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Old 11th March 2009, 08:39 PM   #1
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Default Radio Shack SPL Meter - Anything Better?

I've almost got myself convinced to purchase a Radio Shack Sound Pressure Level Meter. Though it is hard to justify on my poverty level income.

And poverty is the reason for this post.

Is there anything better for the money that either of the Radio Shack Meters?

http://www.radioshack.com/search/ind...d%20meter&sr=1

The stated frequency response is 30hz to 10khz which seem better than most economy SPL meters.

So, now the choices are analog meter or digital read-out.

I would think with an analog meter display I would get a better sense of the dynamics of the music, but couldn't take such precise readings.

The Digital has precision, but lacks the display dynamics.

I'm open to opinions on the Radio Shack, and to suggestions for better SPL meters for similar money.

Though, since I am already stretching my budget, I can't spend much more that $50.

Suggestions? Opinions? Ideas? Options? Whatever?

Thanks.

Steve/bluewizard
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Old 11th March 2009, 09:30 PM   #2
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we use the digital one from radioshack.. i've compared it to some of the ones that our municipal bylaw officers use for noise control and it is pretty actually, although there is no decimal places, but its pretty close. usually same or +- 1db. @ 95db
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Old 11th March 2009, 11:51 PM   #3
Ron E is offline Ron E  United States
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What do you want it for? They are fun to play with, but not as useful as real measurements. They are flat from ~60-1k, then rise about 6+dB to ~6kHz, then drop back to 0dB by 10kHz and are -12 to -20 at 20kHz. Analog is better than digital, IMO, except that you can bust the analog movement if you aren't careful.

The Audio society of MN (www.audiomn.org) is having a meeting Tuesday the 17th, if you can make it.
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Old 12th March 2009, 03:59 AM   #4
fwater is offline fwater  United States
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This Minnesotan doesn't see any info for the meeting on the link. I'd like to make it if there's something of interest...
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Old 12th March 2009, 04:12 AM   #5
Pano is offline Pano  United States
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You should get one, it's a handy dandy tool.

There are even FR correction tables out there for it, if you search hard enough.

As a general SPL tool, it's hard to beat. I've owned several over the past 20 years (keep losing them!) and would not be without.
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Old 12th March 2009, 05:05 AM   #6
Ron E is offline Ron E  United States
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Quote:
Originally posted by fwater
This Minnesotan doesn't see any info for the meeting on the link. I'd like to make it if there's something of interest...
Sorry, we are in the process of moving, need to change our domain registration - a better link would be:
http://sites.google.com/site/audiosocietyofminnesota/
This link is on the original page I linked to. A successful tweeker is going to talk about equipment mods and tweeks and such - see the meeting announcement by clicking the link in the sidebar on the front page. Aside from the meeting topics there are often side room discussions of value.
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Old 12th March 2009, 05:12 AM   #7
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If you have an iPhone/Touch, there's an app for that called SPL. I believe it's $7, but they were going raise it to $10(don't quote me on this, it might be cheaper). It's supposed to be more accurate than the RS model.
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Old 12th March 2009, 06:32 AM   #8
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I'm in sunny southern Minnesota, or as I like to call it audio hell.

Though, I've never had an exceptionally expensive system, it's always been the best system of anyone I knew. But that says more about the quality of my friends, than it does about my stereo equipment.

I have some speakers I built back in college, and while they have served me well for many many years, they are not that well balanced.

Last summer I rebuilt them hoping to improve the bass, and tame an overly aggressive midrange. So, I re-ported the cabinet, put a fixed L-Pad attenuator in the tweeter and the midrange. But now I think I've tone down the treble too much, and the midrange not enough, and I'm wondering about the port tuning.

Also, when I pleaded poverty, I wasn't kidding. So, I'm working on a dirt poor budget here.

First, I though I could do a general frequency response on the speakers, though 10khz would probably be adequate for the speakers I have. That is, the mid to high crossover is 5khz, so if I can get significantly above that, it's probably close enough.

Plus the only source of test signal I have are test tones burned onto a CD (actually, 3 CD's - 10hz to 300hz, 1/3 octave tones, 1/6 octave tones)

Next, I'd like to check the actual port resonance. It seem if I put the SPL meter right up to the port and ran a low end frequency sweep, I could determine the actual resonance point, and re- tune it if necessary.

Finally, I like to run some Pink Noise and measure the woofer, midrange, and tweeter individually at close range to determine the real loudness balance between them. Which in turn would allow me to determine the right attenuation to use to balance the three component speakers.

