[Carlos42]

Interesting post. Thanks so much Mr. TA.I must say that I really like my DT48S's and my new (to me) DT48E's. As an aging former recording engineer
(for RCA records in Hollywood, among other places) I think they do a very good job of letting you hear the music on the record,CD,etc. with a bare minimum
of coloration.At the age of 73, I know that my hearing is not so good (too many years in the 60's and 70's with monitor speakers in the control room
playing loud rock music.)
 
Anyhow, it is interesting to hear that the only difference in the various versions of DT48's is the thickness in the aluminum diaphragm due to different suppliers
over the years. Also, it is very interesting that Bell Telephone Labs had a hand in the design of the DT48. An awful lot of early research in audio, stereo,etc.
was done in the US by Bell Tel Labs in New Jersey. I was a teenager in New Jersey in the late fifties and knew a lot of kids whose dads worked for Bell labs.
One of my old girl friends of that era had a dad that had built his own tape recorder after hours at Bell Labs.(The people that worked there were allowed
to do things like that on their own time using company  equipment as long as the paid for the materials they used.) This was a different era, I don't know that
that would go over very well with today's corporate suits. (I was almost more interested in her dad's tape recorder than my girl friend in those days. Fortunately
I did learn that nothing was more important in my life than girls!)
 
Bell labs closed sometime later and I don't know if it went on existing under another company or what. Anyhow, a lot of seminal audio research was done there
over the years.
 
Mr. TA ,I would be interested to know where you found the information about the DT48 and Bell labs. I do know that they did publish a journal
describing the research for many years. Perhaps the info came from there?
 
As to the vastly different sound of my DT48A's does anyone have any ideas? Maybe mine were damaged in some way. But I do remember
Hugh Allen from Gotham saying that usually it was hard to damage them. There are at least two very different reviews of the DT48A's on the
board with two countervailing opinions of same.Anyone care to comment on this?
 
I must say that my DT48E's are my favorite headphones for listening to music,with the DT48S's a close second.

 

[takato14]

 
As to the vastly different sound of my DT48A's does anyone have any ideas? Maybe mine were damaged in some way. But I do remember
Hugh Allen from Gotham saying that usually it was hard to damage them. There are at least two very different reviews of the DT48A's on the
board with two countervailing opinions of same.Anyone care to comment on this?
 
I must say that my DT48E's are my favorite headphones for listening to music,with the DT48S's a close second.

If you're using the stock DT48A pads, that's likely it. Those pads never sounded good to me by any metric of the term. If you're not using those, then I secede to whoever posts ahead of me.

 

[Carlos42]

Tak, thanks for your input. Yes ,I am using the newest version of the pads.I note that the DT48A
headphones are described as being "audiometric" which to me at least, implies that they are used
by audiologists for hearing tests.I know that what audiologists are basically concerned with is
finding out a subjects capacity for understanding speech.As such, they normally only test for those
frequencies that are most important for understanding speech. Looking back on my file of hearing tests
(a rather disconcerting prospect given my time as a rock recording engineer at RCA Hollywood
in the seventies) I find that I was tested at 250Hz, 500Hz, 1000 Hz, 2000Hz. 4000Hz, and 8000Hz.
What they were(are) looking for is major losses in hearing at these frequencies, losses that would
make hearing normal human speech hard to hear.
 
So, from this I would think that these frequencies are the ones audiologists are most interested in and I would
assume "audiometric" headphones would be essentially flat at those frequencies.  I wonder if DT 48A's would
primarily have a flat frequency response at these frequencies and perhaps not that good a response on the entire
frequency range that we would be concerned about for accurate reproduction of music.
 
This is kind of the way my DT 48A's sound to me.I got them from Gotham Audio in New York when I
was a teenager and I am now 73 years old, if that will give us any kind of clue as to when they were made. They
are serial number 120. As I said before, I notice two very contradictory reviews of these phones on the board and I
personally would never doubt what people hear. So are my DT48A's defective? I certainly
would welcome any opinions.

 

[MrTechAgent]

So, I was in touch with Alex of "http://alexmod.do.am/", he has been kind enough to share my posts on Russian forums. My conversation with him sparked my interest of digging DT48 threads in Russian forums, I know many collectors who have told me about unique examples of DT48's spread across Russia but I never really took the topic seriously, until yesterday. 

I came across this 10Ohm, this is the same one I had pictured in the earlier posts but had to take the photo down because of diplomatic reasons.
I am pretty sure this model was never meant for Production, only a handful were made and finding one in the wild is impossible. 
This one was on eBay and God knows who has it and if he/she realises the significance of what they have with them.



Then we have this gorgeous Green DT48, same as mine except the cups of course. 
Hard to guess who issued them but Beyer has always provided bespoke production runs throughout their operation, they do the same thing for their DT250s in the modern day. 
Whoever it may be, this is one fine example that resides in Russia. 



