Sennheiser HD424 Replacement from currently Production

[tiefbassuebertr]

I am looking for a headphone with comparable parameters to the vintage version from Sennheiser, model "HD-424" (especially the high value of impedance).
What is here a good choice ?
Please note: there was two HD-424 versions in those days:
1) 600 ohms impedance (newer)
2) 1760-2000 ohms impedance (older)
Thank you for your advices
HD424 Radio Sennheiser
The World's Best Photos of hd424 - Flickr Hive Mind

[tiefbassuebertr]

no informations?

[sgrossklass]

The old (2 kOhm) HD424s are, in my experience, a pretty service- and restoration-friendly affair - well, minus the headband padding whose plastic seems to be "sweating" softeners and which hasn't been available for years. They are surprisingly sensitive given their high impedance (a 600 ohm HD420SL is not as loud), but quite devoid of deep bass. Not too bad on '70s/'80s rock, but whenever bass is involved, the difference to modern cans is hard to ignore. Plus there's this funny upper-mids peak.

So which parameters of this model are you looking for in a successor, and why? Do you need something insensitive enough to combat hiss on noisy outputs? Or something insensitive to high output impedance (how much)? Or just something that doesn't pose too much of a load, current wise? Or even something that sounds similar (can't really imagine why though)?

BTW, may I suggest asking in a place that doesn't require you to wrestle with the English language? I know you have an account over there...

[tiefbassuebertr]

Originally Posted by sgrossklass

The old (2 kOhm) HD424s are, in my experience, a pretty service- and restoration-friendly affair - well, minus the headband padding whose plastic seems to be "sweating" softeners and which hasn't been available for years. They are surprisingly sensitive given their high impedance (a 600 ohm HD420SL is not as loud), but quite devoid of deep bass. Not too bad on '70s/'80s rock, but whenever bass is involved, the difference to modern cans is hard to ignore. Plus there's this funny upper-mids peak.

You are right. And this is exact, what I want again. I. e. good speech intelligibility, high efficiency and high impedance. I need it for crystal detector (xtal receiver) without any power supply voltage like battery and without any additional audio amplifying. That means: only passive components like this xtal receiving units:
Gollum´s Crystal Receivers. Construction
and this:
Gollum´s Guest page
and this in German
http://www.qsl.net/dk3wi/detektor.html

My old HD424 was therefore better in all respects than a headphone about
http://www.oldradioworld.de/gollum/guest24.jpg

Unfortunately my old HD424 device with nearly 2000 ohms impedance isn't longer usable because the voice coils are both damaged.

How do I know at used offers (e. g. from ebay) whether it is a 1700 ohms version (I don't want a 600 ohm version)?
And which currently available successor are on the marked with similar parameters?

Originally Posted by sgrossklass

BTW, may I suggest asking in a place that doesn't require you to wrestle with the English language? I know you have an account over there...

Yes, but the results here are (in most cases) better than by German's "HiFi-Forum".
There you will not find members like Dieter Burmester, but here a wide range of all good known developers like e. g. Mr. Nelson Pass, John Curl, Charles Hansen, Jan Didden and much other always present as member. Even Joachim Gerhard (Audiophysik) from Germany you will find here.

[sgrossklass]

Originally Posted by tiefbassuebertr

How do I know at used offers (e. g. from ebay) whether it is a 1700 ohms version (I don't want a 600 ohm version)?

It has metal endcaps on the driver housings, as seen on your pictures. The newer 600 ohm versions are all-plastic.

Apparently the drivers in 2 kOhm HD424s and HD414s are identical.

Originally Posted by tiefbassuebertr

And which currently available successor are on the marked with similar parameters?

Ø
(That's the empty set.)

But you know what I'd try for a crystal set? A modern-day balanced armature IEM, with a transformer. Some of these have pretty phenomenal efficiency - no wonder, it's the same technology as in these old super sensitive Navy headsets, and otherwise used in hearing aids. (Some of their dynamic driver equipped colleagues are also doing well though. Not having to drive a particularly large volume of air has a lot to do with it.) You only need to transform their impedance into the right range. For sensitivity measurement data see e.g. InnerFidelity - you want something with about 0.02 mW or less for 90 dB SPL (that's 107 dB / mW and higher). You may want to use an impedance linearizer circuit if impedance response is too adventurous stock.

Actually even some closed supraaural headphones aren't doing too badly in terms of efficiency, like the venerable HD25-1.

I did look into crystal sets and similar things at one point, but never built one. I normally prefer cruising the waves with some boring newfangled dual conversion, high-1st-IF affair.

[tiefbassuebertr]

Originally Posted by sgrossklass

It has metal endcaps on the driver housings, as seen on your pictures. The newer 600 ohm versions are all-plastic.
Apparently the drivers in 2 kOhm HD424s and HD414s are identical.

