5th August 2009
Tips & Techniques:Getting to know your preamps
Whenever the mood strikes me I'm going to share a nugget of wisdom (with maybe a bit of inadvertent stupidity as well) that might be of some use to someone. I'm not really too concerned with competition in the audio world anymore--I'm focusing more on cooperation these days. Anyhow....
GETTING TO KNOW YOUR PREAMPS
Next to instrument preparation ("getting sounds") and microphone placement the one area I hear younger AE's struggle with is how to effectively use their preamps. Preamp selection is a bit of an issue--choosing the right texture for the instrument/room/mic/track but more often it seems that the preamps are just not gain staged correctly. This is normally *THE* prime difference in audio quality between two engineers using the same chain (room/mic/pre). Generally speaking, if you want to excel in this biz you need to be able to deliver the goods on the preamp side of things.
So that's what we're going to focus on.
First thing: not all preamps are created equally. They don't sound the same. They have different topologies which effect performance. Some pre's like certain mics, other pre's are fairly "mic neutral." There are--most obviously--different levels of quality; you don't really expect an Aphex 207 to perform at the same levels as a 70's 1081 now do you? To further confound the issue preamps often have a 'sweet spot' that varies from model to model, maybe even specimen to specimen.
Let's break apart some factors when it comes to preamp selection and use:
Mic & Preamp Suitability: mics have different outputs--too much signal and you can "overshoot" the sweet spot; too little and you can "undershoot" it as well. A LARGE part of how a mic and pre relationship works is finding one that WORKS TOGETHER; granted, this is going to vary from source to source. Obviously, extremely loud sources or quiet ones are going to influence this equation. In some instances you may find yourself using a pad to lower a really hot source to hit the sweet spot. Heck, you may even swap out a different mic if it's "no big deal" or you think you can end up with a better final product because of preamp characteristics.
Preamp Characteristics: consider the 'character' of the preamp: does it tend to have low order distortion characteristics with a midly compressed top end like a Neve? Is it very transparent and quiet like a Millenium? Is it bright and mildly flattering like a Hardy? Does it need midrange "toughness" like a Helios style preamp? Ask yourself: what preamp flavors are at my disposal and where can I use them best? Keep in mind that "best" isn't always "best for a particular source." Sure, most people would consider something like a Chandler LTD to be a 'better' preamp than a Focusrite Red... but the Reds are really airy (almost obnoxiously so) on top and that can sound really nice for overheads, whereas the Chandler is a bit bigger and meatier--but with a slightly crunchy high end. Pick what is going to be best in this chain, for this track. Another thing to think about is sometimes it's "cool sounding" to use a lo-fi pickup and get a really ****ty sound in there (especially for drum room mics). Don't look at pricetags or street rep--use your ears to decide what's going to work.
Big Guns: this almost shouldn't have to be said, but it's so important I'll mention it anyways--make sure that your most important sources get the best quality preamps. The reality of the situation is that most of us don't track bands out at OceanWay Studios; we don't have piles and piles of dream preamps at our disposal with the ability to order whatever we need in any amount we require. We are often limited in our resources. One of your biggest strengths is going to be how you marshall your forces.
This means you are going to need to prioritize what you are tracking and make sure to get your best mics out in front on the most important tracks. This is going to vary from session to session--you may want to put your "big guns" on the overheads because you'll need the subtlety and nuance for that band; however, if it's a metal band you may want to have those on the kick and snare, which are going to be a lot louder in the mix.
It's not only WHAT you have, but WHERE and HOW you use it.
Getting to Know Your Preamps: this is critical--you've got to know and understand how your preamps not only sound but how they RESPOND to sound. Often this can take years; most top engineers have a ton of experience and know what they like before they ever walk into a room--they also know how it responds, what it's supposed to sound like, and have an intimate knowledge of the 'sweet spot' for the preamp.
Chances are you don't want to spend the next few years getting to learn your preamp before you're using it 100%. There *is* a way to speed this process up:
First, set up a source and select a microphone. Then set the preamp at about 10% of its gain, setting the level at around -6 dbfs on the record, and record a short passage. Push the gain up about 10% more, adjust the recording level to be the same as the first clip, and repeat until you've covered the entire range and spectrum of the preamp.
After everything is done render all the audio files out, name them for the approximate gain used, and put them on a CD to listen to the next day. Pay attention to how the preamp starts to work at higher gain, try to pay attention to the signal-to-noise ratio, headroom, apparent dynamics, tone and other nuances.
Now repeat with a different source, or a different microphone. After a few 'spins around the block' you'll start to acquire an indepth, intuitive feel for how the preamp functions under a variety of conditions, and at a number of different gain settings.
Quick Guide to Setting Gain: a good starting point for setting a preamp is to try it at about 70% of its maximum gain. It is fairly common to see *most* preamps function very well in this range... from my experience a lot of sweet spots potentially live here (keep in mind the source and mic's influence on how hard the pre is getting slammed, and therefore the amount of gain needed). Generally speaking, if you can avoid moving the attenuator (if there is one) from unity do so.
After giving the pre a listen around 70% you can try "sweeping around" a bit. Back the gain down to almost zero to start. Now increase the gain slowly until you start to HEAR distortion (don't look at any meters--LISTEN); once you hear distortion back the preamp down a bit. Now take it a smidge back for headroom. You should be in the ballpark. Now adjust the attenuator to get the desired recording level (if possible).
No Luck So Far: sometimes you may want to find something you're just not quite getting. One method I have tried on preamps with gain + attenuators is to get an initial "safe" amount of gain and recording level as a starting point. Grab ahold of the gain and attenuation knobs with both hands. Now have the musician play while you slowly sweep through the gain levels--while simultaneously adjusting the attenuator to keep things at the SAME VOLUME (so you don't trick your ears and, hopefully, have the sound 'dialed in' when you find it) as you poke around. Maybe something a little crunchy is what you need; maybe something a little more transparent than you usually like.
Either way, this really lets you check out the full spectrum of the preamp on a particular source.
These are kind of basic concepts to think about, but since you're going to be setting a preamp for almost everything you record from now until the end of time, it is important to have a thorough mastery of these simple ideas. Hopefully this helps someone. Please feel free to add anything I may have omitted or something that may be in error.
All the best!
|(84) Comments for: Getting to know your preamps||Page Tools||Search this Page|
|No one has commented on this article.|
|Search this Page|