amplifier bluetooth pc sound out connection

[rahulrahullll]

i have tda 2050 stereo board dual rail supply--------



i have bluetooth module ( blutooth, fm, aux modes) ---with output right and left signal out---

also my pc out right and left signal----

-----i want to connect them together----if i connect pc signal right and bluetooth signal right---together joining them --and attach to amplifier signal input--------and try to switch signal whenever i wish to hear either pc or bluetooth----WILL THAT BE OK----

--------OR IS THERE ANY OTHER WAY ?


-------thank you---------

[Zero999]

The TDA2050 is obsolete and no longer made. It's not a stereo amplifier IC, but mono.

Does the board have two TDA2050 or one? Do you want to connect the left and right channels from your stereo inputs together to drive your mono amplifier? If so, connect them together using resistors, 1k to 10k. Do not connect the outputs directly together, which can cause the output stages to go into current limiting and cause distortion.

[rahulrahullll]

thank you-----

i have 2 pcs tda 2050 board separate which drives 2 speakers--------------


i have bluetooth module ( blutooth, fm, aux modes) ---with output right and left signal out---


also my desktop pc signal out right and left signal----


-----i want to connect them together----if i connect pc signal right and bluetooth signal right---together joining them --and attach to amplifier signal input--------and try to switch signal whenever i wish to hear either pc or bluetooth----WILL THAT BE OK----did you understood---

--------OR IS THERE ANY OTHER WAY ?

--------thank you

[Zero999]

Designate one amplifier board as the left channel and the other as the right. Connect the 0V of both amplifiers together, which will be the case anyway, if they're being powered from the same supply. Connect the left input to the left amplifier and the right to the right.

If you need to switch between two different sources, you need a DPDT switch. Plenty of which can be found using a search engine.

[Brumby]

The two basic problems you may encounter are - ground loops and disparate signal levels.

If the circuits only share one common ground point, then the first problem cannot occur.  This problem is usually the result of two or more circuits being connected to the mains earth as well as via the signal cable.  If it happens, you will get an annoying mains hum coming through your amplifier.

The second problem is more obvious.  Generally, you can expect signals like you are talking about to be around 500mV - known as "line level".  This has been a pretty standard audio level for decades - although some early CD players pushed out 1V or more.  However, if you are picking up a signal from a speaker connection, then the level could be significantly higher.  If you have different types of signal source, you might have a problem with volume differences when you switch between sources - and the higher level source might overdrive the amplifier and cause distortion.  If there is this sort of disparity, then you could try adjusting the output volume of each source (if possible) to bring them to roughly the same level.  (You don't need a meter for this - your ear is quite capable.)  If there is a higher level that can't be adjusted, then a resistor divider can fix that.  If there is a low level signal that just doesn't cut it, then you will need a pre-amp.


HOWEVER - the above is just to cover some possibilities.  In all probability, you could do a simple hook-up and it will work fine.

[rahulrahullll]

---thank you----Hero999 and Brumby---------


Brumby---regarding ground loop----i made common ground for input, output connected to ground 0 v of dual rail transformer

and

--regarding---disparate signal levels----i was thinking to join right pc signal out and right bluetooth out together and 0 v of each together-----and connect them to amplifier input----when i switch on amp --bluetooth and pc both would be on--whichever i like play------------IS THERE ANY RISK OF DAMAGE TO AMP, BLUETOOTH OR PC --IF I CONNECT LIKE THIS  ?

Hero999---------is it this way what you are saying--------join right pc signal out and right bluetooth out together and 0 v of each together-----and connect them to amplifier input----when i switch on amp --bluetooth and pc both would be on--whichever i like play------------IS THERE ANY RISK OF DAMAGE TO AMP, BLUETOOTH OR PC --IF I CONNECT LIKE THIS  ?

--is there any need of DPDT SWITCH  or i can manage by connecting wires as described above---i have never used dpdt dont know how to connect   ?




----------thank you

[Brumby]

You should be reasonably safe with your amplifier - just start off with the volume control down low.

Changing wires will work, but it will soon wear thin - and you should make sure the amplifier is turned down, or better still, turned off when you do so.  Otherwise if you touch the signal wire going to the amplifier, you will get a nice loud BBBRRRAAPPP!!


Try it with the wires and if everything behaves, we can step you through adding a switch.

[rahulrahullll]

thanks----------somehow i manage to know how connect dpdt switch----------


right of pc out to right of switch contacts 1 and left of pc to left of contacts 1----

right of bluetooth to right of contacts 2 and left of bluetooth to left of contacts 2----

and 2 poles at center of switch connects to right and left input of amplifier---


but-----WHERE SHOULD I CONNECT GROUNDS OF PC OUT, BLUETOOTH OUT AND AMPLIFIER INPUT ?

[Zero999]

Connect the grounds together.

[paulca]

Twisting the wires together will "work".  I used to use a single amp to play multiple sources when I was a kid.

However, you will get greatly reduced signal levels and the signals may not balance out, one may be significantly louder than the other.

Line outputs, headphone outputs and speaker outputs expect different impedance ranges.  When you twist the wires together they share the impedance and different line sources react differently.  Most end up quieter by varying degrees and it's sometimes not even symmetrical across the stereo field.

If I twisted together the output of a Sony Walkman and a standalone tape deck headphone out (it was the early 90s) the walkman was almost muted and shifted to the right on balance, while the tape desk worked fine.

The options to avoid this are switched (favoured in HiFis) or mixed inputs (favoured in studios).  The former being much easier. 

[rahulrahullll]

THANK YOU EVERYBODY ----I WILL GO FOR DPDT SWITCH OPTION

[paulca]

Keep this in mind:

https://www.ebay.co.uk/itm/Numark-M101-USB-Mixer/152785200986?hash=item2392b5275a:g:p8MAAOSwjZhZ0ph8

Or any simple 2 channel DJ mixer.  You can get them new from £50 and second hand for peanuts.  Then you can listen to both inputs at once.