Volume Control Resistance Stability Technical Measurements

1) Is the functional status and history of the P&G pot known?
2) Is the Spectral Super Fader the component used in a dmc-30 series preamp or a finished active unit?

This testing method is applicable to component potentiometers and stepped resistance attenuators.
Not applicable to finished active preamps that incorporate the resistance components which includes the dmc-30 series.

*edit*

Thank-you for the opportunity to include these in the collection.
If the SSF is a dmc-30 series preamp then it might be a better opportunity to have respected ears audition the unit.

 

I'd be curious as to how a simple Alps RK27 as the pot compares.

 

See the original post image #9 comparison chart:
https://superbestaudiofriends.org/i...tance-stability-technical-measurements.14602/

 

I came across an excellent study on current noise measurement in resistors and thought it might be relevant to this thread.

https://dcc.ligo.org/public/0002/T0900200/001/current_noise.pdf

Notably, they measure the voltage noise of different brands of resistors as a function of frequency down to 1Hz. They all have a 1/f component, but even within thin-film types, there is a significant spread. Some thin films do better than some wirewounds, when wirewound is typically the lowest noise resistor.

There's also some discussion about how the excitation voltage impacts noise measurement.

The measurement rig is quite clever and simple to recreate.

 

Haven't read the article yet, but my first thought is I wonder if there's any difference between steady state frequency vs modulating/combined/etc.

 

1. Penny&Giles pot brand new in original packaging and loaned by Craig just for the testing.
2. Spectral pot was a sample and he put it in a prototype but never finished or fired up the prototype so it is also brand new except has some wires sticking out of it.

If you are still able, I will send these to you for syence!

 

Would be happy to measure them and add the data to the collection presented.
Is there any desire that I avoid attaching wires to them for measurements?
In the last few weeks I have found better results to be had with very flexible wires between the DUT and Custom 4 wire probe with DUT on an isolation pad. Avoids mechanical vibration between 4 wire Kelvin probes and the DUT contaminating the measurements.