Again, my speakers are old. I don't think it is possible to get the specs on the woofers. I've already contacted CTS to no avail. But the design book I used has some margin notes indicating that the woofer has a resonance of 25hz. It is a 12" CTS with a 32 ounce magnet. The midrange is a 4" x 10" horn, and the tweeter is a 3" x 3" piezo horn. The piezo tweeter has an 8 ohm resistor across the terminals to stabilize the load and it connected to a 3-way crossover crossing at 800hz and 5khz.

The cabinet is about 2.5 cubic feet with a 2" diameter by 4" deep flared port. When I tuned the port, to correct for components taking up room inside the cabinet, I used 2.3 cu.ft. as the internal volume.

Because the midrange horn is so loud, something like 108db/1 watt, I have an L-Pad on it, and it is turned down nearly as far as it will go. But still isn't quite right.

I've considered just getting some software and using my computer to test the speakers, but the entry cost is too high. Even a half-a$$ed job of it is going to cost $150 minimum. But in reality, if I were going to do it even remotely right, it would be more like $500. That's out of my league unless I win the lottery. So, it seems like the SPL meter might be the only option for me. But it is hard to justify the cost when that money could go for groceries, or car repairs, or other unexpected expenses.

I currently have my speakers sitting along side some JBL Venue Stadiums (2x8", 3" cone mid, 1" done high). The JBL seem long on bass but weak in midrange, and my 12" DIY CTS speakers are lean, but clear, on bass and long on midrange. Between the two of them, they sound pretty good.

Still, I either obsess over the idea until it drives me nuts, or just just spend the money and do what needs to be done.

How consistent is the frequency response of the Radio Shack Digital Meter? Are there response correction files for it that I could use to manually correct the readings I take?

One thing I will say about my woofers is that for having been purchase in the very early 80, the cones and surrounds are in pristine condition. The surrounds are as soft and pliable as the day I bought the speakers; not a hint of decay or deterioration.

So, that is my long sad story.

So, I'm looking to maximize my money. Hence the question, is there anything better for the money than the Radio Shack?

Thanks for the info about the Minnesota Audio Society, if I ever win the lottery, I'll come knocking.

Steve/bluewizard
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Old 12th March 2009, 07:21 AM   #9
terry j is offline terry j  Australia
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someone else will be able to provide a link, but I believe you can build your own with a panasonic capsule. that should be cheap enough!
\
a few bibs and bobs to get the signal into your computer (also described I think) and you're away.

anyway, download rew and forget all that cd's with sine waves business. use their generic cal file for the rs meter, and if all you are doing is checking relative driver levels it may be all you need.

while you are at it, you cN NOW measure your in room response, rs meter perfectly adequate for that.
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Old 12th March 2009, 04:00 PM   #10
Ron E is offline Ron E  United States
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Quote:
Originally posted by BlueWizard
First, I though I could do a general frequency response on the speakers, though 10khz would probably be adequate for the speakers I have. That is, the mid to high crossover is 5khz, so if I can get significantly above that, it's probably close enough.

Plus the only source of test signal I have are test tones burned onto a CD (actually, 3 CD's - 10hz to 300hz, 1/3 octave tones, 1/6 octave tones)

Next, I'd like to check the actual port resonance. It seem if I put the SPL meter right up to the port and ran a low end frequency sweep, I could determine the actual resonance point, and re- tune it if necessary.

Finally, I like to run some Pink Noise and measure the woofer, midrange, and tweeter individually at close range to determine the real loudness balance between them. Which in turn would allow me to determine the right attenuation to use to balance the three component speakers.

The cabinet is about 2.5 cubic feet with a 2" diameter by 4" deep flared port. When I tuned the port, to correct for components taking up room inside the cabinet, I used 2.3 cu.ft. as the internal volume.

I've considered just getting some software and using my computer to test the speakers, but the entry cost is too high. Even a half-a$$ed job of it is going to cost $150 minimum.

How consistent is the frequency response of the Radio Shack Digital Meter? Are there response correction files for it that I could use to manually correct the readings I take?

So, I'm looking to maximize my money. Hence the question, is there anything better for the money than the Radio Shack?

I have frequency response measurements I made with 1/3 octave pink noise and a RS SPL meter on some speakers I own and they don't look anything like accurate frequency response curves on the same speakers do, with or without corrections.

If you can burn a CD, you can play test tones through your computer.

An RS SPL meter is not useful for measuring port resonance by putting it on the port, the port output may be broad or narrow - the best way is to close mike the woofer and look for a notch.

You can calculate port resonance from what you have provided.

To measure Frequency response a DIY mic with a panasonic capsule and the program Speaker Workshop will be much better than even a RS SPL and a generic "calibration". Pretty low cost of entry.
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