How to compare, and choose the right recording chain components for the job at hand
By Phil O'Keefe
The relatively low cost of modern recording tools means that even modest home studios often have, or can afford a variety of different equipment. It's not unusual to see recording rigs with multiple types of mic preamps on hand. These might include preamps built into the computer audio interface, plus a few more built into a small mixing console, and maybe even a few outboard standalone preamps. It's also very common to see multiple microphones in a home recordist's arsenal.
This variety of gear potentially gives you multiple sonic options to choose from, especially when you start to combine the two - microphones and preamps - in various different ways. Unfortunately, you'll often run into the situation where you don't have enough of each to do direct side by side comparisons of the different possible combinations - at least not quickly, and without having to re-patch things.
Picking the right mic and preamp combination for the task at hand can be a bit complicated. Whenever it requires unplugging one thing and plugging in something else, or anything that takes time to configure, you've lost the advantage of hearing a direct, instant comparison between the two. Being able to make an instant comparison, in the context of the music, is an extremely valuable tool that makes it much easier to hear and directly compare the sonic differences; allowing you to make more informed decisions regarding what sounds and works best for that specific situation, whether it be which mic works best for a particular singer, or which mic and preamp combination gives you the best sound for the song when tracking a guitar amp or snare drum.
GETTING AROUND THE PROBLEM
Getting around the problem often requires a bit of ingenuity, and some careful patching, and occasionally some willingness to compromise a bit. For example, depending on the specific gear you have available, you may have to get creative with the routing in order to come up with a way to quickly compare multiple combinations.
If you have a a multi-channel mic preamp such as the API 3124+, or a audio interface with multiple onboard mic preamps, or a mixing console with multiple mic input channels and you don't mind using those preamps, setting up comparisons between multiple microphones is relatively easy. Just plug each mic into one of the multiple identical mic preamps, set the mics up in the desired location relative to the sound source (and with their diaphragms as close as possible to each other), and run the direct outputs from the multi-channel preamp or mixing console into the line inputs on your audio interface and assign each one to a separate track in your DAW software. Don't forget to match up the levels (some mics are bound to be more sensitive than others) so you can avoid the "louder is better" bias influencing your decisions. If your DAW allows you to set up mute groups, you can set the mutes up so that when one channel is unmuted, the others automatically mute, making fast, direct comparisons easy. (Fig. 1) Alternatively, you can use a hardware DAW control surface to quickly mute and unmute the individual DAW channels as needed. This method can also be used with a hardware mixing console when using it for comparisons - just use its built-in channel on/mute buttons.
Figure 1: Multiple mic / mic preamp inputs can be assigned to separate tracks in Pro Tools if your interface has sufficient inputs
Multiple mic preamp types can be a bit more difficult to audition simply because it's often harder to feed one mic to four different mic preamps simultaneously, which is the optimum way to audition the sonic contributions of different mic preamps. You can use mic splitters to split the signal and run it to two or three different preamps, and even simple DIY parallel splitters can sometimes work, but ideally you'll want to use high-quality splitters that are equipped with high-end isolation transformers for best results and minimal audible side effects when splitting the signal and running it to multiple preamps simultaneously. Splitters such as the Radial Engineering JS2 ($219.99 "street") and Radial JS3 ($259.99 "street") are a good choice in this application, but I've found something I like even better, and it's also from Radial Engineering…
TWO TERRIFIC TOOLS
If you lack sufficient available inputs on your recording interface / mixer / mic preamp to plug in multiple mics for simultaneous comparison, check out the Radial Engineering Gold Digger. (Fig. 2) It's a four channel, passive mic / line switcher that allows you to plug in four microphones or line input sources and then quickly switch between them. All four inputs are routed to a common output, but it's not a mixer; it's a switcher, and only one input is active at a time. Trim controls on each channel allow you to match levels for fairer comparisons, while 48V phantom power switches on each channel allow you to use it with condenser mics too.
Figure 2: The Radial Gold Digger allows you to connect up to four mics and quickly switch between them for instant comparison
What about mic preamp comparisons? If you have an outboard mixer with onboard mic preamps, and a couple of standalone mic preamps and you want to be able to use a single mic to feed up to four of them at once so you can quickly switch between them and make direct comparisons, then the Radial Cherry Picker (Fig. 3) will make the process much easier.
Figure 3: The Radial Cherry Picker allows you to connect one mic to four mic preamps for instant comparisons
Conceptually, the Cherry Picker does the same thing as the Gold Digger, only in reverse - allowing you to run a single input (such as a mic or line input) to any of four outputs, and switch between the four at will. There is switchable 48V phantom available on the input if you need it. Both units use relays for the switching, have totally passive signal paths, and don't add any noise or degrade the signal in any way. The Radial Engineering Gold Digger and the Radial Engineering Cherry Picker "street" for about $350 each.
Combining the two units (Cherry Picker and Gold Digger) can give you even more flexibility in terms of auditioning what are arguably the two most important equipment elements of the recording chain / signal path - the mic and the preamp. Some microphones sound better on some some sound sources when used in partnership with specific preamps, and the best way to decide what works best is to hear it in context. Again, being able to make fast comparisons between different combinations of microphones and preamps is the ideal that you want to shoot for. By connecting multiple microphones and preamps together with the Gold Digger and Cherry Picker, you can easily and quickly compare various combinations of mics and preamps in context.
By patching the output of the Gold Digger into the input of the Cherry Picker, you can use the Gold Digger to select between up to four microphones (it also works great for auditioning multiple line input sources and different direct boxes too) while using the Cherry Picker to select from up to four different mic preamps. Just click a button on the Gold Digger to select the mic you want, and then another button on the Cherry Picker to pick the mic preamp you want to use with it - you can even hit the two switches simultaneously, and swap between different mic and mic pre combinations very quickly, allowing you to hear which pairings work best for a specific instrument or vocalist in the context of the song.
Once you've experienced the ability to quickly combine microphones and preamps in various combinations and instantly hear the results side by side, you won't want to go back to doing it the old way. The Radial Gold Digger and Cherry Picker are great tools that allow you to make better decisions in terms of how you use the mic and mic preamp tools you already have; giving you the ability to make informed decisions based on comparative listening - and that can really help you make better recordings.
Phil O'Keefe is a multi-instrumentalist, recording engineer / producer and the Senior Editor of Harmony Central. He has engineered, produced and performed on countless recording sessions in a diverse range of styles, with artists such as Alien Ant Farm, Jules Day, Voodoo Glow Skulls, John McGill, Michael Knott and Alexa's Wish. He is a former featured monthly columnist for EQ magazine, and his articles and product reviews have also appeared in Keyboard, Electronic Musician and Guitar Player magazines.