If one does go sub-zero, then the issue is exactly what f the lf pole is for any given cartridge, for a fixed preamp config. If it's low enough, far less of an issue and even at 50Hz any error should be audibly small or negligible.
If the cartridge generator copes well or thrives, of course...……...and generally optimistic yoda is.
LD
If the cartridge generator copes well or thrives, of course...……...and generally optimistic yoda is.
LD
FWIW the typical Grado shows the same mid-dip and peak as some of the MM plots with "optimal" loading. Having no luck yet on distributed models for self resonance at audio frequencies, but I'm beginning to believe there are more than one hard to see/measure things going on here.
BTW there are too many phono threads at the moment to keep them all straight.
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I'm working on a practicable negative impedance converter sketch schematic. Seems to lend itself well to the 50Hz pole for most MM carts. Watch this space.
Meantime yes the 50kHz notch could be self resonance I suppose......but then the mid band sag is also curious. Most inductance measurements use levels which are way larger than real signal levels...……..
LD
Meantime yes the 50kHz notch could be self resonance I suppose......but then the mid band sag is also curious. Most inductance measurements use levels which are way larger than real signal levels...……..
LD
Well, I finished a sketch design and it simulates well. However, it is inevitably somewhat 'twitchy' I suppose in that it depends on fairly exact parameters of the cartridge coil, specifically R, and close tolerance components in the preamp. It would also require totally secure cartridge signal connection to avoid the situation where inputs are o/c or dirty contacts to avoid the risk of instability. Or perhaps protection.
I realise that it otherwise fairly well fits the description as per the DisC article, and also that the author says patents have been applied for. So before wading in with both feet I need to visit the British Library and find the application.
So I think I understand why the preferred route might for RB to sell matched cart and preamps?
LD
I realise that it otherwise fairly well fits the description as per the DisC article, and also that the author says patents have been applied for. So before wading in with both feet I need to visit the British Library and find the application.
So I think I understand why the preferred route might for RB to sell matched cart and preamps?
LD
Which article, I doubt there is any IP without prior art at this time?
EDIT - found the article, this reads like the strain gauge carts that don't need any equalization at all. RIAA is there you can't ignore it.
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Yes, for example it is similar to Aurak for which there definitely is prior art, not least in the form of a lapsed patent. I was concerned in this new stuff not to offend any claim for using negative input resistance, but then that should fail the obviousness or novelty tests I suppose? Emphasise I'm not personally interested in raising any IP, just want to avoid the mire!
The article is here: http://www.phaedrus-audio.com/DisC article_for Transform Media.pdf
Yes. In the sketch I use a shelf filter to provide full RIAA. It all works out very tidy and simple. I would be interested to try a simple 1/f response to listen to, after all its only eq and the ear accommodates within reason. But might as well get it right.
@Bill, on paper the difference between this and Aurak is at lf below c.200Hz where cartridge current is less limited by its self resistance. But only by a factor of perhaps 5 or so. For most of the audioband, impedance of the cartridge is limited by self inductance of cartridge coil in both designs. Current phase at lf is slightly different too. Can't comment on performance just yet, but expect it to be Aurak like.
LD
Well the abstract didn't say anything notable, IMO. How about you precis it, Jan?
LD
Light reading whilst I digest. http://audioinvestigations.blogspot.com/2012/04/equalizing-strain-gauge.html
The article is well worth 8p BTW
The article is well worth 8p BTW
Basically Gary is in complete agreement over EQ for displacement sensitive carts
A very well researched and written article in fact.
He also does quite a lot of digging and discovers (as KevinK has) that the panasonic capsule isn't a perfect strain gauge so additional eq is required to render a flat response. And gives a couple of examples of how the eq can be done.
A very well researched and written article in fact.
Same take as me, Kevin's setup is now sounding pretty good even though there is some evil DSP in the signal chain.
His bespoke valve setup is something to behold, if you ever get over here make sure we all can gather for a listen.