Today’s question comes from one of our readers, Nalin, who asked about the best way to calibrate dual subwoofers using an Anthem AVM 60 preamp-processor.
“I am running two SVS SB-2000 subs and an anthem avm60 processor. Currently, the settings on the two subs are as below:
- Volume 2 o clock position (just above half way mark)
- Phase = 7 o clock position (0)
- Low pass filter = LFE (max).
Do I need to setup/increase the volume knob while the pink noise is running, to see a measure of 75db on the SPL meter? Then do the same to the second sub too? And then have both subs measured to scale to 75db on the SPL meter? And then run the ARC calibration?”
Nalin, thanks for writing in. You have an amazing setup. Anthem’s AVM 60 preamp-processor is a really great-sounding piece of equipment. The great news is that Anthem’s procedure for calibrating dual subwoofers with the AVM 60 is the same as the AVM 50v/D2v process we outlined in our “How To” article, on “How to calibrate dual subwoofers with ARC” on Anthem’s AVM 50v and D2v preamp processors. I recommend that our readers reference that article first for additional background.
But let’s take a look at the process in general and your questions in particular. Anthem’s AVM 60 preamp processor and MRX x20 receivers share the same architecture, core electronics, and operating system so the procedure we’re going to outline below is the same.
In case you’re wondering, the procedure we’ll outline below applies to any number of subwoofers—1, 2, 3, or 4—not just two.
Tools You’ll Need
To get started, you’ll need an SPL meter. SPL stands for Sound Pressure Level. An SPL meter, does exactly that, it measures the sound pressure. You’ll need either a stand-alone meter or an SPL meter mobile app for this duty. The Radio Shack analog SPL meter has been a trusty tool for many audiophiles but there’s no reason why you can’t use a mobile app too. I use either UE SPL from Ultimate Ears or JL Audio’s app on iOS. The UE SPL is purely an SPL meter while the JL Audio app includes an RTA analyzer, speaker polarity test, and several calculators.
Whichever meter you use, set it to “C Weighting” and “Slow Response.” If you’re using the RadioShack meter, you’ll need to dial in the appropriate SPL range to 70 so that you can measure between 70dB-76dB
Step 1: Set Phase on Your Subwoofer
The first step you want to do is go to Anthem’s speaker calibration menu and play pink noise from your subwoofers. You want to measure one subwoofer at a time so make sure you turn one subwoofer off. While playing the pink noise (that shhhh sound) through your sub, change the subwoofer’s phase dial to each position. Measure and note the SPL reading for each setting. Whichever position gives you the highest SPL reading is the correct phase setting. Another way to put it, this SPL reading will also give you the loudest volume. Sometimes, the differences are minor, sometimes, they are dramatic. It depends on your room and your seating position.
Some subwoofers have only two phase settings, (zero and 180-degrees) other subs have four phase setting and still other subs have variable phase settings. Because you are using SVS subs, some SVS subwoofer models have an analog phase dial and other model SVS subs have phase as a menu option in their digital controls. Therefore, do not confuse the “phase” knob with the “volume.” When setting phase, do not adjust the subwoofer’s volume. Leave the volume alone. Move only the phase dial during this step.
Your SVS SB-2000 sub has an analog phase dial on the back. That’s what you should be using during this step. Do not touch the volume knob
If for some reason you can’t use an SPL meter then there’s a general rule of thumb: If you have your subs at the front of the room, that will usually be zero (0) and if you have the subs behind you that will typically be 180.
Step 2: Adjust Each Subwoofer’s Volume with Anthem ARC
Once you have taken care of the phase for each sub, you’ll now turn your attention to setting the sub’s volume. What we’re doing here is getting your subs to measure just around 75dB when playing pink noise.
Once again, use the Anthem’s internal speaker level menu to play pink noise through the subwoofers. Because you have two subwoofers, you want to do this one at time, so turn off the subwoofer you are not using.
Using your SPL meter and measuring from your listening position, adjust the volume dial on the back of the sub so that it hits about 72 dB on each sub. Anthem’s AVM 60 user manual says to measure 71 dB for each sub. Ultimately, there’s no difference in my opinion. If you were measuring a single sub only, then you would set the subwoofer’s volume dial until it measured 75db. Because the combined output of two subwoofers is greater, you need to lower the volume by about 3dB for each sub to compensate.
In case you’re wondering, don’t worry about 71dB or 72dB being too low. Anthem’s room correction—ARC—will then take care of further volume adjustments with its measurements. If you had only one subwoofer then you’d set that single sub to 75db.
Step 3: Run Anthem ARC (Anthem Room Correction)
Now that you’ve taken are of phase and volume, your final step is to run ARC. Follow the steps in the user manual for setting up the calibrated microphone and measuring from five different positions. Make sure that each microphone position is at least 24-inches (two feet) away from the main listening position.
ARC-2, which is the version that comes with the Anthem AVM 60, limits its correction by default to 5,000kHz. I do not recommend attempting to run ARC at anything higher than 5,000kHz. In fact, if you try and change ARC to anything higher than 5,000kHz, you won’t be able to.
Nevertheless, if you insist on doing this (this is mostly the influence from competing systems like Audyssey) then just change the maximum setting in ARC from 5,000kHz to 24,000kHz. ARC will now measure and correct up to 20kHz. Be warned, once you start correcting past 5,000kHz frequencies become too directional for the microphone and you might make things sound worse, not better.
Advanced Calibration with an Anthem AVM 60: Geeking Out With Subwoofer Placement
If you really want to geek out there’s one other method you can use to get the best subwoofer performance from your system. Anthem’s ARC has a “Quick Measure” feature. You can use this feature to find the placement of your subs. You can use this method to compensate for nulls in subwoofer response. Remember it is always easier and better to correct for peaks than nulls.
- Use Quick Measure to get find the location that has the flattest response for sub #1
- Identify the major null in your subwoofer’s frequency response
- Use Quick Measure to find etc location that has the flattest response for sub #2 but pick a location that doesn’t have the same null as subwoofer #1. In fact, you can pick a location for subwoofer #2 that has a slight peak where subwoofer #1 has a null.
- The resulting, combined result when calibrated with ARC will give you the best possible subwoofer performance at all frequencies.
So there you have it. Anthem’s AVM 60 pre-pro and X20 series MRX receivers are superb-sounding pieces of equipment. Hopefully this information helps you get the best out of your setup.