For an MM phono preamp, is a SINAD of over 100dB even theoretically possible using modern state of the art OP amps and circuitry?
Not if you take the thermal noise of the cartridge into account (and certainly not when you take record surface noise and distortion into account as well, but that is usually not done).
Absurdly large signal to noise ratios of MM preamps usually indicate poor design combined with poor measurements: a design optimized for minimum voltage noise and measurements with shorted inputs, which neglects the effect of the equivalent input current noise.
Absurdly large signal to noise ratios of MM preamps usually indicate poor design combined with poor measurements: a design optimized for minimum voltage noise and measurements with shorted inputs, which neglects the effect of the equivalent input current noise.
Review and Measurements of Cambridge Audio Duo Phono Preamp | Audio Science Review (ASR) Forum
Let’s leave the groove noise/distortion out of this for the time being. Above is a $299 phono preamp from Cambridge Audio (Alva Duo) with a SINAD of 90dB. It wasn’t measured with an MM cartridge body attached to its inputs (i.e. a modern Ortofon 2M line), but I’m assuming the results would be similar?
Between ASR, HiFi News, and Stereophile, there have been probably over a hundred phono preamps measured. I haven’t been able to find anything that even comes close to the Cambridge (measurement wise), not even the fantastic sounding preamps such as Parasound JC3+/Jr.
Just curious to see what you guys think is the best we can do at the moment and are there better measuring phono preamps than the Cambridge with documented proof?
Let’s leave the groove noise/distortion out of this for the time being. Above is a $299 phono preamp from Cambridge Audio (Alva Duo) with a SINAD of 90dB. It wasn’t measured with an MM cartridge body attached to its inputs (i.e. a modern Ortofon 2M line), but I’m assuming the results would be similar?
Between ASR, HiFi News, and Stereophile, there have been probably over a hundred phono preamps measured. I haven’t been able to find anything that even comes close to the Cambridge (measurement wise), not even the fantastic sounding preamps such as Parasound JC3+/Jr.
Just curious to see what you guys think is the best we can do at the moment and are there better measuring phono preamps than the Cambridge with documented proof?
having the noise below the audibility treshold can be done with 1950's valves...you don't need 2020 technology to do it.Vinil noise is and will stay as the ultimate problem for as long as it will still be in use which i hardly think it will last more than another 10 years.
Signal to noise ratio is not the biggest problem in listening vinyl, dust is!
Signal to noise ratio is not the biggest problem in listening vinyl, dust is!
Noise measurements with a 20 ohm source impedance are basically meaningless for a MM amplifier. If the amplifier has a low equivalent input noise current, its noise level will be fine with an MM cartridge, if the amplifier has a very high equivalent input noise current, its noise level will be excessive with an MM cartridge connected. There is no way to distinguish between these cases based on a measurement with 20 ohm source impedance.
The same stays with a tapehead preamp...although debatable with today's technology we can get a tiny bit lower noise than 20 years ago for the preamp itself, but with no compander-expander technique there's no way you can get below the tape noise treshold. I wonder if there are any diy projects of remaking the dolby c, s, dbx with newer components, new VCA, new op-amps...maybe much better performance can be achieved this way.
By the way, the usual reference level is 5 mV (*) rather than 11.3 mV, so that makes 7.08 dB of difference for the signal to noise ratio.
The comparison between the noise spectrum and a hearing threshold only makes sense if it is corrected for the critical bandwidth. You can make noise look as low as you like in a spectrum plot by reducing the resolution bandwidth (bin size), but what matters is how much noise there is in a critical bandwidth of the ears of the listener.
(*): Either that or whatever comes out of the cartridge at 5 cm/s when you know the cartridge model.
The comparison between the noise spectrum and a hearing threshold only makes sense if it is corrected for the critical bandwidth. You can make noise look as low as you like in a spectrum plot by reducing the resolution bandwidth (bin size), but what matters is how much noise there is in a critical bandwidth of the ears of the listener.
(*): Either that or whatever comes out of the cartridge at 5 cm/s when you know the cartridge model.
"but what matters is how much noise there is in a critical bandwidth of the ears of the listener"
That's actually very deep and it's linked a lot with Dolby's studies on brain hearing, natural hearing learning curve timings, noise discrimination at different sound levels depending on frequency...that's truly complex.
That's actually very deep and it's linked a lot with Dolby's studies on brain hearing, natural hearing learning curve timings, noise discrimination at different sound levels depending on frequency...that's truly complex.
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It's also the reason why the weighting curve of ITU-R 468 is so different (and more meaningful for noise measurements) than A-weighting. ITU-R 468 is not used that often because it is a nightmare for simulations, calculations and marketing: it specifies a quasi-peak rather than an RMS measurement, which complicates calculations and results in numbers that look worse on paper.
