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I bought vintage binaural headphones from Victor last year. It's from 1976 and still works. If anyone is interested, I have placed the specs and a test recording in the Victor HM-200 folder. When I took the test recording, the headphone was quite heavy. The weight, including the batteries, is approx. 600 g. I looked strange but the ducks didn't care. :-)?

Does anyone know how to open the HM-200 headphones without breaking it? I haven't been able to find a way yet. I'm just curious about the capsule dimensions and what the circuitry looks like and whether more sensitive capsules would fit.

Many thanks!

Heinz

On Mon, Jan 29, 2024 at 03:54 AM, Heinz wrote:

Does anyone know how to open the HM-200 headphones without breaking it?

I have not worked on that model, but headphones like that usually follow the same general construction. The soft earpads have a rim or flange that fits into a slot that runs around the cup edge. Gently pull the pad sideways at one spot to ease the flange out of the slot, then coax the rest of the flange out, all the way around the cup, to remove the pad. Removing the pads exposes some screws; unscrew them, and you're in.

Hope this helps.?

I've opened up a few headphones lately. kennjava's advice is good. I imagine those HM-200s have an inner and outer plastic piece (aka housing/shell) that are held together by two screws.? on opening up a pair of lawn mowing headphones (smoostarts) might be helpful to check out.?

PS Those HM-200s look awesome. I listened to the ducks and the recording sounds really nice. Looking at those specs (SNR of 45dB) I would expect there to be much more hiss in the signal. Pleasantly surprised how clean it was. Either way, sounds great! Would love to find a pair, myself. What did you use to record the mic signals?

Many thanks for your opinions. I really appreciate your thoughts!

Last year I read a lot about the , Soundwalking and Barry Truax . I’m still fascinated by the fundus of valuable information the WSP team put together. And I truly respect the works of Barry Truax.

One day I saw the HM-200 binaural headphone hanging on a shelf at a reuse store. It looked so strange that I had to smile. What's this?! :-) At first I didn’t realize that it was a binaural headphone. When I saw the three quarter inch inch jacks I became curious. Victor binaural headphone! I was able to test the functionality at the store and was happy about the find. Needless to say, it was a bargain. I did some test recordings and wanted to use it for soundwalking in the beginning, but it turned out that the mic capsules on the outer side of the ear cups are very susceptible to wind noise. In addition, the ear pads are made of leather. When you wear them, especially when it's not cold outside, your ears get really hot. It feels uncomfortable after a while. Although I enjoyed listening to what I recorded, using it in combination with a dummy head may be a better choice. When it wasn’t windy or indoors, I was amazed about the spaciousness of the recordings. I usually take the HM-200 with me when I'm recording something interesting and trying out different types of microphones anyway. For example, when I recorded the Suikinkutsu sounds for my @NaturePattern YT channel.

@Johan

Many thanks for listening to the ducks recording and your finding. If you tell me which tests are of interest to you, I'll be happy to assist or send you some other recordings.

@kennjava

You are right! There is a tiny gap around the cup edge where the leather earpads are pressed into. At first I thought it was glued, but that's not the case. I haven't removed the ear pads yet.? When I open it, I upload some photos to the HM-200 folder.

@pete

Many thanks for pointing me to your tutorial. It helps a lot.

The HM-200 is equipped with a 1.5v AAA battery on each ear cup side. I connected it to the stereo mic input of a Sony PCM M10 using an adapter cable and disabled PiP on the Sony.

@andrzej

Thank you. I appreciate your advice! I'm always amazed when vintage things from 50 years ago still work great. I usually leave it as is. If I see room for improvement, I would like to try implementing it. But I agree, the original character of the vintage binaural headphones would be gone if it's not possible to put it back together as it was.

@Johan, Pete & Andrzej

If you want me to pay attention to a HM-200, I wouldn't mind dropping you a note and sending it to you if I stumble across another one.

It appears this device is also known as the JVC HM-200e. more info on this site:
I don't know if your specimen has the foam windsceens, that would explain the wind problems you had. I suppose you could easily fashion some yourself. There's a Victor HM-200 on sale on ebay now, for $480 us. I think those could be easily modified for PIP, permitting to eliminate the batteries and their weight.

On Tue, Jan 30, 2024 at 11:34 PM, Pierre Olivier wrote:

foam windsceens

Many thanks for the information. You're right. I'm missing the foam windshields. I'll try building new ones.
The Victor HM-200 on eBay seems to be way overpriced. There's one on Yahoo Auction in Japan for $43, which seems like a fair price. However, without the original housing and without a dummy head.

Andrzej is wise, and if tho HM-200 still works properly, and? keeping it in?its original condition is important to you, then yeah, leave it alone....?

If they were mine, though, would open them up for sure. That's just how I roll. I own and have rebuilt or repaired several pairs of headphones. New.cables, new drivers... some are now Frankenheadphones made of bits from different brands and models.?

I bet that new Primo or PUI electrets would have better specs than the originals, so that's something that I would change. And I might rewire new mics to use PiP powering rather than the onboard AA? cells.

It should be possible to fabricate some effective wind-shields out of foam or fake fur.

Many thanks for your replies and your interest in this topic.?

Because of the discovery of Johan (I don't perceive the typical hole in the middle…) I would like to follow up a little.

I think it's a better choice to listen to wise men and to leave the HM-200 alone for now. Instead, I will focus on building new microphones and take inspiration from vintage mic building designs. But I agree to kennjava also. To install new Primos or PUI electrets would be an interesting trial.

Regarding binaural recording I found an interesting article. Source: ResearchGate

(some pictures from the archives look really funny… lol :-)?

I thought binaural technology is a very modern technology, but that is obviously not the case.?The HM-200E binaural headphone-microphone combination and its inventors are mentioned in the article.

?

?

I've added a photo of the HM-200 so you can easily see how the capsules are positioned. It’s at a right angle to the sound-reflecting surface of the indicated auricle.

@Johan
When I find one, I'll let you know. The following article about may be of interest to you.

@andrzej
Many thanks! I always try to find a place where there is no wind.?When I recorded the ducks, I may have been lucky that I didn't use microphones with a higher SNR. I'm sure that significantly more background noise would have been recorded.

Thank you and sorry for the late reply!

Heinz

Hi Heinz. Thanks for the follow-up, the pictures, and the link to the binaural review.

I didn't realize that the HM-200 incorporated a sort of pinnae or directional body shape. Interesting.

Yes, binaural techniques are not new. I've experimented off and on with binaural recording for over 30 years now (portable cassette, MiniDisc, and now digital field recorders). From the beginning, I made some binaural mic sets by taking a cheap set of small Walkman-style open headphones, removing the headphone drivers, and carefully installing small electret omni mics, wrapped in soft open-cell foam. I just solder the ends of the the existing headphone cables to the mics, and haven't had hum or noise issues. In use... I just wear them. Portable and stealthy :-) I will also place them around a tree trunk or similar. For the small cost, the results are often great. If you want to start experimenting with newer electret mics, this is a great starting point.

My favourite binaural experiment went like so: On a nice summer day, I put the "mic" headphones on, started recording and went for a walk in a park near us. As I walked, i periodically narrated where i was, the direction I faced, and other geographic references. Then, on a different day, i play the recording back, while walking the same route as cued by the narration. I'd hear something (eg a bike passing me) look in the apparent direction... there's nothing there. It was uncanny how real the playback image can be, when you hear it in the same place it was recorded.