Today's Top Stories:
 • Universal Audio Studio Bundle
• Edirol UA-1XRebate: DigiTech Gig Pak
Universal Audio Studio Bundle
Since we know you'll discover that owning only one of the finest plug-ins for TDM is not enough, Universal Audio's plug-ins can be purchased in bundles at substantial savings. The Studio Bundle includes the infamous LA-2A, 1176LN and Pultec EQ. Plus, if you purchase this bundle before the end of the year, Universal Audio will send you a rebate of $150!
Edirol UA-1X
The UA-1X from Edirol is a powerful, compact, high quality audio interface designed to offer exceptional audio quality on any USB equipped PC or Mac. This device offers a versatile selection of outputs as well as standard RCA inputs. This USB bus-powered audio interface is perfect for most audio applications & is designed specifically to use the USB audio driver included with the operating system.Rebate: DigiTech Gig Pak
Now through the end of the year, when you purchase select DigiTech guitar and vocal processing gear from Sweetwater, DigiTech will send you a Gig Pak that includes at least a DigiTech Gig Bag and In-Ear headphones. Depending on which unit you purchase, you might also receive picks, a guitar cable, headphone adapter and a power adapter! Check it out!
| Recent inSync News: |
| · |
Monday, November 17, 2003 |
| · |
Friday, November 14, 2003 |
| · |
Thursday, November 13, 2003 |
| · |
Wednesday, November 12, 2003 |
| · |
Tuesday, November 11, 2003 |
| · |
View Entire inSync Archive |
|
|
 |
Sign up to receive the weekly inSync summary by email each weekend!
|
|
 |
| Stepped Attenuator |
A type of variable attenuation device using a switch with two or more (sometimes many more) contact positions, each with different amounts of resistance applied. Usually the switches are set up with a gradually increasing amount of resistance on each switch position, which yields a stepped attenuator that gradually lowers a signal level at its output for each subsequent position of the switch. In most cases these are rotary devices, and so they look like a standard potentiometer from the outside, but the rotation isn't smooth and continuous like a pot. Instead there are several "detents," which are the different position of the switch making contact. Stepped attenuators can often be built with higher quality resistors than comparably priced pots, and they tend to last longer, in part because the switches can be made to provide a more robust contact than the strip of resistive material and wiper used in pots. And while they don't allow for continuous/smooth adjustments over their range they do provide an easy means to recall exact gain settings.
|
 View the Complete Glossary |
| Stepped attenuators explained. |
Q: "Why do some mic preamps have stepped attenuators, and why do many of those cause a pop in the audio signal when moved? It makes it impossible to change levels during a performance."
A: Stepped attenuators are used in many different types of preamps in most cases for reasons of quality. Compared to standard potentiometers a stepped attenuator can be more precise, is "recallable," and can provide a higher integrity path for audio. Understanding the way a potentiometer works will provide some insight. A potentiometer uses some type of strip of resistive material, and then a wiper slides across it to provide variable levels. A stepped attenuator, on the other hand, is basically a series of switches, with each position having a specific value of resistor tied across it. Building an extremely high quality, or "audiophile" potentiometer can be considerably difficult and expensive due to the nature of the construction. A stepped attenuator is generally as good as the quality of switching and the resistors that are used. It's not difficult to incorporate extremely high quality resistors into a stepped system, which obviously yields a higher quality result. Additionally the contact that is made between a wiper and the long surface of a potentiometer can become degraded rather easily compared to what happens in a switched system. So, while the two may start off sounding equivalent, a stepped system will generally retain its quality long after the pot's quality starts to degrade. This degradation that occurs in pots is what we eventually hear (once it gets bad enough) as a scratchy sound when moved. It's a result of the contact between the wiper and resistive material becoming degraded and inconsistent, which clearly has ramifications on the integrity of your audio.
The popping is caused by the design of certain (not all) gain stages. There are a few different ways to come up with it, and the details of each aren't really important to get in to here. Suffice to say that any type of switching of audio signals potentially can cause pops (anyone who's ever made a simple A/B switch for guitars has discovered this). The pops can be prevented, but it requires extra components in or around the signal path to do so. A simple capacitor can work wonders for this type of problem, but they can also introduce phase shift problems and other high frequency anomalies to the signal. Since one of the guiding principles of many high end preamps it minimal componentry in the signal path it is sometimes decided to live with the popping to obtain higher overall sound quality. For the most part this makes perfect sense because it generally isn't necessary to be able to change input levels during the actual performance. Even if there were no pop most engineers find the abrupt level change makes it impractical. It's also worth noting that some designs using potentiometers have the same problem, and the pot just helps to disguise it. If you've ever quickly turned a gain pot on a preamp and heard a whooshing or subtle scratching sound you've heard this same problem in disguise. Were that a stepped attenuator it would be a pop.
The best remedy for all this is a good sound check, which hopefully will preclude you from needing to change levels later. If your circumstances dictate the need for a preamp that doesn't pop we'd recommend you get one without a stepped attenuator. There are some designs that use stepped attenuators, but offer a trim control for fine adjustments. In some cases the trim control can be switched in our out of the circuit as needed. |
| View all 1,700+ Tech Tips |
|
