked in that thread, as well as right in this thread too, a valuable tool. There are a number of links in that HF thread that are related & informative.

    I recall when HV/1A were released way back when, and there was nothing like them sounding this good at this price. Stax were great and cost more. I probably wrote earlier in the thread here that HV were well liked right away hitting the market & still sound great today. The detail and full frequency range have always & historically been highly regarded for this type hp, and especially the uniqueness of the driver type. Since then, other drivers followed in a similar type from other brands.

    Good luck with your project, let us know how you make out.
    Last edited: Feb 9, 2017


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  7. luvmusik

    luvmusik HOORAY !...ELECTRICITY !

    Also, reading thread backward, saw post #21 maybe hadn't opened up your LV-10, but I think I'm misreading it.

    Based on post #19, reading you may have opened up LV-10. If the foam that was newly replaced inside is much different (property-wise, may not visibly look different), it could change the sound. Did you listen to them with no internal foam before applying new foam ? Just wondering if maybe that foam isn't "breathing" properly per original Koss spec. Maybe try some different types & thinner or thicker foams to see if they get much closer soundwise to the Koss set.

    Was there anything else done to the LV-10 ?
  8. ChopperChas

    ChopperChas Super Member

    Durham, NC
    I'm using correct Koss-purchased pads for both headphones. I have disassembled and repaired both headphones identically, with the same foam. The only difference is the LV-10 has a new cord. Internally it has very thin wires coated in enamel, instead of wires in their own plastic insulation. I can try putting the original cord back on.

  9. John Buncle

    John Buncle New Member

    I don't agree on your view on the HV/2A's. I have a pair of HV 2/A's (1979) and I have loved them from the minute I bought them in 1980 and they are still working fine. They were particularly fantastic when turned up loud, though not quiet for others due to the HV open design.

    I don't seem to remember having that much trouble disassembling the left earpiece and resoldering the cable in the mid 80's lost about 3" off the left cable.

    I still have the box but it does not provide specs to confirm the details you request. I know I have the "manual" somewhere too, but my filing system would make it hard to find. Been 10 years since I last came across it if I come across I will post them

    The were pretty much the same look as the HV 2's and similar spec. I am pretty sure they were 20hz- 20,000.The original "foam" pads on the 2A's had no doughnut hole but I had to get HV 1/A pads to replace the originals 3 or 4 years ago.

    Chances are I am a bit nostalgic as I much prefer using them to the various Sennheisers and Sony I own when playing Led Zeppelin, Pink Floyd or the Stones. They just seem to balance the sound the same way to speakers I have owned over the years.

    Not as easy to take advantage of the warranties from here in Australia.

    Good luck with the restoration, I reckon it is worth it.
  10. luvmusik

    luvmusik HOORAY !...ELECTRICITY !

    John, if the HV/2A owners manual appears, please post specs ! Even Koss could not find them in their archives. But we did get the HV/2 specs from them. The only specs we are missing is for the HV/2A. We are not sure the model HV/XS ever existed. No one knows anything about an XS anywhere, and it may be folks wrote about their HV/X headphones as "plural", meaning HV/X's, but instead it later became interpreted as HV/X"S" possibly erroneously. I dug deep & did see internet writing of XS, but in fact it may actually only be the HV/X model itself for that reason, yet not sure. Koss has no records archived of a HV/XS model.

    If anyone knows of Koss HV/XS model, has foto, specs, brochure or owners manual - please post. This model may or may not ever had exist.

    As posted earlier, it may have been likely I got a bad set of the HV/2A. I never did pursue a 2nd set & maybe should. Did note I feel it unfair basing any findings on only 1 sample set as I wrote. They were by far the hardest set to find from the whole line; it took me a really long time to locate a set in UK & had shipped to USA here. Maybe they are a bad set. As they were hardest to find & this particular set sounded bad & different, I never searched for another set. Still wonder what is different between HV/2 and HV/2A, or if they are the same model.

