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Anyone good at cable wiring?


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Anyone? Need to make an XLR male to 3.5mm mono jack lead, needs to be quality components and cable, is going from mic preamp to PC sound card.....anyone suggest decent components and how to actually wire the thing together?? Can it be done? Don't want to use a 6.4mm to 3.5 mm adaptar as I've found those things to act like a microphone itself

Ta...

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1st you need to fing a decent 3.5mm jack that you can solder. Maplins have them I think. Failing that Allan Gordon should have them 01379 641441 next day delivery.

As for wiring.... use decent 3 core mic cable. At the jack end, strip the yellow and black wires enough to solder them. Strip the braided screen back as you don't need it at the jack end.Solder the tip connector of the jack to pin 2 of the XLR using the yellow wire. Solder the sleeve connector of the jack to pin 3 of the XLR using the black wire. At the XLR,again strip back the braid then solder pin 1 to pin 3 on the XLR with a short length of wire form the cable.

This should work but it's not a brilliant solution. You would be better using a balanced jack but as I don't know your computer set up I can't say. Proceed with caution and low levels until you know there will be no probs.

I think your prob with adaptors is that your going from balanced to unbalanced cables.

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Not sure i understand why you need to make your own. I feed a AKG C1000S straight into my soundcard via a phono -> 3.5mm adapter. If the mic you're using has battery power then simply using the MIC input on the soundcard and ticking the 20db boost in your Volume Control window should give you enough signal to get a very good recording. What mic are you using?

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Don't want to use adapters, my mic will be in a different room from PC as it sounds like a hurricane, and when I've used 6.4mm to 3.5mm adaptors, the little bastards have acted like a mic and degraded signal, picked up huricane george whizzing away.

Using a Rode NT1A mic (needs phantom powering), first into a behringer mic100 tube preamp thing, which has XLR out only. So I need 3pin XLR to 3.5mm jack with nothing else, and hopefully no degradation of quality....

Ibid, sounds cool, will try it out once picked up parts...only other solution I can think is if such thing exists a sa male XLR to female 6.4mm jack, then using a 6.4mm to 3.5mm jack.....its still getting one more thing in the way of the cables before it gets to the sound card.....

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if i were you i would get hold of a wee mixer...you could plug the mic preamp output into the input of the mixer then use a line output of the mixer into your soundcard. you could even use one of the aux sends on the mixer to control the level...then you could use the mixer to tie up any other stuff you have e.g keyboard, output to monitors etc.

iain

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I take it you don't have a break out box for your computer and are going straight into the 3.5mm sockets?

Are your computer connectors unbalanced?

Yes, pre amps are supposed to be used with a mixer. It would make life a lot easier for you.

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the thing is....mixers cost money and i just spent the last of it on this mic and preamp :dunce:

In a perfect world, I'd have a 12 channel mixer with a stereo phono to 3.5mm stereo going into the line in, this way i could blend 2/3 mics for my guitar, 8 mics (live) for drums with 2 stereo returns etc etc......one day :)

cheers folks

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Keilan, all you need to do is: keep the preamp next to the computer, That way you're big run will be balanced.

Making a cable up would rely on finding the right connector, don't do what Ibid suggested. That is not screened and could pick up interference with even a small run. Screen should be pin 1 XLR to sleeve on jack, pin 2 should be one of the cores to tip on jack. If its a balanced (tip-ring-sleeve) input I think you can guess where the other core goes.

I assume your preamp supplies phantom power?

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Ian,

Yeah the preamp does 48v phantom powering....there was a nicer 1U dual channel version, this is just a box, so will sit on top of pc with pref little as poss cable, 0.5m at most

I've never known how to solder together a mic cable (soldered guitar leads mid set before :D) so will all be new to me, should get the chance this weekend to give it a crack, so will be back here for more advice if it all goes pete tong :D

cheers

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You should be alright with that. The shielding on the pre-amp and computer might not be up to such close contact though.

