Fully Extendible RCA cable over Ethernet Cable

[mbhangui]

My favourite RCA cables have been by making them myself using cat5/cat6 twisted pairs. These twisted pairs have low capacitance and help in making the cable neutral. Over the years, bit by bit I have replaced all commercial cables using twisted pairs and each replacement has resulted in improvement of the hight end treble. Another thing I always did was to make exact length of the cables from the source to the destination. This helps in two things. It further reduces the effect of the cable on the music and also makes the connection a bit tidier.

This is how I terminate the RCA cables using the twisted pairs, filling the opening with molten wax using glue gun and hot air from de-soldering station to smoothen the wax. Having sealed the opening with molten wax makes the cable strong as the twisted pairs are thin and break easily at the point of solder on minor repeated movements of the cable.



One of my longer cables




Now one of the big issue making custom cables is that when I change my equipment or layout is that I have to remake the cables if they turn out to be too long or too short. Some 3-4 years back I had an idea to make an extendible RCA cable. So today I finally made it. Anyone of you can make this at home. This is what goes into making it

Material Required.

You need the following

1) Keystone jacks. We require two keystone jacks to make a RCA cable pair. This is what is inside ethernet panels that you see on walls. It has 8 slots where you can fix wires using a punch down tool. We will come to how to wire this later.



2) Punch Tool



3) cat5, cat6, cat7 cables. You need two 15 cm cables to make a RCA cable pair.
4) Cutter. If you get any standard ethernet crimping tool, you get a cutter like this



Procedure

1. Remove 2 cm of the sleeve from the ethernet cable from one and and 10cm of sleeve from the other end.
2. Connect the 2cm exposed portion to the keystone jack. Here is a youtube video showing how it is done. see this video from 1:12 to 1:46.
3. Untwist the exposed strands and connect the 2cm exposed end to the keystone jack. You will require the punch down tool. It is not difficult. You just need to follow this video. You need to connect two keystone jacks. After you have completed this, you will have the following


4). Now untwist the other longer 10 cm end. and make the following connections

1. Remove 2-3 mm of sleeve from 4 pairs.
2. Twist orange-white and blue-white exposed copper strands together. This will be the ground connection for right channel. Solder this joint to the ground pin of the right RCA plug
3. Twist full orange and full blue exposed copper strands together. This will be the hot connection for the right channel. Solder this joint to the hot (Center) pin of the right RCA plug.
4. Twist brown-white and green-white exposed copper strands together. This will be the ground connection for the left channel. Solder this joint to the ground pin of the left RCA plug.
5. Twist full brown and full green exposed copper stands together. This will the hot pin for the left channel. Solder this joint to the hot (Center) pin of the left RCA plug.
6. Assemble the RCA plug housing. Below is one of the pair fully assembled, while one pair doesn't have the cover assembed.

7) Test the keystone jacks. For this you connect the cable using any ethernet cable. Take a multimeter. Check the continuity of Center to Center for the left and right RCA plugs and also ground to ground for the left RCA plugs. Repeat the exercise for the right channel. If you have punched down correctly the continuity test should be OK. Also make sure that the ground and center pins are not shorted for any of the RCA plugs.​

Now if you want to short RCA cable, connect a short ethernet cable between the two keystone jacks. If you want a long RCA cable, connect a long ethernet cable between the two keystone jacks. If you want a RCA cable of custom length, make your own ethernet cable using a crimping tool. You just need to have Cat6 cable, a pair of RJ45 connector and a crimp tool.

See this video on how to crimp your own ethernet cable here.

The same concept can be used to make a fully balanced cable using XLR connectors instead of RCA plugs. The wiring will be a bit different. I will be making one tomorrow and post the details here in another post.

 

[mbhangui]

Tools used

1. Punch Down Tool. Link here.
2. Ethernet Crimping tool. This comes with ethernet tester, rj45 connectors and cable cutter. Link Here.
3. Cat 6 cable. 100 meters. Enough to experiment and learn crimping and make your own custom ethernet cables. Link Here.
4. Keystone jacks. Link Here.
5. RCA plugs. Link Here.

