John Curl's Blowtorch preamplifier part II

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#65,061
Its distortion of the signals when levels are just above the respective noise floors (dithered or not) that I refer to.
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there is no distortion - as you would understand if took the time to understand dither theory - look at the articles many have linked illustrating that point

optimally dithered digital has no distortion - just unmodulated noise which can be shaped to minimize audibility

then you really can resolve undistorted signal well below the lsb


if you don't want to learn the real theory and practical application of dither then please quit making statements about what digital coding systems can or can't achieve
 
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#65,063
jcx said:
there is no distortion - as you would understand if took the time to understand dither theory - look at the articles many have linked illustrating that point

optimally dithered digital has no distortion - just unmodulated noise which can be shaped to minimize audibility

then you really can resolve undistorted signal well below the lsb


if you don't want to learn the real theory and practical application of dither then please quit making statements about what digital coding systems can or can't achieve
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Right. Sure. That must be what i am measuring. 🙄


THx-RNMarsh
 
#65,064
John,

The resonance may be damped and the freq response flattened with proper loading.... but the decay time at the resonance (Q) is still an issue. Cart resonance contributes to ringing. I wonder what a decay or 'water fall' plot would look like for a cartridge. I dont recall seing this type of response test done on cart.


THx-RNMarsh
 
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#65,065
I will be doing more tests in a few days using a BenchMark ADC1 USB and BenchMark DAC 2. Custom made super pure signal sources (sine wave) of approx -140dB distortion will be used as the signal source. My ShibaSoku 725D and A-P 2722 and Panasonic VP-7722A will be used as the primary analyzers.

Hmmmmm. A very interesting power amp design just arrived... 2 loaded pcb's with DADOD's no gnfb, and of very very low distortion are here to measure and listen.

Make that few days a few weeks.

THx-RNMarsh
 
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#65,066
you do know the difference between THD+N and a pure THD measurement?

you really shouldn't see much difference between the distortion of a dithered 16 sine at -100 dB and the same in 24 bit rez played back on the same DAC

you can see this already done by Atkinson for decade old DAC
 
#65,067
RNMarsh said:
I will be doing more tests in a few days using a BenchMark ADC1 USB and BenchMark DAC 2. Custom made super pure signal sources (sine wave) of approx -140dB distortion will be used as the signal source. My ShibaSoku 725D and A-P 2722 and Panasonic VP-7722A will be used as the primary analyzers.

Hmmmmm. A very interesting power amp design just arrived... 2 loaded pcb's with DADOD's no gnfb, and of very very low distortion are here to measure and listen.

Make that few days a few weeks.

THx-RNMarsh
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Richard, that amp is CFA and not no GNFB.
Damir
 
#65,068
The Hagerman link spells it out quite nicely. If you cannot load the cartridge properly then it will not work as expected, especially if your input was designed with MC in mind so does not try to have minimal C.

Couple of other data points
New Lamps for Old Shure V15. +/-1dB across the audio band. Scroll down and there is the same for the ortofon M2

Load the Magnets!!! - [English] This is interesting as the measurements would point towards the electrical model not being the whole story. You need to measure. Luckily these days the tools to measure are readily available.

Given that a lot of MCs have a 2dB rise at 20kHz anyway as that's what people prefer (blame ortofon for that) and at least for the DIY brigade there is not only measurement capability but also a couple of phono stages designed to minimise capacitance using FR as an excuse for 10x price on the cartridge does seem wrong.

I will give that nothing these days seems to come out as flat as the classic V15. Can only assume the wafer thin Be tube they used and now can't really did something.

For all that my ultimate cartridge is still the MC2000, but that is for sheer masochism.

So...next reason MC are superior?
 
#65,069
gpapag said:
Some authorities raise this to 35kHz (maybe due to smaller tip dimensions and mass ?)

George
Yes, tip mass is very important here, but also the cantilever lenght and stiffness.
Older cutting heads had a resonance around 18 kHz, thus a filter preventing ringing. Now we can trim the cart. resonance in this area and thus compensate the dip in the freq. response.
For quadro it made sense to have the Fres at 30 Khz were the subcarrier is.

My MC is designed with aluminium tube cantilever, in combination with the very low tip mass it simply break up the Fres with selfdamping and thus it can track 30 Khz and more pretty linear, but thats rarely on a record.

Technics made in the 70s very precise Studio MM with linear and extended freq. response.

