Question How to make a longer cable for Remote Volume MRCV1

[jeffinmn]

I have a Seeburg V200 that I've been using a Seeburg amp MRA5-L6 in for about 10 years. It sounds great. Connected to the amp is a remote volume control MRCV1 so I can control the volume and cancel selections from my desk. My basement play area consists of 6 pinball machines and the Seeburg and my desk with the computer. I also have 3 wallboxes around the basement. 

I recently moved the jukebox and pinball machines so that the pinball machines are along a wall all in a row and placed the jukebox at one end of the room about 25 feet from my desk. I did this so that while playing pinball the jukebox is on the side of the player instead of behind the player. Sound is better that way. The cable on the MRCV1 is not long enough to reach from the jukebox to my desk. I ordered a 50 foot 6 conductor cable 18 gauge, and a male and female 7 pin Amphenol plug set. I have a drop ceiling so I can run cables through the ceiling and walls by taking down ceiling tiles. I figured 50 feet to allow for 8 feet up one wall behind the jukebox and down the other wall by my desk. The plug from the MRCV1 has 4 wires on it and then two wires for the reject button. 

The cable is not shielded and I'm wondering it it will pick up hum or not. I noticed that the 4 wires going into the plug are not shielded but two of the wires going to the pot in the MRCV1 are. 

Do you think this cable will work or do I need to get shielded cable? 

[Ron Rich]

Jeff, To answer your first question, I would say to hook one end of your wire to a stationary device, like a wall, and use my winch to pull the wire as long as you need it-- your 2nd question--look at the wire you are using now--shielded or not ? Whatever is your answer is mine too ! ( specs are in your Service,or, I&O Manual) Ron Rich

[robnyc]

"Do you think this cable will work or do I need to get shielded cable? "

Yes, a shielded cable is necessary. Even though the preamp output is a cathode follower, the signal reenters that amp at a higher impedance depending on the position of the volume control.

RobNYC

[jeffinmn]

I see a few different options of shielded cable. I see 6 conductor where each pair of wire is shielded in foil with a separate ground, and another cable which has all 6 wires together wrapped in foil with a ground wire. There is also 18 or 22 gauge thickness. What should I get?

[robnyc]

Jeff, the 22ga stranded is fine. There is no current involved here.
RobNYC

[jeffinmn]

Any recommendation as to if shielding around the outer case is adequate or if each pair of wires should have their own shield?

[Ron Rich]

Jeff,
Unless you wish to pay a "consultants fee", I am not going to dig out my manual,read, and re-wright the page out for anyone--just don't have the time ! So either send me a hundred bucks or, RTFM (Also--Please read "Attn: Newbies", in the above FAQ's) ! Ron Rich

[robnyc]

Feb 17, 2018 23:32:17 GMT jeffinmn said:

Any recommendation as to if shielding around the outer case is adequate or if each pair of wires should have their own shield?

An overall shield is fine. The original cables had the audio wires in the shield and the cancel wires outside, but it makes no difference.

RobNYC

[Ron Rich]

Rob,
One would think it should not make any difference, but it does. The "cancel" circuit was removed from being inside the shield, and made a twisted pair outside the shield, to prevent "popping" at record's end-.

[robnyc]

Rob, I had wondered about this issue of induced transients. In my experience, I've just used multi's where all were inside. These are all Tormat era where the switching is based on triggering a thyratron (SCR in my case)so perhaps the spikes that would occur in the older, direct switching machines aren't a factor here. FWIW, I've also used the shield as common ground for both audio and trip ground in two cases where I had 3-pair cables so the reject was common-ed w/audio. At least in my cases there is no problem.

RobNYC