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Has anyone had a problem with the Cat5 cable causing their amp to run hot. I built a pair following the recipe, and now my Rega Mira/ Mangepan MMG setup runs EXTREMELY hot. Is there a logical explanation to this.
P.S. It's sad because these cable so good.TIA, Dave
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
Won't it be easier to isolate and disconnect (cap off with electrical or teflon insulation tape) one or two 3-pair braids on both ends?Adi
Electrically unconnected braids within a braided bundle give rise to ghost signals and tend to make oscillations worse, it is like having an unconencted secondary on a tightly wound transformer. The braided cables wires are in very close and intimate contact, and alonjg the length, they will couple electrostatically. The capacitance does not go down that much, and the delayed energy stroage goes up.Jon Risch
There is a BIG difference in speaker cables. Both electrically and sonically.Once again, Jon's recommendations fall right in line with other knowledgable experts in the field. While the values for the Zobel network tend to vary slightly depending on whom you talk to, they all tend to fall within a reasonably close range.
For a good read on speaker cables, hit the link below. Once your done reading this, click on "articles". There's plenty of other good stuff to dig into there. Sean
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As usual he brings into factors that don't relate to AUDIO..HV Transmission Lines...speaker wire ain't transmitting HV for hundred of miles..the analogy is flawed. But it thrills the unknowing.
It's possible that you have hi frequency oscillations occuring due to the hi cap. of the cable interacting with the feedback loop of the amp. These oscillations can occur with little or no impact to audible freq.
Jon Risch can probably help out with a zoebel network which helps counter the high cap. of the cables. Or try using shorter cat5 cable(50% shorter if possible) or using fewer strands to reduce the cap. of the cable. try 18 strands instead of 27, I used the 18 strand for 5 months before going 27 strand and the difference in sound was much different, tighter bass and with more impact, was the biggest difference.
Hope this helps,
Heath
Are you saying that the 18 strand was better with tighter bass or the 27 strand was better??
Should have read" and the difference in sound WASN'T much different..."
Heath
Two people have reported their amps run very hot when using the CAT 5 speaker cables. Any idea why this would be?Thanks,
Sean Heisler
D e s i g n _P o r t f o l i o
Are you sure it is terminated correctly ?
Make sure there are no shorts. Otherwise, the only logical explanation is your speaker is drawing more current because of the reduced impedence of the cable (which is good). But your amp should be able to feed it.
Yes, my earlier (and first post) had this as a postscript. My Classe 201 got much hotter than normal after I installed the 27 + 9 biwire CAT5. It was OK using just the 9 in a single run. I have no idea what caused this but discontinued using it after that.
Are you sure it wasn't running hot before you started using these cables? I owned the Mira for a time and that little sucker ran hotter than hell at times. The Mira should be cooking pretty good actually considering the speakers your driving. I don't know, maybe the Cat 5 cables pose some sort of impedence problem, I don't have the expertise here.
Sean Heisler
D e s i g n _P o r t f o l i o
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