What is an attenuator?
Since we sell a huge amount of higher end boutique tube amps, we get asked quite often about attenuators and how they will affect tone, volume, dynamics, etc. This article hits upon some of the specifics of the various amplifier attenuators we carry, but first we'll explain some simple basics (which many of you already know).
What does an attenuator do? Essentially, it allows you to drive your tube amp harder without the associated volume that comes with turning up.
Why use an attenuator? It's well known that the harder a tube amp is driven, the better it sounds. With regard to tone quality, tubes love to be ran hard since they produce their best tone when ran at plate voltage. An attenuator allows you to crank the amp up without blasting your ears because it bleeds off some of the wattage being sent to the speaker. The speaker then reproduces the tone of a cranked amp at a reduced volume.
How do they work? Attenuators are placed between the output of the amp and the speaker. They replicate the ohm load of a speaker so the amp doesn't "know the difference". Most then use a coil to reduce the wattage by converting the excess wattage to heat. The reduced wattage that isn't converted to heat is then sent to the speaker.
What is the disadvantage? Well, there's always a trade-off, but in this case it is negligible. You'll read or hear about people referring to small degrees of tone loss when attenuating. In our experience, the potential tone loss comes moreso from a reduction in the volume of the speaker. Naturally, some of your tone comes from the speaker being driven. When it is driven less, the tone of the speaker will change slightly.
What models do you carry? We carry several models from Dr. Z, Tone King, and Swart. The Dr. Z Airbrake is one of the more popular models that was actually designed by Ken Fischer of Trainwreck fame. It features five settings (four levels of attenuation and a bypass) and a "bedroom level" knob. This model also comes in a smaller package known as the Brake Lite, which is essentially the same thing minus the "bedroom" knob. It's also rather unique since it is designed to be permenantly installed inside a combo amp. Recently, Dr. Z released the Brake Lite SA, which is a stand alone version of the Brake Lite, designed to be used with heads and cabs.
Swart Amplifiers also makes a very popular attenuator called the Swart Night Light. This power attenuator features four attenuation settings and a bypass. One thing that mnakes this one special is the ability to select a mode that uses a light bulb to create some attenuation while also adding a slight touch of compression. Very nice!
All the above attenuators are extremely good values and all but the Airbrake can be had for less than $200, but if cost is not a concern, then check out the Tone King Ironman. This creation by Mark Bartel is perhaps the best guitar amp attenuator on the market, but it does come at a higher price. It features 15 steps of reactive load attenuation, each with pure transformer coupling. Certainly not for everyone, but if top quality is desired at any price, this is the one!