Long audio cable run advice?

[sebdhaese]

Hi,

I'm putting together a sound system in two rooms with about 20 meters of cable distance to cover in between.

My question: Do I put the amp in the first room and run speaker wires to the second room?

Or do I put the amp in the second room and run rca wires?

Which of the two would have the least amount of impact on the sound?

[RasmusDC]

not really sure.. what you are talking about, so you want 2 speaker setups from one amp, why RCA then?

 

normally is not used on speakers.. to be honest, the least amplified signal is the one i would have the longest cable draw on, so i might do long RCA and short speaker cables. since you are drawing an amplified signal. 

 

20 meters is a long draw.. i would normally only do that with digital cables, and even that in cobber based cables can be an issue.

 

so you are sure the signal running RCA is not something that could be converted to digital and back again with a RCA to Fiber converter... so you would have a better signal? or is it simply not worth it?

[sebdhaese]

17 minutes ago, RasmusDC said:

not really sure.. what you are talking about, so you want 2 speaker setups from one amp, why RCA then?

 

normally is not used on speakers.. to be honest, the least amplified signal is the one i would have the longest cable draw on, so i might do long RCA and short speaker cables. since you are drawing an amplified signal. 

 

20 meters is a long draw.. i would normally only do that with digital cables, and even that in cobber based cables can be an issue.

 

so you are sure the signal running RCA is not something that could be converted to digital and back again with a RCA to Fiber converter... so you would have a better signal? or is it simply not worth it?

Thanks for the response.

 

The setup would be like this:

PC -> DAC -> AV Receiver (Amps room 1) -> Stereo Amp (Amps room 2) -> Speakers

 

If I would convert it to digital and back, I would need to buy another DAC and an ADC. That is getting costly.

The Stereo amp does have balanced XLR inputs, could that be a better option?

I would need to get a unbalanced-to-balanced converter then, because the receiver doesn't have a balanced output.

 

Shouldn't it be doable with thick 100% copper cables?

[anothertom]

49 minutes ago, RasmusDC said:

to be honest, the least amplified signal is the one i would have the longest cable draw on, so i might do long RCA and short speaker cables.

That is completely backwards in this case. We're comparing a line level unbalanced signal to an (essentially) balanced speaker level signal. You pretty much won't ever get interference on the speaker level signal, especially in a residential setting, whereas it's very easy to induce interference on a line level unbalanced signal.

 

22 minutes ago, sebdhaese said:

The Stereo amp does have balanced XLR inputs, could that be a better option?

I would need to get a unbalanced-to-balanced converter then, because the receiver doesn't have a balanced output.

Converting to a balanced signal would be much more sensible than digital (presuming you mean s/pdif / toslink, rather than AES) as it's more essentially a more resilient cable and a cheaper conversion. For a cheap way to do it a Behringer DI120 would do, better options exist but would cost more.

[sebdhaese]

1 hour ago, anothertom said:

That is completely backwards in this case. We're comparing a line level unbalanced signal to an (essentially) balanced speaker level signal. You pretty much won't ever get interference on the speaker level signal, especially in a residential setting, whereas it's very easy to induce interference on a line level unbalanced signal.

So you think that it would be fine with good speaker wire? I was planning on using 4mm² (~ 11 gauge)

How is normal speaker signal balanced? It is just 2 wires?

[Derkoli]

1 hour ago, sebdhaese said:

So you think that it would be fine with good speaker wire? I was planning on using 4mm² (~ 11 gauge)

How is normal speaker signal balanced? It is just 2 wires?

You can run very long runs of speaker cable with 11 gauge. I would do short signal cables, then long speaker cable. If your speakers are 6 ohm then you can get 35 ish metres with 11 gauge. With 8 ohm speakers I would say up to around 45-50 metres.

[anothertom]

2 hours ago, sebdhaese said:

So you think that it would be fine with good speaker wire? I was planning on using 4mm² (~ 11 gauge)

How is normal speaker signal balanced? It is just 2 wires?

