Radio Shack SPL Meter Correction Values (All new *.cal files are published!)...

[Sonnie]

As promised I am calibrating 2 ananlog and 2 digital RS SPL meters. This by no means a professional calibration but it will be better than nothing at all and give us some clues as to what we need do with correction values.

These will be calibrated against my professionally calibrated Behringer ECM8000 mic and a Behringer Euroback UB802 phantom power mic amp.

Pre-impulse response window set to Tukey 0.25
Pre-ref Window Width set to 125ms

Here's the response we will use to calibrate the RS mics against (this is about as flat as I could get it):

ECM with ecm.cal file is on Tab 1(red):




Old Analog Meter (with newrs.cal loaded) on Tab 2 (green):




New Analog Meter 1 (with NO .cal file) on Tab 3 (blue):




New Analog Meter 2 (with NO .cal file) on Tab 4 (magenta):





Digitals coming up soon!

[MisterG12]

(we'll be giving 3 away!)

Yesssssss!

[Dent]

Sorry for asking this but what exactly are these graphs showing? I'm not sure what I am looking at. Is it of a sweep measurement with various filters engaged? With the second graph showing the ECM mic and the old analog RS meter with the newrs.cal loaded are these lines supposed to be matched exactly although in the region of 18 Hz and lower they obviously are not so what is that saying?

[Sonnie]

Here's the digital models...

New Digital Meter 1 (with NO .cal file) on Tab 5 (light blue):

Viewed with ECM:




Viewed with ECM and Analog Meter 2:






New Digital Meter 2 (with NO .cal file) on Tab 6 (magenta again):

Viewed with ECM:




Viewed with ECM and Digital Meter 1:






And FWIW... here are all of the responses together:





Now we need to get some correction values... although these look pretty good compared to the older ones.






.


These RS Meters will NOT be for sale. Instead.... Home Theater Shack is going to give 2 of the analogs and 1 of the digital meters away.

Not only will you get the meters and have the proper .cal file for them... but you will also get a brand spanking new BFD DSP1124P.

Yup ... you are reading it right! We will giving away 3 new 1124P's with an RS SPL Meter included. Details and an official announcement to follow soon!


And this is just a snippet of what we will be giving away. Stay tuned for the sho-nuff giveaway that we'll be announcing soon! You DO NOT want to miss out on it!


Of course there will be qualifications and one is minimum post count!

[Sonnie]

Dent wrote:

Sorry for asking this but what exactly are these graphs showing? I'm not sure what I am looking at. Is it of a sweep measurement with various filters engaged? With the second graph showing the ECM mic and the old analog RS meter with the newrs.cal loaded are these lines supposed to be matched exactly although in the region of 18 Hz and lower they obviously are not so what is that saying?

What you are looking at are 4 different RS Meters that have no correction files loaded compared against an ECM8000 that has been professionally calibrated.

The old analog meter has the newrs.cal file correction values loaded in it just for comparision. It's pretty close... close enough.

We will build a new .cal file for the new meters. More than likely we'll let it be the actual newrs.cal going forward since most people have the new meters instead of the old one.

[pierrebnh]

I'm having a hard time importing ndm1.mdat to apply the correction values to it. Is there a procedure I'm missing?

[Sonnie]

Just save it to your harddrive and open it up in REW version 3.29... it should work.


It appears the only significant difference between the new analogs and the new digitals is around 32hz.



I probably should have shown one with the old analog meter and no .cal file so show the difference between the two.

[pierrebnh]

Yeah, I tried File/Load Measured Data Set and File/Import Measured Data and neither worked. One says it's not 3.29 compatible and the other gives a parsing error.

[Sonnie]

Hmmm... it's definitely 3.29 Build 321. Try one of the others and let's see if it does the same.


But if you are trying to determine correction values then you probably need to use Excel and then create a .cal file in Notepad.

[pierrebnh]

That's what I have too. I just wanted to see what the graph looked like with one of your Digital SPL and the .CAL applied. Just to compare with that ECM .

I tried with ndm2.mdat and got the same result. I'll try with IE instead of FireFox maybe...otherwise, no big deal.

[pierrebnh]

Ok well it's doing the same thing with IE. No worries, probably user error.

