pjotr1852
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Pi, amplifier and speakers

Mon Jan 14, 2019 8:06 pm

I read the article of JP Evans to use a Raspberry pi to send on the 433MHz.
I have an amplifier and KEF-speakers. After my removal it's not easy in my new home to connect the speakers by wire again.
Does anybody know if I can use two raspberry's (stereo) 433 MHz connected at the amplifier and two receivers for the KEF-speakers.
If the answer is 'yes': is there documentation about this issue?
Thanks
Pjotr1852

drgeoff
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Re: Pi, amplifier and speakers

Mon Jan 14, 2019 10:26 pm

No, not really.

1. 433MHz units are not really suitable for transmitting audio signals.

2. Your speakers require significant amounts of power. Much more than a RPi can provide. You would need an amplifier between the RPi and speaker(s).

There are Wi-Fi speakers and Bluetooth speakers which might form part of a solution.

pjotr1852
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Re: Pi, amplifier and speakers

Tue Jan 15, 2019 8:39 pm

Hai drgeof
Thanks for your answer.
I know i need amplifiers for the Kefs.
They were very expensive that's why I wanna use them.
Bluetooth is also not an option?

Pjotr

drgeoff
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Re: Pi, amplifier and speakers

Tue Jan 15, 2019 8:59 pm

You cannot wirelessly convey sufficient power to make loudspeakers work. Doesn't matter if it is 433MHz, Wi-Fi, Bluetooth or any other wireless technology.

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Imperf3kt
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Re: Pi, amplifier and speakers

Tue Jan 15, 2019 9:32 pm

drgeoff wrote:
Tue Jan 15, 2019 8:59 pm
You cannot wirelessly convey sufficient power to make loudspeakers work. Doesn't matter if it is 433MHz, Wi-Fi, Bluetooth or any other wireless technology.
Sure you can.
It's just not plausible to use for audio.

https://en.m.wikipedia.org/wiki/Wireless_power_transfer
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LTolledo
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Re: Pi, amplifier and speakers

Tue Jan 15, 2019 9:49 pm

You will still need wires for powering your receiver (BT, WiFi, 433) + amplifier combo connected to your beloved speakers.....

...as I have no knowledge of any practical/out-of-the-shelf method of supplying large power wirelessly over distance .....
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

drgeoff
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Re: Pi, amplifier and speakers

Tue Jan 15, 2019 9:52 pm

Imperf3kt wrote:
Tue Jan 15, 2019 9:32 pm
drgeoff wrote:
Tue Jan 15, 2019 8:59 pm
You cannot wirelessly convey sufficient power to make loudspeakers work. Doesn't matter if it is 433MHz, Wi-Fi, Bluetooth or any other wireless technology.
Sure you can.
It's just not plausible to use for audio.

https://en.m.wikipedia.org/wiki/Wireless_power_transfer
None of those is conveying tens of watts over the sort of distance where the OP would have a real problem to use wires between his amplifier and his speakers.

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Imperf3kt
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Location: Australia

Re: Pi, amplifier and speakers

Tue Jan 15, 2019 10:25 pm

drgeoff wrote:
Tue Jan 15, 2019 9:52 pm
Imperf3kt wrote:
Tue Jan 15, 2019 9:32 pm
drgeoff wrote:
Tue Jan 15, 2019 8:59 pm
You cannot wirelessly convey sufficient power to make loudspeakers work. Doesn't matter if it is 433MHz, Wi-Fi, Bluetooth or any other wireless technology.
Sure you can.
It's just not plausible to use for audio.

https://en.m.wikipedia.org/wiki/Wireless_power_transfer
None of those is conveying tens of watts over the sort of distance where the OP would have a real problem to use wires between his amplifier and his speakers.
Laser, uv, visible light and microwave radiation can all supply the power required over long distances (one common example already in wide spread use is solar power)

But like I said, while technically possible, it isn't practically feasible to use any of these technologies.


Where did you get 'tens of watts' from? Many powered speakers only need 1 to 5 watts to be sufficient for PC use. I made my own 5 watt amplifier based on a PAM8406 that gets loud enough to require me to vacate the room or risk possible hearing damage.
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drgeoff
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Re: Pi, amplifier and speakers

Wed Jan 16, 2019 12:05 am

Imperf3kt wrote:
Tue Jan 15, 2019 10:25 pm
Where did you get 'tens of watts' from?
From the words "KEF speakers" in the opening post and "very expensive" in a subsequent one . One of the best well known names in British Hi-FI loudspeakers for years. More than 40 years since I bought mine.

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Burngate
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Re: Pi, amplifier and speakers

Wed Jan 16, 2019 10:46 am

https://m.uk.kef.com/products/ls50-wireless
They're £2k, so can be described as expensive.
And wireless - they apparently accept wi-fi and bluetooth - though there's a cat-6 connection between the speakers
They need mains power.

Roken
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Re: Pi, amplifier and speakers

Wed Jan 16, 2019 9:56 pm

If you have one Pi physically connected to the speakers, you can use pulseaudio to have all Pis output to those speakers, connecting to the pulseaudio server on the physically connected Pi.

I should qualify: On the client machines (i.e. those not physically connected), modify /etc/pulse/client.conf to include:

Code: Select all

default-server = tcp:192.168.1.64
Replace the IP with the IP of your physically connected Pi.
Headless PI. OMG, someone cut it's head off. Oh, hang on. it didn't have one to start with.

pjotr1852
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Joined: Mon Jan 14, 2019 7:50 pm

Re: Pi, amplifier and speakers

Fri Jan 18, 2019 9:52 am

That was amazing, reading my topic. Thanks for all reply's
Yes the Kefs were expensive.
There is 230V in the neigtborhood.
My idea was using PI like a Sonos or Demon system.
The audio is then going trough the air. Only in the living room is oke.

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