Hi Chris,
You're right on target. Specifying the noise figure with respect to a nominal MM cartridge is useful. In simulation, this is fairly easy to do, where you first look at the noise with an ideal noiseless input stage and then look at how many dB it increases with a "real" input stage.
Over most of the band, the cartridge coil resistance actually dominates the total noise, since the somewhat increased noise at high frequencies due to the resonance is filtered by the 75 us RIAA time constant. Depending on the preamp architecture, the noise density spectrum is usually not flat.
It is also often desirable to evaluate the A-weighted noise performance or noise figure, since different topologies can have different spectral noise shapes. It is easy to put an A-weighting macro into your simulations.
Cheers,
Bob
In contrary, the "Actidamp" has no significant advantages for MC low impedance cartridge - it was developed for the MM ones. In fact, I'm no more interested in this topic (neither in explaining the fundamental physical principles), because I'm focused on the construction of the preamps for the MC cartridges preferably now. Good bye Actidamp, hello MP3 !
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One thing that I feel is missing here, is LISTENING to see if changes occur when you change 'damping' with an MC (and perhaps a MM) phono cartridge. I have used variable damping for many decades, with some success, and I might add, INCLUDING summing inputs, in fact, it was part of my original patent. Check it out. We have known about artificial impedance generation both on input and output for at least 44 years. I made an artificial current drive from a voltage drive rated at 2000W for Ampex Research, in 1969, AND I did NOT invent the idea.
However, I prefer, for audio to do it 'naturally' with a variable resistor. Just wait for future products to become visible. I went, 'all out' because it is that important!
However, I prefer, for audio to do it 'naturally' with a variable resistor. Just wait for future products to become visible. I went, 'all out' because it is that important!
Hi,
Which is what I said: "it does not apply to MC
I agree on preferring MC's, though if money is no object and all else truely equal, use a transformer not an active headamp.
I do not need you to explain the physics (there is nothing unusual about it). I personally found "Actidamp" uninteresting as it improves at substantial complexity and cost something that requires no improvement given the noisefloor of the actual LP and even the improvement actually offered is small enough to be essentially inaudible...
So, "Much ado about nothing".
Ciao T
PS, did I mention that one Phono-Pre based on "Actidamp" sounds notably better with "Actidamp" removed and traditional cartridge loading restored?
Which is what I said: "it does not apply to MC
I agree on preferring MC's, though if money is no object and all else truely equal, use a transformer not an active headamp.
I do not need you to explain the physics (there is nothing unusual about it). I personally found "Actidamp" uninteresting as it improves at substantial complexity and cost something that requires no improvement given the noisefloor of the actual LP and even the improvement actually offered is small enough to be essentially inaudible...
So, "Much ado about nothing".
Ciao T
PS, did I mention that one Phono-Pre based on "Actidamp" sounds notably better with "Actidamp" removed and traditional cartridge loading restored?
John,
Precisely. It is obvious from the debate that there are no obvious direct explanation, such as "more loading damps resonances" for example as to why loading makes such difference in sound quality.
However, the difference are clearly there. A fairly famous turntable designer has one of the Phono stages I designed, with remote controlled cartridge loading. In one of his e-mails he ejaculated "Finally I can get the cartridge loading set in seconds!". He liked even more that he could save several complete setup's (gain, load etc) for different cartridges...
But Vinyl is pretty much history, interesting and living history at that, but history nevertheless...
Ciao T
Precisely. It is obvious from the debate that there are no obvious direct explanation, such as "more loading damps resonances" for example as to why loading makes such difference in sound quality.
However, the difference are clearly there. A fairly famous turntable designer has one of the Phono stages I designed, with remote controlled cartridge loading. In one of his e-mails he ejaculated "Finally I can get the cartridge loading set in seconds!". He liked even more that he could save several complete setup's (gain, load etc) for different cartridges...
But Vinyl is pretty much history, interesting and living history at that, but history nevertheless...
Ciao T
Hi,
Sorry, only on Vinyl.
You can find similar levels of mastering quality well into the 2K's and if in this brave new "High Definition" Age (at Decca for example and of course at Reference Recordings). And I can find many very bad examples of Vinyl, but yes, overall the art seems to have shifted from documenting the musicians performance to actually creating a totally different one...