And use neutrik connectors if you can, they're good quality, good cable grips and re-usable. More expensive, but if a jobs worth doing...

Shit, and minijacks will never take a standard mic cable. I've got some thin install cable somewhere if you can't find any.

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Originally posted by soundian:

Shit, and minijacks will never take a standard mic cable. I've got some thin install cable somewhere if you can't find any.

finally someone realising my requirements :)

what's 'install cable' and will Maplin have what I'm after?

Neutrik jacks it will be, name rings a bell....:thumbsup:

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It's just thin mic cable, normally with a foil shield to reduce diameter. You can't use it on stage, it's too fragile, and cos the diameter of the wire is thinner it's best saved for short, protected runs, like your's.

I don't know if Maplins will have any but if they don't, I'll be in Kef on Sat afternoon, I think I know where mine is.

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Try Maplin for your connectors. Alternatively you can get them online from RS components. Neutrik connectors are cost effective and simple to wire. You can get your cable from RS components as well. Theyve got a warehouse in altens. You can pick up a decent soldering iron kit (wire strippers, etc) for 50 if you can part with the cash. As for the wiring schematics, you are probably best to search on google or audio engineering sites.

i imagine to achieve a mono output, only one of the two cores( live or ground) will need to be connected to pins 2 or 3 respectively. the shield (outer loose wires) will got to pin 1 of the 3.5mm jack.

it can be more complicated if you involve balanced line outputs. this just means that the signal will maintain a certain level when it reaches your PC but involves more wiring.

anyhoo ill not bore you any longer.:dunce:

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Originally posted by acoustically_content:

As for the wiring schematics, you are probably best to search on google or audio engineering sites.

i imagine to achieve a mono output, only one of the two cores( live or ground) will need to be connected to pins 2 or 3 respectively. the shield (outer loose wires) will got to pin 1 of the 3.5mm jack.

it can be more complicated if you involve balanced line outputs. this just means that the signal will maintain a certain level when it reaches your PC but involves more wiring.

anyhoo ill not bore you any longer.:dunce:

The two cores are not live and ground, they are signal and phase reversed signal, with respect to the ground. Wiring pin 3 to a mono jack will give you a phase reversed signal (not always a bad thing, but not always good either).

Balanced doesn't mean the signal will maintain a certain level, it means it carries a phase reversed signal which, when reversed and added to the main signal will boost it, and interference picked up on the run will cancel out. This gives you a much longer cable run before signal degradation and interference become significant.

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I apologise. Upon reading your post I thought you required XLR to unbalanced jack. If you don't, do what Ian suggested. But if you want an unblanced jack, you mustn't connect the screen at the unbalanced end (the jack).

Taking computers out of the loop you can go...pin1 to screen, leave disconnected at jack end. pin 2 to jack tip,pin 3 XLR to sleeve. However, this often doesn't work when connecting to home computers, it picks up a hum. Studio computers are another matter.

In a large proportion of home computers, particulary using creative sound cards, pin 1 must be joined to pin 3 with the screen disconnected. This, as Ian rightly says, can be subject to interference, but it gets past the problems associated with home computers. My daughter uses that very lead on her own computer and it works just fine. It took several hours of experiments to get it to work, as I'd never have thought of leaving the screen out normally, but work it does. Whether it would be just as effective in a room full of studio gear is another story, but you sound as if that's not a problem you'd have.

Incidentally, the thin wire Ian reffers to, is often called signal cable as well, which may make more sense to the Maplins guys.

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To be honest I don't think the shield does much. The signal noise ratio is better though so I suppose that why it works. Anything longer than 2-3 ft and it's not worth it. Unshielded PCs tend to kick out a lot of radiation and the screen on an XLR/unbalanced jack just loves it! Hence chopping it off. Perhaps a resistor in there may be better, I must try it.