 

[mbhangui]

contd...
Today I applied the same concept to make an extendible balanced cable. Apart from being modular, the other advantage is that a single ethernet cable goes from the source to the AMP for both the channels. If you use any commercial balanced cable you will have to use two cables (one for left and another for right). Ulike the RCA connector the XLR connector is well designed. It can be pulled out and inserted easily and is much sturdy. IMHO the RJ45 connector is much more easier to insert and remove compared to the XLR connector. My cable gives me a easy way to connect and disconnect multiple equipments. You have 3-4 dacs and 5-6 amps, no problem. Just connect an ethernet cable between your source equipment and the consuming equipment. You don't even require a RCA switch.

A balanced cable consists of a XLR male connected to XLR female connector. This cable serves only for a single channel. For stereo you will need two such cables unless you use my method.

To make this cable the first thing you need is a pinout of the xlr male and female cable. Here is the pinout


So what I did was the following

1. Connect cat5 cable to the keystone jack just like we did for the extendible RCA cable. Two such keystone jacks are needed. I used 20 cm of cat cable cable. Stripped 5 cm of outer sheath at one and and 8 cm at other end.
   
2. For the right cable, orange wire was soldered to the hot pin, blue wire was soldered to the cold pin and orange-white + blue-white was soldered to the ground pin. This was done for both male and female connectors.
3. For the left cable, brown wire was soldered to the hot pin, green wire was soldered to the cold pin and brown-white + green-white was soldered to the ground pin. This was done for both male and female connectors
4. Using a multimer I confirmed that hot pin on the male connector showed continuity with the hot pin on the female connector. Similarly the cold and the ground pins on the male connector showed continuity with the correspoding pins on the female connector. This test was done for both the left and right connectors.

Soldering in progress







Final Finished two channel balanced cable with an ethernet cable connected.

 

[SatMumbai]

Looks amazing! With some Heat Shrink Sleeve on the twisted pair of cables it might look even more professional!

 

[mbhangui]

Now that the dust has settled, I calculated the cost of a single RCA to ethernet interface comes to around Rs 860 (excluding cost of tools and the cat5/cat6 cable). But once you have converted your RCA inputs and outputs to this RCA-RJ45 interface, the beneifit is immense as it allows ultimate flexibliity in making connections using any ethernet patch cords.

1. Keystone Jack - Rs 60 to Rs 80 on Amazon
2. RCA connector. Rs 600 to Rs 800 for a decent RCA connector pair.
3. Punch down tool, cat 5 cable, ethernet crimping tool (these are shared cost). The total will not cost you more than Rs 2000.

After I made the extendible RCA over ethernet cables using keystone jacks, I discovered many applications for the same. I could think of at least four use cases and tested them. I have now connected my headphone amp using this. My Balanced output dac is connected using this. Also my subwoofer is now connected using this with a volume control inserted in the chain. Few photos below

My Headphone amp can be connected to any of my source by just changing the patch cord.



Headphone amp connected to output of my graphic equalizer. Graphic equalizer also has my RCA-ethernet interface.



2. Volume control with RCA to ethernet interface connected to subwoofer input. So you can insert any volume control, preamp, graphic equalizer in your setup by just using ethernet patch cords.



3. Balanced to unbalanced converter. Reverse is not possible unless we use an active circuit to do phase inversion or use small transformers.



4. Connect source to multiple outputs simultaneously. e.g. you want the source to go to two headphone amplifers, simply connect this RJ45 splitter and use two lan patch cords to connect two headphone amps. You can also use this to connect your source to subwoofer as well as your amp (in case your source doesn't have subwoofer out).

 

[surfatwork]

Over 20 years back, I had the idea of separating the face plate and the main unit of an Alpine car stereo that I had in my car. I did this exact same thing. That allowed me to stow the main unit away somewhere and mount the face plate in the ash tray recess of the dashboard.
No pictures Sadly.

 

[mbhangui]

Over 20 years back, I had the idea of separating the face plate and the main unit of an Alpine car stereo that I had in my car. I did this exact same thing. That allowed me to stow the main unit away somewhere and mount the face plate in the ash tray recess of the dashboard.
No pictures Sadly.

I wouldn't have thought about this 20 years back. But I'm happy that I did. Yesterday it just struck me that I can insert any equipment in the chain as long as the input and output can be connected to RJ45 sockets. So I connected a volume control with this RJ45 socket. Now to control the subwoofer volume, I have inserted this between the output of my source and subwoofer input. Also another pair of inputs on my subwoofer used long RCA cable. I replaced that connection with a single patch cord replacing the RCA cable pair. Slowly I will replace all RCA cable pair with a single patch cord. The number of cable will become half of what it is now. I definitely think this is going to look tidier.

