How many times can you split a line level signal? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 9 Old 02-12-2019, 03:02 AM - Thread Starter
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How many times can you split a line level signal?

I use the Rec Out on my stereo to send a line level signal upstairs to my bedroom over a pair of these:

https://www.leviton.com/en/products/40735-RRW

It has been working well for the last 3 years.

I want to send audio to two more bedrooms. Can I split off this signal into two more lines without issue?

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post #2 of 9 Old 02-12-2019, 04:38 AM
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Quote:
Originally Posted by rmjb View Post
I use the Rec Out on my stereo to send a line level signal upstairs to my bedroom over a pair of these:

https://www.leviton.com/en/products/40735-RRW

It has been working well for the last 3 years.

I want to send audio to two more bedrooms. Can I split off this signal into two more lines without issue?
You can most likely split it several times before you realize any serious loss if your splitters are decent quality.

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post #3 of 9 Old 02-12-2019, 06:56 AM
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Unlike an RF splitter (which provides an impedance match to each destination at the expense of signal strength), a "splitter" when it comes to line level audio is nothing more than means of physically connecting multiple things to a single output. In other words, a "Y" cord. Each destination is connected to the output..and connected to the other destination(s). So there is no quality performance issue, other than good physical construction.

However, every audio output has several critical characteristics to keep in mind. They have a source impedance, and a maximum load they are capable of driving. Think of a source impedance as a resistor in series with an output of zero impedance. That's not exactly what it is, but it works for a basic model. So when you hang a cable on that model, you've added a capacitor (cable capacitance) a resistor and an inductor, which creates a network with a non-flat frequency response. Now before anyone freaks out, the frequency at which the response changes from flat is a function of the specifics. If an audio device has a very low source impedance, and it's driving a cable with low capacitance and low inductance, into a high impedance device (load), the break point is far, far above the audible range. This happens when we plug in a relatively short cable between two normal audio devices.

When you try to split an output to feed several devices, all cable capacitances, inductances, and receiving devices loads add. If the output has a typical line-level source impedance of 1K - 2K, cables are short, and the receiving devices input impedances are high, this might not be a problem at all. But if several devices are all driven through long cables, the high frequency roll-off point drops lower. And, if all devices input impedances added together exceed the outputs maximum capability, other things can happen, like lower level or distortion.

In professional installations single audio outputs rarely drive more than two devices, typically just one. If there are multiple destinations, some form of active distribution device is used providing each destination with it's own low-impedance source.

Back to the original question, the answer depends on how many devices, how long the cables and of what type, and the output impedance of the driving device as well as the intended use. Background music is not critical, and can suffer a bit of high end loss without notice. So likely there will be no perceived issue.

But the other problem more likely to run into is the potential to create ground loops. The chassis of different devices at some distance away and powered from different electrical outlets may be at different ground potentials. The result could be hum. There's a cure for that as well, though, and it's not expensive or difficult.

Go ahead and wire it all up, see what you get. If you have problems, stop back here and we'll take care of them. My bet its, it'll be just fine if you don't go too crazy.

Here's a cheap distribution amp (you don't have to use the video portion).

If you get hum, here's a cheap ground loop isolator.

Note that the two devices above do not do the same thing, and are not interchangeable, but can work together.
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post #4 of 9 Old 02-12-2019, 06:31 PM - Thread Starter
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Thanks for the excellent information.

One additional detail, the connectors I use run the signal over CAT 5E wire, which is 4 twisted pairs, 2 pairs per left or right. I believe these are 22AWG.

Would this factor into the equation?

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post #5 of 9 Old 02-13-2019, 12:42 PM
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Quote:
Originally Posted by rmjb View Post
Thanks for the excellent information.

One additional detail, the connectors I use run the signal over CAT 5E wire, which is 4 twisted pairs, 2 pairs per left or right. I believe these are 22AWG.

Would this factor into the equation?

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Cat5E is fine, so long as you use a balun at each end. You'll recognize the balun, it'll have an RJ45 jack for your Cat5, and a pair of RCA connectors to connect to your device. It's a bit more inside than just an adapter.
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post #6 of 9 Old 02-14-2019, 07:02 PM - Thread Starter
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Originally Posted by jaddie View Post
Cat5E is fine, so long as you use a balun at each end. You'll recognize the balun, it'll have an RJ45 jack for your Cat5, and a pair of RCA connectors to connect to your device. It's a bit more inside than just an adapter.
I don't think the Leviton connector I'm using is a balun. It seems to be working fine for me for the last couple years. What would putting in baluns give me?

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post #7 of 9 Old 02-14-2019, 07:32 PM
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Quote:
Originally Posted by rmjb View Post
I use the Rec Out on my stereo to send a line level signal upstairs to my bedroom over a pair of these:

https://www.leviton.com/en/products/40735-RRW

It has been working well for the last 3 years.

I want to send audio to two more bedrooms. Can I split off this signal into two more lines without issue?

Sent from my ONEPLUS A5000 using Tapatalk
Thanks for asking this! This is one of those questions I've always been meaning to learn the answer to.
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post #8 of 9 Old 02-15-2019, 02:47 AM
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Quote:
Originally Posted by rmjb View Post
I don't think the Leviton connector I'm using is a balun. It seems to be working fine for me for the last couple years. What would putting in baluns give me?

Sent from my ONEPLUS A5000 using Tapatalk
The connector you are using is not a balun.

They reduce noise and hum pickup on long UTP audio runs. If it works for you as-is, great.
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post #9 of 9 Old 03-02-2019, 01:00 PM - Thread Starter
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Would this work in place of the distribution amp?

https://www.crutchfield.com/p_937HA4...AMP-HA400.html

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