[DefectiveAudioComponent]

My Dual DK 720 vintage orthodynamic headphone arrived today in a gigantic package from Germany. It arrived inside an ugly brown leather bag (yes, I know, you will want pictures of this bag...)

The Dual was most likely an OEM headphone that was made by Peerrles MB, between 1977-1979.

First impressions:
Out of the bag, construction appears very solid. It's heavy. It has plastic cups attached to a metal hedband, with a real leather headband below. Very similar to other orthodynamic headphones of the time. The pads however, are made of soft fabric, that should have been covered by pleather. Just like other PMB made cans, the pleather is gone. The cable has a small volume control unit attached to it. That probably is not a good thing.

Without opening it up, it looks and sounds like it's half-open, vented in the back of the cups, except for a thick strip in the middle where the headband is attached.

It is very hard to drive, resting near the 40 mark for convenient listening in the xcan, much higher than with my other orthos.

 

[guyx1992]

PICS!
I have a question. I saw the word "orthodynamic" a few times and although my google searches I still don't have a clue on what it means. Please can you give me the definition of it.

 

[DefectiveAudioComponent]

There is a better description in the beginning of the orthodynamic roundup thread.
In short, the diaphragm is a thin flat film with a spiral voice coil on it, in between two flat magnets with holes in them. It's isodynamic, playing the same tune both to the back and in the front of the driver. This is all unlike normal dome shaped drivers that play in one direction, mainly.

 

[DefectiveAudioComponent]

Pictures!

 

[sachu]

DAC, that looks sweet..almost makes me regret having backed out of the auction in the end..

 

[DefectiveAudioComponent]

Quote:

Originally Posted by sachu /img/forum/go_quote.gif DAC, that looks sweet..almost makes me regret having backed out of the auction in the end..

That was very nice of you. They sound good too

Question is, if I repair the pads, probably I will get more bass, but what will I loose....
I'm currently considering whether they need more bass.

 

[JadeEast]

Any driver side pics? Who am I kidding I really want to see the driver itself.

 

[DefectiveAudioComponent]

Quote:

Originally Posted by JadeEast /img/forum/go_quote.gif Any driver side pics? Who am I kidding I really want to see the driver itself.

Nobody wants to see the bag?

I think it's a normal PMB driver. But there will be pictures.

 

[Acix]

Quote:

Originally Posted by DefectiveAudioComponent /img/forum/go_quote.gif Nobody wants to see the bag? I think it's a normal PMB driver. But there will be pictures.

Cool hp...need more spec about the driver, how they sound??

 

[DefectiveAudioComponent]

Specification:

Technical Specifications
IImpedance: 2 x 110 ohms
Frequency response: 16-20,000 Hz
Sound pressure level: 91dB
Sensitivity: 2 mV
Maximum input: 2 W
Distortion < 1%
Volume control -20 dB
Pressing force: approx 3 N
Weight: 240 g
Cord: 3 m
Plug: ¼ inch

 

[Kabeer]

Quote:

Originally Posted by DefectiveAudioComponent /img/forum/go_quote.gif Specification: Pressing force: approx 3 N

Hmm so does it feel like having 3 Isaac Newtons pressing against your head? Doesnt sound v.comfy, then again 3 of anyone pressing against my head doesnt sound comfy.

....but on second thought mmmm I can think of a few....

 

[Acix]

Quote:

Originally Posted by DefectiveAudioComponent /img/forum/go_quote.gif Specification: Technical Specifications IImpedance: 2 x 110 ohms Frequency response: 16-20,000 Hz Sound pressure level: 91dB Sensitivity: 2 mV Maximum input: 2 W Distortion < 1% Volume control -20 dB Pressing force: approx 3 N Weight: 240 g Cord: 3 m Plug: ¼ inch

Mmmm...very nice, looks like they can have some bass, how is the sound/sound stage?? and what PMB driver they use??

 

[DefectiveAudioComponent]

Well, Isaac is not too comfortable, because he is made of woven fabric.

Yes, it has bass, it's nice and punchy, but not very loud. It has nice sparkly highs too.
(but note that this is a very short listen, without A/B against anything else).
I have not (yet) discovered any missing instruments (which would indicate a dip somewhere in the response curve).

Headstage is great, but then I haven't added any leather to the pads yet.

 

[scompton]

The DT-880 clamps with 2.8N so 3N shouldn't be too bad. Although it doesn't look like the cups swivel. Are they set at a slight angle, or did they assume people's ears are parallel like the T30? I like the 2W max input. Not much chance of blowing these.

 

[DefectiveAudioComponent]

Quote:

Originally Posted by scompton /img/forum/go_quote.gif The DT-880 clamps with 2.8N so 3N shouldn't be too bad. Although it doesn't look like the cups swivel. Are they set at a slight angle, or did they assume people's ears are parallel like the T30? I like the 2W max input. Not much chance of blowing these.

As a pleasant surprise, they actually swivel a bit. Very comfortable actually, apart from the fabric that should be covered by (p)leather. You can't see it on the photo, but the hole where the metal band enters the cup holders is shaped like this ><, with the metal band going in between.