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  • decon
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Loss of sound qualitity caused by signle core cable?
Hi everyone,

I'm been hacking away on my technics 1210 mk2. The main problem with the deck was that the RCA audio output got broken. Therefore I changed the cable. However, when cutting and striping the new cable, I found out that I had bought a single core cable. I went through the hassle of abrade the isolating materials on the cable (crap job). I soldered it on the board, but was very hard to get to stick. The soldering is not a very good job, but it got done.

Now everything is in place, but I feel like the audio quality has dropped, especially in the low end. So my questions is; is it possible that the used cable actually affecting the output from the deck?

  • KozmoNaut
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Re: Loss of sound qualitity caused by signle core cable?
Reply #1
For such a low-level signal, single-core cable is fine. And at power levels where it can actually matter, you would lose high frequencies, not low frequencies.

The most likely explanation is that you need to redo your solder work.

  • Speedskater
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Re: Loss of sound qualitity caused by signle core cable?
Reply #2
The best plan for any RCA interconnect is to use a coax cable.  That would be a single core shielded/screened cable. For stereo, you would need two cables.
Kevin Graf :: aka Speedskater

  • DVDdoug
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Re: Loss of sound qualitity caused by signle core cable?
Reply #3
Quote
but I feel like the audio quality has dropped, especially in the low end.
A bad cable/connection is usually obvious.   If only "feel like" the quality has dropped, it may be OK.    Our "audio memory" isn't perfect.

This in an internal cable, right?    I assume there are no permanently-attached RCA cables dangling-out?

Make sure to try a different external cable too.   It would be a shame to be troubleshooting the wrong problem.    Make sure you're pugged into a phono input (with a phono preamp and RIAA equalization).

Do you have a multimeter to test the connections (resistance/continuity)?

You might have a missing/bad ground connection.    There should be 3 wires/connections - left, right, and ground.   Or there could be separate ground wires for left & right.

A missing ground will exhibit the following symptoms:
- You'll probably get hum,.

- The left & right channels will be subtracted creating a "vocal removal" effect.   Everything in the center will be reduced/eliminated, including the bass.   A mono record will be nearly silent except for the surface noise.

- The sound will  be "mono".   The left & right channels will be identical.

 - If you un-plug one channel, the opposite channel should change significantly.  



...If you can't repair it yourself, it's probably worth having it professionally repaired.  
 

  • pelmazo
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Re: Loss of sound qualitity caused by signle core cable?
Reply #4
Depending of the length of the cable, and its construction, with phono cables there may be a noticeable effect due to a differing cable capacitance. This will also depend on the type of pickup. Sometimes, the phono preamp offers the possibility to adjust the capacitive load, which can be used to compensate for the cable capacitance. It should, however be most noticeable on high frequencies.

What you say about the cable sounds weird. Why would one need to scrape off the insulation on such a cable, be it single core or not? Enameled wires are usually used for coils, not for cables. What kind of cable is it?

  • 4season
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Re: Loss of sound qualitity caused by signle core cable?
Reply #5
Though costly, you can get an exact replacement cable here (near bottom of page):
http://kabusa.com/wirewin.htm

Sounds to me like you were trying to use enameled Litz wire? That can work but tends to be a little tricky. Monster Cable used to use such things in some of their interconnect cables.

  • decon
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Re: Loss of sound qualitity caused by signle core cable?
Reply #6
Wow! So many good answers! I'll try and answer all your question in this post.

First of all, here are a couple of pictures of the area of concern in the technics 1210 TT:
http://s182.photobucket.com/user/koptapad_2007/media/1Undertonearmexposed.jpg.html
https://img6.imageshack.us/img6/3143/1tonearmorg.jpg
http://crossfadr.com/wp-content/uploads/2011/11/IMG_0134-1.jpg

As you can see, there are indeed grounding and sound connections on both cables. I do use two cables, and I have soldered the grounding wires onto the board - at least I think that's what I've done. I'm not completely sure as to what constitutes the 'grounding part' of the cable. I hope this makes sense?... I will try to take a picture of my job later this week, since it takes quite a lot of time taking the TT apart.

I do get a humming sound, but that's probably because the external GND wires was not connected to the amp at the time of testing.

I needed to scrape of the isolation on the single core wire because the solder won't stick to the cable. It had some kind of coating that made it impossible to soldered. This is also why the soldering job was kinda bad.

Buying a official cable goes against everything I know about audio cable (I might be wrong!): "high quality" cables are not worth the price. Also sending it to a repair would be a fail for me. This should be an easy job. I've done more complicated cable hacking in the past. Thanks for the tips though! :) Always appreciated!
  • Last Edit: 25 April, 2016, 12:13:01 PM by decon

  • 4season
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Re: Loss of sound qualitity caused by signle core cable?
Reply #7
Note that this person is pre-tinning the wire using a fairly large tip on his soldering iron:
https://www.youtube.com/watch?v=vCP9xrq0x_Y
Applying that amount of heat may cause some of your vinyl insulation to shrink/melt but a little is probably unavoidable.

