That time when Kenwood put knee guards behind the cups of open headphones

[ericj]

Ever since i started trolling ebay for vintage headphones, probably 15 years now, I've been intrigued by these weird kenwood cans that look like something from a Miyazaki anime.

I was assured by a few people here and in the general internet that they probably sound terrible. The 8 ohm impedance is sort of a giveaway.

I'm referring to the Kenwood KH-71, KH-51, and KH-31.



You can't see it in the photo but they turn out to have open-back cups suspended on a spring steel cardan joint inside that bowl. That looks suspiciously like something a coal miner would strap to their jeans.

The bowls on the KH-31 are orange plastic, obvious from this and other photos.

I just restored (partially) a KH-51. The bowls on these are leather-like plastic with vinyl binding stitched on.

How does the KH-51 sound? They sound like late 70's headphones with paper cone drivers. The treble is a little rolled off and the bass is kinda muddy and reminiscent of putting an AM radio inside a cardboard box but overall they have a sort of balanced signature. There's some bad resonances here and there.

People pay big bucks for the KH-71 in good shape, which has always struck me as odd.

One possible theory is that they are vintage audio collectors who want to own the top of each line. The same guys who pay big bucks for a Pioneer SE-505.

Another is that maybe they are vintage ham radio enthusiasts or maybe they are voiced specifically for AM sideband speech. I'm not sure about this. Kenwood has been a bigger deal in ham radio for a very long time. But outside of the USA they seem to have had some good home audio gear that was well regarded, particularly under their Trio brand.

Anyway, here are some pictures from my mini-resto project. Right now i just have genuine AKG K240 pads stretched over the cups. I have some 120x90 pads on their way from china.

 

[KarlK]

The treble is a little rolled off and the bass is kinda muddy and reminiscent of putting an AM radio inside a cardboard box but overall they have a sort of balanced signature. There's some bad resonances here and there.

Like balanced crap? I had a pair of late 70's Akai phones that I would describe exactly like that. They had a sturdy metal build but they looked like flying saucers and the sound was alien bad but balanced.

 

[ericj]

Like balanced crap? I had a pair of late 70's Akai phones that I would describe exactly like that. They had a sturdy metal build but they looked like flying saucers and the sound was alien bad but balanced.

They weren't an ASE-50, were they?

But no, these sound like 1979's idea of "not bad".

There's a redditor who absolutely loves his KH-71 but i will remain skeptical until i hear one for myself.

 

[KarlK]

They weren't an ASE-50, were they?

Oh nothing fancy like that, if I recall well they were ASE-24's

 

[KarlK]

They weren't an ASE-50, were they?

There's a redditor who absolutely loves his KH-71 but i will remain skeptical until i hear one for myself.

The way those are made seems like almost semi-open with a reflection pad reminiscent of old-style "bucket" thrust reversers they had on previous generation jetliners

 

[ericj]

Oh nothing fancy like that, if I recall well they were ASE-24's

They look a bit like a quadraflex q45, which was a completely wretched headphone.

 

[sKiZo]

(Look more like nut cups to me) <G>

Some of those old phones do serve a purpose other than nostalgia though. I salvaged a set of top end Koss quad phones for my system, and it's not like you can find a lot of those at the local big box store anymore. New pads all round, screens, dust covers, rewound the cords, and replaced the four original dried out drivers with elements from a couple sets of decent Sennheiser closed back phones. All in all, fun little project, and they sound a whole lot better now.

 

[KarlK]

They look a bit like a quadraflex q45, which was a completely wretched headphone.

Those look more like the ASE-40. The ASE-24 wasn't that flat, it had a raised center with a circular vent on top, I guess they were semi open-back, They cost like $125 in 79 but sounded more like $25 cans would today. I was only 16 then and not as discriminate in shopping audio as I am now. Looks mattered more than function back then, I almost bought Bose speakers but the prospect of having that in house so alarmed my father that he bought me Celestion bookshelf units at Xmas saying I wouldn't look back, and he was right.

 

[ericj]

(Look more like nut cups to me) <G>

Some of those old phones do serve a purpose other than nostalgia though. I salvaged a set of top end Koss quad phones for my system, and it's not like you can find a lot of those at the local big box store anymore. New pads all round, screens, dust covers, rewound the cords, and replaced the four original dried out drivers with elements from a couple sets of decent Sennheiser closed back phones. All in all, fun little project, and they sound a whole lot better now.

Hell, some of the cans from the 70's and 80's are actually good to listen to today.

Most of the early AKG professional grade headphones are good, sometimes better than their modern equivalents. For example.

And the Realistic Pro 30 is pretty great if you take the time to modify it, and then there's most of the rest of the first generation of planar magnetics.