Signal cable is great but not very robust and doesn't last when being pulled in and out. Last year though, a friend of mine who's an engineer on the British Antartic Survey gave me some artic shielded signal cable. It's just thin signal cable encased in a weather proof rubber type sheath proofed down to -55! It's so strong you can use it for anything you like, even live stuff. I've run out though. He's due back in the summer and has promised me a drum.

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Originally posted by Ibid:

To be honest I don't think the shield does much. The signal noise ratio is better though so I suppose that why it works. Anything longer than 2-3 ft and it's not worth it. Unshielded PCs tend to kick out a lot of radiation and the screen on an XLR/unbalanced jack just loves it! Hence chopping it off. Perhaps a resistor in there may be better, I must try it.

Have you tried using a cable with no shield? The shield must do something. Anyway, it sounds like for short runs, you're way may be best.

I'm led to believe a 100 micro-farad capacitor in line with the shield reduces noise.

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I've not tried screenless cable. I guess the screen must have at least some effect, even unconnected.

In unbalanced cables, a small 100ohm resistor connected between the screen of the cable and the earth tag of the jack plug will reduce any induced current hum, but this method will slightly increase the risk of RF interference. In this case, connecting a 1 nanofard capacitor in parallel with the resistor will help. Going from balanced to unbalanced though, you need to prevent earth currents flowing in the cable screen and compromising common mode rejection (and letting the hum back in!)

This time you connect a series resistor of about 100 ohms in series with the screen connection at the unbalanced end. This is better than using a resistor in a completely unbalanced system because you're not relying on the screen to act as a signal return path.

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Originally posted by Keilan 303:

Don't want to use adapters, my mic will be in a different room from PC as it sounds like a hurricane, and when I've used 6.4mm to 3.5mm adaptors, the little bastards have acted like a mic and degraded signal, picked up huricane george whizzing away.

I had to read that four times... go away.... have a coffee... think a little... and now I get it. Good point!

The rest of this thread is beyond me. A++ for you all, etc.

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Originally posted by Ibid:

I've not tried screenless cable. I guess the screen must have at least some effect, even unconnected.

In unbalanced cables, a small 100ohm resistor connected between the screen of the cable and the earth tag of the jack plug will reduce any induced current hum, but this method will slightly increase the risk of RF interference. In this case, connecting a 1 nanofard capacitor in parallel with the resistor will help. Going from balanced to unbalanced though, you need to prevent earth currents flowing in the cable screen and compromising common mode rejection (and letting the hum back in!)

This time you connect a series resistor of about 100 ohms in series with the screen connection at the unbalanced end. This is better than using a resistor in a completely unbalanced system because you're not relying on the screen to act as a signal return path.

Without the shield it just acts as an antenna, picking up everylittle burp, hiccough and fart from surrounding equipment. Buzztastic. I think linking the screen to the P.R. signal must give protection to the other core . Otherwise why bother connecting it at all.

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Yep it does help a lot but only for short runs. Bane of my life is RF. I live near a large airbase and all I get is radar blips and HF interference so I've had to get good at screening them out. That and sub sub bass from jet engines!!

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Personally and from great experience in the world of connecting balanced mics to unbalanced connections at the university, I would wire 3.5mm tip to pin 2 on XLR and 3.5mm ring also to pin 2. Connect the screen to pins 1 & 3 on the XLR. That will work a treat. In a run of the length you are doing, unbalanced wont matter much. I have frequently run unblanced signals well over 50 metres with no percievalble problems. Especially for recording.

Badger

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Originally posted by badger:

Personally and from great experience in the world of connecting balanced mics to unbalanced connections at the university, I would wire 3.5mm tip to pin 2 on XLR and 3.5mm ring also to pin 2. Connect the screen to pins 1 & 3 on the XLR. That will work a treat. In a run of the length you are doing, unbalanced wont matter much. I have frequently run unblanced signals well over 50 metres with no percievalble problems. Especially for recording.

Badger

If it's an unbalanced connection you don't have a ring to attach to pin 2.

What do you attach to the sleeve of the jack?

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