How many times can you split a line level signal with a Y cable before signal degradation?

[olds1959special]

Just curious...

I meant to put this in the newbie question section.

 

[solderdude]

That would depend on the performance characteristics of the buffer.
Output impedance, current capabilities and load impedance of the total load (so capacitance of all connected cables and load resistances).

 

[olds1959special]

That would depend on the performance characteristics of the buffer.
Output impedance, current capabilities and load impedance of the total load (so capacitance of all connected cables and load resistances).

Assuming typical performance characteristics of an unbalanced output from an audio interface? Am I asking that right?

 

[Keith_W]

That would depend on the performance characteristics of the buffer.
Output impedance, current capabilities and load impedance of the total load (so capacitance of all connected cables and load resistances).

Well perhaps you could help me answer the question from an electronics perspective (I am a complete electronics numpty). If you split the signal, you are effectively creating a parallel circuit. Assuming the resistance in both parallel arms are the same, the current is halved. My question: does this even matter, if the input is driven by voltage?

 

[Sokel]

Well perhaps you could help me answer the question from an electronics perspective (I am a complete electronics numpty). If you split the signal, you are effectively creating a parallel circuit. Assuming the resistance in both parallel arms are the same, the current is halved. My question: does this even matter, if the input is driven by voltage?

Given that the resistance that source sees is halved (for example, if both of destinations have the same) one can go to non-ideal scenarios.
Add capacitance to this and things can go south pretty quick.

One has to measure to know.

 

[solderdude]

Assuming typical performance characteristics of an unbalanced output from an audio interface? Am I asking that right?

That would completely depend on the output resistance of the audio interface for the line out and load impedances (including cable capacitance).

Well perhaps you could help me answer the question from an electronics perspective (I am a complete electronics numpty). If you split the signal, you are effectively creating a parallel circuit. Assuming the resistance in both parallel arms are the same, the current is halved. My question: does this even matter, if the input is driven by voltage?

When you split the signal and the source is low impedance you effectively will only increase the drawn output current (actually double it when the loads are the same). The output voltage will remain the same.

Things will differ when you have a higher output resistance and split to 2 different input devices. When those input impedances are resistive (most are) then you can expect a volume drop that is higher than when just one load were present. How much that will be depends on the output impedance of the source and load impedances of the load.

You will also increase the load capacitance but when the output resistance of the source is low enough this will not be audible (when using 'normal' interlinks).

 

[MaxwellsEq]

Just curious...

I meant to put this in the newbie question section.

Do you mean daisy-chaining splitters in series, or using a splitter cable with multiple outputs?

 

[olds1959special]

Do you mean daisy-chaining splitters in series, or using a splitter cable with multiple outputs?

Daisy chaining splitters in series

 

[mhardy6647]

3 dB per split, all else being equal... no?

 

[staticV3]

3 dB per split, all else being equal... no?

Splitters connect in parallel so there's no drop in signal amplitude, until you've connected enough sinks that damping factor drops significantly.

 

[MaxwellsEq]

In Thevenin equivalent terms, there's no difference between a single multi-output cable and daisy-chained splitters, but if the cable is questionable and connectors poor, then daisy-chaining could introduce more reactance or noise (and statistically more failure modes)

 

[solderdude]

3 dB per split, all else being equal... no?

Splitters like these simply have all tips connected and all sleeves connected, there are no passive parts inside.

 

[mhardy6647]

In Thevenin equivalent terms, there's no difference between a single multi-output cable and daisy-chained splitters, but if the cable is questionable and connectors poor, then daisy-chaining could introduce more reactance or noise (and statistically more failure modes)

This is all interesting, because I know from the good old days of OTA TV and antenna installations, the insertion loss of a coax splitter for VHF (which I don't think typically provided any passive impedance matching) was taken as nominally 3 dB. I thought it was just the price of doing business when one signal is asked to drive two loads. Admittedly, lots of variables between that case and this, though.

 

[wwenze]

A lot...

