[hagtech]

For those of you who would like a custom range of resistor values for cartridge loading, I've come up with an equation to help you determine the intermediate values.  It uses a geometric sequence.  That is, a constant multiplier between values.  The formula is

k = (r5/r0)^0.2;

or you divide the final value by the initial value, and then raise to the power of 1/5th.  For example, if you want a range from 20 ohms to 200 ohms, then we get k = 1.585.  We use this as

r(n+1) = r(n) * k;

or to get the second value, multiply 20 * 1.585.  The sequence (for this example) is thus

20
31.70
50.24
79.62
126.2
200

And the closest 1% resistor values would be

20R0
31R6
49R9
78R7 or 80R6
127
200

jh

[ecir38]

Awesome, thanks Jim.

[hagtech]

Here's another way to do it.  You'll notice that when I plot the above example you get a straight line with a logarithmic Y axis.



So you can set any two endpoints, draw a straight line, and the intermediate values can be read directly from the graph.  You really don't have to be that accurate, the only reason I specify 1% resistors is that they are metal film types and sound good with very low added noise.

jh

[tubesforever]

Jim I feel dumb asking this question, but what value resistors go in the R2 right and left slots?  I cannot find anything at all in the directions.

Are these dependent on the resistor values selected for the R1 right and left?

[ecir38]

See the second the last page in the manual or for a larger printable version the third pic i sent you.

[hagtech]

but what value resistors go in the R2 right and left slots?

Best to use the guide in the manual which states values for each resistor, rather than their reference designators.  The schematic might be a little confusing (I drew it that way on purpose to make the machine harder to counterfeight).

jh