Stereo source--> Mono Amplifier: How to do it

[sarith]

Well, was listing all options, the end-user can choose what dish he wants, from the buffet :lol: The last picture of the RCAs to RCA (female) has an isolation balun.

:thumbsup:

 

[Aniket]

Then please do give your rationale behind the following statements

Sure.

can you please illustrate how you are using the 1K resistors?

Ideally, it should be like R output ->1K Resistor -> Mono input<-1k Resistor<-L Output

two resistors should be connected together at one end and connected to the input of the Mono Amp and the other ends to the outputs. If you want to be totally safe,Use a couple of 470uF capacitors in series to decouple, and a 47K across the mono amp input

Firstly,

If you are suggesting this outside the enclosure. i.e in the connecting link between the source and the amp( the cable itself), then surely you are going to introduce noise and RF and hum into the signal. the 470uF cap, obviously that would be an electrolytic cap, would act as antenna for RF signals as its case or can would catch RF. then the resistor, if you connect it in series with the cap, then worse, if between the amp input and ground then fine it would damp the noise in the signal, then of course, if it's outside the enclosure in the connecting link, then it's of no use.

Secondly,
It's my own experience, the noise and the RF thing. Let me explain. I was testing my new amp modules and used laptop as the source. what, I did was I made a connector using shielded wires with 3.5mm standard jack to go in the laptop at one end and RCA plugs at the other end. RCA plugs to go into the RCA sockets with 10uF non-polar caps in series with the signal going to the amp input (see pic attached) and 100k resistors across the L, R signals and ground. and the result was disastrous. lots of hum and hissing and RF disturbances. Instead what I did was, removed the 10uF caps and 100k resistors, shorted the left and right signal lines at the RCA socket and placed a 330pF cap across the amp input and ground at the RCA socket. Result was, all the hiss and hum vanished and the amp was dead silent.

That's why I commented:

Alright.... Good.
If you are suggesting this inside the enclosure at the input terminals.

Regards,
Aniket

 

[IndianEars]

That 330 pf accross the input makes me speculate that your amp (is not unconditionally stable) and was oscillating, creating the RF.

I view such (small value) mandatory capacitors across an amp input as a red flag for an unstable amplifier setup / design.

 

[drkrack]

I am making a Small Self Contained speaker which takes the sound input from any iOS device over wi-fi and plays it. That is the larger objective...

It uses a raspberry pi computer

Wouldn't Sending a Mono Output (down mixing to Mono, instead of Stereo Output) From the Rpi Software OS like Volumio, Moode etc an easier option?

Kindly ignore if the possibility of software solution has already been evaluated...

 

[kbhuvi]

Errr
Its a 2013 thread. Its not conclusive but I hope OP has bought a stereo amp by now.

 

[reubensm]

Yes and this thread was intriguing enough for me to play around with the different options mentioned, only to find that the best possible way to pull this off is to use a mixer

 

[SIDEWINDER18X]

Hi Group.
I have a Stereo source and I want to connect it to a Mono Amplifier.

I tried connecting by shorting the two channels via a 1K Resistor but I get very poor quality sound. When I connect only one channel (e.g ., only right or only left) then I get good output.

But I want sound of both channels to come from the mono amp. How should I connect the source?

regards,
Jawed

The most effective way would be to use a summing amplifier built around an op amp....
Vivek

 

[IndianEars]

Bang On The Button, Sidewinder18X ! It would be the perfect solution, technically.

But an Overkill IMHO.

I believe Greenhorn's Solution (Post #2) is probably best in this case, else a simple RCA Stereo To Mono Cable or adapter would be adequate.