Here in the land of engineering, you discover the joy of exponential numbers.

For example, you have a line-in with 10kohm input impedance and an output with 47ohm output impedance. 10kohm vs 47ohm, it feels nothing

You split it to 2 outputs, two loads with 10kohm input impedance each. Load impedance is now 5kohm.
3 outputs, it's 3.3kohms. You need to double again, so 4 outputs, for load impedance to half again to 2.5kohm. Maybe sketchy, but most decent lineouts still do that, and we also have some speaker amp input stages that go this low...

1kohm load impedance, you need to split to 10 outputs

By the time you get to maybe around 100ohm where a NE5532 will start to choke (Info: NE5532 can output 26V at 600ohm), you will need to split 100-way

3 dB per split, all else being equal... no?

3dB of what at where?

If you mean +3dB of power and current sent out from the source, yea.

 

[wwenze]

This is all interesting, because I know from the good old days of OTA TV and antenna installations, the insertion loss of a coax splitter for VHF (which I don't think typically provided any passive impedance matching) was taken as nominally 3 dB. I thought it was just the price of doing business when one signal is asked to drive two loads. Admittedly, lots of variables between that case and this, though.

Ok, there's a key difference between RF and audio here...

Audio are impedance-bridged. Meaning you just provide an output voltage with as little output impedance as possible, into a load that draws a insignificant amount of current compared to the near-infinity current your source is able to output. Want to drop the load impedance? Double the number of receiver? The output doesn't care as long as it has enough current.

RF is impedance-matched. The straightforward meaning you probably already heard of it and can be googled anyway so I won't bore you. But what this also means is, in an impedance-matched connection, the source always outputs a specific amount of output power which can be calculated using the output voltage (squared) divided by the characteristic impedance. (Let's ignore phase.) The truth is a bit more complex (pun intended, not sorry) but at the very least the simple formula holds true when the connection is eventually terminated by a load resistor of identical value as the connection's characteristic impedance. The implication of this is, if you have to split that power to 2 loads, the power each load will receive will be halved since the output's power remains constant.

 

[DVDdoug]

Although there are too many unknowns, I'll throw a guess at you - 5 parallel loads should usually be fine. Probably even 10 loads. I am assuming a solid state source. Tubes (usually) have higher output impedance.

You can try removing the 1st split to to compare no-splits to the maximum to see if there's a loss of signal. But the volume of everything else should be turned-down so the sound in the room doesn't change (if the signal doesn't change).

This is all interesting, because I know from the good old days of OTA TV and antenna installations, the insertion loss of a coax splitter for VHF (which I don't think typically provided any passive impedance matching) was taken as nominally 3 dB.

RF transmission is impedance matched and the cables have a matching characteristic impedance. With a passive splitter you get an impedance mismatch, standing waves (SWR) and return loss. You're not "supposed" to do it but you can often get away with it, especially with an amplified signal (like cable TV) and short connections. If you are splitting an unamplified antenna signal you're more likely to notice the loss.

 

[wwenze]

The passive splitters for RF are made in such a way the impedance is preserved. And thus the -3dB per output.

Which port is input and which 2 ports are output is also fixed.

And we're supposed to do it. A house has heaps of it in the walls to split the TV cable.

 

[Peterinvan]

For RCA Y-splitters, I was using a cheap cable to split the output from my Loki+, that introduced an annoying hum.

I got these from Aliexpress and it fixed the problem.

https://www.aliexpress.com/item/1005007438297879.html?spm=a2g0o.order_list.order_list_main.5.68ad18020KBhHr

 

[olds1959special]

Splitters connect in parallel so there's no drop in signal amplitude, until you've connected enough sinks that damping factor drops significantly.

What would be better, using this, requiring an additional cable?

Or connecting 6-8 splitters together? With these?

 

[staticV3]

What would be better, using this, requiring an additional cable?View attachment 487573
Or connecting 6-8 splitters together? With these?View attachment 487577

No idea. I'd have to measure the resistance.