Home made cables

[DrNomis_44]

There's actually two types of plugs that I use to make all my cables, there's a right-angle one and a straight one, both bought from my local Jaycar Electronics store, here's a pic to show what they look like:




For cabling, I usually buy around 10m of Response WB1530 cable, again from Jaycar Electronics, it is actually described as twin-core shielded mic cable for use with 3-pin XLR plugs but I found that it works perfectly well for making instrument leads, I normally just solder the two inner cores together at both ends of the cable and then solder them to the plugs tip connection after soldering the shield-braiding to the sleeve connection.

The plugs I buy are around $6.00 each, yeah I know that's a little expensive but you're better off paying the money for good quality plugs in the long run cause cheap ones will let you down, usually right in the middle of that nicely prepared solo you've been working on for months.

I don't think I've ever done a mini-tutorial on making instrument cables, so maybe that might be a good idea for a new thread to start in the pedals section, let me know if any of you are interested in me doing one.

[Marcel]

For cabling, I usually buy around 10m of Response WB1530 cable, again from Jaycar Electronics, it is actually described as twin-core shielded mic cable for use with 3-pin XLR plugs but I found that it works perfectly well for making instrument leads, I normally just solder the two inner cores together at both ends of the cable and then solder them to the plugs tip connection after soldering the shield-braiding to the sleeve connection.

I usually do it differently when using two core and shield cable on a TS plug (TS= Tip & Sleeve). I chose one core to be my active and tie the other core to the shield. Main reason being that the two cores are designed to carry the signal in under all circumstances whereas the shield in a shielded pair cable is only there to reduce RFI and induced hum and is typically not for carrying signal currents. For that matter when using shielded pair cable on a TS to TS lead I often terminate the shield at only one end and mark the lead where the shield is terminated as the 'Source' end. It is common practice in all forms of Pro audio and broadcast on any shielded pair cables to terminate any cable shield only at the source, however common domestic (RCA type) hifi audio systems and singe core guitar leads typically use the single core shield as an earth return thus the shields are always connected at both ends.

On a TRS to TRS lead the three are always wired with one core to the T, the second core to the R and the shield to the 'sleeve'... (TRS = Tip, ring & sleeve).

XLR (or Canon) connector in nearly all possible uses/cases (audio & DMX lighting) - pin 1 = Shield, pin 2 = -ve, pin 3 = +ve...

[Simon Barden]

XLR (or Canon) connector in nearly all possible uses/cases (audio & DMX lighting) - pin 1 = Shield, pin 2 = -ve, pin 3 = +ve...

Err, it's normally pin 1 = Shield, pin 2 = +ve, pin 3 = -ve.

Though as long as the shield goes on pin 1 and pin 2 goes to pin 2 and pin 3 goes to pin 3, then the cable will work. Even if 2 and 3 get crossed over, then it will still work, but you'll get a signal with a reversed polarity.

[Marcel]

Err, it's normally pin 1 = Shield, pin 2 = +ve, pin 3 = -ve.

Though as long as the shield goes on pin 1 and pin 2 goes to pin 2 and pin 3 goes to pin 3, then the cable will work. Even if 2 and 3 get crossed over, then it will still work, but you'll get a signal with a reversed polarity.

Phase... symbolised on many bits of gear by the Greek letter Theta, a lower case "o" with a "/ " through it. (I can't find the right keystroke to bring it up on screen).

On a XLR to XLR cable it only matters that pin 1 goes to pin 1, pin 2 goes to pin 2 and pin 3 goes to pin 3. In all cases it we have the shield to pin 1 and the two cores to pins 2 & 3. The electrons don't care what colour the plastic coating on the wires is, just that they get to a destination, so it becomes a decision by the cable builder as to which colour wire goes to pin 2 and which goes to pin 3. Many of the cables I use have Orange & White or Red & Black So I choose to have the Orange or Red wire going to pin 3, however Simon would most probably put them on pin 2. It doesn't matter, so long as both ends of that cable are consistent.

If we have two XLR to TRS leads that are used to go from a mixing desk to say a rack mounted Lexicon effects unit and back again, being consistent and using only cables built to only one of the two wiring conventions the phase of the signal is maintained correct at our mixing console by the consistent wiring convention used and the phase through the Lexicon device really doesn't matter.

The problem comes when we have a reversed phase XLR to TRS or TS lead in the signal path of say a system like a PA system. Again, if all are to the same wiring convention of +ve on the same XLR pin everywhere there is usually little issue. However, if we say have a PA that uses active crossovers for bass/middle and high frequency speakers and somewhere in one of our speaker stacks wiring we have a XLR to TRS or TS (or even an XLR to XLR or a TRS to TRS) that is reverse to all the others then those cabs will be pulling when all the other speakers are pushing we will have two huge problems. One, our system will simply just sound wrong. Our amps will be peaking but we just don't have that chest pumping volume because one set of speakers will be working against the others and cancelling out the sound. And two, we will get feedback which we won't be able to control or get rid of as no matter what we do (hitting the phase switch on the console or adjusting EQ) there is always a speaker somewhere that is in phase with some open microphone on stage causing the feedback. The biggest issue here is wiring inconsistency within that system.

In broadcast and in the recording studio it is less of an issue as feedback is encountered far less often. But it can be a problem for certain effects processors and signal conditioners as they may require the dynamics of a signal to be presented or used in a certain way. An example being in broadcast radio where just before the transmitter many stations employ the use of an Orban Optimod which is a device (much like a PA system active crossover combined with a multiband compressor) that conditions the broadcast audio +ve and -ve voltage values perfectly for the transmitter it is attached to. Reverse the phase of that signal and the station will sound horribly wrong...

In any single guitar rig it is far less of a drama. Most guitarists will get used to what they have, but if a (pin 2 to pin 3 phase swap) change is made then the guitarist will certainly notice. Amp sustain and amp feedback in any given situation will certainly be different. Which is probably why XLR's and TRS's are rare in a guitarists rig, and in practice there is only one reasonable way to wire a TS plug.

In all honesty I'll say Simon is right with +ve on pin 2, but that's not to say that I was wrong with +ve on pin 3. If Simon and I were to each build similar PA systems both would work and both would work well. The huge problem of 'phasing' would only come if roadies hired a system from one of us and then got extra gear from the other and then mixed up the XLR to TRS or TS leads.... An unlikely scenario as Simon is in the UK and I'm in AU...