Radio Shack Sould Level Meter - Analog Meter

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.