In the beginning, amps started out as low-wattage affairs with just enough power to project the guitar in a relatively small venue. Soon, the need for more power gave us amps that pushed hundreds of watts. When that wasn’t enough, amps were daisy-chained in order to be heard in arenas. When PA systems became more efficient, it was possible to amplify music with a lot less power on the guitar amp side. However, recording studio owners desired lower volume amps, which resulted in the design of the master volume. The logical progression of the master volume lead to attenuators, and later power scaling, and then full circle right back to low-wattage amps. Many guitarists have continued the love affair with big, loud amps, yet are having a hard time finding places that will let us wind up our beloved rigs to record them in all their glory, especially at home! And now that many studios reside in homes or areas that require sensitivity to volume, what are we to do?
One decidedly analog approach to reducing volume in our increasingly digital world is the use of an isolation cabinet. The concept is simple: a speaker inside of a box that is sealed up tight and treated acoustically to keep the sound in, or at least to heavily attenuate the signal. By design, iso cabs are made for recording. People have been using iso cabs for years with some success, but the main issue that plagues the majority of iso cabs is a boxy sound. The problem is, by trying to keep sound from escaping the box you have to seal it as tight as a drum, resulting in trapped air that doesn’t let the speaker or the mic breathe like they do in an open room. Top that off with a metric ton of acoustic deadening material and a very small enclosed space, and you have a recipe for muffled tone. Lucky for us the folks at Rivera have a solution.
Your sister is built!
Built of hardwood-core plywood and covered in black Nyflex carpet, the Silent Sister is road-rugged and measures 16”x20”x30”. Rivera added comfortable leather handles on the top and sides of the cabinet, as well as rollers that allow you to easily tote it around like a suitcase on wheels. Inside is a Celestion G12T-75 8-ohm speaker that is pre-wired to a jack panel on the backside of the cab for easy connection to an amp. The two pre-wired microphone goosenecks terminate on a panel with two Neutrik XLR connectors. Access to the goosenecks and speaker comes through the top of the cab with a hinged door that locks with a twist-lock latch. The top door makes it easy to open and adjust the two mics to whatever position you desire without having to get down on your knees to look inside. What really separates the Silent Sister from other iso cabs is a cleverly devised porting/ air labyrinth system that relieves the effects of pressure build-up in a small enclosure while reducing the external volume by about 30dB. Additionally, the design makes use of specifically chosen angles to minimize standing waves and reflections.
Can we get a little quiet, please?
This is the type of device that I’ve dreamed about for years, hoping it would keep the cops from busting down the door because some neighbor didn’t appreciate my riffs. The first test was to see what kind of reduction the Silent Sister provided with my JCM800 100- watt head. Because the speaker inside is a 75-watt, I used the very unscientific approach of not turning the amp up all the way, just to get a feel for the volume without blowing the head or speaker. Setting the amp with the gain on 10 and the master at about 3 you could hear sound coming through the box but it was significantly reduced in volume and for the most part only produced a muffled bassy sound at talking levels. Opening the top lid showed how loud the amp was—night and day with the lid closed. Just to be safe, I engaged a THD Hotplate inline and shaved 4dB off the signal, then cranked the master up to 10. At this point the outside volume washigher than before (obviously) but considering how loud the amp would be without the Silent Sister, it was a comfortable level. You could talk over the volume; it was about the same as watching a football game in your entertainment room with a couple of the guys. Once again I popped the lid open and got a blast of what was happening inside the box. Big, big difference.
This is not the setting you’d want to have with the family sleeping in the other room. Although it’s named the Silent Sister, it should be pointed out that it brings down the volume significantly but does not eliminate it. For a chore like that you’d need a lot more mass, weight and size. Just look in any major studio construction, and you’ll quickly see how much work and money goes into keeping things quiet.