Guitar / bass players like to fill their boards with fun & creative pedals. However; some vital utility pedals are often ignored and this may cause a lot of audio problems. Here is a list of some pedals you might not know that you needed desperately.
Passive instruments typically have high impedance signals – which means that they are fragile and lose their audio quality easily. If you run your signal through long cables or a lot of pedals, your precious guitar signal may turn into mush.
Buffers turn your high impedance signal into durable low impedance signals and prevent signal degradation. Check my dedicated article on buffers for details.
DI boxes serve an ad-hoc purpose: They pick your unbalanced instrument-level guitar signal and turn it into a balanced mic-level signal, which can easily be fed into a mixing desk. If you intend to send your guitar signal directly to the desk, you are definitely going to run your signal through a DI Box.
DI boxes come in all shapes, sizes and quality levels. A quality DI is vital to provide a healthy bass sound to your sound engineer; obviously. Check my dedicated article on DI boxes for details.
Ground loops are the bane of audio quality. In layman’s terms; ground loop occurs when incompatible electric devices share the same power infrastructure and their electric schemes don’t agree. This disagreement results in buzzes and hums through the amps & speakers – even when you turn your guitar off.
This problem typically occurs when you send your signal to multiple locations (desk + amp, for instance). If you have a single ground connection, there would be no problem. Otherwise, more than one ground can cause hum loops – the grounds will fight each other and cause audio noise.
Some pedals and DI boxes have a “Ground lift” option to fulfill this functionality. Basically; if you hear noise, the easiest attempt to remove it is to activate your “Ground lift” and see if it helps. If you don’t have such a switch, you can temporarily add a ground isolator to your signal path; such as Lehle P-ISO.
You need one single ground of your system for safety and shielding. More than one ground can cause hum loops, then you need an isolator like the LEHLE P-ISO. Remember that cutting the ground is useful to avoid hum loops but your instrument has to be grounded “once” in order to have a shield against RF interference.
An isolation transformer is a specific circuit, which passes audio signal over a magnetic field instead of a hard-wired connection. This approach cleans up unwanted noise on the AC line because there is no direct connection any more.
Note that electronically balanced DI outputs are very common on a variety of different audio equipment, and they typically don’t need a transformer for silent operation. A ground lift is enough to solve most problems. However; if your device can’t handle phantom power, putting an isolator in-between might still be a good idea. Otherwise; in a passive DI operation, you might need an isolation transformer for silence anyway.
Both transformers and ground lift switches help you remove ground loops from your signal path, although each does so through a different method.
With transformers, the magnetic field created inside of a transformer allows for audio to pass from the input to the output of the transformer magnetically, with both sides of the transformer not actually making any physical/wired connections with each other. Due to this, the signal path is essentially electrically broken, but still allows audio to pass through it in the form of a “magnetic bridge”. When a transformer is used, the audio ground line is essentially “disconnected”, which prevents a ground loop from forming.
With regards to the ground lift switch, this feature simply just breaks the audio ground connection and prevents a ground loop from forming in a more simple manner. While typically effective, it may not be able to help eliminate 100% of all ground loops formed. In some rare cases, both transformer isolation and a ground lift switch may be required.
The use of a transformer works best when it is placed in-line between the last device in a signal chain (i.e. a DI box or cab sim) and the destination device (i.e. the input on the mixing desk).
Some DI boxes, such as Radial JDI, already have built-in isolation transformers. If you place such a pedal at the end of your signal chain, you can get rid of some unwanted AC noise.
If your DI output is neither electronically balanced nor transformer-isolated, the use of a dedicated in-line isolator such as Radial IceCube is possible. The IceCube can be connected directly between the DI output of your last pedal and the input on the mixing desk, essentially providing the same results and effect that the transformer inside of the JDI did in the previous setup.
Despite our best efforts, some audible noise may leak from our pedalboard and be heard through the speakers. Single coil pickup hum, pedal noise or electric noise are typical sources of that problem – usually beyond our control.
In a live setting, you can “fake” a silent rig by placing a noise gate towards the end of your signal path. A noise gate will mute your sound if it is below a certain threshold. As a result; you hear yourself normally when you play, the present noise is masked with your sound anyway. As soon as you stop playing, the noise gate mutes your signal and doesn’t let the noise leak towards the speakers.
ISP is one of the prominent companies selling noise gates.
True bypass pedals may produce ugly and loud popping noises when you turn them on or off. This may have many reasons; but if the reason is DC voltage in your analog signal, DC filters may help you eliminate that and make the switching quiet.
Note that a DC filter I tried (Lehle) didn’t really help me, but they allegedly helped many others.
Compressors / Limiters
It is important to send a high quality & noise-free signal to the desk. However; it is equally important to control the dynamic range of your signal. This means: Your volume shouldn’t jump dramatically when you turn on some pedals or something.
Compressors and limiters serve this exact purpose. Although they are similar in design, they serve different purposes on a typical pedalboard.
- Compressors are usually placed early in the signal chain and used to reduce your dynamic range. If your volume range is between -12dB and -5dB, a compressor can help you squeeze this into -10dB and -7dB; making you sound more consistent and helping the sound guy balance the mix.
- Limiters are usually placed late in the signal chain and used to catch & limit peaks. Your regular range may be between -10dB and -7dB, but slapping the bass or activating some pedals simultaneously may make you jump to -4dB. If that’s the case, you can install a limiter and make it limit everything to -7dB.
Compressors can also be used as creative sound coloration tools; but let’s stop here for now. For more details, check my dedicated article on compressors. You can also check my bass compressor reviews.