Sennhesier HD424

[PA Ray]

I was going through some of my stored stuff, and came across vintage Sennheiser HD424 headphones. They are in mint condition, except for the disintegrated yellow foam cushions, so I ordered replacement cushions from Sennheiser. I also have a promotional brochure that shows that these headphones are 2,000 ohm impedance. They have the shiny metal end caps, not the later black plastic end caps.

I would like to listen to these using the output from my PC. I would need an adapter since these headphones have a 1/4 inch plug, but my concern is that the PC might not be able to drive these headphones. When I look at inexpensive portable headphone amps, I see nothing that looks like it would work with 2,000 ohm headphones. Any suggestions on where to look or what to do? I don't want to spend a fortune, but would really like to listen to these.

Thanks.

[kannan_s]

You can get an adaptor for 1/4 inch plug to mini headphone plug - I use such adaptors regularly connecting my Nakamichi headphones

[kannan_s]

You get such adapters in radio shack

[PA Ray]

Thanks for the advice about an adapter.
Do you think that my PC will be able to drive these 2,000 headphones or do I need some form of amplification? If I need a headphone amp, how do I find one that will work with such high impedance phones?

[Mooly]

I would just try your phones to begin with. High impedance phones generally need more voltage drive than low impedance. Many headphone stages use a series resistor to feed the phones and so using high impedance one automatically allows for more voltage to be available.

Try them first before worrying there is a problem.

[PA Ray]

Thanks, Mooly

It sounds like I can't do any damage to try the HD 424 without an amp.
I ordered a Sennheiser mini plug to 1/4 female adapter and will give it a try.

I have done a lot of research on the internet regarding impedance of headphones compared to impedance of the source. I must say it makes my head spin. About the only thing that everybody seems to agree on is that the impedance of the headphones should be at least 8 times the impedance of the source. I haven't seen much on the effects of headphone impedance being a much larger multiple of source impedance (like maybe 100 times or more in my case).

[jameshillj]

One of the most surprising things about these old '424s is just how varied they can sound with different types of amplifiers, regardless of impedances, gain stages, etc - they do seem to favour the output transformer or the current buffer drive, despite their higher impedace load and assumed benefits of 'voltage drive' ccts - don't know why - these 'phones have always been a bit of a puzzle and yet the do sound rather good and are rather comfortable for many over long periods.