Re: Vintage Victor HM-200 binaural headphone - How to open?
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.
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Re: Vintage Victor HM-200 binaural headphone - How to open?
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.
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Re: Vintage Victor HM-200 binaural headphone - How to open?
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.
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Le 2024-01-30 09:09, Heinz a ¨¦crit?: Many thanks for your opinions. I really appreciate your thoughts!
Last year I read a lot about the World Soundscape Project ( ) , Soundwalking and Barry Truax Handbook for Acoustic Ecology ( ). 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.
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Re: Vintage Victor HM-200 binaural headphone - How to open?
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.
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Re: Vintage Victor HM-200 binaural headphone - How to open?
Dear Heinz,
Listen to the timid advice of the old "fixer". If something is old and works well, it is best not to disassemble it...? Your recording is great, I would like to have headphones like these!
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
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Re: Vintage Victor HM-200 binaural headphone - How to open?
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?
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Re: Vintage Victor HM-200 binaural headphone - How to open?
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.?
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Re: Vintage Victor HM-200 binaural headphone - How to open?
I listened to the ducks but on loudspeakers. I don't perceive the typical hole in the middle from real binaural. I like that fact.
Hope I cross this headphone somewhere to do further tests.
Thanks, Johan
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Vintage Victor HM-200 binaural headphone - How to open?
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
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Re: Bamboo housing for nature recordings
I have placed the order but it will take some time for the items to arrive.?Until then, I'll think about a possible Sound Sleuth bamboo housing design.?Perhaps a bamboo SASS design would be an interesting housing to test (BASS - Bamboo Ambient Sampling System :-)?.I'll take a closer look at the possible SASS dimensions. However, the surfaces would be round instead of flat. Which will certainly make a difference in terms of audio reflection surfaces. Instead of foam I would like to use needle felt. I'll get back to the group once I've created a kind of prototype. I'm really curious about the sound quality of the PUI AOM5024 capsules already. Many thanks so far to everyone who pointed me in the right direction!
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Re: Suppressing RF noise - ambient mics into CODEC (on headphones)
Half of LNprimer.pdf in my Files is dedicated to RFI/EMI suppression.
RFI is usually due to some internal circuitry demodulating the RF.? You need to get the yucky RF that is coming in to a low enough level so demodulation doesn't happen.? But even 1" of wire or track is enough to act as an aerial ... or even a 1" slot.
The ideal is a Faraday cage (or box when we are considering UHF like cell phones).? Every line coming into or out of the box is shielded and the shields are connected DIRECTLY to the box on the OUTSIDE at RF.? This is the function of the "circumferential capacitor" on the?Neutrik EMC-XLR series connectors.
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Re: Groups.io "reverification" is legit
Thanks Scott
Best Regards,
Jules Ryckebusch
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On Jan 25, 2024, at 15:25, Scott Helmke <scott@...> wrote:
?Hi folks,
Groups.io is doing a "reverification" of some (just a few, I think) members as part of keeping spam at bay. It's legit, be careful as always but this particular thing is legit.
Thanks,
-Scott
--
---- Scott Helmke ---- scott@... ---- (734) 604-9340 ----
"I have ceased distinguishing between the religious and the secular,
for everything is holy" - Joe Henry
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Groups.io "reverification" is legit
Hi folks,
Groups.io is doing a "reverification" of some (just a few, I think) members as part of keeping spam at bay.? It's legit, be careful as always but this particular thing is legit.
Thanks,
-Scott
--
---- Scott Helmke ---- scott@... ---- (734) 604-9340 ----
"I have ceased distinguishing between the religious and the secular,
for everything is holy" - Joe Henry
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Re: Microtech Gefell MV203 Circuit/Repair
Replaced the tantalum cap and the mic is working once again!?
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Jules' Ambi-Alice and the Rycote BBG windshield
Hi everyone, does anyone know if the Ambi-Alice (GoPro mount version) will fit inside the
They make them to fit 20,21,22,and 25mm mic bodies. I think the GoPro mount diameter is 25mm? I can measure to make sure before I buy, but also want to make sure the basket will fit inside the windshield.
?
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Re: Microtech Gefell MV203 Circuit/Repair
You are probably correct. I was basing the value off the input impedance specified in the data sheet.?  Measuring it on the pcb is tricky since the cap is encased in resin and I don't want to mess around with removing it. Probing my LCR meter from the capsule terminal to FET gate gives around 180 pF so 200 pF seems likely 
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Re: Microtech Gefell MV203 Circuit/Repair
C4 is probably 200pF, not 0.2.
Le 23/01/2024 ¨¤ 20:58, Jwaters18 via
groups.io a ¨¦crit?:
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Just got done measuring the blank resistors. They form a simple
2x100Mohm voltage divider with 10Gohm feeding the divided voltage
to the rest of the circuit. Here is the updated schematic with all
component values.
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Re: Microtech Gefell MV203 Circuit/Repair
Just got done measuring the blank resistors. They form a simple 2x100Mohm voltage divider with 10Gohm feeding the divided voltage to the rest of the circuit. Here is the updated schematic with all component values. 
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Re: Microtech Gefell MV203 Circuit/Repair
Capsule is the MK221.
Removing the tantalum cap seems to have restored the correct biasing conditions (65VDC offset at the output) so I will be ordering a replacement (and maybe everything to make another board). I'm about to etch a quick pcb I can use to determine the values of the mystery resistors. I will post an updated schem with the measured values later today.
Thanks for the help!??
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Re: Suppressing RF noise - ambient mics into CODEC (on headphones)
That is worth a shot ?for sure. RF and EMI are deceptive. Your headphones wires can easily act as antennas. ?Having one single ground point for everything helps. People normally think of ground loops happening with higher current draws but with RF a short wire has impedance properties, especially at Cell Phone and RF frequencies.?
Best Regards,
Jules Ryckebusch?
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On Jan 23, 2024, at 09:02, Pete Lewis <petelewis228@...> wrote:
?Hmm... I had a couple thoughts in the middle of the night.
(1) I'm wondering if my output could be causing the issue. The wires to my headphone driver speakers are currently just two wires without any shielding.
(2) I'm using capless headphone mode on the WM8960, which utilized VMID as the source for a buffered GND for the headphones. VMID is also used as the non-inverting input on the PGA (my mic input gain stage), so maybe the speaker wires are acting like an antennae and it's making it's way into the OUT3 pin (the buffered VMID).
As it is an output, I wasn't looking at the speaker wires (or mode) previously, but I'll give shielding the speaker cables a shot, and also I could try switching away from capless headphone mode and avoid any connection from the speaker wires to VMID.
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Andrzej Sochon
Pete Lewis
Mark Day