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Re: Cat5 Causing my Rega amp to run hot?

209.215.72.158

It sounds like the amp is oscillating due to the capacitive load from the CAT5. The full 27 pair version ChrisVH recommends is highly capacitive, about 450-600 pF per foot, with a 10 foot run ending up at about 5000 pF. That's enough to send some amps into oscillations. Double up for bi-wiring, and this can cause even more amps to loose it.

Them answer is the use of a Zobel network to control the impedance the amp/cable combo sees. Many speakers go higher in Z in the HF range, and this can cause the cable to become unloaded at the HF's. Place a a resistor and cap in series, this string across the speaker load. An non-inductive R of about 10-8 ohms, and a high quality non-inductive cap of about 0.27 to 0.1 uF should be about right. One network for each channel.

If the problem persists, then use of a seocnd network right at the amp terminals will sometimes do the trick.

Use only very high quality parts, as they can have an adverse sonic effect, although to test the effectiveness, use of lower quality parts, as long as they are non-inductive, will tell you if it will work or not.

Jon Risch


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