Answered Seeking advice re choice of cable for long run between two amps

nickdc

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I'm hoping to connect the Zone2 audio output (standard rca ports) of an Arcam SR-250 to the power amp input (standard rca ports) of an Arcam A90 in a room at the other end of the house. The cable will have to be routed along the outside back wall of the house and I estimate the length of cable needed will be about 15m. I'd be grateful for advice on all or any of the following:

1. Is this a feasible project - a run that long and mainly exterior?
2. I assume the cheapest option would be to make up the cable myself, but I have limited experience and wonder if the extra cost of having the cable made professionally is worth it.
3. Recommendations for the type, brand or specs of cable I should use, trying to reasonably balance cost and quality.
4. Recommendations for the type, brand or specs of rca plugs I should use. (Assuming I make them up myself.)
5. Links or comments to help me make a good job of such a project.
 
Yes it is easily doable. If you are not comfortable making up the leads yourself most decent independent hifi shops should be able to make them up for you, but you can buy them of Amazon for around £20 and upwards.

If you are looking to run the cables outside I would recommend running them in 25mm round pvc conduit to add some mechanical protection. I recommend 25mm over 20mm as it will be easier to draw the plugs and cable through 25mm.

You may want to look for a well screened / shielded cable as it maybe susceptible to RFI given its length and location.
 
Just a thought but it might be worth asking in the classifieds to see if anyone has any long length component video cables they no longer need. I had some from pre HDMI projector days and did something similar and all seems to have worked fine. Might save you a few quid as not many people have use for them these days.
 
What source(s) are you wanting to send to the A90? Might be a better way.
 
What source(s) are you wanting to send to the A90? Might be a better way.
The SR-250 is a 2-channel AV receiver and as I understand it the zone 2 output consists of the preamp signal, which you can feed to a power amp in an adjoining room. The A90 has a preamp input and a switch to operate simply as a power amp. The SR-250 manual gives the preamp output specs as: Nominal output level = 1V RMS; Output impedance = 560Ω; THD+N (20Hz-20kHz) = -100dB (none of which, I have to confess, means very much to me). The sources I play on the SR-250 include vinyl, cds, music stored on an NAS, internet radio, streamed services etc. All of these except the vinyl can be played on the other system, but not at the same time and/or in sync.
I've already looked into using the local network, as the 250 has an ethernet connection and the A90 is fed by a RaspberryPi, but it's a no-go according to Arcam support - not impossible but an analogue wired connection much more viable.
 
Thanks mushii and Timmy C for your advice and suggestions. Very helpful. The rain having stopped I've now been able to take a closer look outside and it will need just over 20m of cable and I'll have to make it up myself as I won't get the phono plugs through the hole in the wall! I'll be using the existing holes which carry cables from a satellite dish. The walls are of masonry, extremely thick and containing a core of loose rubble - the professional who installed the tv dish had one hell of a job getting the cable through. I think there's just enough room to squeeze an audio cable alongside!
 
.... The cable will have to be routed along the outside back wall of the house and I estimate the length of cable needed will be about 15m. ...

You say "outside back wall" is that outside the house on the back wall or INSIDE the house along the back wall?

Then 15m (~50ft) is that point-to-point or is that the circuitous route the wire will have to follow to make its way around door frames and other obstacles?

Generally 50ft is regarded as the limit for standard wire. At 50ft (15m) the Inductance become significant and starts to rob signal. Though functionally when Wire Resistance is combined with Inductive Impedance, it is will on the somewhat small side.

Check out the Tables in this thread. 5% signal loss is considered acceptable, though I have calculated 1%, 2%, 3%, and 5%.

Actually it is taking too long to find that thread, so I will post the Tables here, though I will keep looking for that thread because there is more information in the discussion -

fivepercentcablec-jpg.560958


threepercentcablec-jpg.560674


twopercentcablec-jpg.560673


onepercentcablec-jpg.560672


Keep in mind that Inductive Signal Loss is Frequency Dependent, it start trimming away at the high frequencies first.