 

[rajan-]

really liked the idea...
especially the DIY balanced cables through ethernet.
I have been experimenting (with baby steps) on balanced components . Now its only between DAC and preamp (I run a DIY transformer based Balanced to SE converter, which is also reversible) .
the cable sizes are a problem. Being in IT I have easy access to all the items you have mentioned.

Are you going to go next step and go to "Dante" networks ?

 

[mbhangui]

really liked the idea...
especially the DIY balanced cables through ethernet.
I have been experimenting (with baby steps) on balanced components . Now its only between DAC and preamp (I run a DIY transformer based Balanced to SE converter, which is also reversible) .
the cable sizes are a problem. Being in IT I have easy access to all the items you have mentioned.

Are you going to go next step and go to "Dante" networks ?

What is the size of the DIY transformers that you are using. I have not yet reached there using transformers. Like you I;m now taking baby steps. For experiment sake I will be pulling out ethernet transformers from a switch. It has 4 windings (2 on primary and 2 on secondary). I have doubts if it can be used for audio, but will try it anyway. The size of ethernet transformer is small and attractive.

 

[rajan-]

What is the size of the DIY transformers that you are using. I have not yet reached there using transformers. Like you I;m now taking baby steps. For experiment sake I will be pulling out ethernet transformers from a switch. It has 4 windings (2 on primary and 2 on secondary). I have doubts if it can be used for audio, but will try it anyway. The size of ethernet transformer is small and attractive.

I didnt use DIY transformer, I made a DIY box using Jensen JT-11P-1 transformers for each channel. These are not exactly cheap. and they are also not exotic like lundhals or the likes.
they are quite small.

wiring pics are in https://www.hifivision.com/threads/balanced-to-single-ended-converter.97789/

the best use case is using these to connect balanced Dac to a SE valve amp. it just elevates the experience to a whole new level.


if you want to just experiment, I am sure there are many audio input transformers in the market. any electronics parts store will have them. 3 leads on one side and 2 on the other.

or commercial ones, These DI boxes are very common in the live / pro audio connections, available in guitar shops.

notes:
when you go from un-balanced to balanced (if you are using 1:1 transformers), you would need to crank up the gain bit more to get similar volume levels. if you use any other ratio transformers, you can on ly use them one way, not in reverse, you would lose the gains in the reverse direction (balanced to un-balanced.

doing balanced to un-balanced single ended conversions without transformers / active components like Opamps , not sure you will get full benefits, as well as risk damaging the amp as (I am assuming) one of the balanced signal wire will be connected to the ground or just left hanging ?.


never thought abt using transformer from ethernet switch as audio input transformer, or how the wiring would work for it. any details / pictures will be much appreciated.

 

[mbhangui]

if you want to just experiment, I am sure there are many audio input transformers in the market. any electronics parts store will have them. 3 leads on one side and 2 on the other.

or commercial ones, These DI boxes are very common in the live / pro audio connections, available in guitar shops.

Using the DI boxes is also in my mind.

notes:
when you go from un-balanced to balanced (if you are using 1:1 transformers), you would need to crank up the gain bit more to get similar volume levels. if you use any other ratio transformers, you can on ly use them one way, not in reverse, you would lose the gains in the reverse direction (balanced to un-balanced.

Thanks for this tip. The ethernet transformers are 1:1 transfomers. There are 4 transfomers inside an ethernet transformer, out of which two can be used to make a SE to balanced connection.

doing balanced to un-balanced single ended conversions without transformers / active components like Opamps , not sure you will get full benefits, as well as risk damaging the amp as (I am assuming) one of the balanced signal wire will be connected to the ground or just left hanging ?.

The cold end will be left hanging (it won't be connected anywhere).

never thought abt using transformer from ethernet switch as audio input transformer, or how the wiring would work for it. any details / pictures will be much appreciated.

I'm not sure these will work. I'm presuming that the impedance of these windings will be very low. But I want to try them out becaue of the tiny size of these transformers. Here is a detailed look inside an ethernet transformer. This is present in all devices that have the RJ45 port.

https://community.element14.com/members-area/b/blog/posts/peek-inside-an-smd-ethernet-transformer

 

[mbhangui]

another pair of female xlr cable and a pair of mail xlr cable completed today to connect my V3 Mono to my DAC's balanced output. This time I used MX platinum connectors. Good connectors I must say. I also used nylon sleeves and heat shrink to hide the twisted pairs.