THAT1510 THAT1512 Gain Resistor Calculator

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THAT1510 THAT1512 Gain Resistor Calculator

Post by mediatechnology » Sun Jun 29, 2008 12:32 pm

Here is a spreadsheet I did some time ago for calculating 12 and 24 step gain controls for the THAT1510 and THAT1512.

The default step size may be modified using the fill down function in Excel. They can also be made uneven with greater precision (smaller steps) at the top range of gain. The values are rounded to E96 1%. Below 10 ohms 5% resistors may be required since 1% values are not usually available. ... n_rev3.xls

EDIT: Updated to Rev 3 9.13.08

Please note that the spreadsheet calculates total resistor values. Only one resistor is in-circuit at any time. The selector switch is "1 of 12" or "1 of 24." In my prototypes I used a 12 position NKK with the end of each resistor soldered to a switch terminal. The far end of the resistors were bused to a common. It makes for a much simpler build when a PC board is not available.

For stepped gain control using series resistors, for example the GoldPoint Mini-V Custom attenuator, the spreadsheet would need to be modified so that the increase for each step is the difference between it and all the values below it.


Here's a pic of a stereo Mini-V Custom:


Beauty eh? GoldPoint also offer a mono single-deck switch.

The GoldPoint Schematic is here:

On the GoldPoint "In" or "Gnd" can be used along with "Out" to convert the schematic from an attenuator to a stepped resistor.

The spreadsheet also contains tables for using an "Rstop" resistor which sets the maximum gain. I strongly recommend splitting Rstop in half and using 1/2 Rstop in series with each Rgain pin (1 and 8) on the THAT1510 or THAT1512. The resistors should be placed near the 1510. This minimizes the effect of switch lead capacitance which can degrade HF common mode rejection. See: ... df#page=17

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