HAA TurboCal Training Course Overview
If you have read any of my past HAA articles (there are two on Level I and Level II training) then you’ll know that I eat and sleep acoustics. You will also know that I have a great deal of respect for the HAA organization. They have a unique perspective on acoustics for home audio and home theater which is to apply concepts, measure, listen and adjust. Now the HAA has come out with a new training course and I was privileged to be able to attend the pilot class.
The course is called TurboCal and it is designed to provide a high value calibration process that is affordable to the consumer and efficient for the calibrator. Most TurboCals are completed in less than two hours. Let me give a little history to put this into perspective. The Level I training was one full day of acoustic concepts. Cool things like 'No Cheap Seats' which calibrates the entire seating area, not just the sweet spot. And then there are more complicated concepts like Speaker Boundary Interference Response (SBIR) which you can read about in my HAA Level I Certification article if you are interested. The Level II training took all of the concepts from Level I and put them into a 3 day workshop which could have easily extended to 5 days if people had the time. The Home Acoustics Alliance Level II Workshop was completely hands-on for the full three days which was great fun and an awesome learning experience.
in somewhat of a contrast, the TurboCal course requires little or no knowledge of acoustics. It just teaches how to calibrate a room in an hour or two and concentrates on the process of calibrating. This training is great for not just the dealer/installer, but anyone who wants to do some basic acoustic calibrations. Most people are not like me where it becomes a fascination, a hobby, and a part time profession. Most just want to get the job done, and the TurboCal class is designed for exactly that. With the addition of the TurboCal workshop, the Level II workshop has been reduced to 2 days and concentrates on the more advanced concepts and their application.
The course was broken up into labs and each lab had several exercises with step-by-step instructions. Why labs, you may ask? Because it is mainly a hands-on course with only 1 hour of lecture time. The first order of business was to set up the new AVPro software, which has been redesigned for the TurboCal class. Everyone who attended the class brought their own laptop and we took some time to install the new software and set it up. This might have gone a bit slowly, but remember this was the pilot class. As a result, subsequent classes now use a "team laptop" approach where 4 or 5 people are assigned to HAA-provided laptops. The next part of the course was to do some initial sonic evaluation, which allowed the student to judge the system as it was currently set up. Then, we were taught to verify the equipment - which basically showed that everything was working and connected properly. The instructors told stories of speakers being wired out of phase internally, which sounds incorrect to a seasoned professional, but which an amateur listener might never recognize the problem. The course followed up this section with Design and Calibration, where most of the class is focused. Finally, it concluded with Report Preparation, which is given to the customer and shows a before and after comparison.
When this course is given to the Home Theater Installer, HAA likes to show them a little more than just how to calibrate. So, they always touch on how to market their company using HAA. As a result, they also addressed marketing audio gear, profitability, and how the HAA tools and training play a role in their business.
The Process Circle - Evaluation, Verification, Design, Calibration
Once the preliminaries were out of the way, the TurboCal course jumped into the iterative process. This process has always been part of the HAA, but the TurboCal course clarified it much better. This section can be summed up as "Evaluation-Verification-Design-Calibration". It is important to understand this process as a circle because once the calibration has been completed, the evaluation has to be done again and the circle continues until you are satisfied with the results.
Just because a custom home theater installer has this sort of business doesn’t necessarily mean that they understand how to listen to a system and properly evaluate its qualities. Evaluation is a very important first step and learning the Sonic Goals is paramount. Clarity, Focus, Envelopment, Dynamics, Consistency and Response are the Sonic Goals. I will touch on these concepts shortly.
The new AVPro software has been nicely set up with some great audio help clips. It focuses on creating an analysis report that can eventually be presented to the client. A custom cover can be designed for the report so that a company can put their own logo in it. It has a mode analysis tool for predicting the low frequency resonances of the room. The main part of it is the Report Card where several acoustic elements are graded to help determine what needs to be adjusted. There is a Summary tool which presents a chart to see how the grading applied. Finally, there is a customizable Master Report which presents pictures, recommendations and results of the complete calibration.
Now there are some concepts in the training, but they are not very technical. There were two rooms set up for our pilot class, but future classes will utilize one larger room, which makes this section more efficient.
Even though the lab book covered some technical concepts, the course did not delve too far into them. Target Response and Reverberation were not addressed in the calibration itself. Concepts of sonic evaluation were covered in detail but not at a very technical level. These concepts were explained in detail using laymen’s terms.
Clarity is the most important aspect and HAA likes to focus on music for a very good reason. Dialogue is important but music spans the entire audible frequency spectrum and its perfection in calibration is more difficult to attain. If well-recorded music sounds good, the rest of the system will follow. And, if any of your friends tell you that all they care about in their home theater system is the dialogue and the explosions, ask them what the last movie they have seen was that didn’t have music.
The concept of Focus may be more commonly known as imaging and sound stage. Each instrument from a recording should be able to be clearly placed from right to left and also even the depth of the stage can be discerned. Hopefully it’s obvious that acoustical instruments are used for this concept and not any kind of electrical band with speakers. And even though you may not listen to acoustical music, it is important for a system to be able to reproduce it correctly. The students in the course were exposed to different clips of music and told exactly what to listen for.
Envelopment is similar to Focus, using spacial cues with the main difference being that Envelopment represents the venue whether it’s a recording studio or a live performance. The venue has its own acoustic qualities and a good system can reproduce that too.