[Sonnie]

pierrebnh wrote:

That's what I have too. I just wanted to see what the graph looked like with one of your Digital SPL and the .CAL applied. Just to compare with that ECM .

You wouldn't be able to do that anyway. You'd have to load the cal file prior to measurement. Unless there's a way to do it that I'm not aware of.

I can tell ya though... If you add the newrs.cal file to any of those RS measurements above.... you get an almost ruler flat response. You'd be right about 80db at 10hz.

[Sonnie]

Okay, thanks to brucek... we have new correction values for the newer analog and the newer digital meters. The old analog meter correction values will not change, however, what model RS Meter you have will determine which correction values you will need.

For the record... from meter to meter of the same model, the measurements are extremely close. brucek took the average of the two meter responses (the average of the two new analog meters and the average of the two new digital meters) and developed corrections values that would correct to an average of the meters. This should keep us very close to the same corrections from meter to meter.

Unfortunately if you have been using the newrs.cal file on one of the newer analgo or digtal meters then your response is NOT correct and you will need to obtain the latest .cal file from the Downloads page.


Below are graphs of what the correction values will look like when you load the appropriate .cal file into REW.


New Analog Model #33-4050 = newrsanalog.cal



-----

New Digital Model #33-2055 = newrsdigital.cal



-----

Older Analog Model #33-2050 = oldrsanalog.cal (no change... only the .cal file name changed from newrs.cal to oldrsanalog.cal)




It is apparent from these tests that the newer meters are definitely much more accurate than the older meter.

[Dent]

Sonnie,

When you say the new RS digital SPL meter are you saying that there used to be an old RS digital SPL meter? The reason I am asking is because I have had my RS digital SPL meter for a few years now and I believe the model number hasn't changed but I could be wrong.

[Sonnie]

I don't know for sure but I think there use to be another one that was an older model #... I'm not positive but I wanted to be safe. If the model # is the same I think you'll be okay.

[DMF]

I have an "older" digital meter. It is flat-sided rather than waisted like the new analogs. On the back it says, "Cat No. 33-2055". That is the one still shown in the RS online catalog. So I guess they are the same.

Anyone have a digital meter with a different catalog number?

[Sonnie]

Good question... I just ask you this over at AVS... lol.

[Robert_Gibran]

Geez, I hope I'm not throwing a kink in things here, and this may be old news, but...

According to Michael Fremmer in the June 06 issue of Stereophile:

RadioShack has discontinued its Realistic analog sound-pressure-level meter. Audio Technologies, Inc (ATI) http://www.atiaudio.com has stepped in and bought the rights to it. They improved the response of the built-in electret condenser microphone and now rate it at 32Hz-20Hz, +/-2dB at 114dB.

RG

[Sonnie]

It seems there's about 4-5 different companies making these meters, or sticking their names on them. We did post about the ATI meters here in another thread somewhere.

If you'll notice that the corrections above are +/- 2db from about 30-100hz... which would coincide with ATI's response claims. Maybe whoever was building the meter for RS improved it before ATI got a hold of it. Seems that way.

[Tony Bauco]

This is for the old Radio Shack analog meter (33-2050). I took Sonnie's low frequency data out to 100Hz, Ilkka's mid-frequency data from 110Hz to 660Hz, the old calibration data from 800Hz to 8000Hz and data from a guy named Salas from 10000Hz to 20000Hz (they were similar to Ilkka's data in this range) and merged them. I then did a spline fit and came up with the following set of correction factors:

