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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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G'day mate, yes it is.  A situation possibly made worse by the fact that quite a few popular commercially made phono stages have default input capacitance values of 220 picofarads, and when interconnect and tonearm wiring capacitance are added, the overall value of input shunt capacitance can approach and indeed exceed 500 picofarads.  The Shure M97xE wants to 'see' around 250 to 300 picofarads 'overall' to sound its best.  Any more than that, and it sounds very 'wooly' indeed!  Regards, Felix.   

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G'day all, after a fairly tumultuous week for a few reasons including getting very annoyed by idiots and ultimately realising that it is not worth getting upset by complete fools, and there is always the Human Rights Commission to make a complaint to anyway, on this Friday evening (as I type this), the 'Carnival of the Animals' is playing on ABC Classic FM via my Tivoli One Radio, and it is a nice way to pass the evening and forget about everything!  Regards, Felix.    

Edited by catman
Grammar.

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G'day all, it is a common question as to when any given stylus needs replacing (at least in the case of a typical moving magnet cartridge anyway), and in the last week I replaced the stylus on my Shure M97xE in here on this system.  I wasn't sure of its length of use in absolute time terms but it still played quite normally, but subjectively it had played a lot of records! 

 

However the new OEM stylus sounds fantastic making the whole thing sound like a different cartridge, so obviously the old stylus 'was' worn.  Interesting!  I only have a simple pocket magnifier with which to view the stylus tip and I have no way to achieve greater viewing magnification, so 'when' is it time to replace a stylus due to wear which will inevitably happen if playing records regularly?  Regards, Felix. 

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worn stylus or worn suspension ?

 

in good quality cartridges that have not been abused, i've found the suspension gives up long before the stylus.

 

be wary of nos stylii

 

;)

Edited by michaelw

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G'day mate, that's an interesting comment as I wouldn't even consider any issue with the stylus suspension.  I wonder!  Regards, Felix. 

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G'day all, I have lots of good and very nice sounding MM cartridge phono stages and most of them are quite straightforward in terms of circuit design.  That is fair enough too, however there are situations where some 'refinement' and adjustability in design is indeed worthwhile. 

 

My Akitika Phono Z DIY phono stage is a good example of this.  Although quite conventional in many respects, the designer's use of 'electronic cooling' does reduce phono stage input noise quite markedly, a real plus with high inductance cartridges like the Shure M97xE.  

 

There are also extensive filtering options 'on board', that I personally don't really use, along with adjustable capacitance loading provisions (which I do).  All up a generally very useful range of user adjustable options.  I wish more commercially made phono stages followed the trends of the Akitika Phono Z.  Indeed some have, but most haven't.  Regards, Felix. 

Edited by catman
Spelling.

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G'day all, just reopening this thread.  The kit phono stage that I rebuilt was the PAIA phono preamp kit and after building it I just didn't like its sound.  I eventually found an interesting builders page that was quite interesting and showed good general performance and reasonably good adherence to the RIAA curve but with some significant lower bass roll off and upper treble boost. 

 

On paper, it didn't look so bad but it was quite audible, and to my ears, not particularly pleasant sounding both bass light and bright, simultaneously!  However completely changing the RIAA values has resulted in a phono stage that sounds wonderful to these ears!  So a db or so can subjectively make a big difference!  Regards, Felix.     

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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.   

 

Not at all. I've about 20 or so cartridges which I enjoy and many are really quite different to each other. Some suit rock, others Jazz, and a few do it all well.

 

I want to record them all for comparison purposes eventually. Maybe this weekend.

 

Sent from my Redmi Pro using Tapatalk

 

 

 

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G'day all, I was listening to The Beatles 'Abbey Road' last evening with my Shure M97xE with optimised capacitance loading and it sounded fantastic to my ears, yet it was 'easy' sound as defined by the Audiophile response curve as used by the Shure 'x' series. 

 

The interesting thing is that although the upper treble is indeed 'softened', it doesn't sound lacking at all, assuming optimum capacitance loading, of course.  I often wonder why Shure went from a ruler flat frequency response right up to 20 KHz during the Shure halcyon days, to the stated preference of the 'audiophile' response of latter cartridge years.  A thinking of the 'times' I guess!  Regards, Felix. 

Edited by catman

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Hello Catman

Just an observation here, I have seen you do a lot of posts about this sort of thing and it makes me wonder.

I mean, I put a record on and listen to just enjoy the music and if it hits that extra audio Nirvana then great.

The thing is I am not cluttering up my mind with thoughts of technical issues.

 

So just wondering if you ever just play music and enjoy the listen without thoughts of " optimised capacitance" etc. :)

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G'day mate, you're not the only person who has made that observation of which I am obviously guilty!  I guess this comes from my general sense of perfectionism and my general electronics training and knowledge. 

 

I'm sorry if this drives everybody crazy but this is all part of my Aspergers nature.  I frequently wish that I could be less critical too, but sadly 'it ain't gonna happen'.  Sorry!  Regards, Felix. 

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No need to apologize. All of us hi fi types are already crazy. Keep on musing. :)

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39 minutes ago, catman said:

G'day mate, you're not the only person who has made that observation of which I am obviously guilty!  I guess this comes from my general sense of perfectionism and my general electronics training and knowledge. 

 

I'm sorry if this drives everybody crazy but this is all part of my Aspergers nature.  I frequently wish that I could be less critical too, but sadly 'it ain't gonna happen'.  Sorry!  Regards, Felix. 

 

No need whatsoever to apologise for who you are mate. Your posts often invite really good discussions. I have an Aspergers family member and they have the most enquiring and agile intellects around.

Be proud and not apologetic:)

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G'day all, thanks fellows!  Regards, Felix. 

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5 hours ago, rantan said:

 

No need whatsoever to apologise for who you are mate. Your posts often invite really good discussions. I have an Aspergers family member and they have the most enquiring and agile intellects around.

Be proud and not apologetic:)

I do too, my nephew and he is uniquely brilliant! Rock on, Felix!:thumb:

Edited by stevoz

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