Hi,
I need some advice for wiring unbalanced line level in a headphone amp.
The chassis is "long", the wire is going from the rear to the front, total of 12 inches.
The input goes directly to the pot, and from the pot to the input on the PCB.
I have done extensive searching here and will use coax from the RCA to the pot.
The inputs on the PCB are very close to the pot, about 2 inches. Should I use the same coax here as well, or will an unshielded twisted pair suffice?
In terms of actual cable, the closest thing I've found which has small diameter for internal wiring is Mogami W2330.
Although I would prefer solid, just because it is easier for me to solder on the pot lugs. An alternative I've found is Belden 8216/RG174.
Are these good options or does anyone have any other recommendations from own experience?
Thanks!
I need some advice for wiring unbalanced line level in a headphone amp.
The chassis is "long", the wire is going from the rear to the front, total of 12 inches.
The input goes directly to the pot, and from the pot to the input on the PCB.
I have done extensive searching here and will use coax from the RCA to the pot.
The inputs on the PCB are very close to the pot, about 2 inches. Should I use the same coax here as well, or will an unshielded twisted pair suffice?
In terms of actual cable, the closest thing I've found which has small diameter for internal wiring is Mogami W2330.
Although I would prefer solid, just because it is easier for me to solder on the pot lugs. An alternative I've found is Belden 8216/RG174.
Are these good options or does anyone have any other recommendations from own experience?
Thanks!
The central conductor in the Belden is copper coated steel and the Morgami is solid copper that is stranded. I'd pick the Morgami but I'm no expert!
Ah yes, had not realized that. It is stranded as well so no improvement over the Mogami (for my requirement)
Rg 400 has a copper stranded core. I have some and it is a bit stiff for some applications.
RG400 Cable | High Frequency Coax with Solid Dielectric & FEP Jacket
RG400 Cable | High Frequency Coax with Solid Dielectric & FEP Jacket
for example RG174 with copper conductor:
RG-174-U Coaxial Cable 26 AWG 100 Feet: Amazon.com: Industrial & Scientific
see Q&A for comments on the inner conductor
RG-174-U Coaxial Cable 26 AWG 100 Feet: Amazon.com: Industrial & Scientific
see Q&A for comments on the inner conductor
As long as the power (AC) is far away, I'd have no problem using unshielded wire for a short run to the PCB.
BTW, you could also consider using twisted (or untwisted) pair inside a braid shield for your signal wires.
Very interesting recommendations by Jon Risch...
in this case, Belden 89259 or 82259
http://www.pitt.edu/~szekeres/sub/usenet/diy1.txt
Peter
in this case, Belden 89259 or 82259
http://www.pitt.edu/~szekeres/sub/usenet/diy1.txt
Peter
It's very impressive that some people can 'remember' sounds heard years earlier, so precisely.
Fortunately, audio signals are often sufficiently robust that using the wrong cable will work OK.VictoriaGuy said:
I agree with you that subjective interpretations are just that, but it can be an indication that some of the physical and electrical parameters can have a positive or negative effect on the sound.
From a personal perspective, I cannot emit judgement before comparing and measuring it myself, but I do welcome other people’s opinions and put it in the balance. Sometimes it’s snakeoil, sometimes it’s worth investigating. The amount of time that will waste trying things will be added to the experience bucket... In my case, I have very limited experience comparing/evaluating internal chassis wiring.
Does anybody have any good reference documents or reviews about audio wires for each function (input, signal, mains AC power, heater, ground bus, etc...)
On my next tube amp project, I will make a point trying a few different input cables.
1- Belden 89259, 22awg, stranded bare copper, FFEP/FEP, 95% bare copper shield, DCR 15Ohm/1000ft, 17.3pF/ft, 0.092uH/ft
2- ....
I've examined quite a few old amplifiers, a few Hammond electric organs, and quite a bit of older (tube) test gear- including a couple of scopes -from HP.
I don't think I ever saw coax cable in any of them.
HF and VHF ham gear did use coax connectors between circuit boards.
You didn't see coax because wiring it takes time and money, so they used simpler methods which they knew they could get away with. That does not mean that twisted pair is the correct wiring method for an unbalanced connection, just that it is not sufficiently bad to matter in many applications. Let me say it again: TP for unbalanced is not better, but it is not always sufficiently worse that it cannot be used.
To me the term "coax" or co-axial cable, applies to an unbalanced, impedance matched transmission line, such as 75 ohm video cable where the source, cable and termination are all 75 ohms.
The stuff we push unbalanced audio through doesn't warrant (or suit) these characteristics, just an outer screen to reduce electrostatic interference to the centre signal core, which doubles as the return path.
OK you could argue that plain screened cable IS co-axial in construction but so is a wire poked through a tube🙄
There are all kinds of ways to improve an audio cable but I don't think any of them match those characteristics of video or RF coax.
The stuff we push unbalanced audio through doesn't warrant (or suit) these characteristics, just an outer screen to reduce electrostatic interference to the centre signal core, which doubles as the return path.
OK you could argue that plain screened cable IS co-axial in construction but so is a wire poked through a tube🙄
There are all kinds of ways to improve an audio cable but I don't think any of them match those characteristics of video or RF coax.
No, a wire poked through a tube is not necessarily coaxial. Coaxial means 'same axis' i.e. the wire goes exactly down the centre of the tube. Then the magnetic fields of the 'go' and 'return' currents cancel.
In some audio applications this is not necessary, so all we need is the electric field screening/shielding of the outer. Unshielded twisted pair will be inferior, although slightly better than untwisted wires. Shielded twisted pair will at best be no better than coax.
I strongly suspect that some people believe that because twisted pair is 'better' for balanced connections then it must be better for unbalanced too. Not true. At best it can almost equal coax, never better it.
Shielded twisted pair is good for pseudo-balanced connections, by which I mean a connection where one end is electrically floating and the other end is unbalanced. A pickup cartridge is the most common example.
In some audio applications this is not necessary, so all we need is the electric field screening/shielding of the outer. Unshielded twisted pair will be inferior, although slightly better than untwisted wires. Shielded twisted pair will at best be no better than coax.
I strongly suspect that some people believe that because twisted pair is 'better' for balanced connections then it must be better for unbalanced too. Not true. At best it can almost equal coax, never better it.
Shielded twisted pair is good for pseudo-balanced connections, by which I mean a connection where one end is electrically floating and the other end is unbalanced. A pickup cartridge is the most common example.
Also, a coax cable has a known intrinsic impedance given by their diameter ration and a log somewhere in the formula.
Simply shielded cable, doesn't.
Simply shielded cable, doesn't.
Looked all over his website for the " controlled subjective listening tests " not even a mention. Then went on to see the usual exagerated claims like skin depth being audible even tho his current sims show very little skin depth effect at 20 khz. Take all his recomendations with a grain of salt and read what DF96 says.
- Status
- Not open for further replies.