DT-48S Re-cable to Stereo

[bluemonkeyflyer]

No luck searching the forums for an answer so I'm posting here. I could figure it out by the process of elimination but that would take a lot of extra work. I hope someone who knows will respond.
 
Which terminal is positive and which is negative?
 
Thanks
 

 

[Aizura]

I don't know the answer to your question. But whatever you do, do NOT solder near the parts where there are screws in the photo, or you'll fry the wires leading to the voice coil. Looks like you already took off the metal parts where you are supposed to solder the wires onto.

 

[bluemonkeyflyer]

  I don't know the answer to your question. But whatever you do, do NOT solder near the parts where there are screws in the photo, or you'll fry the wires leading to the voice coil. Looks like you already took off the metal parts where you are supposed to solder the wires onto.

Thanks for the reply. Yes, I learned the hard way about Beyer driver wires when repairing DT990 600 ohm 'phones. The wires are microscopic, fragile, and near-impossible to solder.
 
I plan to solder the "end pieces" onto the new cable wires and use the screws to secure the cable wires to the metal "blocks." Fortunately, I did not attempt to disassemble the drivers from the cups which would have risked the same result. I inspected the driver wires under magnification and luckily they're still in place. I also tested the drivers using a trick shared by dBel84 --> use a 1.5 volt dry cell battery to test the driver...both drivers still work.
 
Looks like Kool Bubba Ice was banned from head-fi. I hope someone in the know will tell me which sides are Positive and which are Negative.
 
IF all else fails, I will make a guess, solder the new cable to a TRS and check for resistance variation with a DMM. I may then have to de-solder and re-solder the connection...after First unscrewing them from the "blocks."

 

[Claritas]

E-mail Dale Thorn: he might know.

 

[bluemonkeyflyer]

  E-mail Dale Thorn: he might know.

Thanks for the referral.
 
Looking at the top of the drivers, I believe the "block" on the left is Negative. I've re-cabled the vintage 'phones with what I think is Canare Quad wire. It looks the same color as the stock cable and almost the same diameter. I salvaged the stock cable splitter housing and cup entry - strain relief caps. I listened to it and it sounds "right;" much better than in Mono mode. Testing with DMM for Resistance between all TRS sections and both driver terminals
 
appears to read correctly for both channels.
 
This weekend I will test with REW impulse response and my measurement kit. Hopefully, both channel impulse responses will spike UP.
 
I am SO glad I did not try to remove the drivers from the cups! Doing so would have risked breaking the tiny driver wires.
 
 

Beyer DT48S 200 ohm disassembled. Simply remove the screw on the back of the cups. The rear plate lifts right off.
 
Do NOT try to remove the drivers from the cups or you risk damaging the driver wires - the location is shown in one of the pictures, below. Do NOT stick a tool or anything else down inside the hole between the two driver terminals. The wires are attached underneath the terminals and routed through the hole to the drivers. These wires are enamel insulated and smaller than anything I've seen...much smaller than AGW 36.
 
DMM readings show 175 ohms for both channels.
 
 

I cut off the black wire on the blue/left side and the clear wire on the red/right side. On the 6.3 mm TRS plug side, I joined the clear and black wires for common ground. I re-soldered the stock cable wire tabs onto the new wires. The tabs attach to the empty screw sockets on each driver using tiny brass screws. Using tabs instead of soldering directly to the terminals avoids the risk of damaging the tiny driver wires.
 
 

Left Driver
 
 

Right Driver
 
 

New 6.3 mm TRS plug with heat shrink.
Salvaged Stock Cable Splitter...Just needs screws and glue.
 
 

Salvaged stock cable splitter housing
 
 

Re-cabled and stock splitter riveted together.
 
 

New cables with stock strain relief caps.
 
 

Needs a little clean up and rust removal.
New pads would help the sound that's missing bass below 150 Hz.
 

Most of the rust and grime cleaned off