[depon]

Hi,

I want to make a splitter cable/adapter. The stereo source signal is going to split into two cables. The two cables will go through one rotating potentiometer each . Each will then end into its own 4pole socket/jack (R+),(L+),(R-),(L_-). Then one could attach headphones directly or separate (even balanced) headphone amps with headphones.

Will there be any difference in sound quality between the following cases?
If there is a possible preference in sound quality between the following cases, would someone please tell me in what order?
Does the cable length play any additional role in differentiating these cases any further? In other words, will any possible differences amplify in case of a short 0.5m cable or a long 5-10m one?

The difference between those cases have to do with the point where the cable splits... directly at the source point or at the pot-end point.

It would be really helpful for me to know in order to know what kind of cable to purchase since it will have to be a relatively thin one. Specifically, I would know whether I should choose a 4-6 or 8-conductor cable and the answer would save me experimentation time and money + teach me a thing or two.

CASE_1
(R+)-===========(pot1,pot2)
(L+)-===========(pot1,pot2)
(R-)-===========(pot1,pot2)
(L_)-===========(pot1,pot2)

CASE_2
(R+)-===========(pot1,pot2)
(L+)-===========(pot1,pot2)
(R-)------------------=(pot1,pot2)
(L_)------------------=(pot1,pot2)

CASE_3
(R+)-----------------=(pot1,pot2)
(L+)-----------------=(pot1,pot2)
(R-)-----------------=(pot1,pot2)
(L_)-----------------=(pot1,pot2)


Thanks in advance

 

[MindsMirror]

What kind of setup are you planing to create with this?

In general it is not a good idea in hi-fi to use a splitter to drive two different loads from one amp. It is also not good to use a volume pot between the amp and headphone. These things should be done to the line-level signal before the amp(s).

I would only use a cable like this to split your source to two different amps, and in that case you shouldn't need the pots because the amps will have their own. For driving headphones directly, it might work as a quick and dirty solution to let two people listen to one source simultaneously, but I would not use it in a hi-fi setup.

 

[buke9]

I agree what is it your trying to do? Just say what your wanting to do.

 

[depon]

Thank you both for your interest

What kind of setup are you planing to create with this?

I agree what is it your trying to do? Just say what your wanting to do.

Short answer: This is part of a portable mini kit which fits in a LxHxW=50x45x20mm aluminum box. The box in turn fits into a pocket. It is a setup that I've been using for 3-4 years now and I am very happy with it. It is time to update it. This kit makes my everyday "walkman"-cable management a breeze and allows me to share music with a partner very easily. I even use this setup as a rough motorcycle intercom (using two microphones attached to a single smartphone and a smartphone app) .

The source will very frequently be a smartphone. It can also be a computer dac , dap etc.
I imagine that this is considered line level...(?)
The sequence would be
_______
source→cable→pot1→amp1→headphones
_______→cable→pot2→amp2→headphones

The thing is that there are many times that i don't use an amp
source→cable→pot1→headphones
or even
________
source→cable→pot1→headphones
________→cable→pot2→headphones

That is one reason that I need the pots, so that each listener can adjust the volume indepedently in case I don't use the amps. In this kit update I also intend to use the pots to create passive mixers/switches so that I can mix/switch between 2 sources. This would allow me to do some other interesting stuff which I (or you) would rather not mess with you about. Even in the case that I use the pots as passive mixers there would still be the headphone amps to amplify the weakened signals.

For driving headphones directly, it might work as a quick and dirty solution to let two people listen to one source simultaneously, but I would not use it in a hi-fi setup.

What do you mean "quick and dirty" solution?
I have done some reading around the forum and I got the notion that the best/most correct way to split your signal to two headphones would be to split it to two separate headphone amps... though I still have not got a straight answer.... what is your opinion? Is there a better way? I would be very happy to implement any suggestion regardless of the difficulty.
https://www.head-fi.org/f/threads/dual-listening-amp-with-two-headphone-outputs.735133/
https://www.head-fi.org/f/threads/dual-output-headphone-amp.564666/

What would you consider the best/ most correct way to split the signal?
That's where my initial question comes in...
there are some cables out there that could do the job
eg https://www.aliexpress.com/item/10m...32231972438.html?spm=2114.13010608.0.0.0N4nYz
or even braid/make my own one
but before messing up more with my mind or yours, I would be really grateful to have your comment on my initial question in my first post.
Is there any point in splitting the signals close to the source? If the answer is "no" regardless of the length, then things would be easier for me.

