Does anyone care to ask an amplifier designer a technical question? My door is open.

QUESTION: Roger (or Ralph?)...

Question about the effects of different impedance settings and phono cartridges.

I’m a newbie with high end turntables (just replaced my old turntable with a much better one). My phono stage is convenient in that it allows easy access to changing the impedance levels from the front panel. I actually enjoy playing with the impedance settings to alter the sound to taste depending on what I want.

Mine is an MC cartridge and I find an impedance setting of 100 Ohm to be just about right in terms of sounding tonally accurate (like my digital source).

I won’t be telling anyone here what they don’t know when I mention that as I set it to higher impedances, the sound gets brighter and more taught (to more "pinched" and less relaxed/natural sounding towards the high end of the impedance settings). And the sound becomes darker (more rolled off in the highs), richer, more spacious and the bass seems to bloom a bit more in size and lose some tightness. I actually often enjoy just dipping down the impedance from the 100 Ohm setting to the 33 Ohm setting, to enjoy the slightly richer sound sometimes.

So my question is: What exactly is happening to cause the type of sonic changes on hears when changing impedance settings for a cartridge?

My know-nothing layman’s hunch is that it’s similar to how speaker impedance interacts with certain tube amps, where some combinations contour the frequency response...and (sorry for the word) damping factor? (The changes in the bass in lower impedances do give me that "lower damping factor in the bass" vibe).

Thanks..

  and I might add that the 5A rated power cord is reasonably priced on the RAM tubes website.

@ eric - no mentoring relationship w RM other than this thread which I am greatly enjoying....and learning...the Analog circuits book arrived today and I am diving into it with a glass of Malbec and some Peter Gabriel on the box ( shock the monkey ? ) I think my trajectory will include burning amp 2019 IF they will have me. Just about to order the scope, R Vandersteen who I do consider a mentor recommended a used Tektronix TDS 220... but Amazon has a new w warranty Tektronix for not much more than the hawks at ebay want used..

big fun

 @bdp24 I would love to see the Decca notes as well !

as for factorials for decimals, try the gamma function

the gamma ray is also effective for trolls who add ZERO

@tomic601, Oops, I had you confused with clio09! He DOES have a professional relationship with Roger. I’ll put the Decca info up in a thread, for all to see, hopefully tomorrow---Eric.