    The HV have a warm-spot for me, as the HV/1A was the first really great headphone I ever heard when it 1st sold new. I bought it new around 1973-1977 sometime. I think it was 1975-1977 thinking back. I couldn't afford Stax back then, nor heard those until a couple years later. HV line still holds its own today. Then bought an electret Stax the year it released in 1982. Model SR-30 Pro (SR-34 Pro kit) and still have those - they play great also, and this "Pro"-model are much better than standard SR-30 version. Pro meant Professional & runs Low (normal) bias, not High (pro) bias, using a better diaphragm than standard version. Then much later, in these last 5 years have gotten very deeply into headphones (too much), but it is the only thing left to pursue for me in hi-fi.

    John, besides HV/2A, have you heard other Koss/Realistic-RS HV models ?

    Another fellow on thread is restoring a HV set, but not me. Not sure if his set is working now & sound correct, or has maybe damaged or over-driven voice coils.
  11. thomoz

    thomoz New Member

    Atlanta GA area
    The HV/X was also sold as the HV/7 in a different plastic color.
    I've played the HV/X and the Pro-60 side by side and they sounded identical despite the $25 difference in (1982-5 new) price.
    I have a 1983 pr of Pro-60's I use now. The pads are no longer sold by Koss, they ran out in the last year.


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  12. pognoot

    pognoot Well-Known Member

    Aurora, CO
    I just picked up a minty set of HV/1A Plus headphones off the bay. According to the Koss website, these were released in 1987. New foams on order as well.
  13. luvmusik

    luvmusik HOORAY !...ELECTRICITY !

    Whew, long time posting & cool to see some new posts.

    Would like to know more about the HV/7, never saw that one, does anyone have a foto to post of it & what color was it ? The specs would be same as HV/X, if those are the same models, other than color.

    Also grabbed a Realistic Pro 60 here, same exact headphone as Koss HV/Pro (1990). Specs same of course, -
    15 to 22,000 K frequency response, 92 db SPL, 85 ohm, <0.1 % THD, 8.2 oz weight.

    At last also found the final HV elusive model to complete my collection of the entire HV line now. This one slipped by me for years until finding out about it last year...it is the Koss "Easy Listener" Denim Stereophone model (1975). Foto of mine attached below. Some may remember this one - it has a denim (just like blue jeans fabric) headband, blue earcups, gold trim & accents on cups and orange (near-gold color) stichting & logo. The box graphics are also blue jean printed.

    Per Koss reply to my writing this Easy Listener was a cosmetic variant of the HV/1A model, same specs, 15 to 22,000 Hz, more specs seen here on page 1. These really do look cool, a period-piece from the mid '70's era.

    Koss Easy Listener denim headphones.jpg
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  14. luvmusik

    luvmusik HOORAY !...ELECTRICITY !


    Can we please change the name of this thread to " KOSS HV High Velocity Series", please ?

    We have listed all models manufactured with all known specs; help came directly from Koss emails.

    Link in this thread directs to a another AK thread showing internal electronics.

    Here we have the most comprehensive & historical info to preserve about this HV line, not found or gathered into any one thread anywhere on the web, not in HF site, or anywhere else.

    When released, this became a legendary line of full frequency range headphones long ago, emerging as a new fidelity benchmark, among a few others at the time.

    Can we please re-title this thread ?
  15. luvmusik

    luvmusik HOORAY !...ELECTRICITY !

    Anyone, please post your fotos of your Koss/Realistic HV series headphones. As the best database we should show real photos of all models. I started off with the denim Easy Listener, and would like others to join in too ! Cool, reminiscent & still a relevant fine performing line of headphones in today's world.
  16. luvmusik

    luvmusik HOORAY !...ELECTRICITY !

    Edit to my earlier post , mistyped the date....I bought them in 1989 (SR-30 Pro/34 kit with srd-4), the first year manufactured. (the standard sr-30 model was 1982, earlier than Pro version).


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  17. BigElCat

    BigElCat Mmm Hmm Subscriber

    South of Kansas City
  18. luvmusik

    luvmusik HOORAY !...ELECTRICITY !

    Good one BigElCat ! Nice to see you here again.

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