[Lenco K106] What is this cable?

[Mads1478]

Picked up a pair of Lenco K106 headphones today since they were cheap and I figured I'd have a go to see how they sounded, even if I'm inexperienced with the audio world as a whole. I have little idea where to begin with this cable... Is it any sort of old standard?

https://imgur.com/WUy8Cl9

https://imgur.com/DAP3cEV

Most images of the K106 just have a 6.35MM jack attached. There are very few images with the jack and some sort of dongle attached, like such:

https://imgur.com/EUpVFAo

But (besides from the other end of the connector differentiating from my own) these have a shield on the end. I can only assume, then, that there's a ground shield missing on my connector? This pair clearly marks L and R on each ear end, so unless I ended up with some strange mono variant of the headphones, I can only assume the shield broke off at some point, and I'd have to solder on a normal jack.

Thanks in advance.

 

[restorer-john]

It's the truly hideous and unloved 2 pin DIN. Used on amplifiers and loudspeakers originating from European countries in the 1970s and even into the 1980s.

An absolute abomination. Nasty to solder to (they melt), easy to break/short. Just evil things. As bad as the horror-show that was SCART connectors. Something dreamt up in a festering Philips laboratory by a disgruntled employee in the 1960s is my guess.

 

[Mads1478]

Oh, no. At least it's not broken...

So is this a mono connection or does the abomination somehow get stereo out of this setup? Is it worth my wallet to try and get this hooked up to a modern setup? ...Can I slice the whole connector off and replace it with something else, or would I have to replace the whole cable (if just that)?

At least I learned something new today!

 

[AnalogSteph]

I can only assume, then, that there's a ground shield missing on my connector? This pair clearly marks L and R on each ear end, so unless I ended up with some strange mono variant of the headphones, I can only assume the shield broke off at some point, and I'd have to solder on a normal jack.

Sure looks the part. If this was an ordinary loudspeaker DIN, the cans would need to have a pair.

Not sure whether these are worth recabling completely, but with an impedance in the 4-8 ohm range, I sure would want the L and R returns to remain separate up until the plug.

They'll be a bit of a bear to drive either way, and your best bet of them sounding anywhere near what was intended would be using a high-impedance dropper-resistor-fed headphone jack on an integrated amp or receiver.

 

[LTig]

So is this a mono connection or does the abomination somehow get stereo out of this setup?

It's mono.

Is it worth my wallet to try and get this hooked up to a modern setup? ...Can I slice the whole connector off and replace it with something else,

Replace it by a 6.35 TRS stereo jack if the cable itsself is stereo. If not you need a stereo cable.

Edit: flat connector is - and goes to the shield, round pin is + and goes to ring or tip.

 

[Mads1478]

Thank you all.

I took a look inside - three wires going out which is hopeful.

https://imgur.com/2kTn2kv

So, seeing as the stereo is completely removed on the connection, I will likely go the DIN chopping route. I will need to do some research on how to correctly wire the jack with the correct specifications like AnalogSteph recommended - if anyone has guides or previous writeups that would help me achieve this, that would be appreciated.

I have no idea if these headphones are "okay" or "good" or not (there doesn't seem to be too much on the internet, and this thread is now the second result on Google when you search the model). Would someone keep these around for 50 years because they thought the pair sounded good, or because they had the space? I want to find out.

(Why would someone go out of their way to buy a variation of headphones that's mono only?)

 

[LTig]

So, seeing as the stereo is completely removed on the connection, I will likely go the DIN chopping route. I will need to do some research on how to correctly wire the jack with the correct specifications like AnalogSteph recommended - if anyone has guides or previous writeups that would help me achieve this, that would be appreciated.

The two wires going to the round pin should go to ring and tip of the TRS. 50% chance that left and right are now reversed. If yes just exchange them. I"d expect the red wire to be the right channel and blue the left.

 

[Old_School_Brad]

It's the truly hideous and unloved 2 pin DIN. Used on amplifiers and loudspeakers originating from European countries in the 1970s and even into the 1980s.

An absolute abomination. Nasty to solder to (they melt), easy to break/short. Just evil things. As bad as the horror-show that was SCART connectors. Something dreamt up in a festering Philips laboratory by a disgruntled employee in the 1960s is my guess.

Yes! Damned things. Melted, as you say. B&O used this and I'm glad it's gone.