10 -27.00
11 -24.15
12 -21.91
13 -20.13
14 -18.61
15 -17.33
16 -16.15
17 -14.92
18 -13.85
19 -13.01
20 -12.38
21 -11.66
22 -10.79
23 -10.00
24 -9.33
25 -8.80
26 -8.41
27 -7.99
28 -7.50
29 -6.99
30 -6.50
31 -6.03
32 -5.60
33 -5.23
34 -4.89
35 -4.58
36 -4.29
37 -4.04
38 -3.83
39 -3.64
40 -3.46
41 -3.31
42 -3.16
43 -3.01
44 -2.88
45 -2.74
46 -2.60
47 -2.46
48 -2.35
49 -2.26
50 -2.21
51 -2.18
52 -2.15
53 -2.11
54 -2.04
55 -1.98
56 -1.95
57 -1.92
58 -1.88
59 -1.84
60 -1.80
61 -1.77
62 -1.73
63 -1.71
64 -1.71
65 -1.72
66 -1.70
67 -1.67
68 -1.64
69 -1.60
70 -1.56
71 -1.52
72 -1.47
73 -1.41
74 -1.34
75 -1.26
76 -1.19
77 -1.12
78 -1.07
79 -1.02
80 -0.98
81 -0.94
82 -0.89
83 -0.85
84 -0.80
85 -0.75
86 -0.71
87 -0.66
88 -0.62
89 -0.59
90 -0.55
91 -0.52
92 -0.50
93 -0.47
94 -0.43
95 -0.40
96 -0.36
97 -0.34
98 -0.32
99 -0.30
100 -0.27
110 -0.21
120 -0.19
130 -0.16
140 -0.13
150 -0.10
160 -0.08
170 -0.07
180 -0.05
190 -0.04
200 -0.03
210 -0.02
220 -0.01
230 0.00
240 0.00
250 0.01
260 0.01
270 0.02
280 0.02
290 0.02
300 0.02
310 0.02
320 0.02
330 0.01
340 0.01
350 0.01
360 0.01
370 0.00
380 0.00
390 0.00
400 -0.01
410 -0.01
420 -0.01
430 -0.01
440 -0.01
450 -0.01
460 -0.01
470 -0.01
480 -0.01
490 -0.01
500 -0.01
510 0.00
520 0.00
530 0.01
540 0.02
550 0.02
560 0.03
570 0.03
580 0.04
590 0.04
600 0.05
610 0.05
620 0.06
630 0.06
640 0.07
650 0.07
660 0.08
670 0.08
680 0.08
690 0.08
700 0.07
710 0.07
720 0.06
730 0.06
740 0.05
750 0.04
760 0.03
770 0.02
780 0.01
790 0.01
800 0.00
810 -0.01
820 -0.01
830 -0.01
840 -0.02
850 -0.02
860 -0.02
870 -0.02
880 -0.02
890 -0.02
900 -0.02
910 -0.02
920 -0.02
930 -0.01
940 -0.01
950 -0.01
960 -0.01
970 -0.01
980 0.00
990 0.00
1000 0.00
1100 0.01
1200 0.00
1300 0.00
1400 0.02
1500 0.04
1600 0.08
1700 0.13
1800 0.19
1900 0.26
2000 0.34
2100 0.42
2200 0.51
2300 0.60
2400 0.70
2500 0.81
2600 0.91
2700 1.02
2800 1.13
2900 1.24
3000 1.34
3100 1.45
3200 1.55
3300 1.65
3400 1.74
3500 1.83
3600 1.92
3700 2.01
3800 2.09
3900 2.16
4000 2.24
4100 2.31
4200 2.37
4300 2.43
4400 2.49
4500 2.55
4600 2.60
4700 2.65
4800 2.69
4900 2.73
5000 2.76
5100 2.80
5200 2.83
5300 2.85
5400 2.87
5500 2.89
5600 2.90
5700 2.91
5800 2.91
5900 2.92
6000 2.91
6100 2.91
6200 2.90
6300 2.88
6400 2.86
6500 2.84
6600 2.81
6700 2.78
6800 2.75
6900 2.71
7000 2.66
7100 2.62
7200 2.56
7300 2.51
7400 2.45
7500 2.38
7600 2.32
7700 2.24
7800 2.17
7900 2.09
8000 2.00
8100 1.91
8200 1.82
8300 1.72
8400 1.62
8500 1.51
8600 1.40
8700 1.29
8800 1.18
8900 1.07
9000 0.95
9100 0.83
9200 0.71
9300 0.58
9400 0.46
9500 0.33
9600 0.21
9700 0.08
9800 -0.05
9900 -0.17
10000 -0.30
11000 -1.50
12000 -2.50
13000 -3.51
14000 -4.60
15000 -5.74
16000 -6.93
17000 -8.16
18000 -9.43
19000 -10.71
20000 -12.00

Can someone who took data with this meter and a calibrated microphone through the entire spectrum verify if this is close?

[Sonnie]

I don't know of anyone who has calibrated the entire frequency range on this meter. I never could get a flat enough response to compare it.