2. amps-preamps
  3. 165184-159171

Cables for Mark Levinson No. 30.5 and PLS-330

I have acquired a Mark Levinson No. 30.5 digital processor / preamp and the accompanying PLS-330 power supply. I do not have the three cables that run between them. I would like to build some replacements. There are two 5-pin "analog dc" cables, one for the left channel and one for the right; and one 2-pin cable for "digital dc." I have seen the posts here regarding ML cables and connectors. Even before that I had figured out that they use Lemo push pull connectors, which are available. Someone in another post said they used shielded wire when building replacements. I cannot find any pinout info for the cables or ports, or schematics for either unit. I am not sure if all of the pins on the 5-pin ports are used. I have not opened the units up to look inside. I am not sure what to do with the shield on the shielded cable, i.e., where to connect it, leave it unconnected, etc. Can anyone provide guidance?
flip69
flip69 OP
3 posts
 
BTW, the replacements cables referenced in the other threat were probably signal cables, since they were described as having Camac/Lemo connections on one end and RCA connectors on the other.  Since these are dc power cables, I am not sure if they need to be shielded.  That said, the ac power cables for the ML units I have seen were shielded, so maybe these dc cables need to be as well.
flip69 OP
3 posts
 
I have some updated info to share. In addition to my post here, I also posted on a couple of other sites. No one had any conclusive info or thoughts to share. I was finally able to connect with someone at Mark Levinson. They confirmed that these are simply pass through cables. So, in terms of pinout and wiring, it is simply a matter of making the same connections on each end, i.e., pin 1-1, 2-2, 3-3, etc. They also confirmed that these cables are shielded. However, they did not know whether the shielding was attached to the connectors, and if so how (e.g., on both ends, only on one end, etc.). Apparently, all of the people who worked on these units are long gone.

I am familiar with how shielded AC power cords are built. The shield is typically connected only on one end, the end that plugs into the wall. As I understand it, if you connect both ends the sound is degraded. Not sure if the same considerations apply here. It does not seem so, since there is no indication that there was a specific way to plug in these cords, i.e., either end could go into either component. That suggests that either both ends of the shield were attached, or neither end was attached. If anyone has any thoughts on that, let me know. Otherwise, I might start a separate post on how to build a shielded DC power cord.  
flip69 OP
3 posts
 
I did finally resolve this issue, so I wanted to report. Based upon the info from the Mark Levinson people, further consultation with others, and taking resistance and continuity readings from the various pins of the various ports, I decided to wire up the new cables with the shields connected at both ends. The units work/sound great, so I did not bother to try any other shielding configurations.
 
So, to review, I used Lemo connectors, size FGG.1B.305.CLAD52 for the five pin ports, and FGG.1B.302.CLAD52 for the two pin ports. "CLAD52" refers to the outer diameter of the cable, so you will need to check that one and adjust accordingly depending on what cable you use. I used shielded cable, with the shields connected to the housing of the connectors at both ends.
More to discover