Moderator: Good evening and welcome to our chat with Jamie Anderson of SIA Software Company. Jamie, could you give us some background about what you did before SIA, for those of us too lazy to read the bio?

Jamie: I've got an EE (electrical engineering) degree from Worcester Polytechnic Institute (WPI), a Masters of Fine Arts (MFA) from Yale Department of Drama, and then spent six years at Meyer Sound as SIM and technical support manager. This was followed by three years as an independent engineer, working with k.d. lang and Dave Matthews Band, and now I'm with SIA.

Harry: How about starting with the basics of how the program works and your goals? I find a lot of visiting engineers don't have any clue what the Transform Function is about, and simply want to see the RTA (real-time analyzer) display.

Jamie: SMAART is pretty simple. You get the reference signal, you get the measurement signal, and you compare them. If you have a problem, it is in one of those steps. One of the truths of computers is that they do what you tell them to do, not what you want them to do. The problem quite often with SMAART is that people confuse what they want to measure with what they are measuring.

Jamie (continued): There are two basic types of measurement that SMAART does: single channel and dual channel. Single channel measurements (RTA, Spectrograph, SPL) tell you about a signal at one point in the system, while the dual channel measurement (Transfer Function and Impulse Response) uses a comparison of what went into a system, to what comes out, to measure what a system did to the signal passing through it. This is what makes SMAART so powerful - you just need to make sure you have chosen the appropriate two signals.

Ken: Why should you use SMAART instead of a RTA?

Jamie: SMAART can be a RTA, which is just a measurement tool. SMAART is extremely useful for mixers and it gives great tonal content information. The RTA just isn't the right tool for measuring system response. It can't give you any information about timing, or whether the information it is getting is signal or noise.

Jamie (continued): Take the example of a system with two drivers, 100 feet apart. You could tonally balance the two drivers so that they read flat on an RTA with pink noise, but they would be a mess to listen to if they don't get properly time alignment. That is what SMAART's Transfer Function with Phase Response, as well as the Impulse Response measurements, is for. It is really a case of choosing the proper tool/measurement for the job at hand.

Harry: Can you explain proper connections and then tell us how to set the various parameters? Also Level Setting, Delay Locator, and what to look for when using the Transfer Function.

Jamie: The proper connections are those that deliver the two measurement signals you need to the computer. I'm not trying to be cagey; it's just that there are so many different ways of managing your measurement signals. The key is that you want to get the reference and measurement signals you select into SMAART, and at a good level. That would be somewhere around -15 to -12 on the input meters.

Jamie (continued): Pink noise is easier to use because it has a low crest factor - it isn't really dynamic or "peaky". With music, it's harder to get the signal levels to stay at the optimum levels. When setting your delay, you have to keep in mind how much HF (high frequency) is in your source, and how far away you are from it. You want your delay measurement window to be at least three or four times the delay you're expecting to see. The reason I am concerned about the amount of HF? If you only have LF (low frequency), as in trying to measure a delay on a sub, the Auto Delay Function is basically useless.

Harry: How do you go about aligning them (two speakers, 100ft apart)? I have been using the Impulse Response for one, then the other, and then doing the math... Is there a better method?

Jamie: First, pick the position you want to align them at. This is key. Remember, one delay time does not work everywhere. Think of two pieces of string attached to the speakers. As you move around, one goes slack while the other stays tight. After choosing your alignment point, measure the arrival time of the first speaker. I use the Impulse Response measurement directly for this.

Jamie (continued): The Auto Delay Locate Function just does an Impulse Response measurement and chooses the tallest peak. I like to see the entire response to make sure I'm not being fooled, and then I turn the first speaker off, turn the second on, and measure its arrival. Whether you do the math in your head, or on a napkin, or using SMAART's Compare Delay Function is up to you.

Devin DeVore: What are your thoughts on applying Fletcher-Munson curves to SMAART measurements? SMAART is linear and our ears aren't.

Jamie: Fletcher-Munson (F-M) is definitely important - I find it comes into play when looking at responses of different areas of your system, such as down front versus mix position. Regardless of what curve you end up with at the mix, you're going to want to take F-M into consideration when looking at the response up front.

Jamie (continued): It will most likely be louder down there, so you want to allow for more LF to deal with the increased level. This is also a good rationalization for dealing with LF buildup in front of the subs… :>) To be honest, I think the key here is paying attention to level variations throughout the room and show and account for that in your system response curves. The starting point is kind of arbitrary.

Devin DeVore: Think we'll ever see a 'reference level' standard in AES like the projection world has?

Jamie: Maybe, but I'm not sure how useful it would be. Sorry about the lame answer.

Moderator: Since the F-M curves flatten out at higher SPL, the area down front can sometimes sound "over-hyped". These are the kinds of decisions we make as humans. It's your gig as the sound guy… Am I close to correct?

Jamie: I guess this speaks to our goal of uniformity as system engineers. We have to balance measured uniformity with perceived uniformity. Plus, we often fail to take level differences into consideration when comparing response curves. Level uniformity can go a long way to providing an excellent environment for mixers and artists. And yeah, we always have to be taking the human into consideration when making alignment decisions.
This is why auto-align is a pipe dream.

Devin DeVore: Funny you say that ... I learned the most about 'mix energy' and frequency masking from mastering engineers, and I've been applying that knowledge to system tuning. Anything thoughts on frequency masking and SMAART?

Jamie: Yes, but I'm not sure I can type out a sufficient answer. In general, though, systems that are smooth in response, not "peaky", tend to be far more useable. They don't need to be "flat". But having one range of frequencies as a stand out makes for a bumpy ride as a mixer. On that subject, the RTA works as a great mix tool for doing channel EQ (equalization) for just this reason.

Jamie (continued): If you do a long average of a signal - say a guitar - the curve won't be flat, but it probably shouldn't be peaky. An engineer I worked with - Grant MacAree on k.d. lang - showed me this technique for sound check. He'd have each person play their instrument nice and evenly, and we'd do a long average. And wouldn't you know it, those pesky peaks that you try to use your channel EQ to tame show right up on the RTA trace.

Joel: During a live performance, how can we adjust the analyzer to consider the sound coming from the stage as noise, and try to eliminate it from the readings?

Jamie: First rule during a show is measure twice, cut once. In other words, be VERY careful. Watch your measurement for areas of stability and instability. The key to getting a good, usable measurement during a show is getting a mic position that is dominated by the speaker(s) you are trying to measure. Often the mix position is the worst place cause it has left, right and stage showing up.

Jamie (continued): Use lots of averaging, and use your ears. To be honest, I sometimes turn Transfer Function off during a show if I can't get a stable measurement. It's better to do nothing than make random adjustments based on bad measurements.