looking for the correction table for the Radio Shack SPL meter... (1 Viewer)

[John Doran]

does anyone know if the DIGITAL SPL meter from radio shack suffers from the same low-frequency inaccuracy as the analog one?

and, if so, does anyone have the complete correction table?

thanks,

- jd

 

[Lynn Little]

Yes it does. Here's the correction table:

10hz.....+20db
12.5hz...+16.5db
16hz.....+11.5db
20hz.....+7.5db
25hz.....+5db
31.5hz...+3db
40hz.....+2.5db
50hz.....+1.5db
63hz.....+1.5db
80hz.....+1.5db
100hz....+2db
125hz....+.5db
160hz....-.5db
200hz....-.5db
250hz....+.5db
315hz....-.5db
400hz....0db
500hz....-.5db
630hz....0db
800hz....0db
1k.......0db
1.25k....0db
1.6k.....-.5db
2k.......-1.5db
2.5k.....-1.5db
3.15k....-1.5db
4k.......-2db
5k.......-2db
6.3k.....-2db
8k.......-2db
10k......-1db
12.5k....+.5db
16k......0db
20k......+1db

 

[John Doran]

Lynn,

thatnks a lot.

would you happen to know what the corrections are for the intervening frequencies? i'm specifically looking for them from 10hz-100hz at 1hz increments.

do you know where i might be able to find them?

thanks again for the help - i really appreciate it.

- jd

 

[Lynn Little]

"i'm specifically looking for them from 10hz-100hz at 1hz increments."

Wow! I don't know where you could find a correction chart with such minute increments. Sorry...

 

[Seth_L]

would you happen to know what the corrections are for the intervening frequencies? i'm specifically looking for them from 10hz-100hz at 1hz increments.

do you know where i might be able to find them?

Do you know how to interpolate? You can approximate them yourself.

Seth

 

[John Doran]

Do you know how to interpolate?

not logarithmically, i don't.

if someone has a formula i can apply, i'd be all too happy to do so...

i mean, i can approximate, but i'd rather be exact, since, to me anyway, being out 1 or 2 or (more likely) 3db matters in the plotting of the in-room frequency response of my sub.

- jd

 

[Jeremy Stockwell]

Here's the interpolated values I used for 10-80 Hz.

JKS

1020
1118.25
1216.5
1315.25
1414
1512.75
1611.5
1710.5
189.5
198.5
207.5
217
226.5
236
245.5
255
264.66
274.33
284
293.66
303.33
313
323
333
343
353
363
372.5
382.5
392.5
402.5
412.5
422.5
432.5
442.5
452
462
472
482
491.5
501.5
511.5
521.5
531.5
541.5
551.5
561.5
571.5
581.5
591.5
601.5
611.5
621.5
631.5
641.5
651.5
661.5
671.5
681.5
691.5
701.5
711.5
721.5
731.5
741.5
751.5
761.5
771.5
781.5
791.5
801.5

 

[John Doran]

thanks a lot jeremy - i appreciate your taking the time.

- jd

 

[Edward J M]

John, there is a fix for the RS meter, if you are willing to buy some capacitors and break out the soldering iron. I don't have it here at work, but it is saved on my home PC. It doesn't look too hard, and the instructions are detailed. If I owned one, I'd certainly perform the mods.

After the mods, the meter is supposedly accurate to well below 20 Hz. One easy way to tell, run a before/after FR sweep under identical conditions and compare the results.

Send me PM if interested.

Regards,

Ed

 

[BradJudy]

I believe Link Removed that Edward is referring to.

I also recently purchased one of these meters and I'm a bit concerned that the multiple correction tables I have found don't all agree. I'm planning on importing one into Speaker Workshop and playing around with it.

I am considering the mods I linked to, but have not performed them, nor do I know what an appropriate correction curve would be for a post-mod meter.