How to wire my Tascam set-up correctly (M-512, 238)?

[GalAtiya]

Hello guys! wonderful to find a forum dedicated to Tascam.

I have at my home studio the tascam M512 . currently i am waiting for the 238 8-track to arrive.
I have the pb-64 patchbay also , to make repatching easier.

In the meanwhile i am in the process of getting all the right cabling so i can set it up neatly and in the "healthiest" way.I fully understand the signal flow (what goes where), my question is concerning more with the cables type, so i went thru the M512 manual, and the relevant page is attached: https://imgur.com/a/HQaGgzo

And to be more specific, i have this pretty neat 32-way RCA snake, i bought not so long ago. It features Mogami snake of some type (it's apparently from the 80') + Switchcraft connectors. overall it seems very decent, but:
-it is just under 20ft
-it features 2-conductor cables (both conductors to signal) +shield
-the snake has only cotton insulation ( i assume this is pretty standard)

basically...the manual suggests to use a very different cable. it seems that the Belden 8218 is no longer in production, and by going over several cables retailers in my area, 1-conductor cables seems to be more rare theses days. (i find coax but not line level audio) And actually, what would be the difference if i take a 2-conductor cables and wire it as a 1-conductor?

I am not running high-impedance circuits, so i am just wondering wether it's really critical, or Tascam just wanted to sell their low-capacitance cables. all my current set-up is wired with sommer 2-conductor wires, and it all sounds pretty neat.



Any input is welcomed...cheers

 

[jslabovitz]

Assuming the 32-channel snake functions (which you could confirm with a continuity meter or test tones), I’d just use that, and see how things go. If you need to upgrade later, then you can do so.

If the cable you own was considered high quality in the 80s, it may well be *better* than many modern cables. I’ve discovered that my stash of 1980s-era cables tend to be better built, of better materials, and more reliable than much modern junk.

I’ve regularly done 20-foot runs of -10dB levels with unbalanced cable and never had a problem. (I’ve also avoided stringing AC lines in parallel with the signal lines, and made sure all equipment was using the same circuit.) Unless you have some severe interference around your setup, the inherent noise of your 520 will probably dwarf anything picked up via the cable.

I built my own 10’ RCA snakes, with 2-conductor cables, and wired them exactly the way yours is done. So that definitely works.

I’ve gone through all this before (and am doing it again, in upgrading my 520 to a 320), and my conclusion is: be practical and pragmatic, and presume that things will change. In other words, don’t feel like you have to have the perfect situation now. Just get it hooked up and make some music!

 

[Mark Richards]

The information you referenced here (https://imgur.com/a/HQaGgzo) is spot on.

Unbalanced cable runs under 4 meters are serviceable generally as longs as the cable is not inexpensive junk. Good quality hi-fi cable will work. Hi-fi audiophile cable will work better, although as with all all audiophile products, the law of diminishing returns applies.

Without getting too much into the tall weeds, unbalanced cable runs longer than about 4 meters will work well if the cables are specifically identified as "low capacitance, low loss". That means there's very little high frequency roll-off introduced by the cable run (for comparison: low capacitance cable has a capacitance of about 15 picofarads per foot v. about 300 picofards per foot found in typical consumer cables). The greater the capacitance and the longer the run, the more pronounced the high frequency roll-off.

To minimize RFI (Radio Frequency Interference) from rheostats, lighting, computers, AC lines, etc., the cable should also have very high density bare-copper braided shield, as opposed to the typical loosely braided and wrapped shielding found on most consumer cables.

I second what jslabovitz wrote above:

be practical and pragmatic...don’t feel like you have to have the perfect situation now. Just get it hooked up and make some music!

Hope this has been somewhat helpful.

 

[SkywaveTDR]

Lots of good info here. I have pretty much wired my studio with good cables I got from Tascam as I worked there in Chicago. The low capacitance cables were made with Belden cable. In the time from that I have worked in Radio and they do everything in balanced lines except when in the studio for near location runs to equipment. It all worked well. The problems I have had were when in a urgent need I tried to use a cassette deck at a transmitter. Well that was never going to work without a Faraday cage. Although I guess it all has to do with how the antennas are situated.
Some tape deck were used at ESPN transmitter when 911 hit and the Hancock Building was evacuated. It was 50KW but I think the building was better shielded than the brick transmitter building I tried in IN.
With today's garbage increasing in the air that we don't see such as cell phone and all this wireless stuff, well shielded cables are a must- some studios make you turn off cell phones as they can cause interference even when not used. Off is the only safe state for a studio. In Radio over the years I used this cable called Gepco type that comes in single and dual (stereo) configuration and has two conductors and a drain wire as well as 100% foil shield. I have even used it for unbalanced cable runs. In a case where I need a long run and good performance I can use a RG6 cable that is for sure low cap as it is made for 3GHz digital TV and once terminated it can have adapters added to it such as F-RCA easy, I use some of this cable on the test bench. The only complaint there is with RG6 is it is not very flexible.
I am still using some of the Gepco dual EZ cable when wiring from Audio Precision to decks and have had no problems, yet I am under ground and not near a transmitter.
Hook up what you have and see if it works, if not then look for other options.

 

[GalAtiya]

Thanks guys for your comments..things do start to look clearer.

@jslabovitz:
Iv'e tested each cable and the snake is fully functional.Overall is seems very well built.
So yes, the 20ft issue got me a bit worried, but it seems that many people runs unbalanced lines for about this length. I guess i'll just try.
By the way, how did you ground your system? the M-512 has a two-wire AC line coming out of it with no ground..and if i remember correctly from my electricity course, i rather have the mixer as the only grounded device in the chain.
I agree with your final statement ..but i did move to a new place just recently, and i felt like i better investigate this subject and try to make the right decision rather then wiring the entire system incorrectly.

@Mark Richards
What you say about the capacitance of a cable is very interesting. I failed to find any info regarding the cable type i have (this is the specs of the current Mogami snake), and it seems that i might gotta have a capacitance meter in order to check my cables. i do have a professional bench multimeter (this one), with capacitance measurement - can you advice on that?

I can confirm that the snake's cables does have a bare copper shield.

We do live in much noisier world then 1982 ..

cheers

 

[Evgeny]

I failed to find any info regarding the cable type i have (this is the specs of the current Mogami snake),

It's written on that page: "Capacitance at 1kHz, 20°C — 130pF/m(40pF/Ft)", so 40*20=800 pF.

and it seems that i might gotta have a capacitance meter in order to check my cables. i do have a professional bench multimeter (this one), with capacitance measurement - can you advice on that?

It measures just nanoFarades, so 800 picofarades means 0.80 nF. You may check this by measuring capacitance between shield and center contact of any RCA-connector of your snake.