Bang & Olufsen did MI Systems , pretty good!

Grado also makes MI today, they sound mainly different because they assemble the cantilever with different material, parts and damping with a kind of paint, next different tips. MI are sensible for hum due stray fields.

Many todays MCs have the Fres between 11 and 16 khz and must be heavy damped, here comes the Q-Factor in the game. So i cannot see a positive influence here.

And many manufacturers glue their superduperfancy gems in front of the cantilever( with a ton of glue) and thus the moved mass increase a lot while the fres decrease. Simply because they are not able to drill such a small hole in the cantilever and save cost.

So many people better buy a MM and use correct load with capacitance, thats a lot cheaper and better than a ringing MC.



I quote from that page:

"Dadurch entsteht bei der Abtastung die Spurverzerrung, die im wesentlichen Klirrfaktor k2 besteht. Neumann baute 1968 den Tracing Simulator, der dieses Problem löste."


Frank, there, they say that in 1968 they built the Tracing Simulator allright but there is no declaration of universal adoption on every lathe of them, although one can infer from the past form of the verb (löste) that they would provide the Simulator as an option for all their lathes, so that there would be no such technical problem from then on if the customer wished to. 🙂

Yes, George , you are right, the did not wrote every, my fault, sorry. i have to take this back.
But in reality they did it ( so told me my MC Maker, and he is the real guru).
But i don't know if the use the tracing simulator was automatic or possible to switch off. So its still a secret for me, which records are precompensated or not.
Royal sound of course is pre compensated, Dynagroove is also.
Since Neumann was a real market leader for cutting lathes , we can assume that many records are done this way.
Frank



George
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#65,070
so which tip for pre-1968 stereo vinyl?

One area where MM does have an edge is that you can keep a selection of stylus profiles according to the record and its vintage. All a bit anal but if you are going to play vinyl in the 21st century you might as well go the whole hog 🙂
 
#65,071
For me spheric, nothing else.
For older and newer records, of course.

Its not perfect, but lesser errors anyway.

Dr. Peter Goldmark developed the Vinylrecord with spheric tips 25um mono.
Later it was made for stereo and 17 um spheric.
Both best compromise.

A better idea for old records is RIAA/ AES Stage with variable Equalizer, since they had different standards.

Thats why i use the FM 222 Phonostage with this feature. Works wonders due that.
 
#65,072
john curl said:
You will be stunned, because IF the mechanical resonance was high and damped, you would NOT have any high frequency response at all.
Yes, you have a 4 pole Butterworth filter (best case) with a rolloff just around 20KHz. There is no way around it. In my measuring experience, MC cartridges have a fairly damped resonance between 30KHz-50KHz or even higher sometimes, making a 2 pole rolloff after. Just look at the measured risetime between a typical Shure and an Ortofon MC. Just look! Do I have to look up the numbers for you?
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Well, you can start by broadening your net a bit, not generalizing from the particular, and not making an intellectually dishonest argument by deliberately ignoring the interplay between electrical and mechanical.
 
#65,073
I don't tend to go old enough to need variable EQ, although there is an archival phono stage design in LA. As far as my research goes, anything after 1955 is RIAA.

Not got much Mono, but was so amazed by a DG mono recording I got in an ebay 'collection' I picked up that I may start looking for more and having a dedicated Mono rig. But as Scott likes to point out, ADC and digital eq has a lot going for it.
 
#65,074
The only reason MC can be superior is the mass of the coil can be inferior to the mass of a magnet for the same efficiency.
Reason why we don't build Speakers with moving magnets and coils chassis side ;-).
I don't know if this would be true with the use of modern neodymium magnets. Who is still developing this middle aged Vinyl technology ?
 
#65,077
SY said:
And the lowest effective tip mass cartridge ever was... an MM.
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So, as it is easier to deal with a magnet in a cantilever than a coil and his wires, the only reason why some could prefer a MC (on a theoretical point of view) is he can sells preamps specially developed for it ? 😉
BTW: Efficiency means power, not only voltages.
The mass of a laser beam is extremely low, and the wear of its friction against the plastic disc too.
 
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#65,079
SY said:
I own both and have preamps optimized for each type, so I have no horse in this race.
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On my side, because i don't like all those artificial electronic distortions, i tend to stick at this:
EdisonPhonograph.jpg

https://www.youtube.com/watch?v=EOiFt47CsXo
 
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