Koss HV/1LC restoration

BigElCat

Mmm Hmm
A couple of weeks ago, I started working on my Realistic Pro-60 headphones. Pro-60s are re-badged Koss HV/X headphones. I originally purchased my first pair of Pro 60s after listening to a pair HV/1LCs. At the time, I thought they used the same driver element. I remember being disappointed in the Pro 60s, as compared to the sound of the HV/1LC. I soon started digging the Pro 60, and even bought a second pair in the early 90s.

I recently discovered that the HV/X (Pro 60) shares nothing in common with the HV/1LC. The 1LC uses the same "series one" driver as the HV/1, and the original ProAAA. Koss retained the design of the driver, and the current model ProAAAT uses an updated (and degraded) version. Several sources on the internet opine that this driver made the best sound of any dynamic driver ever produced by Koss. So this is why it was my 'first love' when it came to headphones.

Enough back story, already.

I decided I needed a pair of HV/1LCs, and took a chance on Ebay. The left "speaker" was said to be intermittent. I found that the slip-on connector had come loose from one of the pins on the driver. It was exactly what I was hoping for....because the replacement drivers aren't available.

DSC00104.jpg An overview. Disassembly requies a 4mm nut driver.

DSC00102.jpg The coveted series one driver, ferrous magnets, nylon housing

DSC00101.jpg Deteriorated scrim cloth

DSC00103.jpg New scrim, gave the pot a deoxit Tx.

The project is coming along nicely. I just ordered a pair of white PU leather ear pads. I'll post some more pics later in the week.
 
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I have both the realistic LV-10's and the HV/1A "Plus". I still have found nothing on the plus models. They even say digital ready on them, so have got to say they were made somewhat later than the regular 1A models. The LV-10's take some power. Even a run of the mill headphone amp doesn't really get them them going. The 1A "plus" are somewhat more efficient and sound very good. Actually they are my preference for long term listening over my ATH M50's. I'm wondering if perhaps the driver is the same as the ProAAAT.

Thanks for the pics. Look forward to seeing the completion.
 
I forgot to state in the previous post that the LV-10's are the Realistic re-badged version of the HV/1's.
 
I have some LV-10s that I picked up from the Goodwill "surplus" store, where the unsellables go to be sold by the pound and after buying replacement foam from Koss ($5 a pad, a little pricey, but nice that it is still available) and some cleaning I really like the sound. Even work with my Ipods!. Don't have a dedicated headphone amp so I don't know what I am missing, but I am impressed with what I got for less than $2 (before refoaming!). With long term listening the foam still makes my ears a little warm although not as bad as the vinyl pads on my AKGs or ATH40s.
Haven't opened them up but I would guess that the scrim foam is probably in sad condition too. What is the first step to disassembly as I couldn't figure out what to do and didn't want to break them (they sound so nice and no known internal issues). And where do you get new, replacement foam scrim sheet? I have some Shure mikes that could uses that too.
 
What is the first step to disassembly as I couldn't figure out what to do and didn't want to break them (they sound so nice and no known internal issues). And where do you get new, replacement foam scrim sheet? I have some Shure mikes that could uses that too.

Step 1: Remove the adhesive and foam residue from the faces. I used a dull knife to scrape, and finished with rubbing alcohol. Do NOT use acetone on Koss plastics.

Step 2: Remove the three hex head screws that keep the ear cups together. They're standard thread...lefty loosey...counter-clockwise to remove. A normal 4 mm socket requires alot of pressure to fit in the 'well'. A precision nut driver would be better. I resorted to using a small flat blade screw driver, and dug it into the sides of the hex. You don't want to round the heads off. The screws are very soft aluminum.

The three pins.jpgThree 4 mm hex head bolts

Pin partially removed.jpg Partially extracted.

Pin.jpgThe screw itself.


Regarding the scrim cloth....I used fiberglass air filter material. It's sold at Walmart as inserts for heat vents. It lasts forever. The white color showing through the little vent holes looks boss.

scrim material.jpg The scrim material. Fiberglass air filter.
 
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I have both the realistic LV-10's and the HV/1A "Plus". I still have found nothing on the plus models. They even say digital ready on them, so have got to say they were made somewhat later than the regular 1A models. The LV-10's take some power. Even a run of the mill headphone amp doesn't really get them them going. The 1A "plus" are somewhat more efficient and sound very good. Actually they are my preference for long term listening over my ATH M50's. I'm wondering if perhaps the driver is the same as the ProAAAT.

Thanks for the pics. Look forward to seeing the completion.

I haven't seen anything about the plus model either. The driver 'design' is still used in the Pro AAAT, but the materials have changed. They now use a light weight rare earth magnet instead of the ferrous based magnet. They say the plastic housing is inferior to the original as well. The new diaphragm is coated with titanium. They say this new design does not sound as good as the original.

