AVS Forum banner
1 - 19 of 19 Posts

·
Premium Member
Joined
·
776 Posts
Discussion Starter · #1 ·
I'm not going to have the time to learn REW or the equivalent.

I have two subs and would like to use a spl meter only at MLP to measure the different outputs at various frequencies.

My subs came with a test cd that has diff frequencies, like 10, 20, 30 etc up to 120.

It would be nice to see if any of the frequencies have major dips.

What if I played the diff frequencies at my average volume (-10) and simply wrote down the spls? This should work to see if there are any major areas for improvement, right?
 

·
Banned
Joined
·
5,866 Posts
yes but you don't know how accurate your dB meter is, how much it is out. So you need correction values, and even then those values may be different to your dB meter, compared to another identical one, and another identical one that has been calibrated.
 

·
Registered
Joined
·
3,767 Posts
I used Real Traps test tone for sometime to do this before I purchased the Omnimic. The Real Traps tones are free and come with graph paper to plot the frequency response. It can be tedious. Radio Shack analog meters have some correction tables to use. I hope the OP has some DSP/PEQ to make adjustments.
 

·
Registered
Joined
·
12,044 Posts
I'm not going to have the time to learn REW or the equivalent.

Simply wrote down the spls? This should work to see if there are any major areas for improvement, right?
Of course it will work.
People used to use Excel and manually plot a line chart prior to REW.
It's old, and extremely time consuming, and requires manual C-weighted correction values. But it works.
(-3db @ 32hz and -6db @ 20hz. Flat between 100hz to 2khz)

REW has C-weighted correction values as an automatic-correction option (and is fast, and most accurate and in-depth analysis.)

The Static SPL values shouldn't be off by more than +-4db for most brands of SPL meters.
The relative SPL values are probably 2-4db as well: between 20hz to 5khz, depending on the quality of the unit you bought.
 

·
Premium Member
Joined
·
776 Posts
Discussion Starter · #5 ·
Of course it will work.
People used to use Excel and manually plot a line chart prior to REW.
It's old, and extremely time consuming, and requires manual C-weighted correction values. But it works.
(-3db @ 32hz and -6db @ 20hz. Flat between 100hz to 2khz)

REW has C-weighted correction values as an automatic-correction option (and is fast, and most accurate and in-depth analysis.)

The Static SPL values shouldn't be off by more than +-4db for most brands of SPL meters.
The relative SPL values are probably 2-4db as well: between 20hz to 5khz, depending on the quality of the unit you bought.
Well this is a perfect opportunity for another stupid question. I didn't want to start a new tread over it.

I'm obsessed over my audio right now. I tend to get obsessed with things, it's a personality quirk I suppose. But I really enjoy this new hobby.

Are most posters on here audio engineers or have advanced educations in audio?

Most of the stuff I read is way over my head. I've read posts about REW and can't comprehend most of what I read or where to start. And I'm a very successful and intelligent person.

Is there an 'Audio for Dummies' book? Should I look into some college courses. I really enjoy screwing around with my HT but it drives me nuts that I don't know what I'm doing.
 

·
Registered
Joined
·
3,767 Posts
Most of us went to audio avs or other forums universities, lol. Just stick around and keep asking question.:) There are some people of varying background that we all learn from with great audio knowledge.
 

·
Registered
Joined
·
13,491 Posts
It doesn't get much easier than the REW guide linked in my sig. ;)
 

·
Premium Member
Joined
·
14,086 Posts
I'm not going to have the time to learn REW or the equivalent.

I have two subs and would like to use a spl meter only at MLP to measure the different outputs at various frequencies.

My subs came with a test cd that has diff frequencies, like 10, 20, 30 etc up to 120.

It would be nice to see if any of the frequencies have major dips.

What if I played the diff frequencies at my average volume (-10) and simply wrote down the spls? This should work to see if there are any major areas for improvement, right?
You can certainly do what your describing. However, it is a VERY time consuming process, especially if you want to try various configurations, placements and settings. Your time would be MUCH better spent learning REW or OmniMic or XTZ Room Analyzer. Once you conquer one of those measurement options, you'd have the skills forever and the efficiencies that go along with them.

Good luck!

Craig
 

·
Premium Member
Joined
·
776 Posts
Discussion Starter · #12 ·
With Omnimic you can be up and running with good measurements in 30 min. It is more expensive for the Omnimic system compared to REW and mic.
Thanks for the advice. I just want something that would help me put my subs in the best locations and determine the best VTF mode for my room. It looks like this will do that.

Do I need anything else to use this effectively? I have the HT set up and a laptop w/ HDMI. Anything else required?
 

