Signal Attenuator for Kaiju - Did I calculate this correctly?

[Deke609]

I want to add an attenuator to my Kaiju rebuild similar to the coarse attenuator of the Bee/MoreQuiet. I'm thinking 0 dB, -5 dB, -10 B, -15 dB, and -20 dB. Reason: the rebuild will have 3K3:16/32/64 OPTs for my 200R headphones, and I want to play around with finding the sweet spot on the BeeQuiet attentuators when the Kaiju is configured for 32R or 64R output impedances.

I have in mind a 2 deck, 2 poles per deck Electroswitch switch. I've figured out how to wire the switch to make it work, but I'd appreciate someone checking my voltage divider calculation to hit my target dB attenuations. Please see attached example of my -5B calculation.  Did I calculate this correctly? I want to be sure before I order the resistors.

(And, yes, I could just use the PEC pot trimmers on the Kaiju, but I want a switch with Mills MR resistors like the Bee/MoreQuiet - I plan to add a bypass switch across the PEC pots (I've never needed to use them))

cheers and MTIA, Derek

[Paul Birkeland]

The easy way to do lots of these calculations over and over again is to use Excel or web calculators.

https://ohmslawcalculator.com/voltage-divider-calculator
http://www.sengpielaudio.com/calculator-gainloss.htm


If you have each of those calculators open and next to each other, you can whip out your resistor values pretty easily.  You don't have to keep the input impedance exactly at 100K, so for your -5dB position, you may end up with a 47K and 56K, which would still be about -5dB.  This is especially true if you plan to get fancy resistors that don't come in a bunch of values (this is a big part of the reason we use RN55 resistors for our attenuators).

I would no use wirewound resistors for an attenuator for a broad variety of reasons.

[Deke609]

Many thanks PB.

And thanks for the links. That makes it simpler. But I think I'll continue with the manual/mental calculations b/c I only have 4 calculations to do, and more importantly, I need the math practice.  It took me longer than I care to admit to remember what the opposite of log₁₀ is!

...  we use RN55 resistors for our attenuators).

I would no use wirewound resistors for an attenuator for a broad variety of reasons.

This is very helpful info. I will look at the RN55 resistors.

cheers and thanks, Derek