RIAA LCR Mythos

Ex-Moderator
Joined 2011
Great reference for passive RIAA network design! Thank you for spending the time to put it together.

I am having some trouble with the Excel worksheet, after the component values are calculated with the new inputs, hitting the max error button does not seem to do anything - no error but after several minutes - the status remains at 0%, the program just sits there... Tried it both on my Mac and PC, same results - rather no result... Any pointer would be appreciated.

Jaz
 
Thanks for your fast response.
Sometimes I also had the problem when I calculated the "maximal Error". Clear is that the calculation takes a couple of minutes and sometimes the status remains on 0% but at the end I got the results. I'm sure there is a bug in the implementation of the code, may be a problem that excel claims the whole execution time. I will ask my colleagues for solving the problem. Can you please tell me if you get after calculation (after the several minutes) a result or is the tool or computer crashing; would help me to sole the problem. I also try to speed up the calculation, maybe with an compiled program. I keek you on track and again thanks for your response.
 
Ex-Moderator
Joined 2011
Error Message

Claus,

Here is a screen shot using Excel 2011 on the Mac: changed L1 and L2, and the max error run completed after about 4 min.

An externally hosted image should be here but it was not working when we last tested it.


Don't worry about my comments on the PC version, since I was using Excel 2004 (after converting your xlsm file to xls), so its results were not valid.

Jaz
 
Last edited:
Hello Claus,
thanks for your interesting work.
I'm a complete idiot in LCR circuits but your tube schematics turn on my brain,
and I'm dreaming to build an LCR RIAA.
The schematic in your study are tested and working?
In your opinion which is the higher impedence usable for a good working LCR RIAA net? I'm thinking at a tube driver like D3A.
Do you have ever tested Bestpentode configuration?
Ciao
Guglielmo
 
Hello guglielmope,
the schematic I provided as examples in my document are not tested. I developed these schematics from my experiences with these tubes, their technical data and of course my tool. Probably, they will work according to the simulation but maybe some bias point shall be modified during testing.
I also looked behind the interesting best pentode approach but I decided not to follow up because of the contradiction of high output impedance of the best pentode and goal of small impedance for the RIAA network. As a second stage after the RIAA network it should be a good idea to try this option because of their (partly promised) advantages, e.g. low noise, high gain, low distortion. For sure the miller capacity is very low compared with a triode, but if the RIAA impedance is low the advantage regarding high frequency cut-off is negligible.
Regarding your question about “higher impedance … good working” I have no good answer because I never used a passive LCR RIAA network before. Maybe you get an answer from the community.
Claus
 
Jaz,
I thought this is all described in chapter 7ff including the mentioned equations. I used the chosen values including their inputted tolerances and calculate all possible combinations with minimum and maximum values. So all done with VB within Excel. From all calculations the values with the maximum linearity error is the result.
This is in comparison to Monte Carlo a complete analysis; and it is not done with SPICE. Hopefully, I could answer your question.
Claus
 
I was ask some questions regarding the filter impedance of the network. I updated my tool. Now you are able to switch the plots: Filter gain (linearity) or Impedance (seen from the source into the filter with correct Ro). Please find the new version attached. I have not yet updated the article.
Claus
 

Attachments

  • CalcRIAAComp1.1.zip
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Claus,

Many, many thanks for posting your software. I just discovered this thread and it's really helpful in understanding how the component choices affect the end result. I'm also amazed at how accurate one can get the final result with a little care and attention to details - great engineering!

Again, many thanks for you efforts!

James
 
so, I can not find DIY core material very quickly.Since this is a DIY forum, maybe someone has a hint where to find it, and what is recommended,maybe such as small laminated E I core?
Normally, I prefer to build all parts which Iam able to for myself, even when this parts do not look so perfect then commercial parts, you know what I mean.
And I have a old small winding machine for coils, so I want to try it and wind some L `s for Riaa..thanks Armin
 
I was ask some questions regarding the filter impedance of the network. I updated my tool. Now you are able to switch the plots: Filter gain (linearity) or Impedance (seen from the source into the filter with correct Ro). Please find the new version attached. I have not yet updated the article.
Claus

Claus,
this is amazing for the LCR filter and very usefully that you provide a methodology to design any kinds of impedance filter.Thanks you again.


Best Regards
Leo