[shirleywhite]

Hi all
I'm a noob/novice to this diy forum - hope this isnt a stupid question - appreciate a quick bit of advice.
Had an old pair of Superfi 5 phones with intermittent left channel/ cable break near plug end etc. Decided to attempt diy fix. Cut  plug off - found working set of cheapish buds - cut phones off then stripped both lots of wires.  I burnt off the coatings - then twisted ( and soldered! ) the 2 whites - the 2 reds ......... and also the 2 "grounds" to the "single ground the plug end seemed to have. (I think!!)  The phones work well - both channels - except for one thing.  There's now a slight but noticeable "left skew" (?) - ie I notice from my favourite music that the vocals - which should be straight in front/centre - are now slightly to the left. (I double checked by putting the superfis in other ears - got slight right bias vocals!  Also immediately checked with my Etymotics - vocals dead centre now!) ( I plugged into a laptop and could use a balance slider - slightly to right - to make sound "correct"!)
 
Is there an obvious answer please??  Have I mis-connected anything??  Is it possible to have "stronger" connections than "others" ??  ( I know that sounds odd ..... but all wires are quite thin - my superfis are very very small/thin -  but the new plug end was thicker - does that make any difference? did I leave some/more  insulation on (say) white v red - can that cause what i'm hearing???
 
Apologies for my "noobness" - any advice really appreciated. Thanks.

 

[gimble]

For an ideal wire, no, that shouldn't happen. But an ideal wire is just an equipotential which perfectly connects two points in a circuit without otherwise perturbing the circuit characteristics. Real wires are nothing like that, although they're usually close enough if you don't push it.
 
The wires for both channels should be roughly the same length (if possible), and your solder joints should be "good" (which is a potentially lengthy topic). If these things are not true, then maybe Weird Stuff will happen. A good first check would be to measure the resistance on all channels from one end to the other. If you get a significant value, then start looking for what you did that caused it. Capacitance is a bit trickier to measure since you generally need to get at it through the decay constant.
 
Post photos of your solder joints if you can. Getting a usefully detailed photo of something that small with the equipment most people have available is a bit tricky though.

 

[shirleywhite]

Hi Gimble
 
Thanks for replying - appreciate your time & trouble. Your "same length" and "good solder" points make sense!   I'm going to give the thing another go next weekend with a different "plug and end" - one which matches the wires on the superfis better!
 
Regards  

 

[kalinowski]

I'd agree with gimble: it's probably bad solder joints fault. the resistance of a wire per meter is so small that difference in wire length can't make any harm to the signal. If it's that kind of cable that has the wires "painted" with isolating stuff rather than in pcv insulation make sure you clean it well before soldering. I had similar problem because of that.

 

[shirleywhite]

Hi Kalinowski
Thanks also to you for replying. The (new) plug end had pvc insulation which I cut back quite easily. But the superfi wires were the "painted" insulation types. I initially tried "scraping" the insulation off with a fine blade - but I then tried to "burn" off by holding the wires over a lighted match briefly!!  ( to be honest I wasnt 100% convinced I'd prepped all the wire ends all that well!!)  Add to that my solder skills are very very rusty............. and I guess that could account for the slight problem I ended up having.   As I said earlier - I'm going to start again and redo everything this weekend ( am away on a work trip till then) Will report back !!  Thanks again for responding.

 

[shirleywhite]

Hi all
 
Well - I'm more confused than before!   I should have said at the start that the "new plug I was using simply had red plus white plus "copper"(ground?) wires................BUT the superfi phone end seemed to have FIVE wires!!   A red plus a white - which I connected to the red and white plug wires. Last week I connected just  a copper coloured wire on the phones - and got the effect I described above.  Tonight I connected two copper/ground coloured wires to the single plug one - this time I got a "right" sided skew of the vocals.  Not huge - but noticeably not centred. I tried adding in the "5th" wire ( which was a red&white striped I think) but that seemed to make no difference.  I've tried googling for wiring guides etc but they all seem to insist it's just the "3" - red/white/ground and that's it.  Can anyone guide me in the right direction please!?
 
Thanks.

 

[tomb]

5 wires implies that the left and right channel wiring is shielded.  You're mixing up one of the shields with the signal ground in each case, I'd guess - that's why you're getting a left channel skew, then a right channel skew.  Figure out which two wires are the shields and don't solder them to the signal ground.
 
Sounds to me that the red/white striped wire is actually the signal ground that's shared between the two channels.  The copper is just the shield wires.  You should solder those to the housing of the plug, if available.  If not, then leave them disconnected.

 

[shirleywhite]

Many thanks Tom!!    That kindof makes sense ( to me - being very much a noob in these matters)  I'm going to have another go at this tomorrow.  ( though the wire length of the phones is getting shorter and shorter with each botched attempt!! Still - i've got a couple of "extension" cables I can always factor in!! )
 
Thanks again - appreciate your time & trouble.
Regards.