Using 4mm² you can push a lot more power a lot further than the 20m you're planning.

The way speaker drivers work, using a positive and a sudo-negative (which specifically isn't a ground, effectively makes it a balanced signal. It's the voltage differential across the terminals that drives the speaker rather than the absolute voltage level when referenced to a ground.

[ShearMe]

17 hours ago, anothertom said:

The way speaker drivers work, using a positive and a sudo-negative (which specifically isn't a ground, effectively makes it a balanced signal. 

Speakers do not function on balanced signals, only interconnects do. If you do not have 3 conductors you cannot have balanced audio.

 

https://en.wikipedia.org/wiki/Balanced_audio#Internally_balanced_audio_design

[anothertom]

2 minutes ago, ShearMe said:

Speakers do not function on balanced signals, only interconnects do. If you do not have 3 conductors you cannot have balanced audio.

 

https://en.wikipedia.org/wiki/Balanced_audio#Internally_balanced_audio_design

You're simply wrong.

 

A balanced signal only requires two conductors, for the sake of argument a normal side and an inverted side (but this equally could be a positive and a non-ground zero). The signal is not referenced to a ground at any point, which is part of why it has the noise-rejection characteristics, but as the magnitude of the difference between the two signals (the normal and inverted). That a ground is usually included within the cable is not for use as part of the signal, but to maintain a constant ground through a signal chain. Hence, a speaker is effectively balanced, though in a different way to the signal from a microphone.

[ShearMe]

30 minutes ago, anothertom said:

You're simply wrong.

 

A balanced signal only requires two conductors, for the sake of argument a normal side and an inverted side (but this equally could be a positive and a non-ground zero). The signal is not referenced to a ground at any point, which is part of why it has the noise-rejection characteristics, but as the magnitude of the difference between the two signals (the normal and inverted). That a ground is usually included within the cable is not for use as part of the signal, but to maintain a constant ground through a signal chain. Hence, a speaker is effectively balanced, though in a different way to the signal from a microphone.

I'm thinking we're both wrong after digging into it a bit more. https://www.soundonsound.com/sound-advice/q-how-impedance-balancing-audio-different-normal-balancing

 

Yes, a speaker is naturally balanced..... IF both terminals have the same impedance to ground. You're not going to get common mode rejection if one terminal is grounded locally.

[circeseye]

• Eight-ohm speakers: 16-18AWG for 50 feet or less, 14AWG up to 200 feet, 12AWG for longer runs
• Six-ohm speakers: 16AWG for 50 feet or less, 12-14AWG for longer runs
• Four-ohm speakers: 12AWG for 100 feet or less, 8-10AWG for longer runs

https://www.cmple.com/learn/learn-about-choosing-the-right-type-gauge-of-speaker-wires

[anothertom]

6 minutes ago, ShearMe said:

I'm thinking we're both wrong after digging into it a bit more. https://www.soundonsound.com/sound-advice/q-how-impedance-balancing-audio-different-normal-balancing

 

Yes, a speaker is naturally balanced..... IF both terminals have the same impedance to ground. You're not going to get common mode rejection if one terminal is grounded locally.

Not sure what you think that article is saying, just an explanation of the different ways of balancing a signal. And again shows that using two conductors you can send a balanced signal (just in three different ways).

And why would you ever connect either terminal of a speaker to ground? That just wouldn't work*. It needs to be a full circuit through the amplifier to be able to actually drive the speaker properly.

 

* technically you could simply use a variable negative voltage to drive it within only half of the driver's excursion, but that's a horrible idea and would end with a hot melty mess rather than a speaker.

[ShearMe]

3 minutes ago, anothertom said:

And why would you ever connect either terminal of a speaker to ground? That just wouldn't work*. It needs to be a full circuit through the amplifier to be able to actually drive the speaker properly.

I thought that is what you were suggesting with the "Psuedo-ground" statement.

 

That's why I even popped in a reply. It's a very bad idea that gets used in automotive....