Originally Posted by Stephan Mire
mthomas47, first thank you for creating this thread. I must apologise in advance as I haven't read the entire thread, just about 6-7 pages and I wanted your feedback on this.
When setting speaker/subwoofer levels, I've always used my AVR internal test tones and a Ratshack SPL meter, C-weighting and Slow. Some people I've spoken to have recommended that I DO NOT use the internal AVR test tones, and instead use an external source (test disk), or REW for the tones.
What is your take on this?
Second question, some people have recommended I ditch the Ratshack meter and instead get a UMIK-1 as it's more accurate for setting speaker/subwoofer levels. Is there any truth to this?
You are very welcome! The thread itself is an interesting discussion forum, but the real purpose of the thread was to create a "Sticky" thread for the Guide. I hope that over time (because it's very long to read all at once) people will find the encyclopedic Guide useful too.
From your first question, I take it that you aren't using an auto calibration routine in your AVR. Most modern AVR's will measure speaker/subwoofer levels and auto-calibrate them to the same volume levels. Doing it that way will be especially helpful because the AVR will automatically calibrate your speakers/subs to Dolby/THX Reference. Section II-A of the Guide explains that process in some detail. That is the process I would recommend using.
If you do want to calibrate your HT system yourself, there is nothing wrong with using the internal test tones in your AVR. Using an external disk is preferred when checking levels that have already been auto-calibrated by your AVR, but most AVR's do that auto-calibration very accurately. (There may be some specific exceptions to that, but Denon/Marantz, Yamaha, NAD, Sony, for instance, should all be pretty capable.)
There is no question that using a UMIK-1 would be a more accurate way to measure SPL than with a Radio Shack SPL meter. Particularly for the lower bass frequencies played by your subwoofers, the inexpensive SPL meter will be extremely inaccurate. There are correction tables that are available online to help account for the inaccuracy of uncalibrated SPL meters, but they simply offer relatively more accuracy. They still aren't giving you real accuracy.
A UMIK-1 has an error factor of approximately +/- 1.5db all the way down to about 10Hz. But, combined with REW (which is a free download) the UMIK-1 allows you to do much more than just measure SPL. It also allows you to measure your frequency response, among other things, which can be very useful in a number of ways. There is a pretty good learning curve involved in the effective use of REW, but there is also a lot of help available in learning to use REW and to interpret the results.
Here is a link to a thread devoted to the use of REW:
My advice would be to start by using the auto-calibration routine in my AVR, if you have one. If you don't have one, then a calibrated microphone, such as a UMIK-1 would definitely be a better way to set volume levels, especially for subwoofers. As noted above however, if your AVR does have an auto-calibration routine, that is typically a very reliable way to set equivalent volume levels for all of your speakers/subs. Then, if you wish to add more subwoofer volume, for instance, simply add whatever amount sounds correct to you.
As you read more of the Guide, and as you are more willing to go further down the rabbit hole in pursuit of improved frequency response, you may wish to explore the use of REW for its own sake. That's the point at which I would add a UMIK-1, unless you don't have auto-calibration.
I hope this helps!