Connecting 1 pair of speaker to 2 audio sources - Page 1
Forum section: electronics / projects

author: kian0079
author_rank: Contributor
timestamp: May 28, 2024, 02:47:02 am
content: Hi all,I have 2 different audio sources (a mp3 audio chip and bluetooth audio module) which I am trying to share 1 common pair of speakers. I was wondering if I can just connect the speakers directly to both sources or I would need an analog switch or something to switch the speakers between 1 of the 2 source? Only 1 source will be playing at any point in time.Thanks in advance.

author: ejeffrey
author_rank: Super Contributor
timestamp: May 28, 2024, 03:17:34 am
content: Are these powered speakers? Line level signals can be mixed with resistive combiners or with a simple opamp mixer. High level amplifier outputs should be switched with a mechanical switch or a relay.

author: themadhippy
author_rank: Super Contributor
timestamp: May 28, 2024, 03:20:21 am
content: If its speaker level outputs then your best to switch between the 2 otherwise 1 device will be feeding power into the others output stage,and thats a good way to let the smoke escape.

author: kian0079
author_rank: Contributor
timestamp: May 28, 2024, 06:47:58 am
content: These are just normal 8 ohm speakers。 The outputs of the of the mp3 and bluetooth module both have the speaker + and - outputs. It doesn't have any high power amps. These are earphone speakers.

author: aeberbach
author_rank: Regular Contributor
timestamp: May 28, 2024, 07:19:42 am
content: The device you need is a mixer. You will be able to find one with a built-in amplifier to drive unpowered speakers, search for something like "2 in 1 out stereo mixer amplifier".

author: donlisms
author_rank: Frequent Contributor
timestamp: May 30, 2024, 08:18:42 pm
content: Mixers are not generally designed to accept speaker-level signals as inputs, though you might be okay under some circumstances. They're never really designed to drive speakers with their outputs, either.I think the device you need is called a "switch."

author: Buriedcode
author_rank: Super Contributor
timestamp: May 31, 2024, 03:05:33 am
content: For two speakers, and two independant sources - that do not share a ground and have differential outputs to the speaker - a 4PDT switch would do. thats 4-pole (4 individual switching elements) Dual Toggle - which means the common of each switch connects to one of two connections.4-pole because each speaker has two connections, so Lspeaker+, Lspeaker-, Rspeaker+ and Rspeaker-.Now, they can be harder to find than simpler DPDT (dual pole, only two switches), but required because your sources may not share the same power supply, and they may (probably) drive the speakers differentially, that is both speaker+ and speaker- are outputs, rather than one "hot" output, whilst the other speaker connection is ground/0V.Thankfully, these days with aliexpress and many amazon/ebay electronics sellers, you can easily get 4PDT toggle switches:https://www.amazon.co.uk/5566AX408-6-35mm-Miniature-Toggle-Switch/dp/B0CJ31J3TX/ref=sr_1_5?c=tsfor example.Doing this electronically, solid state, using analogue switches could be tricky, as that would require a ground reference from each source and may involve them sharing the same power supply, which starts to get complicated and could introduce ground loops. Generally, if you're unsure of the signals, and you only need one thing switched at a time - a old fashioned mechanical switch will make life much easier. And if you require it to be switched by a signal, then a relay does the same job.

author: tooki
author_rank: Super Contributor
timestamp: May 31, 2024, 01:11:37 pm
content: Quote from: kian0079 on May 28, 2024, 06:47:58 amUnlikely. Earphones are practically never 8 ohms. (8 ohms is not entirely unheard of, but is exceedingly rare. 16-600 ohms is the usual range, with 32 ohms being typical of earphones and headphones for battery-powered portable gear, hundreds of ohms for large headphones intended for non-portable use.)Please share the EXACT makes and models of each playback module and of the speakers or earphones you intend to use.