I carefully sliced into the sheath and then 'peeled' the sheath off....I can refit it pretty easily.
The braid was not contacted by the knife and didn't shift to any degree.
I don't think the tonal change is due to changes in cable geometry and consequent changes in electrical values.
Dan.
Waly,
I have a few cables that use RG-174 for audio test leads and have had them for over 15 years. There are no anomalies in their dimensions or performance. It is also used in 10 MHz applications (bench frequency reference) inside equipment when they don't use hardline. I can't see any evidence of your claims being an issue at these lower frequencies. I have seen RG-174 used at 100 MHz frequencies in oscilloscopes before as well. My definition of audio frequencies does extend to 1 MHz to take into account misbehaving circuits, but normally it is accepted to be a 100 KHz bandwidth.
Waly, there are labs everywhere using RG-58 type cables in applications far more stringent than audio where they can't afford signal leakage or signal pickup from these cables. I have never worked in a lab where they used RG-59. RG-6 yes, but not RG-59 ever. This cable run is between the frequency standard receiver and hte antenna. I also use RG-6 between my GPS receivers and the antenna. The loss in RG-59 is too high to be acceptable. THe only other place RG-59 is used is between the FM antenna and the equipment under test. I use RG-58 right up until it hits the 50R to 75R matcher and then to the antenna terminal(s) on the tuner section of a receiver or tuner under service.
I don't believe you have ever been exposed to these cables in a practical setting. You have never seen them used outside of your TV set.
-Chris
That is the entire point. A ridiculous connection that would allow the outer jacket to have a greater effect on the signal. I was exaggerating to show what would be needed to affect the sound the way Dan is suggesting it might. Please re-read my post more carefully.
I disagree with you rather strongly. There are labs that use RG-58c/u for signals in the audio band quite successfully. In fact, RG-59 is also an RF cable with a solid core making it less suitable for running signals on a non-permanent basis. Electrically these two cables differ mostly in their characteristic impedance. The connectors used with RG-59 requires a solid center conductor whereas a termination onto BNC can be done with stranded centers. You can also terminate RG-59 with a BNC designed for the higher impedance. The mating connector must also be rated for 75 ohm as the center conductor has a slightly different dimension, close enough to ruin the 50 ohm part (I think, not sure on that). RG-58c/u can have a foil shield as well, but it isn't that effective. Not compared to the woven shield. Just look up the % shield coverage for the two cables.
Well, the shield is compared to the frequencies you are trying to block. RG-174 is good enough for HP to use inside instruments, and several other test equipment manufacturers for low frequency use. It's also great for signal shielding inside the chassis if you can't use hook-up wire.
I have a few cables that use RG-174 for audio test leads and have had them for over 15 years. There are no anomalies in their dimensions or performance. It is also used in 10 MHz applications (bench frequency reference) inside equipment when they don't use hardline. I can't see any evidence of your claims being an issue at these lower frequencies. I have seen RG-174 used at 100 MHz frequencies in oscilloscopes before as well. My definition of audio frequencies does extend to 1 MHz to take into account misbehaving circuits, but normally it is accepted to be a 100 KHz bandwidth.
Waly, there are labs everywhere using RG-58 type cables in applications far more stringent than audio where they can't afford signal leakage or signal pickup from these cables. I have never worked in a lab where they used RG-59. RG-6 yes, but not RG-59 ever. This cable run is between the frequency standard receiver and hte antenna. I also use RG-6 between my GPS receivers and the antenna. The loss in RG-59 is too high to be acceptable. THe only other place RG-59 is used is between the FM antenna and the equipment under test. I use RG-58 right up until it hits the 50R to 75R matcher and then to the antenna terminal(s) on the tuner section of a receiver or tuner under service.
I don't believe you have ever been exposed to these cables in a practical setting. You have never seen them used outside of your TV set.
-Chris
There also could be trace amounts of ferrous contamination that would require occasional demagnetization.
My grandgrandfather did one of the first live recordings in the world with Paul Voigt as recording engineer, he wrote textbooks on acoustics and acoustics of musical instruments, was known composer and organist, was music teacher to 10 year old Alfred Brendel and now I'm a dentist. Go figure...😀
first-public-registration-of-a-gramophone-record-in-europe
Hi Dan,
-Chris
Well, that explains what you have done. But Ed is right, there would be a slight compression due to the outer jacket , or the shield would be able to slide around in normal use. Only enough to mess up the braid a little.
-Chris
Confirmed, I checked the service manual on vinylengine.com, the 126MkIII used a DC motor but the other versions all used a low voltage (~12V?) AC synchronous motor. If the motor seems to be bad, it could well be the electronics that drive it, or the motor clutch could be worn out.
Hi Scott,
Now you've done it. All kinds of "cable people" won't be able to sleep now until they have bought a bulk eraser!
-Chris 🙂
Now you've done it. All kinds of "cable people" won't be able to sleep now until they have bought a bulk eraser!
-Chris 🙂
Hi nezbleu,
I have a TD-126 MKIII somewhere. I just have to find it.
Yes, most Thorens motors are slow RPM AC motors that run with a quadrature drive signal. I have repaired many of these over the years. That includes the TD-125 MKII ( I have one of these, and a TD-126 MKII that uses an AC motor. My mother still has the TD-160 my father bought in the 70's. I think it is running fine. As long as the bearings remain lubricated, they shouldn't fail. But for those that do, I will need a different solution that may as well be crystal controlled and variable speed. These cover 33.3, 45 and 78 rpm electronically, no stepped pulley.