Dynamics is an easy concept to understand, but a hard one to reproduce. It is just the difference between the softest sounds and the loudest sounds. You may think, “What is so hard about reproducing that?” Well if you have some ambient noise like air conditioning flowing through the vents or even an AC register vibrating on the wall or ceiling you won’t hear the softest sounds. So now you raise the volume to hear them and have limited your dynamic range.
Finally, Response is the frequency response of the system. It can be measured and heard. Everyone is familiar with tone controls which change the frequency response by raising or lowering the low and high frequencies. The idea is to have an even and smooth response. HAA has found that perfectly flat, meaning that the measured frequency response is horizontal from the lowest frequency (20 Hz) to the highest frequency (20,000 Hz) is not ideal. A little bump in the bass and slight taper on the high end was found to be the most pleasing response. But the smoothness of the response should not be compromised. There should not be any fluctuations (peaks and valleys) for any frequencies. In laymen’s terms, the response should not have some frequencies too loud and others too soft. Listeners may not be able to pick out every nuance in the response, but they can hear large deviations and can definitely pick out when music is too boomy or has too much treble (high frequencies).
The course taught each of these sonic goals as the students listened. Then the students graded what they heard. After grading the sonic qualities, the methods to correct them were taught and it was not a one-to-one basis. In other words, there wasn't just one method to correct one sonic quality. One method of correction can change many sonic qualities. Also, one method of correction may make one quality better and another worse. That is why the training is so important; you just have to understand what is being done.
Methods of Correction
Equipment functionality (verification phase) is something the HAA stresses highly. It has been explained that not only can equipment be connected incorrectly but sometimes equipment just doesn’t work correctly. For instance, a polarity check is performed for speakers being wired incorrectly either by the customer or internally by the manufacturer. Other than polarity, all speakers’ frequency response was measured. These measurements told the calibrator quite a few things. It verified that the speakers are functional. It verified that the receiver/processor was set up and working. It is possible to have a crossover set for one speaker and not another which can be quickly seen with a response measurement. It also let us know how a speaker is performing individually which helped later when the response at the listening area was taken. If it was found that the speakers have a peak in their response then it wouldn’t be a surprise to see it in the response at the listening area where the room has also come into play.
Once the equipment and setup were verified, the microphone was moved to the listening area where the room itself came into play. Checking speaker levels was first and very important. The levels had to match. It seems like every consumer would automatically do this check, but some just don’t know - and just setting the levels equally in the receiver/processor menu is not good enough. Because rooms vary by design, one speaker might have to be closer to the listening area than its match so the settings would force one to be louder than the other. Setting the delay for the speakers was next and this part was easy by just using a tape measure to the sweet spot (as a central reference point). Although, the AVPro software lets the calibrator do “before and after” measurements, this was the Turbo Cal course, so the changes were made immediately. The exercises in the lab walked the students through this calibration step-by-step including how to use the test equipment and take the measurements.
Since the set up was deliberately incorrect initially and then corrected, it was time to re-evaluate the system by listening. At this point, the system sounded better but it still needed work. Many of the new receivers/processors come with microphones and speaker adjustment software built in. These measurement-adjustment systems may or may not be accurate but the one thing they cannot do is speaker placement.
Speaker placement was a crucial step in the calibration and most people don’t pay any attention to it many times because of the wife factor. The Turbo Cal course did not get into the detail of this step that the Level II course did, but it had to be addressed. Some basic placement was done with the front speakers, left-center-right (LCR) and then everyone listened. We also moved the seating area (which is done even less than moving speakers). Having the seats in the center of the room was not a good place - mostly for bass response, but that’s where the seats were and needed to be moved. Then the speakers were moved again and re-evaluated. Hopefully the iterative process of calibrating has become clear because every time something is changed, the system has to be re-evaluated for the results.
Subwoofer placement in the Level II course also went into a lot of detail, but in the TurboCal course it was kept to a minimum. Some basic placement was done keeping the sub out of the corner because, as you may know, a subwoofer in the corner excites all room modes which causes horrendous peaks and dips in the response. The one thing that the course did not cover (surely due to time constraints) was generating an overall Target Response. Even though I think this step is important, achieving the correct Target Response will inevitably involve acoustical treatment on the walls and that takes a lot more time and money. The TurboCal course was just not set up for this level of calibration.
After everything had been adjusted, the system was re-evaluated again and, although it was not acoustic nirvana, the room sounded 99 percent better than when we started. The course still left time to create a final report using the AVPro software, which is what would be delivered to the customer. The report may seem irrelevant to some people, but it is more than just something to leave the customer. I think the report holds value in educating your clients. It’s always easy to listen to someone explain things, in this case acoustical elements, and to nod your head in agreement. But a few days or a week later you’re thinking about what your calibrator said and may not be sure what he was talking about. With a printed report, the elements are explained and how they apply to a customer’s individual setup has been noted with the element. So why is that important? Well, the more people understand about their sound system (and what's been done to improve it), the more they will enjoy it and when the wife says “I don’t like where those speakers are placed,” hopefully she can understand and appreciate the desired location.
The TurboCal course is really just a quick way to get some really good sound in a system. It benefits the Installer, the customer and even the Do-It-Yourselfers. With a little practice, the Installer can get in and out in a couple of hours and leave their customers very pleased with a decent setup. The Do-It-Yourself person can get some good basic knowledge of how to setup their system and keep that knowledge for future systems. The HAA is a great organization and now delivers another no-fluff course that takes one more step to what probably over 90 percent of home theaters need - which is better sound.
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