CAT5 DIY Speaker cable question

Discussion in 'Archived Threads 2001-2004' started by Ryan T, Nov 16, 2002.

  1. Ryan T

    Ryan T Second Unit

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    Hi,
    Lately I've been researching the CAT5 DIY speaker cables. I found this site..
    http://www.venhaus1.com/diycatfivecables.html
    and made one cable about 5ft long to see if there really was a difference in sound quality between CAT5 and standard 12 Ga. wire. I did notice an improvement in overall clarity. The CAT5 sounded a lot cleaner and more open than the 12 Ga. My question is if I make two 5 ft CAT5 cables for my main speakers is the capacitance going to hurt my H/K AVR 120? I played music at about 95 to 100 dB's with the cable I made and it didn't sound like it was having any trouble. I just want to make sure I won't blow up my amp. Thanks.
    Ryan
     
  2. Michael R Price

    Michael R Price Screenwriter

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    Ryan,
    I built similar cables and my amp has not had any problems (due to the cables at least [​IMG]). And if it does cause the amp to run hot for example, you can make a little Zobel network to compensate for the capacitance. Don't worry about it.
     
  3. Ryan T

    Ryan T Second Unit

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    My amp runs pretty hot with regular 12 Ga. There is no fan in it so I don't think I would be able to tell a difference in how hot the amp is running with the CAT5 cables. Could someone explain what it means when an amp oscillates? Is it something that is audible? I just saw this

    "While the high capacitance is virtually a non-factor as far as sonics go, it MAY be a problem for unstable amplifiers and cause them to oscillate. This can be mitigated by NOT using very long lengths of cable (>8 ft.), and making sure your amp isn't one of the few that are unstable into high capacitance loads. Most modern properly designed amplifiers should not have a problem."

    I'm planning on making the cables under 6 ft. Is that short enough not to worry about the capacitance? Thanks.

    Ryan
     
  4. Dereck Graefer

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    Someone correct me if im wrong, but wouldn't the combination of low inductance and High capacitance be the cause of potential oscillation? Doesn't a combination of low inductance and high capacitance create a resonance circuit? I'm assuming yes. Also, another assumption im making is that a receiver pumps out constant current. Right? Again im assuming yes. So this constant current into a resonance circuit causes Oscillation. So if you use a smaller cable, you making a smaller capacitor, so the effect is minimized or non-existent. Right?
     
  5. Dereck Graefer

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    Forgot to mention this.

    I made a 5-1/2 foot long cat 5 cable using the recipe from the link that was posted. I haven't had any problems with it. If I had to guess I would say 6 feet is safe. But that's just a guess.
     
  6. Paul Stiles

    Paul Stiles Agent

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    An inductance in parallel or in series with a capacitance will have a resonance whose "sharpness" or severity is affected by resistance in the circuit. For common lengths of speaker cable, any resonant frequency produced by just the cable inductance and capacitance will be waaaaaaaaaay above the audio range.

    What causes most amps to oscillate is too much load capacitanc, this load capacitance being the capacitance presented by the speaker AND that of the cable. A speaker may present a highly capacitive load to an amp (electrostatics are noted for this) as may the speaker cables used. Some spaakers present less capacitance than others and the same for cables. Replaceing a low capacitance cable with a high capacitance one may cause a previously well behaved amp to become an oscillator.

    Some amp designes can handle a capacitive load better than others. One common way of "helping" an amp to handle a capacitive load is to place an inductor between the speaker and the amp output. If you look at many amp schematics, most will have an inductor in parallel with a low ohm resistor at the output. When the amp is driving a severely capacitive load, the inductance will limit the output output current at high frequencies. The side effect is there will be some high frequency peaking (overshoot and ringing on squarewaves), and in extreme cases, oscillation may still result. Some amps have such robust output stages and good designes that they can drive a severly capacitive load (speaker and cable) without the need for an output inductor and without oscillation or severe ringing.

    Paul
     
  7. Aaron_Smith

    Aaron_Smith Stunt Coordinator

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    I can't imagine that 5' of cable is going to make any appreciable difference or instability provided that you use enough of it- at least 2 runs for each speaker. FWIW, I went to the trouble of making the braided cat5 cables and was not impressed with the results with either my PSB image's or my vintage Advent loudspeakers. Results may vary, but I'm happily back using 12ga. zip cord. It's a worthwhile experiment, but it is a time consuming project and the results are much less noticeable than moving your speakers a few inches in any direction.
     
  8. Dereck Graefer

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  9. Ryan T

    Ryan T Second Unit

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    I did a side by side test between my cheapo (Road gear) 12Ga. and the CAT5 cable I made. My speakers are GR-research AV-1's. I used a RCA Y-cable to split the left signal from my CD player into the left and right CD inputs on my receiver. I used the balance control to switch between the left and right speaker. A few other friends and I could tell a difference when directly comparing the 12 Ga. and CAT5 cables. The 12 Ga. seemed to muddy up the bass and midrange and distort the highs a little. The CAT5 cleaned up the highs and seemed to bring out the midrange a little more. I'll admit it wasn't a huge difference but I think the improvement in sound clarity is worth the effort put into the cables. I think I'm going to go ahead and make another cable. If I start having trouble with my receiver I will just switch back to 12 Ga. Thanks for the help.



    Ryan
     
  10. Aaron_Smith

    Aaron_Smith Stunt Coordinator

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    Not to split hairs, but by using the y-cable A/B method you are effectively halving the input impedance of your amplifier, which I would think is more likely to have an audible effect than the switch you made to the cables in the first place.
    However, these are the pitfalls of the "better cable" debate. Congrats on finding an inexpensive way to make a satisfying change to your system.[​IMG]
     

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