Cables - Signal loss - Buffers

There is a lot to say about cables, quality, affect on your signal, etc. I'll try to explain the fundamentals of guitar and speaker cables, signal loss and the help of buffers.

One important note: never use a guitar cable for speaker connections and vise versa!


Guitar cables
The output signal of a passive electric guitar is weak (high impedance) and directly influenced by the capacitance of cables and the impedance (resistance) of the used effects and amplifier inputs. When you only use a short guitar cable of high quality you won't notice much signal loss. But when you use several effects and longer cables, the loss is apparent for most people. Typical signs are loss of highs (brilliance), less clarity, weak low end, mediocre attack, etc. To prevent this low capacitance cables should be used, in combination with a way to change the high impedance signal of your guitar to low impedance.

For normal guitar cables the most important factor regarding the signal loss is the capacitance of the cable. This is measured in pF per metre or feet. If the capacitance of the guitar cable is high then you will notice that your guitar lacks some presence/highs. Sounds a bit like you've turned your tone control on your guitar down a fraction. Because capacitance is directly related to the length of the cable, the longer the cable the more noticeable the signal loss becomes.Now there are some guitar players who love the way their guitar sounds with long guitar cables, but I rather have this factor over my sound more in control. Due to the low power nature of the guitar signal, resistance is not really a factor.

A standard guitar cable has a capacitance of aprox 120 pF/m, a good cable has a capacitance below 100 pF/m and a high quality guitar cable has a capacitance below 50 pF/m. So a standard guitar cable of 6 metres has a capacitance of 720 pF, while a high quality guitar cable would have a capacitance of 300 pF. How important are these figures? Well connect a guitar cable of one metre between your guitar and amp and then change it with a cable which is 6 metres. Most guitar players will notice the difference.

What can you do to prevent signal loss? Well there are several options:

  1. Live with it,
  2. Buy extremely expensive low capacitance gold/silver audio cables,
  3. Buy active pickups for all your guitars,
  4. Buy on board preamps for each guitar you own,
  5. Buy an effect pedal which slightly boost the signal,
  6. Buy a unit which changes the impedance, such as the VHT Valvulator,
  7. Use a cable with a built in buffer.

Option 2 is a pretty nice solutions if you are a purist, but will cost you a fortune. The most cost and signal affective solutions are 3-7. They all change the impedance of the guitar and "protect" it against signal loss. Changing the impedance does not have to influence your sound, sometimes they are designed to boost the signal as well with some extra volume.

Because options 1-6 all had their down sides for me, I worked on a cable with a built in FET buffer placed in the jack that goes into the guitar. That way all my guitars have a buffered signal and I don't have to modify anything. The signal has improved a lot: besides the restored highs, I also noticed the clarity was much better, the attack more defined, the low end became powerful and the response of the volume knob was better. But best of all, when compared to a short high quality cable there was no change of my sound or the volume!  For more information on the buffer, check the Briljant Box Custom & Reactive Cable and the Guitar Signal Buffer page at the schematics section.

Shielding
To prevent noise, hiss, radio interferance a good shield is vital. Especially when you run them next to adapters, mains cables, transformers, etc. Never use cables with foil shielding, they will make a lot of noise.
 Although the "armoured cable" does an excellent job in shielding, the quality of the cable it self is quite poor, so do some research before you spend money on hoaxes.

Materials
Most cables are made from oxygen free copper (OFC). Many high quality cables use silver and gold. The difference in conductance between copper, silver and gold won't be noticed too much. The main advantage is the way they react to oxygen. Silver and gold are more prone to to this and this prevents the cable from getting "rusty".

Cores
It's preferred to use a cable with two cores and a shield, like a standard mic cable. They can be soldered semi symmetric which is the best way to prevent noise. For more on this topic see the Cable Wiring - Semi Symm page.

Connector
Always use high quality (jack) connectors from brands like Neutrik or Switchcraft. They are designed to survive road abuse. There is nothing more irritating then unplugging your cord and finding out that the tip of the connector broke off and is still in the amp.

 

Speaker Cables
With guitar signal cables, the capacitance was the most important factor, with speaker cables the resistance of the speaker cable is the key factor. Which is measured in most cases in Ohm/100 m or in Ohm/km. Anything from 6 Ohm/km is good.

Speaker cables are different from guitar cables. They have no shielding, but two thick cores. The more power your amplifier produces the thicker the cores have to be. For normal guitar amp use a 16 gauge cable would be a good choice. For minimum signal loss it's recommended to use 12 gauge speaker cables for 100 watt amps or longer speaker cables. The resistance of a 16 gauge cable is more then doubled, compared to a 12 gauge cable. Using even lower gauge (thicker) cables wouldn't give much more benefit. And finding suitable connectors will be quite difficult.

When you open a Marshall speaker cabinet you'll notice they use very slim cables. Upgrading to 16-12 gauge cables will improve the sound of the cab. Bogner for example uses 12 gauge for internal wiring of all their cabinets.

There are a wide variety of speaker cables available. When you buy it, keep a few factors in mind:

  • Gauge (how thick is it)
  • Resistance
  • Materials
  • Ease of use

    A lot of people who are on a tight budget use lampcord as speaker cable, although this is a far better choice then a guitar cable, it's not really designed for such use.


    For more information: