DISCLAIMER

DISCLAIMER: Vacuum tube circuits work with dangerously high voltages. Do not attempt to build circuits presented on this site if you do not have the required experience and skills to work with such voltages. I assume no responsibility whatsoever for any damage caused by the usage of my circuits.

All rights of photos and text reserved. Usage of photos or text from my blog on other websites or for any other purpose only with prior permission. If you want to use any material from my blog please contact me by email.



Tuesday, October 11, 2011

How important are wire and cables really?

Hi!

Cables are a hot topic among audio geeks. Especially on discussion forums they cause heated debates which never seem to come to a conclusion. In this post I will try to shed some light on this topic from a different angle.

If you do not have the skills and experience to build your own audio gear, all you can do in terms of cable is exchanging interconnects, speaker wires and power cords. In this case a valid question would be how much of an improvement can a high quality interconnect bring, when the wire inside the components are of a lesser quality. If you look inside a typical preamp for example you have considerable lengths which the signal needs to bridge: from input jacks to the input selector switch, from there to the gain stage, on to the volume pot, back to a gain stage and then to the output jack. Some preamps might have more or less gain stages, some use PCBs, others point to point wiring and many a mix of both. Very rarely you will see the same type of cable as is commonly used between components. So how much can a better quality interconnect really achieve in this scenario?

It is a bit different if you build your own gear and can choose the connection methods inside the components and use your wire of choice wherever possible. But still there are many pieces of the signal path left which you cannot change. Let's have a look at our favorite amplification devices: The typical vacuum tube. In a triode, the signal has to travel through many connections and pieces of wire, many of different materials and very different connection methods, mechanical contacts, welded, crimped and soldered. The signal comes to the socket where it is soldered to a lug. If you are lucky, the solder lug and connection element to the tube pin are made of a single piece of metal. Sometimes, especially in sockets for larger tubes there are two. From the socket there is a mechanical contact to the tube pin. In Octal tubes, the pin is actually a shell which contains the wire which goes through the glass, it is soldered to the pin inside. Also the pins of  directly heated triodes like 2A3 and 300B which have UX4 bases are made like this. The wire which traverses through the glass is not selected based on good sound, not even by good electrical properties. Here the thermal and mechanical behaviour is important so that no cracks in the glass appear when the tube heats up and cools down. Sound wise this type of wire is probably at the same level as barbed wire used in fences. Let's move on with the signal path. Inside the glass, there is another piece of interconnecting metal between this wire and the vertical rods which hold the electrodes like plate, grid and cathode. The actual electrodes then are clamped or welded to these rods.

So on average there are about 5 pieces of different metal and 5 connection points through which the signal has to travel. And that for each electrode of the tube. Assuming triodes only this sums up to 15! And remember, probably none of the materials used are made of your favorite best sounding metal, also no audiophile solders used. In an optimized vacuum tube based audio system and assuming analog playback you will have at least 5 tubes in the signal path between cartridge and loudspeaker. Probably more. That sums up to about 75 connections and pieces of metal through which the signal traverses. But this is not all yet. You have a similar picture in the passive components like capacitors, transformers, etc. rarely the actual wire used in the windings of the transformers is directly brought out to a solder terminal. Especially in potted transformers there is often some piece of litz wire used to connect the solder terminal to the actual windings. Again these are minimum 4 connections. In addition you have jacks, selector switches, volume control, etc.

So conservatively counted this sums up to maybe 125 such connections per channel in your system. Most of them you cannot access and have no chance to use your favorite wire or connection method. This must cause sleepless nights to any cable fetishist. Considering this, how much influence can wire really have on the sound? Especially interconnects between components. Well designed components will have low output impedance so that cable parameters like inductance or capacitance will have no significant effect on the signal. Many of the connections inside components mentioned above are high impedance connections which are much more prone to be influenced by wire parameters, yet those are outside of our control!

Consider this if you are worrying if your wire and conenctions are optimized. Even if you replace all internal wire of all your gear with the best you have access too and carefully control all solder joints and connections, you only optimize maybe 10-20% . Not really worthwhile to get paranoid about.

Yes I also still optimize the wire, using teflon insulated solid core silver for internal hook up and for the inteconnects which I make myself. And yes, wire does make a difference in sound. But the difference is very small compared to the improvement which can be obtained by optimizing other aspects like circuit topologies, type of RIAA EQ, amplifier circuits, etc.

Glossy HiFi magazines seem to have steered the attention of ther readers away from the really important aspects towards such much less important details. Often you will read endless descriptions about cables, their construction and how they influence the sound. Rarely circuit topologies, amplification devices, capacitors or transformers are discussed. With optimizing these things the real differences in sound can be obtained.

