[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.

I understand there is at least one KH-71 here on head-fi.

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.

 

[GREQ]

Nice! Thanks for sharing.
I think these are the first photos of the internals I've seen.
That definitely scratches a big itch for me.

Cool to see the perforated dust-cap on a small headphone paper-cone driver.
I've only seen that used on a very limited number of vintage loudspeakers, where the whole cap was replaced with some kind of mesh fabric.

 

[ericj]

Nice! Thanks for sharing.
I think these are the first photos of the internals I've seen.
That definitely scratches a big itch for me.

Cool to see the perforated dust-cap on a small headphone paper-cone driver.
I've only seen that used on a very limited number of vintage loudspeakers, where the whole cap was replaced with some kind of mesh fabric.

Yeah, pretty interesting. I wonder if the lower and higher end models differ other than the bowl material.

I also wonder if these would make an interesting nearfield speaker in the right enclosure? who knows.

There are two KH-71 on ebay right now, at $150 and $250, and those numbers have the decimal point in the wrong place for the sound quality these produce, if it's anything like the KH-51. And since they are all 8 ohm, well, maybe it is.

On a whim i ordered on aliexpress what are alleged to be Onkyo ES-FC300 drivers preinstalled in the baffle (with tuning vents) and i wonder how much of that baffle will have to be trimmed to fit it in place of the grill and driver on these. Those are a closed headphone but who knows. Maybe with some tweaks they might sound ok, or at least better. Cost all of $15.

Oh, they are as heavy as they look. I need to throw them on the digital scale and get a number.

 

[znev777]

I've always been afraid to take mine part, very interesting! The kh-71's don't sound as bad as I was expecting, but the tuning is a little wonky as you described. Soundstage and imaging are decent, and the cup resonance adds a little spice.

 

[ericj]

Does attaching a pdf work? here's a pdf of the original ad flyer.

 

[GREQ]

Does attaching a pdf work? here's a pdf of the original ad flyer.

It didn't work.

If you're using Windows 10 it might be easier to do a quick screenshot - press "Window Key + Shift + S" and crop the area you want to copy, then just paste it with standard CTRL+V.

 

[ericj]

It didn't work.

If you're using Windows 10 it might be easier to do a quick screenshot - press "Window Key + Shift + S" and crop the area you want to copy, then just paste it with standard CTRL+V.

I just extracted the images. Was hoping to avoid that step i guess.

 

[ericj]

The 120x90 pads i ordered turned up today and they fit pretty loose. I mean i don't think they will fall off but maybe the 110x90 oval pads from the same vendor on ebay would fit better.