Radio Shack Sould Level Meter - Analog Meter

You might want to contact Rives Audio and ask them this question. They sell a system calibration/test CD that is specially-designed to accommodate the non-linearities of the Radio Shack meters ($18 at RivesAudio.com).

On the Rives site, they have a link to Radio Shack p/n 33-4050, so I assume they would recommend the 4050 series.

We've been in contact with Radio Shack over the last year. They informed us of the change over way before it was actually implemented. They even sent us the manual for review. However, what was missing was a unit for testing. We have one now, but did not get one in advance. They did tell us that the change was not performance related. It turns out the two appear to respond identically (at least within our tolerence of measurement). They did some cosmetic things with the new model and I believe they replaced some components internally (perhaps SMDs in some cases--although we have not opened the unit up) for more cost effective manufacturing.

I see it now on the Radio Shack website. Part # is 33-4050 (& not 31-XXXX)!

Looks better than the older one. Same flawed performance, I suppose, that needs appropriate compensation!

Sorry for the wrong part number. I am still not sure which one to buy. My local Radio Shack has both the old and the new. I am not familiar with SMD to tell whether it is a good thing or a bad thing. Also until Rives tests the new one, we will not know whether it has the same calibration. Rives site says buy the new 4050. When I sent them a message of which one to buy to Rives, since I have access to both, they told me the older model 2050. Needless to say, I am very confused.

SMD stands for Surface Mount Device. It's a way to package ICs that are being used in the SPL meter so that they consume less space on the PC board. Also, there are machines that are used to mount these ICs & solder them (i.e. it is automated) hence the lower cost. SMDs were done mostly from a manufacturing cost stand-point.
Functionally, the SMD parts are identical (& many times better) in functionality.

Per Rives' response, perf. from either SPL meter is identical within the limits of their measurable tolerances. So, in practise, both SPL meters are identical!

My conclusion: buy the latest analog SPL meter & use the same SPL correction factor disk from Rives to account for the low & high roll-offs.

Hope that this helps.

I have the old 2050 style myself, and will be ordering the Rives test CD this week. I think it will be a great investment and provide far more accurate and predictable results then the noise generators built-in to my equipment and the other test disks I have (Avia, Stereophile, XLO/Sheffield Labs).

We'll see.....
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Sorry for the confusion between the call and the site. On the site we show and link to the new model as the old model is "no longer available" according to Radio Shack. We know that there are still 2050s in about 400 stores across the country. We know the reliability and the precise curves measured on quite a few units over a different period of time. I suspect the performance is identical with the new model--but we have not yet done the same extensive testing as of yet.