I will not go into depth about power cords. Here the situation is even worse. Lengthy discussions about power cords and even silly things like fuses. Yet silence about power transformers, their core materials and if they have screens. Rectification devices? Rectification scheme? Filter topology? All these things have a huge influence on power supply performance and how sensitive a component reacts to disturbances from the mains.

All these more important aspects should be thought through and optimized first. Then it is worthwhile to also focus on details like wire. What is the point of a 200 Euro power cord on an amp with a crappy power transformer, and cheap filter chain? The reason why a power cord makes a difference (if there really is one) is most likely because of the cheap and noisy power supply it feeds. I'd rather fix the power supply in this case. Similar story with interconnects. If you hear a big difference between two cables, it might not be an indication of the quality of the wire, but rather a hint that the component driving the cable has an inadequate output stage which is affected too much by cable parameters.

Best regards

Thomas

9 comments:

  1. Hi Thomas,

    Really an interesting posting, tendencially matching my own experience: if you have a high quality component the sound is less affected by the cable. Indeed I made some interesting experiences by changing many connectors between my components over the years. But in the end cables are boring.

    By the way, there is a famous full range provider of hifi components from UK with focus on tubes. Their current price list shows that they offer a "state of the art" speaker cable (3m, stereo, bi-wire) for EURO 76,200. That´s even to much to be a joke - that´s for people being brain washed...

    Best regards,
    Carsten

    ReplyDelete
  2. It would be nice to inform the "power cord" fanatic people about how bad the main supply is. Its far from 230V sinus 50Hz. No cable in the world can remedy this. (maybe a cable on a magnetic core - but hey thats an inductor - not a cord)

    Its also interesting discussing bandwidth in cables regarding the audio spectrum (10Hz-50kHz (20kHz with some overtones for those with golden ears)). If the bandwidth is critical just use RG58 or equivalent RF cable - its used for extreme bandwidth RF signal - audio should fit and you get good screening for free.

    Electric current don't move faster in 99.99% copper compared to the 95% that cost a fraction.
    (most electrons are more not moving much anyhow - think of the cable as a water pipe - some water entering some OTHER water exiting)

    For amplifier cables just buy an expensive fridge and make you own supra conductor - its probably less expensive anyway...

    /The electric engineer

    ReplyDelete
  3. Amen

    Preach it brother!

    I have a friend who brings over high priced cable and I never notice a difference.

    I'll spend a little money on cables but only for looks. Why own nice gear and ugly cables?

    I could care less for megabuck cables or magic crystals or cryo'd blah blah blah :)

    ReplyDelete
  4. Hi Thomas,
    In my house is the power supply still a topic.
    Your advice, using an isolating transformer, was the answer to this problem.
    Maybe it can be a hint for others, too. Since I use this kind of transformer, I hear no differences between power cords anymore. The positive effect is more than obvious. In my opinion even 10 times 'better' than any power cords could be.

    Regards Martin

    ReplyDelete
  5. What is this optimization you mention few times?
    Accordingly to which target parameters?

    Audiophiles look for aftermarket cables to tweak the sound for their own taste and ears (claiming of course that they got an improvement on absolute scale)

    Which cables parameters really matter for sound?
    What is the correlation between resistance of cable and phase distortion? How cable capacitance influences sound warmth?

    ReplyDelete
  6. Hi Michael,

    not sure which optimization you mean. The point about this article is: Optimizing the circuit and passive components will yield orders of magnitude better results then playing around with cables. Well designed components will not be influenced much by cable parameters of interconnects.

    Best regards ... Thomas

    ReplyDelete
  7. Hi Michael,

    I just saw that there was some discussion about this in a forum in Israel. I tried to make sense through google translate. I probably misunderstood you. I thought you are asking about cable optimization since this comment was to the cable post. If I understand correctly, you wanted to know how I optimize my amplifiers in general.

    Of course mainly to my own idea of good sound, which means high resolution, yet a warm and musical sound. As neutral and transparent as possible.

    My design philosophies to reach this:

    Only as much gain as necessary.
    As much headroom in each stage as possible
    Selection of linear tubes and op points
    elaborate power supplies with tube rectification and choke input filters
    Mostly transformer coupling
    Very elaborate passivley filtered filament supplies
    Good passive components like caps, transformers, chokes.

    Hope this answers your quesiton

    Best regards

    Thomas

    ReplyDelete
  8. Would you be willing to elaborate on your teflon and silver interconnects? I realize and agree that this is a relatively minor aspect of system optimization, but I'm curious nonetheless.

    Great blog by the way, very interested in the 6CB5A amps.

    ReplyDelete
  9. Hi!

    Not sure what you are intrerested in. There is not really much to elaborate about. You already wrote it in your comment teflon insulated silver (thin solid core). And no, I will not bother to write an article about it ;-) There are too many other things which are 10 times more worthy to write about.

    Best regards

    Thomas

    ReplyDelete