Help with wiring colors on old headphones

Only tangentially related, and mostly useless:

Amateur radio folks like building direct conversion receivers (i.e., mix down to baseband). They're simple, hence little, and they work pretty well. Their biggest problem is that they have no audio image rejection at all -- listening with a 7040kHz oscillator, you'll hear a signal at

You can get around this by making a so-called "phasing" receiver (basically an image-reject downconverter, but ham radio has its own terminology), but then you're back to something complex.

If you build an I/Q downconverter, and amplify each channel to a headphone channel, then apparently you get a spatial perception of the tones -- upper side tones sound like they're coming from a different point in space than lower side tones, and (presumably due to the phase shift in the amplifiers, I don't know) high and low tones do as well. It's claimed that this makes it easier to use for morse code reception.

I've always thought that was interesting, but haven't tried it.

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-holography

Learn a bit about Kemar Manikin here:

That's the _second_ biggest problem - the biggest is that they're an unlicensed transmitter.

Hope This Helps! Rich

Ham radio operators are * licensed * uses of the band from 7MHz to 7.3 Hz - aka the 40 metre band.

In an case, spurious emissions from a flea powered local oscillator is not a transmitter requiring a licence.

Wot a j****ff.

..... Phil

If they are the standard voice coil types, put them in front of a stereo speaker and drive the amp with a sine wave. The headphone 'speakers' will act as microphones. Use an oscilloscope on the pairs of leads to determine phasing.

No, it doesn't help and is misleading, Rich. 7040kHz is an amateur frequency. So, it is legal for "Amateur radio folks" as Tim indicated.

John

Even licensed radio amateurs don't want the local oscillator of a direct-conversion receiver to radiated. The design of the receiver usually ensures that any radiation is negligible.

Many people don't realise that any superheterodyne receiver is potentially capable of radiating. Just try listening to the same station on two cheap FM receivers in the same room, and you'll probably see what I mean.

Is there going to be a prize for suggesting the most obscure (but effective) way of determining the phasing?

Was this some kind of dummy head recording or some kind of ambisonics (Gerzon) WXYZ recording ?

Puking two speakers with front panels against each other is a quite easy way to check polarity. If the polarity is correct, you will hear some low frequency sounds emitted from the combination. If the polarity is wrong, you will hear only mid- and high pitch sounds, since the low frequency air is moving between the cones of the speakers.

With headphones, you either get "in head" or unrealistic sound depending on the phasing of headphones.

Sennheiser did the wiring correctly by keeping all four wires separate and connected to a 4 pin DIN plug and by adding a 4 pin DIN to 6.35 mm plug adaptor.

As a kid, I was really pissed of by the convention of using common returns in headphones. I was testing frequency diversity reception of the same broadcast programs on two different shortwave bands with two receivers. Unfortunately, the other receiver was of AC/DC type with the full 220 Vac in the chassis. Thus I had to rewire the phones so that one side could (potentially) siting on 220 Vac, and the other side sitting close to ground potential.

After this alteration, I had no problems with this arrangement.

No problems, no problems, no problems :-)

Digital alteration of the phase and amplitude response with frequency applicable only to sounds with reasonably complex harmonic content.

The demo was a church bell that was made to ring up then down on axis, left then right as in a ping pong stereo demo and finally at the corners of a rectangle. It just sounded odd on loudspeakers.

If my memory serves I think they said that sounds coming from above have slightly more high frequency components and a phase lead. The adjustment fools the brain into putting the sound where it "belongs".

Regards, Martin Brown

"Ian Jackson"

Insert a pin through a hole in the earphone grille and let it rest loosely the diaphragm.

Use the AA cell test.

One polarity will evict the pin.

.... Phil

In message , Phil Allison writes

I reckon that one's certainly for the shortlist for the prize.

Of course, the principle is not new. You can test loudspeakers with a battery, and watch which way the cone kicks. That would be difficult to do with headphones, and 'kicking the pin out' overcomes this problem.

Only if badly designed. Ever hear of balanced mixers?

Plug in both earphones or speakers with random wiring and play something in stereo. If it sounds right, you're done. If the orchestra sounds like a ping pong game, switch polarity on one earphone or speaker. If you can't tell the difference, replace the listener and try again. I hate to admit it, but I've done it this way a few times. I'll accept my price in US dollars.

I'm reminded of a 52-year-old article in "Popular Electronics" about building your own stereo headphones. After assembling them and putting them on, you were instructed to phase one driver for the best bass.

Incredible.

Good job the phones were well insulated, otherwise..ZZZT !

;-)

Search Google for "disposable headphone covers". Something like these: (towards bottom of page). Pack them with something soft (foam, tissue paper, rolled cloth, old rags, etc) and place them over your headphones.

Or, if you're into crochet, you can knit your own:

If not, try old socks:

Full disclosure: I haven't tried any of the above, but have made some covers from cloth, elastic, some foam, and with a serger.