What speakers cables have high RF protection??

sts9fan · « **on:** 12 Mar 2007, 03:26 pm »

So I live in a pretty noisy area and am looking for some good cables for my Zu Druids. What types of speaker cables can give me RF protection? I am not looking to spend too much. <$200

TheChairGuy · « **Reply #1 on:** 12 Mar 2007, 03:52 pm »

The LAT International SS-1000's are shielded and very quiet (I used them while living in Washington DC just 100 years from the main TV and Radio towers so I know they work). They can be found used a very reasonable prices.

Any twisted design should have a little better RF rejection than others (Kimbers and Cat5/6 cables)...at the expense of higher capacitance, typically.

gooberdude · « **Reply #2 on:** 12 Mar 2007, 04:36 pm »

My expereience with cables that refect RF is way limited, but an old roommate has a pair of ridiculous Essence speakers...probably the best speaks i've heard. Every 1/2 an hour or so, with the system on or off, you can hear middle eastern jargon screaming through his speakers...been that way for years.

A few months ago i brought over my anti-cables, and for the 2 days i lent them to him nothing happened (so he sais)

His cables cost $3K a pair and are a huge diameter with shielding...

He must not have liked the a-c's too much since he hasn't bought a set, but they did work to curb this one issue. My friend is convinced cabbies here use really hi-powered 2 way radios rather than cell phones.

crazy when you hear words pop out late at night when all is quiet...all i hear is 'Jihad! Jihad!', even though they are just jibber jabbering.

cbalano · « **Reply #3 on:** 12 Mar 2007, 06:21 pm »

I recommend going with the cheapest cables you can get, and buy three or four Machina Dynamica's Clever Little Clocks.

sts9fan · « **Reply #4 on:** 12 Mar 2007, 06:43 pm »

So you think anticables have good RF rejection?

cbalano · « **Reply #5 on:** 12 Mar 2007, 07:03 pm »

Alternatively, you can create a kickass electromagnetic field conditioner yourself:

Step 1: Purchase two rolls of Aluminum foil from the nearest grocery store. Purchase 1 roll of Aluminum tape from your favorite home improvement store (like Home Depot).
Step 2: Store one aluminum roll and the aluminum tape in a freezer bag and put it in the freezer for 4 days.
Step 3: Wrap freezer bag with aluminum foil from the 2nd roll, then wrapped it in a thick towel and put it in the freezer for 12 more hours.
Step 4: Unpack the frozen roll and tape and put it in the refrigerator for 48 hours and then I put it in the coldest part of the house for another 24 hours.
Step 5. Count the p-traps in your house/apartment. (A p-trap is the curved portion of the drain pipe under your sink). Wrap ALL the p-traps in your house with the cryogenically treated foil. Use aluminum tape to hold the foil tight around the p-traps. Big Big improvement!!

gooberdude · « **Reply #6 on:** 12 Mar 2007, 07:07 pm »

I don't know, other than what i stated about my friends situation. We're not even sure what the cabbies use to talk with one another, but my friend (an engineer) claims its from hi-powered 2 way radios...which are supposed to be illegal here in Chicago.

i let him borrow the cables just to see what they sounded like compared to his uber $ set...removing the cabby talk was just a side benefit.

You could e-mail Paul Speltz about it too. if his cables won't work he might know what will.

Have you heard interference before or just trying take care of an issue before it arrises?

living so close to downtown, and in a large bldg myself, i've had no issues with any Speltz wiring.

Now, insert an unshielded IC in between my amp/preamp and its a difft story....but i think the amp
has a lot do with that issue. unshielded IC's are not a problem running from a source to the preamp.

matt

Dan Banquer · « **Reply #7 on:** 12 Mar 2007, 07:33 pm »

Try this link for more info:
http://www.audioholics.com/education/cables/bulletproofing-your-system-from-interference?searchterm=Bulletproofing

and BTW: twisted pairs are generally good for rejecting low frequency magnetic field. Also remember this: the shielding is only as good as the system grounding.
Have fun:
d.b.

Scotty · « **Reply #8 on:** 12 Mar 2007, 08:23 pm »

I think you should check with manufacturer of you power amp and ask them what provisions have been made to keep RF from coming back into the feedbackloop of the amp from the speaker cables. If adequate filtering has been done at the output of the amp no shielding of the speakercables may be needed
and you can save some money and hassle.
Scotty

In The Groove · « **Reply #9 on:** 12 Mar 2007, 08:31 pm »

I've read that JPS is well shielded. I've had good luck with Cardas.

Dan Banquer · « **Reply #10 on:** 12 Mar 2007, 11:59 pm »

Quote from: Scotty on 12 Mar 2007, 08:23 pm

I think you should check with manufacturer of you power amp and ask them what provisions have been made to keep RF from coming back into the feedbackloop of the amp from the speaker cables. If adequate filtering has been done at the output of the amp no shielding of the speakercables may be needed
and you can save some money and hassle.
Scotty

I'm sorry, I need to interject a few things about some of the gross misconceptions in the above quote on negative feedback and interference.
If you understand the basics of negative feedback then you must realize the output is always referred to other side of the diff amp at the input so the output is in a constant state of correction. So interference by definition can not really enter the amp at it's output. In addition any competently solid state power amp has a zobel filter at the output to attenuate any interference even further.
Interference of this type on speaker cables is caused by high frequency fields is actually an issue with the loudspeaker as the impedance of typical loudspeakers is quite high at RF. The high impedance acts as an antenna receiver and the speaker cable is the antenna that RF is induced onto. If the RF carrier has audio on it, and enough power, the breakthrough will happen and you can hear the audio portion of the RF transmission.
This is pretty rare and you have got to be living in close proximity to some kind of transmitter.
I hope this clears a few things up,
d.b.