Koss pro4aaatHV1a.jpg

New one is on the left, series 1 on the right.
 
Here's a heads-up: there are a pair of Realstic LV10 cans up for auction right now. Pads are completely missing but Koss has the HV1A pads listed on their website for 5 bucks.

I had the LV10 on my watch list but just got a pair of Pro/4AAA instead. 4AAA pads are NOT listed on the Koss site even though the 4AAAT is a current model. Anyone know if another model cushion would fit the older 4AAA?
 
Here's my Pro 60s (HV/X clone) with generic 90 mm velour pads. I used a bead of black RTV silicone to adhere them.

DSC00109.jpg

They're very comfortable.
 
Here's my Pro 60s (HV/X clone) with generic 90 mm velour pads. I used a bead of black RTV silicone to adhere them.

View attachment 484975

They're very comfortable.

How do the Pro 60's compare to the HV/1's sonically? You mentioned at the start of the thread they use a completely different driver. The more I listen to my HV/1A's the more I appreciate them compared to modern cans that I have heard, including my ATH M50's. Not saying they are better, they just deliver a deep warm laid back sound I have not heard duplicated. But in the area I live we only have the big box stores and their products. I'd love to give the higher end senns or grados a good auditioning.
 
I'm pretty sure the HV/1LCs are going to sound better than the Pro 60s, but I don't have the ear pads on the 1LCs, yet. IIRC, the 1LCs were my clear choice over the Pro 60s back in the 1980s. The HV/1s weren't available locally back then, and it seems like they retailed for about $15 or $20 more. I settled for the Pro 60s.

The construction of the Pro 60 / Koss HV/X is considerably 'cheaper' than the 1Ls. The HV/X just snaps together using plastic tabs, with a little glue around the driver element. The element itself appears to be a cheaper unit, polystrene plastic rather than nylon. The 1LC driver is held in place by 4 rivets, the X driver lacks those.

It seems to me that there are sound quality differences between my 2 sets of Pro 60s, as well. The black ones in the picture don't sound as good as my original pair. The originals have better construction, and a brushed aluminum frame. I may transfer the velour pads over to the originals after I redo the cording.
 
Interesting thread. As I type this I'm listening to jazz on a pair of HV/1's I bought new in the early 70's. They still sound great secret all these years. I did buy new foam pads about a year ago directly from Koss for $5. :thmbsp:
 
Interesting thread. As I type this I'm listening to jazz on a pair of HV/1's I bought new in the early 70's. They still sound great secret all these years. I did buy new foam pads about a year ago directly from Koss for $5. :thmbsp:

Looking at the equipment in your sig, that's a nice statement for the HV's. I've got mine on listening to some old TJB. Herb Alpert made some amazing recordings for the early to mid 60's.
 
@gbroot...yep they really aren't bad. I really don't like listening with headphones but they certainly have their place ie. Wife watching TV that I'm not interested in. Granddaughter visits a lot and though I love being with her (2 1/2 years old) when she watches Sesame Street headphones are awesome. I have several pairs and am struggling with the best for my needs. I borrowed my son's Sennheiser HD280 pro. Awesome sound but fairly large and bulky for long sessions. My other son loaned me his Bose TP-1. They are a good trade-off between decent sound and lightweight compactness. I'm interested in test driving Grado SR125i as they might just fit the bill and are still fairly compact. I love my Grado phono cartridge and it's US made. I should mention that I spend a lot of time listening to music...most of the day every day. :music:
 
I should mention that due to their design they are somewhat lacking on base. Especial double bass. I just bought a Bose TP-1A on eBay. I really like my son's. Nice lightweight over ear design with very nice sound. I'm also going to buy a new pair of Grado's
 
I should mention that due to their design they are somewhat lacking on base. Especial double bass. I just bought a Bose TP-1A on eBay. I really like my son's. Nice lightweight over ear design with very nice sound. I'm also going to buy a new pair of Grado's

My HV/1A "Plus" cans easily match my M50's bass and have better bass than my 1A's. I still haven't found anything on the "plus" model. I'm still thinking these were a special order item, as they were used to do hearing tests at a medical center.
 
The earpads I ordered from Amazon (link above) do not work on these headphones. I'll most likely order the originals from Koss.

Bummer of an update :nono:
 
Wow. That was over 8 months ago.

I simply called the customer support phone number on the Koss Website, a nice woman answered, and stated she could sell me the earpads for, IIRC, $4.40 a pair.

I said, "Really? How much for shipping? She said that included shipping.

5 days later, they arrived for less than $5.00. They seem a little thicker than the originals, and they're not as comfy as the velours, but the price and fit are perfect.

DSC00042.jpgDSC00041.jpg

Project done!
 
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