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Quick question about daisy chaining

Printed From: Speakerplans.com
Category: General
Forum Name: 12v Powered Systems
Forum Description: From Mini-rigs to ICE, all your low voltage audio needs here...
URL: https://forum.speakerplans.com/forum_posts.asp?TID=105845
Printed Date: 25 May 2022 at 3:24pm
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Topic: Quick question about daisy chaining
Posted By: TheORig
Subject: Quick question about daisy chaining
Date Posted: 05 November 2020 at 6:33pm
Hi all, 

Just a quick question about daisy chaining battery powered speakers!

I'm looking to build a few 12v battery powered speakers using class D amplifiers.

Most amplifiers I have looked at only have an AUX in. 

My question is: 

Is there a way to daisy chain the speakers using some form of aux splitter cable? (Ie one that connected from your phone, to the speaker, with an additional aux out you could then connect to a second speaker and so on) & would this affect the sound quality / volume as it goes down the chain?

or

Is there a way to wire an AUX out to the amplifier directly and install it on the amplifier face plate so I can daisy chain the speakers without affecting the sound quality / volume?

I'm unsure if the signal would need to be boosted somehow to maintain volume & quality and if so how this is achieved?

Any advice greatly appreciated!

Thanks in advance,
Theo Smile



Replies:
Posted By: studio45
Date Posted: 07 November 2020 at 2:24pm
You'll need to do some reading up on line level impedance and signal distribution. 

Basically line level signal sources are usually rated to drive into a minimum impedance (AC resistance to ground) of 1000 ohms or so, if you want to get all the available voltage (signal level) out of them. If you try to drive an impedance lower than 1000 ohms, you will lose some voltage level, and possibly gain some distortion. It's kind of the same as trying to run a power amp into too low an impedance, except at vastly lower power levels.

A typical line input might have an impedance of about 10,000 ohms. When you make a Y-split at the input, you are making parallel connections. So, the impedances of all the inputs divide in parallel according to the parallel resistor formula. One is 10k, two would be 5k, three would 3.33k....etc.
So, you could in theory chain up about 10 devices before the combined total impedance drops below 1000. if you need to use more than that, you'd want to get a line driver with two or more buffered outputs - then each output could drive up to 10 devices.

Note that the 10,000 ohm figure is not a standard. Some devices will be more like 47,000 ohms. Some may be less. It would be important to know this exactly in your application. 

The usual configuration of a line input is to have a load resistor to ground very near the input connection, probably the first component in the circuit after it in fact. The signal is then coupled via a capacitor to the actual line input amplifier. As the input amplifier itself has a very high input impedance (1 MOhm or more) that load resistor essentially determines the input impedance. So, if (with the device's power off) you measure from the input to ground with a multimeter, you should be able to determine the input impedance quite accurately. However, if there are any other AC paths to ground before the line amp input, you would need to know those too. EG there could be another resistor on the other side of the input cap. A schematic of your amp would be useful here.


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Studio45 - Box Builder Commotion Soundsystem -Mobile PA


Posted By: TheORig
Date Posted: 02 December 2020 at 11:23am
Thanks for the detailed reply!
 
I've began some research into the recommended areas. I don't have the schematic of the amp but I can tell you I plan on using the Zoudio AIO4CH  https://zoudio.com/product/aio4ch/ " rel="nofollow - https://zoudio.com/product/aio4ch/  ;

I would be using audio from a mobile phone into the aux in, which I plan to split to include an aux out. Then taking a second aux cable from the aux out and into the next speakers aux in, etc etc.

Thanks for your advice though, I clearly have a lot to read up about!

Theo :) 


Posted By: lutkeveld
Date Posted: 03 December 2020 at 7:57pm
Great choice on the amp ;)'

Both are possible, the principle is the same, only the point of splitting is different.

If you make a simple schematic of how you want to wire it, I can have a look to confirm if it would work or not.


Posted By: bitSmasher
Date Posted: 04 December 2020 at 8:48am
I'm yet to try it out yet, but I've bought a small cheap headphone distribution amp (that runs on 12v) for this purpose...
Might be an idea to explore, I'm hoping it will work as intended but the days of mobile rig linkup parties are a fair way behind us 


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https://www.instagram.com/batteryacidsoundsystem/


Posted By: TheORig
Date Posted: 04 December 2020 at 10:33am
Hi Lutkeveld!!

A great choice indeed ;)

I've made an incredibly basic diagram to help explain my thinking. Hopefully this image link works!

https://imageshack.com/i/poOmWMbXj" rel="nofollow">


I'm guessing I would need some sort of signal booster where I have the question mark and arrow if i wanted to daisy chain the speakers indefinitely?

And if anyone has any recommendations for something that would work to achieve this, i'm all ears.

I know the minirigs have an aux in and aux out and you can daisy chain loads of them, i've not heard of a limit to the number you can link together either, this is the principle i'm trying to achieve. 

If I didn't add any form of powered boost where the question mark is, then as mentioned above I presume the number of speaker I could daisy chain would be limited to a specific number.  

Also would there be anyway to wire the aux output from the board at some point after the bluetooth module? 

Like the minrigs, you can either bluetooth to the first speaker, or have a wired aux connection into the first speaker, then from the aux out using wired connections, continue to daisy chain as many as you like. This would be the perfect solution for the projects I have in mind. 

But either option 1 or 2 would be great if theres a way of achieving it :) 


https://imageshack.com/i/poyPjYv1j" rel="nofollow">


Please excuse my lack of knowledge in the area but got to start somewhere!

Appreciate all the advice!

Theo Smile


Posted By: slaz
Date Posted: 04 December 2020 at 9:42pm
Are you understanding what Studio45 posted on this ? We all know what you mean by daisy-chaining, he explained the issues very well.

If using a standalone BT receiver, better check its outplut level .... it'll likely be quite low - something akin to the output of a modern phone (i.e. very low). This in turn will mean you're very likely to need a line driver of some sort to get enough enough signal into your amplifier(s).

A line is just an amplifier to boost audio signals at high(ish) imedance (well - high relative to speakers).



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REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON


Posted By: TheORig
Date Posted: 05 December 2020 at 9:51am
Hi, Yes sorry, I think I understand the concept. I'm still reading up about everything, was an incredibly detailed post.  I haven't yet had a chance to measure what these output levels will be from either Bluetooth or aux and have been looking into line amplifiers but have got a little confused, do you have any links/examples that I can look at.

Thanks


Posted By: TheORig
Date Posted: 05 December 2020 at 10:06am
I'm going to do more research today and will post a more educated reply and schematic soon.
 
Thanks 😊 



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