Ciao T
Sorry, only on Vinyl.
You can find similar levels of mastering quality well into the 2K's and if in this brave new "High Definition" Age (at Decca for example and of course at Reference Recordings). And I can find many very bad examples of Vinyl, but yes, overall the art seems to have shifted from documenting the musicians performance to actually creating a totally different one...
Ciao T
Hi Thorsten,
I enjoy both.
Thanks to you and to your CDP, now I enjoy well recorded CDs close to the way I enjoy well recorded and preserved vinyl records…
Indeed, the art of recording, in most part, seems to have moved away from the aim of preserving as much as possible of the sense of attending live concert. To me it's a pity.
John,
I'm not sure what you mean when you said you've changed "damping" on an MC or MM cartridge. We've already pretty much all here agreed that the load resistance on a cartridge cannot change its mechanical damping, be it MC or MM - the electromagnetic coupling is just way too weak to make a difference. That just leaves electrical damping of the cartridge inductance against the cartridge load impedance. That is very important for an MM, but everybody knows that.
You are certainly right about the importance of listening when it comes to issues of the cartridge/preamp interface that we have been discussing.
Cheers,
Bob
The video doesn't appear to be yet available, but I am asking the AES if they would mind me making the preprint generally available as a pdf for download (it's around 35MB with all the images). In the meantime, anyone on this list interested in acquiring a copy should email me at john_dot_atkinson_at_sorc_dot_com
Email addy edited by moderation to prevent harvest by spambot..The AES has made the audio recording available at http://softconference.com/aes/sessionDetail.asp?SID=281052 but it's $18.00. I also repeated some of the points in a subsequent video podcast at http://www.hometheater.com/content/podcast-84-john-atkinson .
Happy New Year - John
John Atkinson
Editor, Stereophile
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Ok, so you're just referring to loading, presumably that of an MC cartridge if you are talking about to within 1 ohm. I assume you are adjusting to within 1 ohm by listening. Not sure I'd call what you are doing damping, though, since our long-ago discussion of MC cartridge inductance would seem to suggest that any resonance agaist 100-200pF would be way ou there. I'm sure the effect is real, I just don't know what to call it.
Cheers,
Bob
It can be audible, PMA, and that is good enough for me. You know, 35 years ago, I contacted Ortofon to ask them their opinion what loading resistance for their 2 ohm phono cartridges. They said 75 ohms, probably pulled out of the air to match the wire impedance. I KNOW that below 75 ohm loading will cause a 'darker' sound, and 50K ohms will cause slightly 'tizzy' sound with some MC cartridges. The Vendetta phono stage has the feature that you can adjust the load from 10-200 ohms while playing a record. I have found the 'sweet spot' a number of times, and my associates are much more precise than me about this. This is my experience and I stand by it.
This is fine, and I do not argue with this. The MC preamp I designed (and sold the design) some 4 years ago also has a possibility to set the load resistance, starting from 10 ohm.
And even for MM the R//C input impedance can be optimized for the specific cartridges. The 47k is not always an optimum, though it is "standard". We discussed this some time ago and you disagreed.
I said "main issue", that means, that IMO there are other influences, mostly geometrical and mechanical, that may be important than a cartridge loading resistance.
And even for MM the R//C input impedance can be optimized for the specific cartridges. The 47k is not always an optimum, though it is "standard". We discussed this some time ago and you disagreed.
I said "main issue", that means, that IMO there are other influences, mostly geometrical and mechanical, that may be important than a cartridge loading resistance.
Since we agree, PMA, let us not quibble. I must admit that in some cases, cartridge loading other than 47K for a MM cartridge could SOUND BETTER, even MEASURE BETTER, however for MM cartridges, 47K is part of the RIAA standard, so deviation is a departure from the RIAA 'compromise' that phono cartridge manufacturers are supposed to conform to. Both you and Thorsten have strongly disagreed with me, at times, on conformity to this standard, and I must admit, that I am designing a good deal more variation in my all-out phono design, even for MM cartridges. But we have to have 'some' standard to conform to, and I will chose the RIAA, for the most part.
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