Speedskater
Major Contributor
I would say that any XLR to RCA interconnect cable that has the XLR pin 1 connected to the RCA shell, should have a heavy braided shield connected at both ends.
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Balanced TRS to unbalanced RCA - conflicting information
I simply assume it is a differential amplifier output when they say balanced, which is, as you rightly say, not a balanced output, as the word "balance" means.
Speedskater
Major Contributor
We seem to have inter-mingled two different subjects:
1] interconnect systems
2] internal circuit design
1] interconnect systems
2] internal circuit design
Balanced in the audio world does not always imply fully differential circuitry. I have used pro mixers with balanced I/O that was internally single-ended but had a resistor on the (-) side to match the series resistance of the driver and receiver. Impedance-balanced, if you will, but not truly differential. You can create balance with a balun... 
There is sort of a range of circuit designs from fully differential, to quasi-differential (e.g. using an inverter on one leg), to balanced via impedance matching but not differential, to single-ended (RCA/TS connectors).
As @Speedskater said we are starting to diverge so I'd best shut up.
There is sort of a range of circuit designs from fully differential, to quasi-differential (e.g. using an inverter on one leg), to balanced via impedance matching but not differential, to single-ended (RCA/TS connectors).As @Speedskater said we are starting to diverge so I'd best shut up.
To add to this: It's worse in most cases. With unbalanced interconnects you are much better off with the heavy gauge breaded shield of the cable to deal with ground currents between equipment. It has a much lower impedance than a thin wire as return. For magnetic shielding at mains frequencies you need anyway 5mm thick copper shield to be effective... It is therefore also best to keep your signal wiring as far away from mains wiring as possible. Mains cables can make hell of magnetic and static noise, especially with power amplifiers. Have seen many expensive set-ups with expensive mains cables, where the mains cables happily party together with the signal cables...
What makes you think this?
why 5mm and waht would you define as effective?
i have tested 3mm thick coax cables they shield excellent at mains frequencys
RCA cable Magnetic interference measurement and comparison
Cables are cables and there is no difference?! I designed a test to see if they perform significantly different in therms of "magnetic shielding" or Leakage inductance. This test dose not test for ground loop currents but interference from close by magnetic in homogeneous magnetic files. The...
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Not at all.
Often by keeping signal wires and power wires far apart you increase the ground loop area.
The bigger the Area the more B field your loop "antenna" is picking up.
with proper cables no problem at all:
even in one cable combined this works fine over 10m
It's from an IEEE publication long time ago about low level signal integrity. It contained an in depth analyses of the magnetic screening effect of coaxial cables at low frequencies. At low frequencies this solely depends on the induced eddy currents flowing in the outer conductor. The less resistance it has, the more effective the magnetic screening. That 5mm was the outcome I remember of a numerical example, it amazed me too.
I did a test with my Krell KST-100 once: I put a 75cm RG59 coax interlink with RCA connectors along a standard IEC mains cord to my KST-100. On the spectrum analyser, mains spurs were about -70dBV to -90dBV at iddling and extended far beyond 1kHz. With nowadays Sinad and IM distortion numbers it would not please me at all. But hey, this is the DIY department. Anyone in doubt can test it themselves. Very educative to see what different cable makes do... You only need a decent soundcard and some (free) FFT software like Arta: https://artalabs.hr/ and some free time.
cavedriver
Senior Member
I have a related problem to this thread- I'm trying to connect a minidsp flex with balanced out to my sub or an amp with RCA unbalanced inputs. I understand the wiring diagrams given here and on the minidsp "help" on this topic, but neither minidsp or Amazon seem to have this actual configuration for sale. It's worth noting that virtually any XLR to RCA adapter or cable (Neutrik or anyone on Amazon) will connect the 1 and 3 pins to the (-) on the RCA. From what I understand you should NOT do this to the minidsp outs?? I'm looking at the XLR cables and adapters because I can't find anyone even selling the TRS to RCA cable, the thinking being use a TRS to XLR male cable (which I bought with the minidsp) to an XLR female to RCA cable to my amp(s). Is this correct and does anyone have a link to a product that gets me there?
At this point my desperate solution is just use one RCA out from this cable since the one side is only connected to the tip and sleeve of the TRS plug so at least it doesn't short the two connections together, even if there's presumably no connection to any shielding on the cables.
At this point my desperate solution is just use one RCA out from this cable since the one side is only connected to the tip and sleeve of the TRS plug so at least it doesn't short the two connections together, even if there's presumably no connection to any shielding on the cables.
Shorting pin 3 to gnd doesn't harm your DSP. The outputs are protected by a small series resistor. But it loads that leg unnecessary heavily. It is most time not a real problem but it can impair quality of signal at pin 2 sometimes. Point is every prosumer maker has its own way of implementing balanced outputs. If you want always on the safe side avoid conversions between balanced and unbalanced.
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Threads like this give me brain ache trying to understand them lol. The result, for me, is that i make every effort to pick components with connections that don't require any type of adapter.
cavedriver
Senior Member
It would be nice if minidsp would just sell the part per their recommended wiring just as they sell TRS to XLR cables.
As far as "why", I'm doing this firstly to run a sub, which is apparently a common interest among minidsp purchasers and a problem if you want balanced connections on your mains and/or want to use one of the current affordable Hypex amps that tend to be wired with balanced inputs. I also have a temporary situation that I want to test building a 2x2 amplification of a pair of budget speakers that I got to play around with and I only have one 2-channel balanced amp so I'm using a spare amp with RCA inputs for the tweeters until I decide if I like the outcome before I go buy a 4-channel balanced input amp for long term.
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