Stereo to Mono lead

[TynanW]

A technical question . . . . !

I am making a lead, to come out of the Luxsin X9 (headphone amp) RCA stereo out, and into an active mono speaker (Aventone MixCube). I am summing the Left and Right ground wires, and then running each of the Left and Right signal wires through a 4.7kΩ resistor first, before also summing them as well . . . the idea is to stop any voltage feeding back into the X9's RCA outputs.

Can anyone who is better at the technical stuff tell me if this looks ok to them ? Thanks in advance !

 

[Count Arthur]

I've come across similar solutions, but the value of the resisters, looks a bit high.

Simple Way to Convert Stereo to Mono

Simple Way to Convert Stereo to Mono: This is going to be a tutorial on how to take a stereo audio source from a phone for example and convert it to a mono signal to use with a mono amplifier or a two channel amplifier( I'll show you how to do this), and anything that needs a mono signa…

www.instructables.com

 

[Devnull]

Do a search for Rane Note Why not Wye. IIRC should be 470 ohm and the summed output tied to ground through 10k, maybe 20k

 

[TynanW]

I've come across similar solutions, but the value of the resisters, looks a bit high.

Simple Way to Convert Stereo to Mono

Simple Way to Convert Stereo to Mono: This is going to be a tutorial on how to take a stereo audio source from a phone for example and convert it to a mono signal to use with a mono amplifier or a two channel amplifier( I'll show you how to do this), and anything that needs a mono signa…

www.instructables.com

Do a search for Rane Note Why not Wye. IIRC should be 470 ohm and the summed output tied to ground through 10k, maybe 20k

Thanks for the responses . . .

From what I have researched (bear in mind I am not a electronics guy, so take what I say with a pinch of salt) . . .

Tying the summed output to ground (a 'ground lift' or ground isolation') is only really needed for longer runs in noisy environments, my lead will be just 1.5m long and used at home, so I figured I'd keep to the more simple design, less for me to screw up.

And apparently that 470 Ω value is something that has been around forever, probably as far back as the 50s/60s, it comes from classic passive mixer designs where low-impedance summing was needed for pro audio consoles and headphone mixes, and became a standard that has simply been passed on through decades without really adapting to half a century of improvement in electronics and modern line level gear !

Apparently a better range is 2-10 kΩ

 

[SSS]

A technical question . . . . !

I am making a lead, to come out of the Luxsin X9 (headphone amp) RCA stereo out, and into an active mono speaker (Aventone MixCube). I am summing the Left and Right ground wires, and then running each of the Left and Right signal wires through a 4.7kΩ resistor first, before also summing them as well . . . the idea is to stop any voltage feeding back into the X9's RCA outputs.

Can anyone who is better at the technical stuff tell me if this looks ok to them ? Thanks in advance !

View attachment 474518

Seems OK to me. It is beneficial to have the resistors near the following amplifier input. Reason is that then the low output impedance of the Luxsin X9 can drive a cable capacitance better and noise from outside into the cable may be lower.

 

[TynanW]

Seems OK to me. It is beneficial to have the resistors near the following amplifier input. Reason is that then the low output impedance of the Luxsin X9 can drive a cable capacitance better and noise from outside into the cable may be lower.

Thanks for the input !

I think I followed most of that . . . so basically it's better to position the resistors at the speaker end (it's an active speaker with built in amp) rather than at the X9 end ?

I have made an illustration, so you are saying the lower version (pink) is preferable ?

 

[SSS]

Thanks for the input !

I think I followed most of that . . . so basically it's better to position the resistors at the speaker end (it's an active speaker with built in amp) rather than at the X9 end ?

I have made an illustration, so you are saying the lower version (pink) is preferable ?

View attachment 474704

Right. The pink one is the thing. Although you need stereo cable instead of mono cable in the yellow version. I sugest that you use a stereo cable where both channel leads are tied together. Depending on the type of connector at the mono end it is wise to put the resistors into the connector, especially when a screened one.

 

[TynanW]

Right. The pink one is the thing. Although you need stereo cable instead of mono cable in the yellow version. I sugest that you use a stereo cable where both channel leads are tied together. Depending on the type of connector at the mono end it is wise to put the resistors into the connector, especially when a screened one.

