olds1959special
Major Contributor
Mogami 2964
-
Welcome to ASR. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!
What wire to build my own RCA interconnects?
- Thread starter motorider
- Start date
Speedskater
Major Contributor
All the common coax cables that have an old RG designation and a braided shield are great for audio signals.
For a relatively small diameter and great flexibility but still good performance I have good luck with Belden 1505F. https://www.belden.com/products/cable/video-cable/coaxial-video-cable/1505f.
RG58 is very similar to RG6 (or RG59) and is essentially equivalent for audio cables. RG6 is very commonly used for video cables, has slightly less loss at RF frequencies (decades above the audio band), and handles more current, mainly a consideration for satellite dishes that send DC along the cable to power the amplifier mounted on the dish. For audio, RG6 is overkill, and is thicker and stiffer than RG58 (50 ohm) or RG59 (75 ohm) cables that are commonly used for audio RCA cables. The copper braid shield is typically 90~95% coverage, plenty for audio, and is more resistant to damage from flexing than the 100% foil shield typical of RG6.
Short answer: RG58 is fine, better than RG6 for you, so use it and be happy.
HTH - Don
I went with some WBT knockoffs and a 250 ft roll of 8mm monoprice microphone wire:
The cabling is an actual 8mm diameter, but at least half of that is insulation:
Sold as "oxygen free" and 97.5% shielded. Meh, true or not, cabling seems nice enough.
That's all soldered construction inside. The grub screw is only used to reinforce the mechanical connection between cable and barrel.
Center wires all combined for the pos pin, shield and the drain wire combined for the neg. Center wire is about 16G total. All of it is copper. Some short runs, some are 15-20 feet. There's a lot of it in the room, I've only got about 30-40 feet of the 250ft roll left.
All of it is dead quiet. Completely transparent to the signal, as cables should be.
Cost a little over 250 bucks to do it all. That's a little more than a buck a foot and an afternoon of lazy work. Was a great deal for that much RCA cabling IMHO. I've never believed in spending big bucks for premade cabling when you can make it just as good with a little care and attention. Not to mention, it's all custom length to my specific application. Not too much, not too little. All of it is "Goldilocks" length.
All it was really intended to do is tidy it all up the system, since this is the final state of my audio stuff until it all goes out into my estate sale (hopefully not the near future!). But there were some imbalances or something in my old mix of cables and making it all "uniform" made some channel imbalances disappear. Not that the cables "fixed" it, but the old premade cables were inhibiting it somewhere and it didn't become obvious until I changed the cabling.
Since it is intended to be the final form, I made some "organizers" in cad and 3d printed them out:
The top split loom holds the 12G RCA brand copper speaker wires.
Those are all about looking neat and tidy instead of a big bundle running along the base boards. It's not about "elevating" them off the floor or anything like that. I did it that way purely for neatness and organization, especially because there's some of the runs that are right out in plain sight. Black wire against white baseboards isn't really something you can hide, so might as well make them look neat and tidy instead.
The cabling is an actual 8mm diameter, but at least half of that is insulation:
Sold as "oxygen free" and 97.5% shielded. Meh, true or not, cabling seems nice enough.
That's all soldered construction inside. The grub screw is only used to reinforce the mechanical connection between cable and barrel.
Center wires all combined for the pos pin, shield and the drain wire combined for the neg. Center wire is about 16G total. All of it is copper. Some short runs, some are 15-20 feet. There's a lot of it in the room, I've only got about 30-40 feet of the 250ft roll left.
All of it is dead quiet. Completely transparent to the signal, as cables should be.
Cost a little over 250 bucks to do it all. That's a little more than a buck a foot and an afternoon of lazy work. Was a great deal for that much RCA cabling IMHO. I've never believed in spending big bucks for premade cabling when you can make it just as good with a little care and attention. Not to mention, it's all custom length to my specific application. Not too much, not too little. All of it is "Goldilocks" length.
All it was really intended to do is tidy it all up the system, since this is the final state of my audio stuff until it all goes out into my estate sale (hopefully not the near future!). But there were some imbalances or something in my old mix of cables and making it all "uniform" made some channel imbalances disappear. Not that the cables "fixed" it, but the old premade cables were inhibiting it somewhere and it didn't become obvious until I changed the cabling.
Since it is intended to be the final form, I made some "organizers" in cad and 3d printed them out:
The top split loom holds the 12G RCA brand copper speaker wires.
Those are all about looking neat and tidy instead of a big bundle running along the base boards. It's not about "elevating" them off the floor or anything like that. I did it that way purely for neatness and organization, especially because there's some of the runs that are right out in plain sight. Black wire against white baseboards isn't really something you can hide, so might as well make them look neat and tidy instead.
Last edited:
Wayne A. Pflughaupt
Senior Member
Adding to the the discussion of ohm ratings for the various RGs, I recall when I was researching my DIY article on making your own cables, I came across something that claimed RCAs are 25 ohm connectors! Kinda puts all those concerns about the cables to bed, doesn't it?