  • pelmazo
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Re: Loss of sound qualitity caused by signle core cable?
Reply #8
As you can see, there are indeed grounding and sound connections on both cables. I do use two cables, and I have soldered the grounding wires onto the board - at least I think that's what I've done. I'm not completely sure as to what constitutes the 'grounding part' of the cable. I hope this makes sense?...
There are actually two different grounds, the signal ground and the chassis ground. The signal ground is connected via the braided shield of the audio cables. The chassis ground is a separate wire connecting to a ground post on the amplifier.

Take care when soldering to a PCB, because it is easily damaged. Too much heat may detach a soldering Pad from the board.

  • DVDdoug
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Re: Loss of sound qualitity caused by signle core cable?
Reply #9
I'm still not convinced there's any thing wrong with the sound after the repair.  ;)   You may have ugly solder connections, but there's probably nothing functionally wrong.

If you've got sound, you've got a connection and the sound doesn't cut in-and-out when you wiggle the connections, you've got good connections.

None of those photos are of your turntable, right?

With 4 connections on each end, there are lots of ways to get the wiring wrong.   But, since it's pretty easy to identify the connections, I'm assuming you've got it right!

The photos show shielded cable with the shield (ground) soldered to the R- and L- pads.  And of course, the shields go to the grounds on the RCA connectors.

Since it's a short cable-run the wire isn't critical, but it should be shielded.   Some cables with braided shield are not 100% shielded (it's not a tight weave) and it would be best to get a 100% shielded cable to minimize hum pickup.

If the cable is unshielded (or poorly shielded or if you've got the shield & hot mixed-up)  you'll probably hear hum when you touch the plastic insulation.   



  • decon
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Re: Loss of sound qualitity caused by signle core cable?
Reply #10
As you can see, there are indeed grounding and sound connections on both cables. I do use two cables, and I have soldered the grounding wires onto the board - at least I think that's what I've done. I'm not completely sure as to what constitutes the 'grounding part' of the cable. I hope this makes sense?...
There are actually two different grounds, the signal ground and the chassis ground. The signal ground is connected via the braided shield of the audio cables. The chassis ground is a separate wire connecting to a ground post on the amplifier.

Take care when soldering to a PCB, because it is easily damaged. Too much heat may detach a soldering Pad from the board.
Yes I'm aware of this :) I've done the same as in the pictures posted before.

I'm still not convinced there's any thing wrong with the sound after the repair.  ;)  You may have ugly solder connections, but there's probably nothing functionally wrong.

If you've got sound, you've got a connection and the sound doesn't cut in-and-out when you wiggle the connections, you've got good connections.

None of those photos are of your turntable, right?

With 4 connections on each end, there are lots of ways to get the wiring wrong.  But, since it's pretty easy to identify the connections, I'm assuming you've got it right!

The photos show shielded cable with the shield (ground) soldered to the R- and L- pads.  And of course, the shields go to the grounds on the RCA connectors.

Since it's a short cable-run the wire isn't critical, but it should be shielded.  Some cables with braided shield are not 100% shielded (it's not a tight weave) and it would be best to get a 100% shielded cable to minimize hum pickup.

If the cable is unshielded (or poorly shielded or if you've got the shield & hot mixed-up)  you'll probably hear hum when you touch the plastic insulation.   
Thanks!

No the pictures are not of my TT, but this is very much like the soldering job I've done. I'll try and get some pictures of my job asap. The TT is at my locale hacker space :)

Wiggling the cables did not seem to produce any noise or drop out.

  • decon
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Re: Loss of sound qualitity caused by signle core cable?
Reply #11
Note that this person is pre-tinning the wire using a fairly large tip on his soldering iron:
https://www.youtube.com/watch?v=vCP9xrq0x_Y
Applying that amount of heat may cause some of your vinyl insulation to shrink/melt but a little is probably unavoidable.
Hmm I feel like I really tried to apply a lot of presoldering on the wire. However, it just would not stick. In the video he talks about isolation on the cable. This is exactly my problem, which is why I tried to scrape using a abrasive paper for metals.

  • DVDdoug
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Re: Loss of sound qualitity caused by signle core cable?
Reply #12
Quote
Now everything is in place, but I feel like the audio quality has dropped, especially in the low end.
One more thought...    If the polarity of one channel is reversed the left & right soundwaves will cancel and you'll get a loss of bass   (i.e. one woofer pushes-out while the other pulls-in).     That can also happen if the phono cartridge is mis-wired.

The easiest way to check that would be to reverse the + & - connections on one speaker.    If the bass gets weaker, the turntable connections are not reversed.   If the bass improves, you've got a problem with the turntable wiring.      Oh...  Try it first with a CD or MP3 to make sure the speakers are correct to start with.   ;)

 

  • decon
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Re: Loss of sound qualitity caused by signle core cable?
Reply #13
Hi all. Sorry for the late answer here! I did fix the problem with a new cobber cable, and a better preamp :)

Here are some pictures:
http://imgur.com/a/LOVNa

The second pic is the old job. The copper on the PCB fell off when I took off the old cable. I therefore had to solder the new cable onto the small connector as you can see in the pic.