Scotty · « **Reply #11 on:** 13 Mar 2007, 12:44 am »

Hey Dan, I thought that in order to hear an RF signal containing audio modulation you had to detect the signal. How does this take place in a loudspeaker. Or in other words where does the diode effect occur in the speaker. Regarding the the amplifier question,if an output inductor of some kind as well as a zobel network that has a sufficiently low filter pole is present,maybe he doesn't need the shielded speakerwires. He hasn't actually said he has a problem with RF noise. Maybe his amps are properly designed? If the speaker itself is the culprit, perhaps a simple zobel network across the speaker input terminals would take care of the problem.
Scotty

Dan Banquer · « **Reply #12 on:** 13 Mar 2007, 11:25 am »

As I mentioned in the link I posted Belden offers twisted pair with a foil shield in 14 AWG and 12 AWG. If I remember correctly the Belden numbers are 8718 & 8720. The shield is tied to the case of the power amp. I don't know of any diode effect in the speaker, although there may well be one, but this is more about the voice coil impedance at RF for this application. BTW: I am puzzled as to why one would put an additional Zobel filter on the speaker when you should have one on the amp, and the availability of the shielded speaker cable. Why add more stuff across that crossover? Why add more reactance to the load?
d.b.
P.S. I found I needed to use this stuff because I live within 50 or yards of a rather large Ham Radio antenna and his 100 watt transmitter. Again, I would like to emphasize that shielding on speaker cable is rarely needed, and really only if the user is in close proximity to some reasonably high power transmitters.

sts9fan · « **Reply #13 on:** 13 Mar 2007, 12:33 pm »

I am not sure I need it but I do live quite close to some very large towers. ~500 yards. Dan you may know where I am taking about. There are a few large towers new You Do it Electronics. Well I live almost under one. I have no idea what it does but I do hear voices through my speakers. Maybe it is my ICs

Dan Banquer · « **Reply #14 on:** 13 Mar 2007, 12:52 pm »

Quote from: sts9fan on 13 Mar 2007, 12:33 pm

I am not sure I need it but I do live quite close to some very large towers. ~500 yards. Dan you may know where I am taking about. There are a few large towers new You Do it Electronics. Well I live almost under one. I have no idea what it does but I do hear voices through my speakers. Maybe it is my ICs

I think you need to do at least two things. One is to read the link I posted thoroughly, and since you live in or close to Natick, you need to be follow good grounding practices, and take the shielding and filtering stuff mentioned in the article very seriously. Either that or move to Boxford.
d.b.

rollo · « **Reply #15 on:** 13 Mar 2007, 02:22 pm »

Quote from: sts9fan on 13 Mar 2007, 12:33 pm

I am not sure I need it but I do live quite close to some very large towers. ~500 yards. Dan you may know where I am taking about. There are a few large towers new You Do it Electronics. Well I live almost under one. I have no idea what it does but I do hear voices through my speakers. Maybe it is my ICs

Not sure about RFI, but if you live real close to power lines go to radio shack and buy a Gauss meter. Take a reading. If it is over 100 Gauss be concerned and call the utility company. The Govt recommends anything over 100 Gauss is harmfull. As far as RFI is concerned there is a product called the Sniffer which will locate the offender in the system.

rollo

sts9fan · « **Reply #16 on:** 13 Mar 2007, 03:21 pm »

I don't live very close to any major powerlines. Just the regular street ones.

Scotty · « **Reply #17 on:** 13 Mar 2007, 08:09 pm »

Dan, can you hear the ham operator with the just the loudspeaker and a speaker cable for an antenna hooked up, and no connection to the power amplifier? The zobel on the speaker terminals can help clean up the reproduction of high frequency
transients and tame sibilance problems due to ringing. The use of networks like this is often a two edged sword,you tame the problem but you may loose some air and extension.
Scotty

Dan Banquer · « **Reply #18 on:** 13 Mar 2007, 10:26 pm »

Quote from: Scotty on 13 Mar 2007, 08:09 pm

Dan, can you hear the ham operator with the just the loudspeaker and a speaker cable for an antenna hooked up, and no connection to the power amplifier? The zobel on the speaker terminals can help clean up the reproduction of high frequency
transients and tame sibilance problems due to ringing. The use of networks like this is often a two edged sword,you tame the problem but you may loose some air and extension.
Scotty

Not quite: I can remember shutting down the power to the amp and receiving the transmission. I also remember talking with one pro audio guy who was stuck setting up next to a TV transmitting tower who found the same thing.
BTW: Take a look at the impedance plots out to 2 Mhz in the link: They keep rising after 2 Mhz!
http://www.audioholics.com/education/amplifier-technology/switching-amplifiers-the-technology-and-the-issues

d.b.

Scotty · « **Reply #19 on:** 14 Mar 2007, 04:48 am »

You might have heard the result of the voltage on the rails dropping and the
diff pair becoming unbalanced which could have resulted in the RF break through.
You kind of have the ultimate noisy neighbor from an RF standpoint.
Scotty