Here is one of the places were I analyzed Inductive Signal loss.

Cable Length as a Precent of Speaker Impedance Table -Post#14-

The analysis makes some assumptions that maximize the losses, I have a more realistic analysis, but it will take a while to find it. Off the top of my head, at about 3500hz, the Inductive Impedance is about 2%; at about 14,000hz, the Inductive Impedance is about 5%. At 50ft, Resistive loses are about 1.5%. Again, I will try and track that down and post it, but at the moment, the Forum Gods are working against me.

Steve/bluewizard
 
The SR-250 is a 2-channel AV receiver
I know, I have one. ;)

I was thinking that if it was only streaming required then that could be done with a couple of ChromeCast Audio devices, but that's no use with CD/vinyl.

I'd suggest taking advice from a cable manufacturer like Van Damme as well as using a protective conduit as previously suggested. You'll want a decent grade of cable due to both the length of the run & the environmental considerations of it being outdoors. You can get wall plates with screw terminals to make the installation easier & then just use regular cables between the wall & components.

I'd probably be inclined to stick with a regular line level input on the A90 so as to retain local volume control in each room rather than relying on the SR250s remote being in the right room at the right time!
 
As you can see from Post#7 above, the length of wire hinges on the Impedance of the Speakers, but common 13ga, which would be Euro 2.5mm² is good to 30m or 100ft.

Again, still not clear if you are actually running the speaker wire outside the house. If you are, then you need Outdoor Wire, which limits the possibilities a bit.

If inside the house, any common speaker wire is fine.

This KableDirekt comes in various lengths and is pure OFC copper - 50m x 2.5mm² = £36.40 -

https://www.amazon.co.uk/KabelDirekt-speaker-2x2-5mm²-Transparent-polarity-Red-Copper/dp/B01LFA7MHM/

You really don't need anything more complex than that, unless the wire is outside the house.

Here is one example of OUTDOOR/Direct Burial Speaker Wire -

https://www.amazon.co.uk/MutecPower-OUTDOOR-Speaker-Waterproof-protected/dp/B073RMNXDZ/

Just to illustrate that such wire actually exists.

Steve/bluewizard
 
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Thanks, BlueWizard for all your input, which is very informative and I shall retain for future reference, but atm, as the previous poster says, I'm not asking about speaker cable, but two-channel audio cable suitable for a preamp to power amp connection.
 
I'd suggest taking advice from a cable manufacturer like Van Damme as well as using a protective conduit as previously suggested. You'll want a decent grade of cable due to both the length of the run & the environmental considerations of it being outdoors. You can get wall plates with screw terminals to make the installation easier & then just use regular cables between the wall & components.
Thanks. Yes, I'll definitely use a conduit. And talking to manufacturers seems a good idea too, as so far I've not found much available online. Am I right in assuming "thicker is better"?! Eg I found this: BKL Electronic 1106001/25 Audio cable 2 x 0.14 mm² Black 25 m from Conrad.com which is also available as 0.38mm2. Presumably the latter would be better?
 
Thanks, BlueWizard for all your input, which is very informative and I shall retain for future reference, but atm, as the previous poster says, I'm not asking about speaker cable, but two-channel audio cable suitable for a preamp to power amp connection.

Sorry, my mistake, it never occurred to me that someone would run RCA Cable for 50 feet outside their house (I'm assuming).

But the problems are the same. However, I don't think they make Outdoor Coaxial Cable. Though you might get Antenna Cable to work. These are cables that typically start with the letters RG-xxx (RG-6, RG-58, RG-59,...).

One of these, though I don't know which one, has stranded wire for the center conductor. If I can judge by this photo, RG-59 has a Stranded Center Conductor -

"Belden 1505F RG-59/U Coaxial Cable 22 AWG Stranded Copper Conductor Dual Shield 75 Ohm Per ft. USA" from www.parts-express.com!

Again, this assumes you are running the cable outside the house. If inside the house, you can buy Shielded Cable in bulk lengths.

