Some interesting stuff here on this. LD what do you think about the claim that virtual ground operation turns MM to a perfect displacement sensor? Funny they actually show and old piezo-cart one tube player "Look no RIAA". As Kevin has found the strain gauge carts are far from needing no EQ.
DisC and PHATHOM
These guys base their stuff on one wire unbalanced phantom power so there is a 100% compatibility with anything. I would still opt for balanced phantom, plenty of arms use 5 pin DIN which does not require rewiring for balanced operation. I have all this info in my Linear Audio article, all the historical EQ's (courtesy Gary Gallo) and some ideas for phantom powered impedance converters so you can use a Scarlet 2i2 or any sound card using P48. They could easily be in the headshell. I'm sure we could come up with a virtual ground head amp that would operate the same way.
I have long thought about the pre-amp/buffer in the headshell idea which brings up a third possible interface, fully open circuit (just thinking out loud). Greater than 10meg||10pF is easy right on the pins.
DisC and PHATHOM
These guys base their stuff on one wire unbalanced phantom power so there is a 100% compatibility with anything. I would still opt for balanced phantom, plenty of arms use 5 pin DIN which does not require rewiring for balanced operation. I have all this info in my Linear Audio article, all the historical EQ's (courtesy Gary Gallo) and some ideas for phantom powered impedance converters so you can use a Scarlet 2i2 or any sound card using P48. They could easily be in the headshell. I'm sure we could come up with a virtual ground head amp that would operate the same way.
I have long thought about the pre-amp/buffer in the headshell idea which brings up a third possible interface, fully open circuit (just thinking out loud). Greater than 10meg||10pF is easy right on the pins.
resonant frequency f =1000/(2.pi.sqrt(M.C)) where M is total mass and C is compliance. Show me how increasing mass increases frequency?
Scott: All good ideas and all ones I want to try. I've read that DisC article twice now and still not sure if there is anything special about that cartridge other than being a good impedance match.
BTW @billshurv I took your advice about 15 months ago after I destroyed my Ortofon Black (it’s sitting forlornly on my windowsill - I’m hoping one night the spirits move in mysterious ways and it heals itself) and put the Black stylus on a Red body and it’s worked perfectly. I have tried two AT carts on my Michel + Rega rig but the Ortofon tweaks my fancy the most. I ended up giving one of the AT’s to my son (huge vinyl fan) and he promptly ditched it and went for an Ortofon Red. To be fair, the AT’s were only about £50 each, so not their top end stuff by any measure.
So, I owe you one 🙂
So, I owe you one 🙂
Some of the numbers don't parse very well but the one wire plug-in power on mics is ubiquitous these days. They mention a micro-power dual from us but there is still some missing information, the 1k THD is not so good (-70dB). I need to read all the stuff, but it is clear RIAA is both constant amplitude constant velocity and neither type of transducer requires no EQ at all.
As Ortophon shows here Resonance frequency the resonance frequency is referred to the lower frequency source generated by the vinyl warps.I was thinking about the high content of high frequencies on the disk that can be a second resonance source with stiffer rubber holding the conical stylus as in DJ cartridges .Is it a myth?
Well I think it doesn't happen naturally. One could arrange that in the same way one can compensate to form an RIAA pole from the 'unnatural' L/R cartridge time constant, via compensation I suppose.....?
Yup, but parasitic coil C presents a problem, doesn't it?
Just my 2p worth.
LD
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Always happy when a vinyl story works out. I am fond of the ortofon generators, I just wish they hadn't upped their prices so much. And I didn't have a collecting habit...
Some of their arguments are intriguingly close to the Graham Slee blog that was posted. I'm all for people trying something new, but making it a closed system really does limit the potential market.
the cantilever will have multiple resonant frequencies that are damped by the rubber. A low compliance DJ stylus will have MORE damping than a lightweight hifi one. Effective mass only comes into play at low frequencies. Where a DJ cart 'may' have issues is that the chunky cantilever, being more massive may have a resonance in the audioband. But as most of these are still thinwall aluminium the mass is lower than one might think. I have a Shure SC35 just for testing this theory. It's a low compliance brute with a 5g recommended VTF.
