Radio Shack SPL Meter Question...

Grimster74

Okay, I know we've all been down this road before but I have to ask the question again. I purchased the Radio Shack SPL meter a while back and this weekend will be the first weekend the wife and kids won't be home since I've purchased it. This weekend is going to be the ideal time to setup my H/T. So, the question is, how do I go about setting up the speakers again. Have the general idea, just need someone the clarify once again and were better to go then the Polk Audio Forum. I've seem to have misplaced the Avia setup disk, (or someone just hasn't returned it) is it a must have to setup the speakers or does it just make things easier. Any help would be greatly appreciated.

Grimster74

By the way, I finally got some pictures posted in the System Showcase yesterday. Take a look if that helps any.

ChrisDurano

Hey Grim........ I like your showcase. Very nice and clean. So you're going to move everything downstairs? Too bad with all the sweet wiring work you did. Anyway, I like the way you have it setup in the showcase (ie. dipolar on sides, direct radiating on rear). If you can find your Avia disc, you should set use the speaker test tones and set your receiver's volume around 70 to 75 dbs. Then you can use your SPL meter to adjust each speaker volume until there within 1 decibel of eachother. I like to use the "C" weighting on the SPL meter. Good luck and don't forget to update your pics.:)

faster100

This is from DR.Spec


1) Get yourself a properly calibrated SPL meter.


2) Use the test tones on the receiver, or a calibration DVD. The DVD is supposedly better, but both methods are acceptable and WAY better than calibrating by ear. Note, the following is for the 75dB tone method - I know one DVD test disc requires 85 dB instead, but you get the idea.

3) Set all the individual speaker volume controls on the receiver to 0. Set the sub volume control to -5.

4) Play the center channel test tone and measure the SPL AT your listening position.

5) Adjust the Master volume on the receiver until the test tone for the center channel speaker is showing 75 dB on the SPL meter.

6) DON'T touch the Master volume ANYMORE, and write down the Master volume setting.

7) Switch to the test tones for the mains and surrounds and adjust the individual speaker volume controls on the receiver (NOT the Master volume) until they also read 75 dB at the listening position.

8) Switch to the sub test tone and adjust the plate amp volume control AT THE SUB (NOT the receiver Master volume, and NOT the receiver sub volume, which should be left at -5) until the SPL meter reads about 75 dB at the listening position. If you like your bass a bit on the hot side, adjust the sub amp volume control until you hit 78 dB at the listening position. The bass tone will fluctuate some on the SPL meter, so try to take an average.

Your system is now properly calibrated, and the Master volume setting you wrote down will get you pretty close to reference level SPL peaks for both surround sound and bass.

Doc

kberg

Just an addition to the above, set your SPL reading to "slow", not "fast" response for C-weighting.

Dr. Spec

Also addition:

Some Master Volumes default to 00 with internal test tones.

Doc

Grimster74

Okay Doc, first off, just want to thank-you and everyone else in this forum that have been very helpful. My next question is, can someone explain the term "AT REFERENCE SPL", seems THAT term can be taken many different ways and I'd just like to know the correct definition. Oh yeah, this Sunday a buddy of mine owns a RTA Meter and he will be coming over to help me setup that extensive EQ on that Sony receiver of mine.

Dr. Spec

Reference Level is defined by Dolby Labs as 105 dB bass peaks from any surround channel, and 115 dB bass peaks from the LFE channel. All as measured at the listening position.

If there is a simultaneous bass peak in a surround channel and the LFE channel, the resulting SPL is approximately 121 dB.

If you set your speaks to small, that means the subwoofer needs to be capable of potentially delivering a 121 dB bass peak.

The only way to truly calibrate your system to Reference Level is with a DVD like Avia, Video Essential, Sound & Vision, etc.

Depending on how the DVD is mastered, RL is often too loud for comfort. But it is a benchmark by which we can all judge the playback volume of our HT systems. For example, I can say I watched Die Another Day at 12 clicks under RL, and you know exactly how loud that is if your system is also calibrated the same as mine.

Doc

Grimster74

So in your opinion, what should I set my speakers at, should all the speakers be set to small, or should the fronts be set to large and the rest to small and so on, and so on. Thx.

Dr. Spec

All small, 80 Hz crossover to the subs.

At a minimum balance all channels with SPL meter and test tones.

At best use a calibration DVD and balance all channels through the DVD player and also calibrate master volume and speaker levels to Reference Level. RL will be 75 dB or 85 dB depending on the calibration DVD.

Doc

section19

Being new here, I've been perusing some of the older threads looking for information and knowledge.

So I have a question regarding calibrating my speakers.

I now have my mains hooked up the Polk way (through the sub) and set to large (sub off). When I calibrate the system I'm assuming I'm going to need to hook them back up the non-polk way (straight from the AVR, sub on and cabled from the direct line to the AVR sub out). Is that correct? That will be a bit of a hassle but I'll do it if I have to.

That said, how will my calibration settings be affected if I switch back to the Polk way after I've finished setting all the levels?

Thanks.

burdette

Doc... what is a click? Is that dB? I'm assuming it is because there is no standard decrease/increase in power for changes in volume setting for different amps/receivers. Volume controls and the numbering systems that goe along with them are VERY different brand to brand.

Is it correct that the nickel answer to "what is reference SPL" is simply a particular volume in your room (the 105 and... 115dB peaks you mentioned)? Which means even if you and I were running the exact same rig, but different sized rooms, our calibrations and ultimate "master volume" setting for reference SPL would be different... we'd both measure the same peaks on our trusty meter.. but how we got there is particular to each system/set-up....?

Dr. Spec

Originally posted by burdette
Doc... what is a click? Is that dB? I'm assuming it is because there is no standard decrease/increase in power for changes in volume setting for different amps/receivers. Volume controls and the numbering systems that goe along with them are VERY different brand to brand.

Is it correct that the nickel answer to "what is reference SPL" is simply a particular volume in your room (the 105 and... 115dB peaks you mentioned)? Which means even if you and I were running the exact same rig, but different sized rooms, our calibrations and ultimate "master volume" setting for reference SPL would be different... we'd both measure the same peaks on our trusty meter.. but how we got there is particular to each system/set-up....?

Good point. The Denon 3803 has 1/2 dB Master Volume increments and it is very accurate per my SPL meter. Yes, when I use the term "click", I mean a 1 dB increment.

Your understanding of RL is perfect. The only real variable is how hot the sub is running. Most people go 3-4 dB hot for HT but it varies significantly.

Even if we had different rigs, amps, speakers, rooms, etc., if we calibrate to the same benchmark, it will be the same SPL at the listening position, assuming (as you rightly point out), our Master Volume settings truly indicate a 1 dB change with each whole digit increment.

oc

gidrah

Originally posted by section19

I now have my mains hooked up the Polk way (through the sub) and set to large (sub off). When I calibrate the system I'm assuming I'm going to need to hook them back up the non-polk way (straight from the AVR, sub on and cabled from the direct line to the AVR sub out). Is that correct? That will be a bit of a hassle but I'll do it if I have to.

That said, how will my calibration settings be affected if I switch back to the Polk way after I've finished setting all the levels?

Thanks.

This is where it pays to be lazy. Calibrate it the way it is now as things would definately change if you changed methods.

On the other hand, you might want to calibrate it the way it is now, listen, hook it up the other way, re-calibrate, & listen again.

section19

Thanks for responding, gidrah. I appreciate it. I guess I'll try it first the way it's hooked up now and see how it sounds.

Thanks, again