Interesting to know - thank you very much. Do you know, what the other suffix "X", "SL" and "XL" means?

Originally Posted by sgrossklass

A modern-day balanced armature IEM, with a transformer. Some of these have pretty phenomenal efficiency - no wonder, it's the same technology as in these old super sensitive Navy headsets, and otherwise used in hearing aids. (Some of their dynamic driver equipped colleagues are also doing well though. Not having to drive a particularly large volume of air has a lot to do with it.) You only need to transform their impedance into the right range.

This could be also of interest. But I haven't check this until now. Because the HD424 is for me a good known part I will purchase a used device at first step. Then I have a good basis for comparison to the currently modern In Ear Monitors so as various devices for impedance transforming.

Originally Posted by sgrossklass

I did look into crystal sets and similar things at one point, but never built one. I normally prefer cruising the waves with some boring newfangled dual conversion, high-1st-IF affair.

I will check any old stuff from my first days with AM radio experimenting. Additional I have discovered by chance this video on youtube:
http://www.youtube.com/watch?v=FdTOf5-s4Cs
based on
http://electronbunker.ca/FMCrystalSet.html
and
http://theradioboard.com/rb/viewtopi...54def3651aed1d (Square helical resonator)
Until now I thought, it would be impossible in case of FM broadcasting

[sgrossklass]

Originally Posted by tiefbassuebertr

Interesting to know - thank you very much. Do you know, what the other suffix "X", "SL" and "XL" means?

For all I can tell from the back of user manuals, HD414X and HD424X were available in the late '70s, in between the original HD414/424 models and their later 600 ohm versions (those with the painted labels). Not sure what the difference to the older non-X models was, they seem to have much the same specs and construction.

HD4xxSL ("slimline") models are another line entirely, ca. mid-'80s. A '414SL has nothing to do with any of the old '414 models, it seems like a 420SL equipped with all-foam pads and stuff.

Never seen XL.

Finally, there was the HD414 Classic, a 1995 anniversary version rated at 52 ohms. Their "modern" cable should usually give these away (which is not to say that an old one couldn't have a modern-day replacement cable, but I'd usually expect the old steel jobs with red/yellow connectors).

[tiefbassuebertr]

good informations.
An other information, that's very hard to find (at least for me), are values about the efficiency (by home audio and PA loudspeakers usual - e. g. 100db/2,83V resp1W at 8 ohms/1m)
Concerning my old HD424 (no longer in working condition) I know, the efficiency was much more better than by the typical vintage headphones like the follow:
http://www.ebay.de/itm/ES-12-Alu-Bak...item4ab6461d98
or
http://www.ebay.de/itm/Sehr-alter-gr...item2571bf7719
But until now I haven't find combarable measured values.

Do you know closed headphones like the AKG K77 about
AKG K-77
but in similar efficiency than the old HD424 (and high impedance) ??

[sgrossklass]

Using my sensitivity test-track (Scorpions - Blackout; old rock like this does not rely much on the frequency extremes) and the near-ideal voltage output of my Clip+, my HD424 needs about 9 dB more level than a HD580. Which means that, for the same power, the oldie actually is a dB or two louder. (Obviously the drivers are much closer, and there isn't a lot of bass, so the '580 is the technically better model as you'd expect.)

Approximate sensitivity (broadband): 93 dB SPL / 1 Vrms
Approximate efficiency (broadband): 98-99 dB SPL / 1 mW

(By contrast, the HD420SL ends up below its specified 94 dB / mW in the same test, playing about 2 dB quieter than its 2 kOhm ancestor. That's K240 territory.)

Looks like tracing Sennheiser's model lines wasn't a new idea. (Page uses Shift_JIS encoding.)

Hmm. The specs even amount to 99 dB / 1 V (1 kHz). Now I did put in new damping foam at some point... but I don't think this would account for such a big difference.

These foam pads seem to degrade faster than I thought. I put on new ones when I got the '424, and with the phones having spent most of its time in the drawer, they are not looking that pretty now and are starting to crumble here and there. Oh my - seems that was 7 years ago already. Time flies...

[tiefbassuebertr]

Originally Posted by tiefbassuebertr

How do I know at used offers (e. g. from ebay) whether it is a 1700 ohms version (I don't want a 600 ohm version)?

Originally Posted by sgrossklass

It has metal endcaps on the driver housings, as seen on your pictures. The newer 600 ohm versions are all-plastic.

Sennheiser inform me by phone, that the impedance for the "HD424-X" (HD-424X) is 2000 ohms/each system (produced in the 70s) and for the "HD424" 600 ohms/each system (start production: 1976).

If one have the "X" version, this isn't identify by the metal endcaps - only in the owner's manual and on the package.

by this link and in the attachment there are additional pics
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