This Van Damme 4-CORE Wire could potentially carry both Left and Right Signals in a single cable -

Van Damme XKE Starquad 4 Core Cable. Balanced XLR Mic. Screened Bulk Reel TOUR

Bulk Cable - -Parts-

Of, again for inside, cable like this would work -

Sommer ONYX 2025 Unbalanced Twin Stereo Splitter Cable

Van Damme Twin HiFi Interconnet. Hi-Quality Stereo Shotgun Cable

But it is questionable how long these Audio Cables will stand up to sunlight and the weather when placed outside.

Still not clear on that point, whether the cable will be inside or outside the house. But outside cable, technically, has to literally be OUTSIDE Cable.

Any chance you could run the cable under the Floor?

Steve/bluewizard
 
For safety and to prevent the possibility of hum loops due to ground potential differences and the possible pick up of interference from near by mains cables (and the fact a long wire acts like an aerial), I would suggest you run an optical cable and use a Analog to Digital converter followed by a Digital to Analog converter (Toslink).
 
You could also consider using a Audio to Bluetooth converter and then a Bluetooth to Audio if you are close enough and not too worried about delayed audio.
 
Am I right in assuming "thicker is better"?
I'd have thought so but that then may create problems getting it through the wall. Hence my suggestion of talking the manufacturer to confirm suitability for the actual application.
 
Curious if it is possible to use XLR Cables which are Balanced Lines which are far more immune to picking up noise. If you have the cash, you could potentially consider RCA to XLR-Balanced converter and XLR-Balanced to RCA at the other end.

ART CLEANBox Pro Stereo Level Converter

The whole purpose of XLR-Balanced is to be able to run cables a significant distance.

Just as a point of reference, here are what XLR Cable look like -

Pro Neutrik XLR Cable 5m Black

Neutrik NC3MXX 3-Pin XLR Male Plug

Switchcraft XLR Female Plug

You would most likely have to terminate the ends yourself.

There are bulk cable wires that will support TWO/Stereo Balanced Lines -

Sommer Peacock Balanced Twin Splitter Cable (DMX Compatible)

But again, you run into the Inside/Outside dilemma. Outside cable has to be OUTSIDE Cable, weather and ultra-violet resistant.

Steve/bluewizard
 
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Some 20 years ago we had a requirement to run a TV and Video signal from a satellite reciever to a data projector in a conference room in another building at my Institute. My technicians, without my knowledge, . Constructed a SCART cable from multiple lenghts of satellite grade coaxial cable... A SCART CABLE and connector as USED IN europe , is a fore runner to HDMI, but analogue sound and video. The stereo analog sound signal is ,identical to that in a typical RCA cables but also it contains 3 video cables for RGB and another cable line and frame synch. Our cable was close to 100 metres.
Had I known in advance, I would have considered it a foolishness. Any way it worked perfectly. .
The only extra elements needed was that we terminated the cables ,at the projector with 50 ohm loads .
So my expereince is .
1.Get satellite grade coaxial cable,this may be eitther 75 or 50 ohm .. does not matter which.
2. At the transmitting end solder or screw in good quality RCA plugs.
3. Weather proof,by preference,but not strickly necessary as the cables should last 15 years ,.by using a conduit.. hose pipe, ? drain pipe ?.
4. At the reciever end, which will be going into the CD input of tthauxilary amplifier, it is desirable to terminate the cables. A resistor of value 50 or 75 ohm, ..even a cheap 20% tolerance carbon ,1/4 watt connected between the screen or braid and the central conductor. The screen continues then to the external or earth part of the RCA connector, and thet central conductor to the inner contact of the RCA. .. the selection of 75 or 50 ohms depends on the cable selected. The other advantage of these resistances is that they will kill any voltages induced by the long run.. Of course two resistances are needed, one for each channel.
 
