Under The Radar (Part 2) Stereo Re-cabling Yamaha HP-50A Ortho-dynamic Headphone

Last week I post the Beyerdynamic HP-100 here review and somehow I am not quite satisfy the overall result. The main reason for that is this headphone is very hard to drive, it is heavy and bulky. I think I never get along with any Beyerdynamic headphones anyway:)

So I move forward to something unpolished jewel headphones around year 70s to 80s. They are not as hype as today market, yet they are built for professional user. So I get this used but surprisingly like new headphone, the Yamaha HP-50 for only US$35. Very cheap in my opinion. But I cannot using this headphone out of the box because this HP-50A is mono version headphone. I need convert to stereo first by re-cabling this headphone.

Firstly I need to explain the detail of this Yamaha HP-50A. You probably might know (or not) that this headphone is ortho-dynamic type which completely different construction with regular dynamic headphones.

While the dynamic headphones works like a speaker: the piston coil around the magnet and push the membrane to create a sound wave, this ortho-dynamic is like a coil around the membrane and sandwiched to magnets. You will find ortho-dynamic headphone popular on 70s to 80s before going to more efficient dynamic headphone.

I will share the detail of this ortho-dynamic driver while I doing the re-cabling in this post.

The specification are clearly said on the box. This is 300 ohm mono with 93 dB sensitivity. It would be 150 ohm in stereo after the modification and the sensitivity naturally will also increase. Interestingly the box said that this headphone is intended to use with Yamaha electro organ. Honestly I think I make a wrong decision by buying this headphone anyway, but please continue reading.

This Yamaha HP-50A is all plastic covered by leather. The plastic color is white but a little tends to brown. The leather color is dark brown and covering the pad and the head band. Again, you can expecting the leather quality for old product like this is far superior than today. No sign any cracks or peeled off leather anywhere. When wearing this headphone, it is comfortable. It is light weight, only less than 250 gram.

It is very common for any headphones at that era that only touch your ears rather wrap all your head. This is makes wearing this Yamaha HP-50A is just like not wear any headphone on your head.

This is the original connector looks like. The coil cable with mono 6.5 mm jack. Modify to stereo need to replace whole cables. Now I will see how to open the pads first.

I find opening the pad are very easy. Only gently pull the plastic from the pad and housing. They attached by plastic clips inside the housing and thankfully no clips are broken during this process.

This is what ortho-dynamic driver looks like. You clearly see only magnet with membrane in the center. But in detail, there is a coil around the membrane that creating the sound wave.

Careful not to drop this driver because magnets really easy to shattered when get impact.

The original mono connection is in series from left to right drivers.

I using Canare L2b2at stereo cable to make this stereo connection. Each driver will go separately to the stereo mini jack.

Here is the finished re-cabling the Yamaha HP-50A headphone.

This re-cabling works is just like OEM looks.

This Yamaha HP-50A is now become a stereo headphone.

How does it sounds?

Short answer is smooth and very enjoyable. I immediate notice the vocal sound is smooth and clear. The presentation not warm in my opinion, more like natural but not dry.

Although this headphone is small in the size of the driver and the pads are only touching your ears, but the bass is there. The bass is roll-off and less control in my opinion but still okay and quite enjoyable.

On the treble section, I think this headphone is not bright at all. The high frequency is roll-off and for some user will find this headphone is less resolution and dull. This is could be the minus point for this HP-50A.

For long listening session I feel comfortable with this headphone but I noticing again that the overall sound quality is actually weighting on the vocal section with fair amount of bass and treble. Not very clear in overall music presentation but still okay for this price range.

The sound-stage from this headphone in my opinion is almost the same like Beyerdynamic DT-100 but this HP-50A slightly more 3 dimensional and better staging. This means better.

This HP-50A is not the easy headphone to drive. Although the DT-100 is more harder to drive but again I should using the Bottlehead Crack headphone amplifier to drive this headphone well. So you got the point that this HP-50A will only stay on my desk rather for on-the go headphone because of its low sensitivity to drive with any internal DAP amplifier.

With this little amount of money, I could enjoy the old school, retro ortho dynamic headphones. It is sound like an old days and don't you expected to against today dynamic headphones that way more efficient and fuller in music presentation.

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