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catman

Catman's Analog Musings

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G'day all, I wasn't happy with the sound of one of my DIY MM phono stages so I decided to completely change the RIAA network values to the same one's used in the excellent Bruce Heran op amp design.  I had to 'redesign'

the circuit board slightly, but all was eventually done ok, although I now have a question.  The Heran design RIAA network consists of two cascaded RC networks and the question, is the position of the network 'reversible' with respect to the op amp output and inverting input.  I did try this....and I'm not sure about this.  Can anybody definitively answer this question?  Regards, Felix.    

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If the network consists of two Parallel RC networks in series between the Op-Amp output and the inverting input, with or without an additional series resistor then YES you can reverse the order of the individual Parallel RC Networks.


 

 

The thing to consider is the physical size of each parallel network, as the inverting input may pick up interference if a network with a large physical size is connected, I would connect the larger network to the output and the smaller to the inverting network.
 

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G'day all, thanks for all comments.  This is actually quite interesting to me, as from the past I am aware of at least one phono stage design with the first RIAA stage dealing with the treble EQ,  followed by the bass EQ in the second stage with the claim of much lower record scratch being evident, yet I have seen the same circuit approach analysed negatively.  Interesting.  Regards, Felix.   

Edited by catman

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G'day all, a bit of a conundrum in a sense.  Two cartridges that I really like (ok....love) equally, the Shure M97xE and the Ortofon Super OM 10. 

 

I find both of them very sonically satisfying in just about every way.  They both sound their best with careful capacitance loading (especially the M97xE), but I could happily live with either one in all honesty.  Interestingly enough although the M97xE is often called treble 'soft', I honestly don't think that it is, assuming optimum capacitance loading, (possibly that is a big assumption). 

 

In fact I do regard the M97xE with the OEM elliptical stylus as sounding particularly 'nice' in the treble range, without sounding dull or 'soft' in the slightest!  A very musical sounding cartridge! 

 

If anything, the Ortofon Super OM 10 is a bit more 'neutral' but still musical, if that makes any sense!  I do love them both.  Regards, Felix.   

Edited by catman

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I have both these cartridges, but haven't played with capacitance load.  Might I suggest the cheap AT3600 as being just as 'nice'.   Also, the older Shure carts, such as the M75/91/95

 

 I would not put any in the same league as my Stanton 681eee, or even less so, the AT440MLa/b,   but they find regular use on my 'other' turntables.

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G'day all, no real conundrum really, it's just that two cartridges with distinctly different sonic signatures can be equally appealing and engaging.  I think that is quite interesting.  Regards, Felix.   

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1 hour ago, catman said:

G'day all, no real conundrum really, it's just that two cartridges with distinctly different sonic signatures can be equally appealing and engaging.  I think that is quite interesting.  Regards, Felix.   

 

It is.  In fact, I tend to use the cartridge most suited to the type of music I am playing.  Some are better for jazz, and acoustic stuff, others for classical, and others for rock.

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@catman I had a  M97xE once and thought it was very neutral and treble soft.

With you posting I know now I never got the capacitance right.

Maybe the  M97xE is more fussy than most cartridges to get this right, as there is so many conflicting reviews on this cart in the forums everywhere?

Edited by rocky500

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