Sub Calibration with an SPL Meter

AlexanderS · 03-05-2004, 01:21 PM

Hey guys. Im trying to calibrate my HC6 sub. Ive managed to calibrate my other speakers to 75db but when I keep that same setting and switch to my sub the SPL meter goes off the charts. I have the subwoofer level at around 40% eyeball, the crossover turned to max and at 120 in the receiver, and the phase on 0. Am I doing something wrong or is the level too high? Thanks.

Nathan Stohler · 03-05-2004, 02:05 PM

It's too high.

My subwoofer doesn't have any tick marks for the level control, so I set it squarely at 50% (12 o'clock) to make it easy to remember, and I set the subwoofer to -5 dB on my receiver.

A lot of people find that when they calibrate their system, they had their sub level too high. I certainly did. If you prefer a higher level of bass, there's nothing wrong with running it that way.

Kevin C Brown · 03-05-2004, 08:01 PM

In fact, because the Radio Shack meter is less sensitive at lower freqs, you should actually adjust the sub's level so that it is a few dB's *below* 75 dB.

Phil Iturralde · 03-05-2004, 08:17 PM

The recommendation from Dolby Labs (my brother's friend works there) is start @ 75 dB for either their DD-EX and original Video Essentials DVD(s) dedicated LFE test tone and see if that balances well with your HT system. If it's sounds a bit anemic @ -10 dB below REF Level, ... then add 1 or 2 dB or more LFE trim until you're happy and it's not boomey, overbearing or bloated. Overall balance is the key!

In my case, I've set my SVS 25-31PCi @ 77 dB (lowest needle swing 76 dB / highest 78 dB) using Dolby Labs DD-EX dedicated LFE test tone & @ -10 dB below REF Level, ... it sounds glorious!!!

Phil

AlexanderS · 03-06-2004, 12:04 PM

So I should use the level's in the receiver and not on the back of the sub? Maybe set the sub's level at 50% and adjust the receiver's output?

When measuring do I keep my receiver at ref level and adjust the sub level's from there or should I back down the volume? Thanks.

**HTF Ads**

Edward J M · 03-06-2004, 12:52 PM

Quote:

So I should use the level's in the receiver and not on the back of the sub? Maybe set the sub's level at 50% and adjust the receiver's output?

No, set the sub level in the AVR to around -5 (on a scale of -10 to +10). Adjust the sub level at the sub amp. Only fine tune with the AVR, but keep it in the negative range regardless. Reason being is to minimize distortion from the sub pre-out.

Quote:

When measuring do I keep my receiver at ref level and adjust the sub level's from there or should I back down the volume? Thanks.

The AVR master volume should be kept at Reference Level for ALL channel balancing and calibration. Never touch the Master Volume control - only adjust the channel levels. In the case of the sub, see above.

If you are using a calibration disc, you will be shooting for either 85 dB (S&V and Avia) or 75 dB (VE).

The DVE disc has (or had) a serious subwoofer calibration tone problem. It was mastered at too high of a level. Go here for more information:

http://www.hometheaterforum.com/htfo...hreadid=184659

Regards,

Ed

AlexanderS · 03-06-2004, 04:56 PM

I thought the S&V disc used 75db? Thats what I used to calibrate with S&V and DVE.

Edward J M · 03-06-2004, 05:22 PM

No, Avia and S&V use 85 dB for Dolby Reference Level. VE and DVE use 75 dB for Dolby Reference Level.

The Ovation products are encoded at -20RL, and the JKP products are encoded at -30RL. Hence the difference in volume requirements when calibrating for RL.

You can certainly use 75 dB for Avia or S&V. The Master Volume setting at this point will just be -10RL.

Many people listen at -10RL anyway, so there is really no problem doing this.

Personally, I always calibrate to RL at Master Volume 0.0 so it's easy to do the math in my head when discussing playback volumes. -10 on my Master Volume is exactly -10RL, and so on.

Ed

AlexanderS · 03-06-2004, 06:34 PM

Well I went ahead and calibrated with S&V. I set my receiver to -5 and sent the level tone out. I ended up with my receiver at -4 and my sub level around 35%. I couldn't nail down a reading though. It kept fluctuating so I went with the setting that fluctuated between 70 and off the scale. What do you guys think?

Kevin C Brown · 03-07-2004, 12:18 AM

Play some CDs and DVDs that you are familiar with and see how it sounds. Adjust from there.

Edward J M · 03-07-2004, 01:08 AM

Quote:

I couldn't nail down a reading though. It kept fluctuating so I went with the setting that fluctuated between 70 and off the scale. What do you guys think?

I assume you're going with 75 dB at all channels?

If so, set the RS meter to the 80 scale on C-weighted Slow. It will fluctuate far less and will be easier to get an average reading.

On the 80 scale, the -5 point on the meter will be 75 dB.