 

[MindsMirror]

Thank you both for your interest
What do you mean "quick and dirty" solution?
I have done some reading around the forum and I got the notion that the best/most correct way to split your signal to two headphones would be to split it to two separate headphone amps... though I still have not got a straight answer.... what is your opinion? Is there a better way? I would be very happy to implement any suggestion regardless of the difficulty.
https://www.head-fi.org/f/threads/dual-listening-amp-with-two-headphone-outputs.735133/
https://www.head-fi.org/f/threads/dual-output-headphone-amp.564666/

What would you consider the best/ most correct way to split the signal?
That's where my initial question comes in...
there are some cables out there that could do the job
eg https://www.aliexpress.com/item/10m...32231972438.html?spm=2114.13010608.0.0.0N4nYz
or even braid/make my own one
but before messing up more with my mind or yours, I would be really grateful to have your comment on my initial question in my first post.
Is there any point in splitting the signals close to the source? If the answer is "no" regardless of the length, then things would be easier for me.

I mean that using a splitter from one amp to two headphones will work, but it won't be ideal for sound quality. Since you are asking these questions, I figure that you are wanting to optimize sound quality and you probably want to use the best approach which would be to split the source to two amps.

The reason that splitting one amp to two headphones is bad is because the headphones can interact with each other. A headphone driver also acts like a microphone. By connecting them with a splitter you allow some distortion generated in one headphone to be sent to the other. You can experiment and experience this yourself by connecting two headphones to a splitter, tap on one headphone and you can hear the sound coming through the other. Also two headphones provide a much more difficult load for the amp compared to one. Distortion, crosstalk, frequency response, etc. will all be worse.

For splitting the source to two amps, apart from the redundant volume pots your solution is the right way to do that. For this kind of setup there is no need to run separate wires to the two pots because the amp inputs are high impedance, meaning the cable does not carry any current. I would use case 3.

I haven't thought too extensively about the other use cases of mixing two microphones or two sources, so maybe leaving the pots on the splitter does fit your usage well enough even if it is not perfectly optimal for the two amps setup.

 

[depon]

That was really helpful!!!! Thanks!!
I will take everything into the deepest consideration.

One more tiny question though if you have the kindness:

For splitting the source to two amps, apart from the redundant volume pots your solution is the right way to do that. For this kind of setup there is no need to run separate wires to the two pots because the amp inputs are high impedance, meaning the cable does not carry any current. I would use case 3.

For the scenario that for some reason I don't have two amps with me... (eg I am on holiday-camping-whatever and I don't want to carry too many devices that need charging)
would there be a point to use case 1? Would case 1 for example lead to less interaction between the headphones?
See, I already own the 9pin cable the link of which I sent you. It would not be that much big of a deal.
Case 1 would only be slightly less convenient because I would need 10pins (L+,L-,R+,R-)X2 + (M+,M-) , which means that I will have to add the extra pin myself. (Strip 10pins and use soft-flexible silicone heat shrink)
If case 1 is better, I won't hesitate for a second to implement it. Convenience comes last. I would even do it providently if you think it wouldn't harm anyway... just to be sure that I have done my best.
Of course if case 2 or even case 3 would have the same or better results, then it would be at least dumb to choose case 1.

Just a comment to make some things clear: XD
Of course this is not a matter of life or death XD XD The thing is that regardless to the effect all this will have in my quality of life, I don't like the idea of setback. This is not entirely about the effect on myself... i may very possibly build this system for my partner or kids in the future and I want to know that I have given a good assist. The system could at any time take upgrade in certain parameters ( eg better amps, better headphones, better cables), but it would be good to know that everything else (eg technical design) have been done the best possible way, and that I would not reproduce mistakes of the past.

 

[MindsMirror]

Yes, case 1 would theoretically be ever so slightly better, or at least not worse. That is unless you want to start considering really minor things that you'll never notice like the weight and flexibility of your cable. Two extra wires add weight, another point of failure, etc.

 

[depon]

Thanks MindsMirror! You were most enlightening!!!