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Old 4th December 2005, 12:05 AM   #1
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Default Cat5 speaker cables, my amp doesn't like them

I just made a 6' 6" 4-pair CAT5 speaker cable and after 5 minutes the amp started distorting a lot and was really hot. I measured 62șC with my DMM. The impedance was OK.

My other dual-coax OFC cables are not doing this.

The speakers are Yorkville Traynor CS-1012H PAs. They are 8ohm 100w.

What could have happened?
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Old 4th December 2005, 12:11 AM   #2
tade is offline tade  United States
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You are sure you have no short? Check the cables with a multimeter to see if the positive and negative sides are connected. Its that or oscilation. If that is the case someone more knowledgeable than i will have to help.

Did you diy the amp?
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Old 4th December 2005, 12:18 AM   #3
anatech is offline anatech  Canada
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Hi DragonMaster,
Have you tried real speaker wire?

I work with CAT-5 almost every day, I don't recommend it for speakers or signal. I use it for 70V lines sometimes when there is no choice, and inputs to paging amps. They are really 600 ohm balanced. Short runs only.

What does work really well on CAT-5 are telephones and lan signals.

-Chris
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Old 4th December 2005, 12:29 AM   #4
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Quote:
Check the cables with a multimeter to see if the positive and negative sides are connected. Its that or oscilation.
I triple checked everything and there's no problems with impedance or poor connections.

Quote:
Have you tried real speaker wire?
No, that's the kind of thing that I don't have

The OFCs work well but not the CAT5s


Quote:
I work with CAT-5 almost every day, I don't recommend it for speakers or signal.
And a lot of people are telling they are good for these apps...
I trust you more than these guys.

The most standard wire I have is NMD-90 but since the speaker side connectors are 1/4 jacks it would be pretty hard to connect.


The double OFC coaxes is the best cable I have got until now but I wanted to try other cables just for fun.
http://provowire.com/print.asp?prodid=6


Hey, I'm forgetting these 50' long 10 AWG twisted-pair wires that came with the speakers.

And if we still talk about coax, what about RG-8?
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Old 4th December 2005, 12:46 AM   #5
anatech is offline anatech  Canada
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Hi DragonMaster,
I realize that wire is hot topic, with many fads and firm believers, so I will put my flame suit on. (couldn't find it, might be in the wash)

The best wire I have seen over 20+ years is a 16GA fine strand copper "zip cord" style. Heavier if you are running a long distance or high power. 12GA is overkill normally and a real pain to work with. 10GA is worse. 18GA is fine for many applications too. The great thing about the fine strand is that the wire is very flexible and generally easy to solder.

No such thing as oxygen free. Copper reacts with oxygen quickly near the cut ends. What happened before the insulation went on?

Now I know the Yorkvilles have 1/4" connectors, but they are the worst. Don't forget the contact with the hot tip is a tangent against an arc. Not real good contact area. I bet that RCA's have more contact area and at least they don't short on the way out. The cheap push clips might be better even. Any chance of changing to speak-on's or binding post's?

You have no idea how many blown amps I've repaired over the years due to the plug coming out or partially out while the amp was running. Many times this happened more than once.

-Chris (ducking)
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Old 4th December 2005, 01:07 AM   #6
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I'm not going to flame you since the wires I have were the first that my speakers were connected to since I've got them.


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You have no idea how many blown amps I've repaired over the years due to the plug coming out or partially out while the amp was running. Many times this happened more than once.
My Toshiba amp is amazing. I've disconnected my 1/4 jacks while the amp was on lots of time and it still works fine. Note that my dual coax cables have one 1/4 jack per coax to make things simple. Luckily, the speakers have two input jacks.

When I was 7-8, I was connecting the speaker outputs of the amp to an RS project board, often plugging the 8 ohms main speakers in parallel with the 4 ohm on the board... and the amp is rated 8 ohms. I guess I shorted both leads a couple of times too.


I don't know if it would be really simple to change the jacks, they are mounted on the Xover PCB and the plate with the connectors in the back of the box is pretty small. The box material is 1" thick, not the easiest to work with.

Well, the 10AWG cables I've got are multi-strands so they are pretty easy to work with. The gain is pretty low with this stuff also.

Well I could buy 16 AWG wires next week because the local electronics store is closed on Sundays.
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Old 4th December 2005, 01:25 AM   #7
anatech is offline anatech  Canada
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Hi DragonMaster,
My gosh, you are so lucky. And you tempted fate on many occasions. Can I have some of your luck? Please??

I am very happy nothing bad happened to you yet. For most of us, it only needs to happen once and bang. Do you have any idea how many people trip on speaker wires in temporary setups? The 1/4" jack always seems to come part way out and POOF. Amp repair time.

If you can get in there, just wire the new jack type in parallel. Stick something in the old 1/4" holes if you want.

-Chris
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Old 4th December 2005, 01:49 AM   #8
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My gosh, you are so lucky. And you tempted fate on many occasions. Can I have some of your luck? Please??
I'm not always lucky. With DIY, yes, but NOT with commercial equipment, everything I buy requires to be repaired to work : Panasonic CD/MP3 portable player, Nakamichi BX-2 and PlayStation. That's in fact every commercial electronics I bought since I'm born. And I buy everything at least twice the price than what it should have been. My CD/MP3 was 200$ when I bought it ... two months later, same model upgraded : 80$. BX-2: Paid 80$ becuase it as serviced hen in fact I had to rebuild two motors. PSX : Bought it 30$ online while others get them for 10$.

But, like I told, with DIY, I have not much problem. I never killed a component with my soldering iron, apart from these #!%*#?* LEDs. I also never killed something by connecting it wrong, again apart with LEDs.

Quote:
Stick something in the old 1/4" holes if you want.
Now that's not an option as the 1/4 jacks are holding the PCB.

Gotta drill some holes in the back plate!

What kind of plugs? I never worked with something else than 1/4 jacks and push clips(THAT's even worse than 1/4 jack with soldered cable ends.)
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Old 4th December 2005, 02:51 AM   #9
anatech is offline anatech  Canada
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Hi DragonMaster,
Binding posts with 3/4" spacing are useful. You can put the mating dual banana jack on the wire. Pros & cons: Better connection, can slip out, easily reversed.

You could just insert the wires in the holes and tighten the nuts. Pros & cons: Better connection, not easily pulled out, easily reversed, time to connect.

Speak-on connectors. Pros & cons: Better connection, locking type, can not reverse polarity, high cost (not compared to an amp repair).

Any other connector can be used. Jones plugs, molex connectors and trailer plugs. I prefer a semi-standard connector. Something recognised as an audio connector (don't use AC mains hardware ).

-Chris
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Old 4th December 2005, 09:08 PM   #10
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I could try binding posts maybe.

I'll see that later.


But now, I found why the amp was overheating :

I had the OFCs connected to the "A" terminals of the amp, and the CAT5 to the "B" terminal.

What happened was when the A switch was on the off position, it was shorting both terminals. I didn't thought that thiscould happen as the same thing is not happening with the B switch.

The amplifier connects A and B in series when they are both on. So I would have never tried that.
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