Fuc*ing Russians, always one step ahead! 
Goes without saying but if anyone has either of these and happens to read this, please PM me. 
Money no object for these. 

Also, here's a link to the tread on doctorhead.ru (http://forum.doctorhead.ru/index.php?showtopic=10881). 
It has priceless information, there's a PDF in there where there's the part number for the DT48S Earpads and tons more. 

 

[Carlos42]

Well, I managed to make a 12db. 8 ohm L pad to use with my various headphones. My 1960's DT48A's really sounded a lot better using the L pad on the speaker terminals of my Nad 705 receiver to feed them. As opposed to the regular headphone jack which has a 330 ohm resistor in series with each  side of the phones. As I remember it Gotham gave you the resistors to build an L pad on the output of your amplifier  for the HD 48A's,
so that must have been the recommended hook up in those days.I tried to find the L pad I built when I first got the HD 48A'S in the early sixties,
but to no avail.It is really amazing  and criminal the way things can just disappear in a mere sixty years time. The DT 48A's mid range and high
end really came alive with the L pad and I think the bass response improved some, also. i will have to do a listening test on my relatively new DT 48E's and my (I think)  early seventies DT 48S's.
 
I would be very interested in what other folks' experience has been listening through L pads on the speaker output terminals of their receiver/amplifiers. etc. I should add here that headphone   jacks were non existent on the gear of the early sixties.At least that is the way remember it. And that is the way my stuff was in those days. So the only way to listen to some headphones was off the speaker  terminals. I should add that my48a's are the five ohm version, serial number 120.
 
So what is the experience of others in this regard?I am dying to know!

 

[Lighthaven69]

So I just discovered by dad's old DT-48s from 1995 and can someone tell me what they are for and should I sell them or something, since I probably have no use for them as I have new headphones coming in already.

 

[Carlos42]

You might give them a extended listen before you plan on getting rid of them,a lot of us really like them. Admittedly, it is an
acquired  taste, but in a world where it seems that a lot of headphones have a very unnatural sound they are a breath of fresh air.
There is none of the exaggerated bass that seems to plague  so many headphones these days, and the mid range is to be found nowhere else. I recently got a pair of Beyer 1350's and I can't listen to them because of the greatly hyped bass response that
seems to be standard these days. I imagine this is probably a marketing decision  made to make them more easy to sell.
 
What model are they and what do they look like and what is their condition? If you want to sell them put them on the for
sale section of this board and please let me know!

 

[Lighthaven69]

I think they are the original model, good condition though a little worn, pads have been changed once. I will probably post them in the sale section later.
 
There seems to be some interference in the cable, the left speaker is dead unless I change the angle of the cord a bit, then both speakers work perfectly. And I am talking about the head of the cable which I plug in my computer.
 
https://www.bhphotovideo.com/images/images1000x1000/Beyerdynamic_404306_DT48E_Stereo_Headphones_272007.jpg this is the model, at least its what they look like, cause the text has been worn out a bit.

 

[Carlos42]

So what is the impedance of your DT 48's" It is given in ohms and should be marked on both of your speakers/phones.

 

[Lighthaven69]

The cups are worn out from that section so I can't see the ohms, but my father said 200 ohms and since he used them for many years, it's probably accurate.

 

[Carlos42]

Thanks for your quick reply.If i may be so bold as to ask,what did your dad use them for? Was he perhaps a
professional audio guy?

 

[Lighthaven69]

Yes, he was a sound recorder for many years professionally, so he needed headphones for that.

 

[Carlos42]

TEST

 

[Carlos42]

Does anyone here know the proper way to tune a DT 48 earphone? As near as I can
tell, this involves setting the magnet to the correct distance from the diaphragm.
You have to position the magnet by turning it on its screw threads to the optimum
distance from the diaphragm. From what I have read, this adjustment is made at
the factory and shouldn't have been moved. Unfortunately it obviously has been moved
on at least one of the phones on one of my sets of DT 48's. This phone was distorting
quite badly on bass.I took it apart and found someone had screwed the magnet up
tight against the other part of the phone.(This would be the natural thing to do if
you were not aware that it was an adjustment.)  Anyhow,I backed it off a quarter turn
and the bass distortion disappeared. Still, I would like to know the right way to make
this adjustment and if it could be made by the Beyer folks in the US. Failing that,
is it something I could do myself?
 
DT 48 fans let me know what you think, I would be most grateful for any info!

 

[Carlos42]

I wonder how many different impedance's  DT 48's have been made in over the years? I am familiar with these variations: 5 ohms,8 ohms
25 ohms and 200 ohms.Anybody know of any others?