Phono rig capacitance


I have read up on LPFs (low pass filters) and corner frequencies. and found the following... this equation gives the -3db corner frequency: Fc = 1/(2*Pi*R*C), inductance is ignored but can be impleneted using the R-adjusted instead of R as SQRT(R*L), geometric average. Though the value may not be significant, which is why I usually see it omitted.

I am interested in:

1. how one computes the -0.5, or -1db or any db cut in frequency NOT just the 3db corner frequency.

2. How to compute the corner frequency for the cartridge to SUT, given the amount of capacitance in the interconnect. For the example I suppose using the all familiar cinemag 3440 makes sense and for the cart the denon 103.

3.Same as above, but to compute for the interconnect from the SUT to the preamp..

4. Same as above but compute for the interconnect from the preamp to the power amp.

5. And perhaps the same for loudspeakers as well.

The goal is to find a value that ensures there is no roll off taking place and to select a suitable wire for each interconnection in a phono based playback system using an MC cartridge->SUT->Pre->Power.

I know, less capactiance blah blah blah, buy a 4 thousand dollar cable blah blah blah is the usual answer, but I am looking for a more scientific and technical approach to selecting wires that are in the ballpark of what makes sense based on well understood engineering principles.

I know that there are several members with advanced degrees in electrical engineering or are technically apt (Almrag, Atma, Raph etc...) and I am hoping that one of you can find the time to chime in please.

Thanks guys, looking forward to hearing your take!
dfel
Looks like so long as L4 is at least 100mh things look normal. The pairwise inductance have been chosen to give a 1:10 ratio i.e/ as per the source it is the sqrt of the inductance ratio. (L4,L5)->(1uH, 100uH) ; (10uH, 1mH) ; (100uh, 10mh) ; ( 1mH, 100 mH) ; (10mH, 1000mH) were all giving weird results as in the first circuit and the gain was below the approximate 20 Db I was expecting as per the normal calculation given the turns ratio.

Once I used values in the form of ( X, 100X) where X was greater than 100mh things normalized and stayed normal. I tried (100mH, 10000mH) all the way to (10H,1000H) the gain stayed constant, the low freq roll-off disappeared as the values got pumped up, though it makes little difference as much of this activity was below 20 HZ. The ultrasonic peak remained above 100K and well outside of the audible range, its shape was slightly altered as the values went higher.

So as it sits now. I am very curious know exactly what an actual spec for the prm/sec inductance values are in transformers that we use. NO manufacturer has this spec on their website that I have been able to locate, so hopefully cinemag emails me back. I will report back once I know OR if anyone else has a reliable source for these specs please post.
Dear Dfel,
Go here: http://www.jensen-transformers.com/

That's the home page. On the left hand margin you will see a vertical listing of links. Click on any or all of the links listed under "Applications". Plus, the principles of Jensen are some very nice, very smart, and very knowledgeable guys, when it comes to SUT design and implementation. They typically will share their expertise over the phone, if you have a specific question. (Disclaimer: I have no affiliation with Jensen whatsoever. I don't even use a SUT.)