 

[DoctorRobert]

In defence of my former employer, in the Netherlands and other countries of Europe you are not allowed to use banana plugs on speaker -or other- cables as you can also stick them in wall sockets. 230V and speakers are not a good match. The DIN speaker connector is safe and has a fixed polarity. But yes, soldering was no fun and their clamping force and related contact resistance could be better.

 

[DVDdoug]

I will need to do some research on how to correctly wire the jack with the correct specifications

TRS stereo wiring

I assume you can solder?

Do you have a multimeter? That makes it easy to "ohm-out" the connections, including checking/confirming the connections between the solder terminals and the business-end of the new plug.

In resistance mode, the you'll probably hear a click when you connect to the drivers so that will also help you to sort-out the left, right, and ground connections (although it looks like you can see the color codes already).

If you don't have a meter, a 1.5V battery will also make a click when you connect and disconnect it, but it will probably be loud so don't try it when wearing the headphones.

 

[AnalogSteph]

So, seeing as the stereo is completely removed on the connection, I will likely go the DIN chopping route. I will need to do some research on how to correctly wire the jack with the correct specifications like AnalogSteph recommended - if anyone has guides or previous writeups that would help me achieve this, that would be appreciated.

Right now it looks like the cans are wired as follows:
Blue: Left+
Black: Left-
Red: Right+ --> to black in cable to right earcup
Right- seems to be branching off from Left- at the left driver and then going to right earcup.

If you just want to go the chopping route, connections at the new TRS plug should be as follows:
Tip: blue
Ring: Red
Sleeve: Black

The only reason they got away with the shared ground return was the hundreds of ohms of output impedance in traditional integrated amps and receivers that's effectively in series with the drivers (typically anywhere from 150 to 680 ohms, maybe 120 in a preamp). With 330 ohms, 8 ohm drivers and 1 ohm in the cable (quite typical for e.g. a 3 m Sennheiser cable), out-of-phase crosstalk (red) is being kept to less than -50 dB which is fine (the rule of thumb is -40 dB or better):

Meanwhile, on a modern low-impedance output things are far less pretty:

20 dB is definitely not cutting it. It would be somewhat like having a stereo expander turned on.

They may also be relying on non-constant driver impedance response to be modifying the frequency response, one more argument for using a traditional headphone jack. (I can think of a few headphones from the '90s that get pretty thin if driven from a "modern" output, e.g. Beyerdynamic DT831, 931, even arguably the Sennheiser HD580 which rather likes ~75 ohms at least.)

If you were to ditch the 3-conductor cable for a 4-conductor job so each driver can have a separate ground return to the jack, things on the crosstalk front would improve quite dramatically:

And no, I wouldn't really recommend integrating the resistors into the cans, unless you happen to have a headphone amp that can push a lot of voltage. I suppose you could put in something on the lower side like 100 ohms (3 W types recommended) and just about get by with a Topping L30 II. For a more standard headphone amp, it would probably have to be more like 39 to 47 ohms (1-3 W).

I would suggest you do the minimum needed to get them working decently at first. Average 1970s headphones tended to be heavy, uncomfortable and pretty crummy sounding. Sennheiser HD414s were a revelation at the time.

 

[Mads1478]

I've acquired a headphone jack part and plan to perform the operation soon. I'm not expecting miracles here; at worst, it's a learning experience. I don't have a dedicated amp on hand so we'll just have to see how modern technology makes them sound (my ears aren't yet finely tuned so my standards may be low). While I haven't tried wearing them for extended periods, they don't feel uncomfortable, but they still have a musky smell I need to remove.
Thank you all for the information. I hope to provide an update soon.

 

[Mads1478]

Unsurprisingly, they sound just okay.

Seems like modern songs don't work too well, but they'll pair well with a record player. If I had to think about it, it's highly lacking in the bass department, probably.

My other audio sources work much better across the board, so this one isn't becoming any sort of daily driver.

I am truly grateful for all the feedback.

 

[AnalogSteph]

If I had to think about it, it's highly lacking in the bass department, probably.

No surprise. They may be relying on high source impedance to help that area out. You could test that if you have any standard onboard audio headphone outputs of no great repute... you know, 1 Vrms and change, 75 ohm series resistance. It might be a bit quiet but possibly still good for an impression.