Lots of interesting comments and good advice accruing here - many thanks to all. I need to sift through it all and think through my strategy. Cash is an issue, in that the project is not so important to me that I'm prepared to throw hundreds of pounds at it, but if I got a good solution I was sure would work I'd be happy to outlay up to £100, possibly a bit more. Once I've decided on the cable to use I could at least buy that (though presumably it's the biggest part of the outlay, unless I'm going for additional boxes of one sort or another), and test it out by simply laying it loose across the house. Only if it worked would I then have the extra expense and hassle of actually fixing it, with conduit, on the outside of the house. And yes, for those who've asked, I do mean the exterior wall of the house, exposed to the elements (though very little sun as it's a shaded north facing wall). Going under (solid!) floors or through interior walls is a non-starter, by the way. Again, thanks for all the helpful comments.
 
Although I'm not suggestion you shouldn't consider the right cable for the job, I bought a cheapy 10m regular internal HDMI cable from amazon or ebay and ran it through and along an outside wall in cheap flexible conduit. Been set up like that for 10 years now and still doing it's job just fine and at a very low cost.

Also came across this but have no real experience with making audio cables so not sure if it's any good to you...

Indoor / Outdoor Stadium Cables - Belden
 
I think that there is a lot of very good advice in this thread and some of it very technical but honestly, the OP would be better off just buying a 15 - 20m £30 cable from amazon, and just plug it in and see if it works. If it does, run it in the conduit, if it doesn't, or gets a lot of interference send it back and look at an alternative, such as pair of cheap ADC/DACs and a 15m toslink.
We are very good at overthinking stuff on these forums, but honestly, we aren't building the next Super Hadron Collider or installing a safety critical control system, its a pair of 15m cables linking two amps. Sometimes suck-it-and-see is the best approach.
 
I think that there is a lot of very good advice in this thread and some of it very technical but honestly, the OP would be better off just buying a 15 - 20m £30 cable from amazon, and just plug it in and see if it works. If it does, run it in the conduit, if it doesn't, or gets a lot of interference send it back and look at an alternative, such as pair of cheap ADC/DACs and a 15m toslink.
We are very good at overthinking stuff on these forums, but honestly, we aren't building the next Super Hadron Collider or installing a safety critical control system, its a pair of 15m cables linking two amps. Sometimes suck-it-and-see is the best approach.
A 50 metre drum of quality satellite cable from B&Q will cost 32 quid. A good enough quality RCA made up cable say 3 meres anything between 2 quid and 10 quid . . The more expensive ones have better connectors .. cut the RCA cable in half and splice both ends onto the coax cable. .. soldering is nice, but even screw connectors will do. Acquire your two resistors ..or do witthout.. i am recommending getting them , some sticky tape or better self amalagmating tape and you are sorted... 50 quid?. I
The point of my earlier post was that sending the RGB and video synch signals is much more denanding on the cables than the audio ,so there will be no problem . Its a pity your distance was not a bit shorter as the smaller drum is 25 m at half the price.
Satellite cables is well protected from outside weather.I have sections running in gutters for a decade now.
 
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@RBZ5416 He could still buy the cable and test. If it works cut the phono plugs off one end, strip and re-solder a new set. One less set of plugs to re-solder. Honestly this is not rocket science. As somebody who did years of CI's this is standard bread-and-butter kind of stuff. As an installer this would have been done and dusted in an hour, including installing the conduit.

The problem has been described and potential solution(s) put forward. Go forward and test the hypothesis - standard science / engineering 101.
 
@RBZ5416 He could still buy the cable and test. If it works cut the phono plugs off one end, strip and re-solder a new set. One less set of plugs to re-solder. Honestly this is not rocket science. As somebody who did years of CI's this is standard bread-and-butter kind of stuff. As an installer this would have been done and dusted in an hour, including installing the conduit.

The problem has been described and potential solution(s) put forward. Go forward and test the hypothesis - standard science / engineering 101.
Thanks again, mushii - I think this is the way I'm headed. Just needed the reassurance from those with the knowledge and experience that I wasn't missing something obvious. If I can get hold of some cable like the Belden that Timmy C posted a link for, I might even dispense with the conduit. Unfortunately Belden is US based; I'm actually in France so need to look at what's available here as well as UK and Germany - bound to find something suitable.
 

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