·
Registered
Joined
·
3,767 Posts
You need to have a way to make adjustment of the bass/sub. A mini dsp, built-in plate amp DSP/PEQ, or something similar. The first thing is to be able to see how the subs and room response are at the MLP. Ominimic will be a great start.
 

·
Registered
Joined
·
12,044 Posts
Are most posters on here audio engineers or have advanced educations in audio?
Most of the stuff I read is way over my head. I've read posts about REW and can't comprehend most of what I read or where to start. And I'm a very successful and intelligent person.
Is there an 'Audio for Dummies' book? Should I look into some college courses. I really enjoy screwing around with my HT but it drives me nuts that I don't know what I'm doing.
I've been at this audio game for 14 years (and by some peoples definition, that's a small amount of time.)
But no, it's not like I just learned it all yesterday.

It's like swimming or riding a bike or driving a car. At first you are a nervous-wreak filled with fear, uncertainty, and lack of knowledge/skill. Then it becomes old hat and relaxing... or even boring.

I'm a software developer with an average IQ of about ~120 or so (depending on the exact questions and how much I care to participate).
If I put 2-7 years of effort into it I could probably build my own REW (it's not THAT hard, but it is a [email protected]* tonne of WORK though!)

There are varying degrees of software developers, from poor to godly.
If you are good at math and are only book-smart/scholastic (spock-like), that is a good START, but you still won't be a GOOD software developer.
To be a good software developer requires a person to have good math skills but also an inventor-mindset. If you lack either, you won't be a very good developer AT ALL really...
An inventor mindset is a very rare brain that can output more knowledge than what goes into it, or is at least: very observant, tinkerish and a problem solver, or a boundary pusher (thinks outside the box).
The very thing that even the very best computer-AI is extremely-poor at... oddly enough. (and probably never will be good at, or even decent at)...heck, even 90% of most human-AI is poor at that task (i.e. the 99% sheeple/useless eaters :p)

There are 4 types of people in this world:
1) Those who buy bags of ice of their own volition. (rich/lazy sloths / the foolish / the unprepared)
2) Those who can sell ice to Eskimos. (Opportunistic Wolves. Probably owns a freezer too!)
3) Those who make their own ice with freezers.
4) Those who are able to invent/make freezers/electricity, to cool water, to sell both freezers and bags of ice to the 99% who can't do either (for various rimes and reasons.) ;)
Anyways... back on topic! :D

It takes time, it won't happen overnight. (Unless of course you have an IQ of 150+ and REALLY concentrate HARD while burning the midnight oil! Nearly anything is possible with sufficient effort and brainmatter I suppose\conjecture... :D)
 

·
Premium Member
Joined
·
776 Posts
Discussion Starter · #15 ·
You need to have a way to make adjustment of the bass/sub. A mini dsp, built-in plate amp DSP/PEQ, or something similar. The first thing is to be able to see how the subs and room response are at the MLP. Ominimic will be a great start.
So with Omnimic and laptop it would show me the 'dips' and whatnot and then I could mess with the subs VTF and move them around in real time until I see the best overall output?

I think I could then rerun Audyssey xt32 with multi sub eq to improve it even more.
 

·
Registered
Joined
·
3,767 Posts
Yes, you could do that and most likely get some improvement in the room FR. REW and Omnimic are powerful tools and not to pair them with DSP/PEQ would be selling your system short. You can always add these later. Since you are on this forum, it is obvious you want good sound and the DSP/PEQ is just a small investment.

The Ominimic comes with everything you will need. If you have a computer and monitor, you are good to go!
 

·
Registered
Joined
·
12,044 Posts

·
Premium Member
Joined
·
776 Posts
Discussion Starter · #18 ·
I have Denon AVR X4000w.

There is a 'level' screen that lets you cycle through each speaker while it emits a pink noise.

When I measure each speaker with spl, they are at 75 DB

What should subs measure on spl? Should they be approximately 75 DB also? SPL meter is 'Mastech MS6700' and I do not have correction tables. Just wondering what they sould be at BALLPARK.
 

·
Registered
Joined
·
3,366 Posts
Here's an excel spreadsheet I've used in the past:

http://www.avsforum.com/forum/attachment.php?attachmentid=306250&d=1413057263

Like others have said, this is very time consuming...but it can be very helpful.

I eventually went with Omnimic for a measurement rig. If OM was around when I started doing this, I would have saved many many hours...it is so much easier and more effective.

If you can swing the cost, you can take measurements in 10min after you get it. If you have the time to learn it, REW is just as good (or better) and is free, but as mentioned, you will still need to purchase a mic.
 
1 - 19 of 19 Posts
Top