Regards,
Wayne A. Pflughaupt
25 ohms!?!?!?! Have not heard that, but since there are so many different "flavors" of RCAs, who knows? The ones I have measured have been around 75 ohms but it was originally designed as an audio, not RF, connector and so RF impedance was never part of the original spec AFAIK. Not until they stuck with it for video cables, probably for a cheap connector they already had vs. any real desire for signal integrity, did the RCA become "specified" for 75-ohm cables. I have measured anywhere from around 50 or 60 ohms up to maybe 80 or 90 ohms but have not measured them all -- not a thing for me since the RF connectors I used were generally rated for higher range and needed much better capture and RF characteristics. I am not even a fan of BNCs; they tend to get loose over time, and there's no way to make (and keep) them hermetic (though some specialized versions exist, e.g. HP/Agilent/Keysight versions). Folk get away with RCAs on video cables because they are cheap and the discontinuity is usually short enough to not cause big problems, especially given the relatively high signal level and short cable runs.Adding to the the discussion of ohm ratings for the various RGs, I recall when I was researching my DIY article on making your own cables, I came across something that claimed RCAs are 25 ohm connectors! Kinda puts all those concerns about the cables to bed, doesn't it?
Regards,
Wayne A. Pflughaupt
It's important to emphasize again (and I know you know, Wayne!) that RF impedance is irrelevant for audio signals.
sam_adams
Major Contributor
- Joined
- Dec 24, 2019
- Messages
- 1,576
- Likes
- 3,958
Below are some coaxial cable characteristic impedance calculators to assist in making a rudimentary determination of the impedance of your RCA connectors. To use them you will have to sacrifice at least one connector to determine the insulator diameter and the material. Deciding what the insulator material is will be the most difficult part. Just remember, that for our frequencies of interest, characteristic impedance does not matter.
https://www.pasternack.com/t-calculator-coax-cutoff.aspx
https://www.everythingrf.com/rf-calculators/coaxial-cable-calculator
I posted a less than comprehensive list of Belden, and a few other manufacturer's, coaxial cables that could be used for interconnects along with some construction tips in another discussion.
A new entry in the Belden product line is Belden 9223 Audio coax.
Just to note, I'm not shilling for Belden. The examples given were to illustrate some coaxial cable types that could be used and Belden provides specs for their cable that many manufacturers do not.
I posted some comparative measurements of a few cable samples to magnetic interference from an AC transformer in another old discussion. Make of them what you will.
https://www.pasternack.com/t-calculator-coax-cutoff.aspx
https://www.everythingrf.com/rf-calculators/coaxial-cable-calculator
I posted a less than comprehensive list of Belden, and a few other manufacturer's, coaxial cables that could be used for interconnects along with some construction tips in another discussion.
A new entry in the Belden product line is Belden 9223 Audio coax.
Just to note, I'm not shilling for Belden. The examples given were to illustrate some coaxial cable types that could be used and Belden provides specs for their cable that many manufacturers do not.
I posted some comparative measurements of a few cable samples to magnetic interference from an AC transformer in another old discussion. Make of them what you will.
This is extremely important if you want to pass microwave frequencies.
Speedskater
Major Contributor
The Radio Frequency Characteristic Impedance of a cable or connector only matters when:
The length of the cable or connector is a significant fraction of a wavelength at the frequency in question.
So at 50 megahertz that length might be in the neighborhood of one meter.
The length of the cable or connector is a significant fraction of a wavelength at the frequency in question.
So at 50 megahertz that length might be in the neighborhood of one meter.
What you and @SIY said and I want to third the statement in bold. It is not something worth considering for audio frequencies.
As an aside, I am not fan of Pasternack, too many bad cables and components over the years. No idea about their cable calculator, however; it is probably fine (if unnecessary for audio signals).
RF Impedance is irrelevant at audio frequencies. The only thing that matters is resistance, inductance, and capacitance (RLC) and for interconnects among local components even those do not matter since lengths are short. Companies like Belden, Gore, and Suhner provide that data for their cables.
As an aside, I am not fan of Pasternack, too many bad cables and components over the years. No idea about their cable calculator, however; it is probably fine (if unnecessary for audio signals).
No. And major disadvantages. Neither are optimal, but RG-6 is considerably stiffer and harder to handle. Unless you're trying to transmit VHF or UHF, you'd do far better with a very hum-drum flexible vinyl-insulated cable.
No, both will work fine, RG-58 is more flexible
Thanks, I already have a 300 feet roll of RG-58 coax cable.
The copper cladded aluminium and aluminium braid is psychologically tormenting
At the usual lengths, the estimated level drop is 0.0002dB - as opposed to the superb 0.00015 you get from pure copper.
At the usual lengths, the estimated level drop is 0.0002dB - as opposed to the superb 0.00015 you get from pure copper.
Thanks @Ropeburn - So at 6 feet the level drop would be completely negligible.
Hence, the notion that copper enables better treble frequencies is not true, right?
The fractional attenuation is linear - is that correct?
Similar threads