"Depending on the type of connector at the mono end it is wise to put the resistors into the connector"

My skills at soldering and my sausage fingers might prevent that from happening ! : ) So the resistors might just have to live outside the connector (but you are right, it would look neater if they were in the connector)

. . . . . .

"Although you need stereo cable instead of mono cable in the yellow version"

I'm a little confused by this ? Both versions are the same, yellow and pink, I've just positioned the resistors near one end or the other . . . maybe I don't quite understand what you're saying.

Here . . . I have stripped off all the plastic, just to leave the bare wires, to avoid confusion, two channels (stereo) going into one channel (mono).

I

 

[Sokel]

"Depending on the type of connector at the mono end it is wise to put the resistors into the connector"

My skills at soldering and my sausage fingers might prevent that from happening ! : ) So the resistors might just have to live outside the connector (but you are right, it would look neater if they were in the connector)

. . . . . .

"Although you need stereo cable instead of mono cable in the yellow version"

I'm a little confused by this ? Both versions are the same, yellow and pink, I've just positioned the resistors near one end or the other . . . maybe I don't quite understand what you're saying.

Here . . . I have stripped off all the plastic, just to leave the bare wires, to avoid confusion, two channels (stereo) going into one channel (mono).

View attachment 474716
I

It's actually easier to solder resistors at the connectors leads than wires.
You can avoid stray strands this way and the intra-resistance may be better (infinity)
Just keep their leads short, insulate them with some heatshrink, etc.

 

[antcollinet]

"Although you need stereo cable instead of mono cable in the yellow version"

I'm a little confused by this ? Both versions are the same, yellow and pink, I've just positioned the resistors near one end or the other . . . maybe I don't quite understand what you're saying.

In the pink version you need 2x cables from Output to input, since summing is done at the input end.

In the yellow version you only need one cable since summing is done at the output end.

 

[TynanW]

In the pink version you need 2x cables from Output to input, since summing is done at the input end.

In the yellow version you only need one cable since summing is done at the output end.

Thanks for the explanation, that makes sense, but the original post confused me with the comment: "you need stereo cable instead of mono cable in the yellow version" . . . . which sounds like it is suggesting that in the yellow layout I need to replace the mono cable with a stereo cable ?

Lol, as you can see I am easily confused : )

 

[antcollinet]

Thanks for the explanation, that makes sense, but the original post confused me with the comment: "you need stereo cable instead of mono cable in the yellow version" . . . . which sounds like it is suggesting that in the yellow layout I need to replace the mono cable with a stereo cable ?

Lol, as you can see I am easily confused : )

A stereo RCA cable is just 2x mono cables.

 

[TynanW]

A stereo RCA cable is just 2x mono cables.

Yes, even I understand that ! Lol : )
Not sure how that relates to:"you need stereo cable instead of mono cable in the yellow version" ?
Anyhow, pretty sure I have the design right, I appreciate everyone's input.

 

[antcollinet]

Yes, even I understand that ! Lol : )
Not sure how that relates to:"you need stereo cable instead of mono cable in the yellow version" ?
Anyhow, pretty sure I have the design right, I appreciate everyone's input.

OK - now I think I understand - I think he means (I'll add some words)

You need a stereo cable (in the pink version) instead of (the) mono cable (you need in) the yellow version.

 

[SSS]

Thanks for the explanation, that makes sense, but the original post confused me with the comment: "you need stereo cable instead of mono cable in the yellow version" . . . . which sounds like it is suggesting that in the yellow layout I need to replace the mono cable with a stereo cable ?

Lol, as you can see I am easily confused : )

I am sorry that my sentence was not clear enough. I meant that for the pink version you need a stereo cable instead of a mono cable in the yellow version.
Of course you may also solder the yellow version if it is easier to do and you need only a mono cable. It should also work if the cable is not super long (> 10 m or so).
My intention was to give the optimum version as to my experience with level dividers and stereo/mono adapters. Yellow version, for this one could calculate the low pass cut off frequency when cable length and capacitance/meter or total capacitance for the length as well the input capacitance and resistance of the following amplifier is known.