Oh Scott: You've unfortunately reminded me that I was going to hunt out a micro acoustics crystal cart for experiments. I'd love to find someone who can strip the eq circuit out so it can be used straight into a hiZ input.
I deconstructed one of those years ago, I might even have the pieces somewhere. IIRC there was a thick film R or two and an SMT C in the headshell not much more.
That and the number of people it would offend. Doubly so when real estate is limited so there is no room to roll in magic capacitors 🙂
Did you manage to work out if you could get it back together again afterwards? That's usually the tricky bit!
Did you manage to work out if you could get it back together again afterwards? That's usually the tricky bit!
I re-read that DisC article last night. They've managed to get the LR pole down to 50Hz, which is pretty heroic as (with L in mH) the L/R ratio is 3.18. Normal MMs are in the 0.6 range and the highest ratio I have found is the Panasonic EPC205CII at 1.4. I hate to think what they had to compromise on that to skew it so far. Certainly fat wire.
But as Scott said, that won't give you an EQ free response. You still need to deal with the 500Hz zero (which is easily done).
Interestingly they also do a transamp for the AT series of cartridges £3000! As we know its 2 opamps to implement this per channel that's a slightly scary markup (but nice shiny box). Oddly their phantom powered cartridge and matching preamp is only £1000.
Man behind this is Richard Brice, who I've never heard of.
But as Scott said, that won't give you an EQ free response. You still need to deal with the 500Hz zero (which is easily done).
Interestingly they also do a transamp for the AT series of cartridges £3000! As we know its 2 opamps to implement this per channel that's a slightly scary markup (but nice shiny box). Oddly their phantom powered cartridge and matching preamp is only £1000.
Man behind this is Richard Brice, who I've never heard of.
Following your links yesterday I found Marcel's letter to the editor (Linear Audio) talking about the stylus vibrating while you measure it (???). Mechanically speaking stylus up or down on a surface is the entire gamut of mechanical terminating impedance and any reciprocity in the system would show up as a change in electrical characteristics at the pins. How this myth has propagated is beyond me.
It can be done with a negative R input impedance I suppose. Brace yerself, but why not? Alternatively, compensation by way of appropriate filter after the first stage, which doesn't strictly count in my book. Can't think how otherwise?
IME the AT generator handles TI loading. The results are easy to trial with the Aurak single ended sketch schematics I put up years ago. Easy to prototype for the price of a few pints. Anyone found enjoying it can provide the balance of £3000 or so in beer 😉
LD
I suppose that negative R input impedance could also yield a displacement sensitive response, as per the claim, if the resulting pole was low enough....?
Edit: Oh boy, this is interesting.
LD
Edit: Oh boy, this is interesting.
LD
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In theory a strain gauge is a perfect to DC displacement sensor, in fact I have used semiconductor strain gauge pressure transducers as microphones that go to DC (but only to 3kHz or so). The cartridges OTOH still have all the stylus/cantilever mechanical issues as Kevin has found out and then there is still the RIAA. Even if slavish adherence to the curve is overkill plowing right through it must have some audible consequence.
LD: You only need L to be 3x R in order to get the 50Hz pole. HOW you get R that low is the challenge and I cannot think that is ends up with an optimal cartridge.
In my studies Hans pointed out that PI.L-R with a 500Hz pole is the universal setup for the Aurak concept as it works with everything I have found bar grado. 2L-R is ideal for Ortofon and AT. Time for us to knock up a PCB for people who want to try and can't deadbug?
In my studies Hans pointed out that PI.L-R with a 500Hz pole is the universal setup for the Aurak concept as it works with everything I have found bar grado. 2L-R is ideal for Ortofon and AT. Time for us to knock up a PCB for people who want to try and can't deadbug?
I think it can be done in the preamp, for regular MM cartridges, by presenting a negative R input impedance...………..
Why stop at zero?! That's the eureka moment.
Yes 2L-R is a common rule, I came up with it years ago and it works for most carts as you say.
LD