Threshold Coda Phono Stage Toggle DIP Switches

Hi Al,
thanks for responding. I feel that the manual should go into detail for anyone who has not used these switches before. I do not really understand your explanation, so lets take your first example.

"With the 22 switch on, you would have 22 ohms in parallel with 47 K, which is 22 ohms to a very close approximation."

Could you please let us know what this statement means and also how it may relate to the math formula ? in other words, are you saying that with the 22 ohms switch on that it over rides the 47 k and just becomes 22 ohms (and not 22 K)? I am really confused. But I have confidence you can help us understand. and the "to a very close approximation" phrase is also confusing to me as to what this phrase really means.

The "very close approximation" statement reflects the fact that for resistances in parallel, if one resistance is MUCH higher than the other, then their parallel combination as calculated with the formulas I described will be approximately the same number as the lower of the two resistances.

For the example you cited, using the reciprocal of the sum of the reciprocals formula (which applies to the parallel combination of any number of resistors):

1/(1/22 + 1/47000) = 21.9897 ohms.

Using the other formula I described, which applies to the specific case of exactly 2 resistors in parallel, gives the same result:

(22 x 47000)/(22 + 47000) = 21.9897 ohms.

21.9897 ohms is "to a very close approximation" equal to 22 ohms.

It's not that the 22 ohms "overrides" the 47K, it's that (based on the formulas) 47K becomes an insignificant contributor to the overall resistance when paralleled with a MUCH lower value.

Best regards,
-- Al

Thanks Al,
Now I can re-calculate and you have helped me to be able to do that! Thanks loads,
Ted

I would email the company whose product it is. I have gotten fast responses and correct information on my 30 year old Threshold Amp. They are a great company and will be more than willing to help.