Reducing Hum & Noise


If you take this in account when trying to solve your problems, you will save yourself a lot of money and annoyance. Several factors can cause hum and noise in your system. You can either learn to live with it, use a noisegate (to pretend everything is fine), or you can solve the problems and enjoy your hum free system.

Reduce the gain of your high/mid gain sounds as much as possible
More gain = more noise. You boost the volume, so all present noises and hums will rise as well.

Keep mains cables and adapters as far away as possible from audio cables
Mains cables and adapters cause noise hum/noise when they are too close to audio cables, or even audio units, such as wah wahs. Keep them as far away from each other as possible. If mains and audio cables have to cross, make sure they do this at a 90 degree angle.

Use good shielded cables and equipment
To prevent radio russia, mobile phones, etc. from interfering use the highest quality of shielding available. This goes for all your signal cables (except speaker cables), guitars and audio units. Sometimes the internal transformer in a unit causes hum, thanx to bad design or cheaper elements. There are special shielding kits available to reduce their hum.

Keep tuners out of your signal path

Tuners = noise. Even higher price units, such as the ones from Korg, will add noise and reduce your signal quality. Use a fx send, headphone out, rec out or whatever to feed the tuner with a signal, but never place in in series in your signal line.< BR >
Try to use as less gear as possible
In most cases more gear increases the chances of hum and noise. An exception is a good switcher/looper/mixer ofcourse. But lots of units placed in series will raise the amount of hum. Try to eliminate all units that you really do not need from your signal line or setup at all.

True Bypass all stomboxes/units when they are not used
Although a stompbox/effect may be switched off, in most cases they still influence your sound. Rarely this has a good affect on your sound. Most wahs can easily be changed to true bypassed, which is highly recommended. With most stompboxes it's a lot harder. You could built your own true bypass box for each effect, but there are also commercial units which solve this problem. A 19" programmable looper, such as a Rocktron Patchmate, is a good solution too.

Split signals properly
When splitting the signal causes hum, use a splitter which uses a buffer and/or audio transformer. Most active splitters use a buffer circuit, but this is not always a good solution. Audio transformers are always a good solution to prevent groundloops and other forms of hum.

Buffer long cable runs
Guitar signals are unbuffered, unless you use active guitars or pickups. The unbuffered signal is a very weak and the capacitance of a cable has a large influence on it's sound quality. A very common reaction is loss of highs when long length of cables are used. Using low capacitance cables (< 20pF/feet) is always a good idea, but won't really solve the problem. Using a good design buffer circuit as soon as possible is a good solution. This will change the impedance of the signal, the volume stays the same, but it is powerful enough to run through long lengths. There are several preamp circuits available, VHT have built a nice Valvulator which does the same. But you can easily make your own. See REACTIVE CABLE and SCHEMATICS. Note: not all devices like a buffer signal, such as Fuzz Faces.< BR>
Use the best tubes you can afford
Tubes make your sound, unless you have a solid state amp. So their quality has a big influence on your sound, hum and of course noise. See See TUBES.

Get your tube (power)amp biased properly
A non biased amp can create some serious hum and noise, besides poor signal quality. See TUBES
Use quality pickups and make sure they are waxed right
They are the first thing to amplify the sound of your guitar. They are the source of your sound, so pay attention to them. To prevent unwanted feedback and the likes, good waxed pickups is a must. See links

Use regulated voltage adapters
In most cases they'll provide a cleaner and more stable power. Especially when connection more then one unit to an adapter, it's important to use a regulated one.

Give a wah exclusive power
Wahs don't like it when they share an adapter, so give them their own adapter, or use batteries.

Same mains phase
Because we have alternating current, our mains have a phase. If different units are receiving different phases (+ or -) then this will in most cases cause extra noise. Paying extra attention to the correct phase of your mains cables is something not many people do, simply because they don't know or don't believe. Too bad, because it's plain science. See LINK naar pdf doc.

Ground all your devices, but not more then once

If you've done all the above and still have too much noise there are a few things you can do to reduce the noise. Sometimes a bad (preamp) tube may cause hum/noise. Try swapping them around and see if the problem is solved. Also a bad biased (power) amp with poorly matched power tubes can cause a hum as well. But groundloops are most common source of hum in larger and more complex setups. But even with a basic setup, groundloops can occur. They can be tricky to find and may take up a lot time to solve. But all groundloops can, and should, be solved!.