Best practices on running multiple power amps?

[rj2wells]

I have two sets of speakers and I want to drive them from two seprate power amps, like, Fosi v3's.

The setup would be: (audio source) -> (potentially a DAC) -> [two different amps] -> two sets of speakers

My naive idea is just to split the RCA cable between the source/DAC and the amps, but I'm not sure if that's the best way. My concern is about timing effects and/or other gotchas. In theory the speakers are far enough apart that it shouldn't matter a whole lot - but sound from one room will blead into the other, since there's an open hallway between them.

Anyway, are there best practices here I should think about?

 

[staticV3]

I would first try a generic RCA splitter cable:


As long as the input impedance of your two Amps isn't too low, no issues should arise that aren't already inherent to RCA, e.g. GND loops.

 

[Speedskater]

Two thoughts:
a] need a plan for adjusting both systems.
b] turning OFF one amp may impact the sound quality of the other.

 

[rj2wells]

Thanks, I will try the RCA splitter cables! I have cables, a wire stripper, and some banana clips so I will just make what I need.

Initially this is going to be two sets of speakers and amps - one in the living room, one in the dining room. These are ceiling speakers that were installed by a pervious owner of the home, and my goal is to light them up on the cheap - using these Fosi amps, just to get it going.

In future if I catch the bug I may expand this system to include speakers in the kitchen and speakers outdoors. At that point I will have four "zones", and my idea is that every time I add a new "zone" I will add a new $70 amp to cover that zone. So in the future I may have to split that RCA cable twice, to make four zones.

Is there a limit on how many times you can split it? And if I start approaching that limit, or these "adjusting both systems" and "one amp may impact the sound quality of the other" issues start cropping up, what is the "right" way to implement multiple zones? Is the only right way to buy some big honking integrated amp with lots of zones, or can I make my plan of piecemeal expanding my system with additional power amps work?

 

[staticV3]

Is there a limit on how many times you can split it?

Yes. The more Amps you plug into the DAC's Line out, the higher the load becomes that the DAC has to drive.

For efficient impedance bridging, the load impedance should be 10x the DAC's output impedance or more.

You can use a parallel resistor calculator to calculate the total load impedance, given the input impedance of each Amp.

If the input impedance is unknown, then you can use a multimeter to measure the AC voltage drop of the DAC's Line out once the Amps are plugged in, and calculate the damping factor accordingly.

 

[rj2wells]

The other way I could go would be to daisy chain the amps with line out or pre out from one going to the input on the next. My worry would be that each step in the chain would add a slight timing delay.

 

[Holmz]

I have two sets of speakers and I want to drive them from two seprate power amps, like, Fosi v3's.

The setup would be: (audio source) -> (potentially a DAC) -> [two different amps] -> two sets of speakers

My naive idea is just to split the RCA cable between the source/DAC and the amps, but I'm not sure if that's the best way. My concern is about timing effects and/or other gotchas. In theory the speakers are far enough apart that it shouldn't matter a whole lot - but sound from one room will blead into the other, since there's an open hallway between them.

Anyway, are there best practices here I should think about?

1. why?
2. for what purpose?
3. what do you hope to gain?

 

[kemmler3D]

my idea is that every time I add a new "zone" I will add a new $70 amp to cover that zone. So in the future I may have to split that RCA cable twice, to make four zones.

I'm going to suggest you consider using WiiM Minis (or pros if you want to splurge) to feed the amps, they're about $60 each if you can find refurbs on eBay and you don't need to use splitters, run wires all over your house, or be concerned with the effects of impedance.

$60 is more than a decent quality, long RCA cable, but the prices should have the same number of digits.

I've got a handful of them in my place and they work nicely, even if you don't do streaming, you can use one of them as an analog input (I've got one with a turntable connected to it) and stream that to the rest of them.

What you're planning on doing should work, but you might run into funky problems as already discussed in the thread. Running an RCA cable long enough to reach multiple rooms might pick up interference, also.

Oh, and welcome to ASR!

My worry would be that each step in the chain would add a slight timing delay.

This is the only thing you don't need to worry about here. Analog audio will have effectively zero delay - once it's in the analog domain, the sound moves at the speed of electricity. The sound moves through the air vastly slower than the signal moves through the wires / amps.

The only time you really need to consider delay is when you're doing digital stuff, especially with multiple analog-digital-analog conversions, DSP, multiple DACs, etc.

 

[rj2wells]

1. why?
2. for what purpose?
3. what do you hope to gain?

I'm going to suggest you consider using WiiM Minis (or pros if you want to splurge) to feed the amps, they're about $60 each if you can find refurbs on eBay and you don't need to use splitters, run wires all over your house, or be concerned with the effects of impedance.

$60 is more than a decent quality, long RCA cable, but the prices should have the same number of digits.

I've got a handful of them in my place and they work nicely, even if you don't do streaming, you can use one of them as an analog input (I've got one with a turntable connected to it) and stream that to the rest of them.

What you're planning on doing should work, but you might run into funky problems as already discussed in the thread. Running an RCA cable long enough to reach multiple rooms might pick up interference, also.

Oh, and welcome to ASR!



This is the only thing you don't need to worry about here. Analog audio will have effectively zero delay - once it's in the analog domain, the sound moves at the speed of electricity. The sound moves through the air vastly slower than the signal moves through the wires / amps.

The only time you really need to consider delay is when you're doing digital stuff, especially with multiple analog-digital-analog conversions, DSP, multiple DACs, etc.

I guess I should provide a bit more context.

A previous owner of the house created some kind of multi-room audio system. They have already pulled speaker wire, through the walls, to a single central location from every room. All of this terminates in a cabinet that has a huge number of speaker cables coming out of a conduit. What remains of this system today, in addition to the wiring, are working in-ceiling speakers in the living room and dining room, and speaker wires that terminate on top of some cabinets in the kitchen where it would be trivial to connect a pair of bookshelf speakers. There are more wires to places as well but it's less obvious how to get it set up and/or would require some actual work.

(It took me a good amount of time poking around with a multimeter to identify which wires connected to these speakers, and then to identify the speakers - but I've done that now, and they work.)

My goal is to get what remains of this system working again. The dining room and living room speakers just need to be connected to an amp, and getting a pair of bookshelf speakers for the kitchen is trivial. So those three zones I will light up fairly quickly.

I like the wiim idea. I guess what I can do to start is put a single wiim in place, and just try and split the signal from it to the three different amps. If it starts to be a problem I can add a second wiim, or a third. That's a good path that doesn't involve throwing out stuff if it doesn't work.

I would note all the equipment is going to be colocated in this cabinet. The amps, wiims, DAC's, are all going to be together in one place with speaker wire carrying the signal out to the different rooms.

 

[kemmler3D]

I guess I should provide a bit more context.

A previous owner of the house created some kind of multi-room audio system. They have already pulled speaker wire, through the walls, to a single central location from every room. All of this terminates in a cabinet that has a huge number of speaker cables coming out of a conduit. What remains of this system today, in addition to the wiring, are working in-ceiling speakers in the living room and dining room, and speaker wires that terminate on top of some cabinets in the kitchen where it would be trivial to connect a pair of bookshelf speakers. There are more wires to places as well but it's less obvious how to get it set up and/or would require some actual work.

(It took me a good amount of time poking around with a multimeter to identify which wires connected to these speakers, and then to identify the speakers - but I've done that now, and they work.)

My goal is to get what remains of this system working again. The dining room and living room speakers just need to be connected to an amp, and getting a pair of bookshelf speakers for the kitchen is trivial. So those three zones I will light up fairly quickly.

I like the wiim idea. I guess what I can do to start is put a single wiim in place, and just try and split the signal from it to the three different amps. If it starts to be a problem I can add a second wiim, or a third. That's a good path that doesn't involve throwing out stuff if it doesn't work.

I would note all the equipment is going to be colocated in this cabinet. The amps, wiims, DAC's, are all going to be together in one place with speaker wire carrying the signal out to the different rooms.

Thanks, that actually makes more sense.

In this case, splitting the signal with wires should be OK (more or less). Splitting the DAC output too many times might make the amps unhappy, but that's a bit outside my wheelhouse.

One WiiM will work as a streamer, and like you say, if you want to add more separately controlled zones you can add more WiiMs. Likewise you can add totally separate systems in different rooms on the same WiiM setup to extend further, if you want.

 

[rj2wells]

Well I have not used a wiim before, I have seen videos where cheapaudioman claims they can be synchronized with one another? So if I have 2-3 of these connected to different amps i can control them all together from one place either through bluetooth or the wiim app? And they will synchronize their output? If so that is a good solution if splitting doesn't just do it.

 

[kemmler3D]

Well I have not used a wiim before, I have seen videos where cheapaudioman claims they can be synchronized with one another? So if I have 2-3 of these connected to different amps i can control them all together from one place either through bluetooth or the wiim app? And they will synchronize their output? If so that is a good solution if splitting doesn't just do it.

Yep that's their main use.

 

[rj2wells]

Yep that's their main use.

Great! I have a plan

 

[rj2wells]

I am trying the WiiM idea. It works out overall but it has some limits. The WiiM platform doesn't have the concept of a high pass filter and doesn't have a proper LFE. So subwoofers are a bit of a hack, you can play games with the EQ to simulate a filter but you can't completely take the bass load off the main speakers.

But other than that it's working out