Thanks, Chris
I have a TD-126 MKIII somewhere. I just have to find it.
Yes, most Thorens motors are slow RPM AC motors that run with a quadrature drive signal. I have repaired many of these over the years. That includes the TD-125 MKII ( I have one of these, and a TD-126 MKII that uses an AC motor. My mother still has the TD-160 my father bought in the 70's. I think it is running fine. As long as the bearings remain lubricated, they shouldn't fail. But for those that do, I will need a different solution that may as well be crystal controlled and variable speed. These cover 33.3, 45 and 78 rpm electronically, no stepped pulley.
Thanks, Chris
I get to go to bed with my very own solder chick every night. She used to (many years ago) work the Tek 465 assembly line, ending up assembling the horizontal amps.
Cheers
Alan
Cheers
Alan
Try this as a plausible explanation- if there is a voltage difference between the center conductor and the shield (like audio signal) and an acoustically coupled vibration modulates the distance between the center conductor and the shield a voltage will be impressed on the center conductor. I know a guy who made perimeter alarms using a shielded cable strung through chain link fencing this way. They worked really well. Maybe what you get with the jacket stripped of is a subtle reverb. . . .
Except for some low end cabling most shielded coax uses a full braid. The Served shield (not braided) is not too useful for RF but makes for a much more flexible cable. And there are cables with only a foil shield (actually metallized mylar). Works well at higher RF but not well at low frequencies since its surface resistance is pretty high.Typically 95%. RG6 Quad is two layers of braid at 95% and two layers of foil and gets the shielding quite high. Its required for CATV networks to keep the interference from "leaking cables" at a minimum. Its less of an issue with DTV but still can be a problem. Usually not that stuff is called Cat 6 cable.
Most RG174/RG179 uses a PE inner insulation, not Teflon. And they have 95% braided shielding. The Teflon stuff has a different designation and uses silver plated braid (most is tin plated) and costs a LOT more. I have not seen any where the center managed to poke through the shield from bending (I'll look more) but it seems unlikely. It would be obvious with a TDR. Its hard enough to get it to poke through after stripping the jacket off to terminate the cable.
Except for some low end cabling most shielded coax uses a full braid. The Served shield (not braided) is not too useful for RF but makes for a much more flexible cable. And there are cables with only a foil shield (actually metallized mylar). Works well at higher RF but not well at low frequencies since its surface resistance is pretty high.Typically 95%. RG6 Quad is two layers of braid at 95% and two layers of foil and gets the shielding quite high. Its required for CATV networks to keep the interference from "leaking cables" at a minimum. Its less of an issue with DTV but still can be a problem. Usually not that stuff is called Cat 6 cable.
Most RG174/RG179 uses a PE inner insulation, not Teflon. And they have 95% braided shielding. The Teflon stuff has a different designation and uses silver plated braid (most is tin plated) and costs a LOT more. I have not seen any where the center managed to poke through the shield from bending (I'll look more) but it seems unlikely. It would be obvious with a TDR. Its hard enough to get it to poke through after stripping the jacket off to terminate the cable.
Carbon black is used in the outer covering primarily to give it long lasting UV protection but it will aid in shielding as well.
Aspects of Conductive Filler Loading on EMI Shielding and DC Volume Resistivity | Interference Technology
Transmission coefficient in cables coated with ferrite-graphite-paraffin | Download Scientific Diagram
THx-RNMarsh
Shielding of Boxes and Enclosures (Part 1) << Electronic Environment
Aspects of Conductive Filler Loading on EMI Shielding and DC Volume Resistivity | Interference Technology
Transmission coefficient in cables coated with ferrite-graphite-paraffin | Download Scientific Diagram
THx-RNMarsh
Shielding of Boxes and Enclosures (Part 1) << Electronic Environment
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I must live on another planet, I never seen a RG174 with PE isolation, and yes, brand name RG174 is expensive. I'm not excluding some cheap knock-offs are made on a ship sailing on the South China Sea.
Doesn't need to poke through the shield. Just hard bend (outside the recommended spec) a piece of such RG174 cable and use your favorite TDR. The discontinuity will poke you in the eye. Much worse that for RG58, but then RG174 has other advantages.
I use RG-58u to make the phono cables I sell. It has a solid core conductor. It's not the lowest capacitance but it works a lot better than most other stuff sold as audio cable.
The outer covering (protection against water. UV, abrasion etc) also adds to its' rigidity... removed could allow greater 'microphonics' from the cable with movement/vibration.
THx-RNMarsh
http://www.materialenkennis.nl/dico/UserFiles/File/PolyCond.pdf
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Agreed.Quote:
Originally Posted by 1audio
Try this as a plausible explanation- if there is a voltage difference between the center conductor and the shield (like audio signal) and an acoustically coupled vibration modulates the distance between the center conductor and the shield a voltage will be impressed on the center conductor..
Agreed, though don't think this is significant enough to be the main cause of the subjective change in this case.
Dan.
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Sorry, I double checked, the teflon insulated RG174 is actually RG188 or RG316. We don't use any RG174.
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With the limited current capacity of small signal amps, the C dominates in importance. But in PA, the C is second to the Ls of the cable. Just the opposite in first order importance.
THx-RNMarsh
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