MC Phono Pre Noise Floor

joshvito

Active Member
I have a Parasound zPhono preamp that I run in MC mode. While I think the audio it produces is very good for its price point ($200). There is also a lot of noticable static/noise from the unit. When music is loud, it is mostly not noticable. However, you can hear it in between sides and during quieter parts of the tracks.

So, I have been looking around to upgrade the Phono Pre, as it is the weakest link in the signal chain.

Is there a number/spec that can tell me this noise floor? I've been looking in the $500 price range, but not sure if it's worth the upgrade (e.g. produce a quieter background). There are also a lot of models in this price range.

Alternatively, what MC Phono pre's are you running and how noisy are they?

PS. The noise I am describing is NOT ground loop hum. Sound goes away in MM mode.
 
S/N ratio (signal to noise) will tell you the noise floor. Quick look at the manufacturers website shows for your unit it's 84dB for MM (that's good) and 58dB for MC (that's unbelievably bad for a modern unit). Usually I'd guess something is amiss when people experience noise issues (grounding, unshielded cables, some defect etc.) but with your phono pre in MC mode, it might actually just be that noisy. From the specs it's clearly designed for MM cartridges and the MC feature is just a stop-gap at best.

Generally speaking noise is not something you need to worry about much in most modern phono preamps, aside from the MC stages in cheapest units. General guidelines based on my experience - under 70dB each decibel counts, if you reach >70dB that's usually good enough for most people and as you get close to 80dB, then each more dB is just a bonus but of little practical importance. But one person's 'silent' might be another's noisy, it all depends on what sort of listening volumes you use and just how black you want those backgrounds to be (and what the rest of your setup is capable of).

The difference between 58dB and 70dB is about 4-times louder noise with the 58dB unit. That gives you some idea.
 
The difference between 58dB and 70dB is about 4-times louder noise with the 58dB unit. That gives you some idea.

Thanks for this, very helpful. Without experience with a bunch of equipment, these numbers really didn't mean much to me. Until now!
 
No. The transformer itself does not generate any noise. It is a passive device. It does need to be isolated to prevent RFI/EMI from being picked up (place away from power supply transformers).
 
Parasound claims that .9mv will produce 1.1 volt output, but depending on your MC, that might not be enough gain, hence, the noise floor moves up.

BTW, the OP hasn't claimed what cartridge he is using, so the point of this thread is useless without it.
 
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I've been using the Music Hall PA 1.2 with Denon 103r LOMC with great results. Absolutely dead quiet. $175

feature list
  • gain mm/mc 40dB / 60 dB
  • input sensitivity mm/mc 5mV/1kHz / 0.45mV/1kHz
  • input impedance mm/mc 47Kohms/120pF / 100 ohms/120pF
  • output voltage typically mm/mc
    300mV at 1KHz – 3mV (MM Input) / 0.3mV (MC input)
  • total harmonic distortion mm/mc <0.01 / <0.05%
  • riaa curve accuracy 20Hz-20kHz / 0.5dB
  • snr mm/mc -86dB / -68dB (-94dB / -75 dB A weighted)
  • input voltage 15V/300mA AC
  • external power supply
  • rigid extruded aluminum chassis
Just curious, how close is your amp, outlet, power strip, turntable, etc. to the preamp? Have you tried moving it?

VV
 
On the advice of my price-is-almost-no-object audiophile friend, I went with a Benz-Micro Lukaschek PP-1 T9 MC phono preamp. Just MC, no MM. Dead quiet. Beautiful music-making.
That and the Benz-Micro Wood SL are the only expensive (to me) pieces in my system, and it seems there is no other way with these two components.

EDIT: I first used a Project Phonobox II, and it had a lot of thermal noise/hiss. Then I tried the MC head amp/phonostage in a Rotel RX-855 dual mono receiver. It was better, but this unit made a low ("C" pitch) electronic farting sounds every couple of minutes. Bugged the hell out of me, waiting [uptightly] for the next PHFART! Then I tried a Harmonious Audio head amp (battery powered), which was cheap, pretty quiet, and OK sounding.
 
Parasound claims that .9mv will produce 1.1 volt output, but depending on your MC, that might not be enough gain, hence, the noise floor moves up.

BTW, the OP hasn't claimed what cartridge he is using, so the point of this thread is useless without it.

Actually his sig says Ortofon Quintet Blue. 0.5mv output and recommended load >20ohms.
 
Parasound claims that .9mv will produce 1.1 volt output, but depending on your MC, that might not be enough gain, hence, the noise floor moves up.

BTW, the OP hasn't claimed what cartridge he is using, so the point of this thread is useless without it.

I am using Ortofon Quintet Blue.
 
I've been using the Music Hall PA 1.2 with Denon 103r LOMC with great results. Absolutely dead quiet. $175

feature list
  • gain mm/mc 40dB / 60 dB
  • input sensitivity mm/mc 5mV/1kHz / 0.45mV/1kHz
  • input impedance mm/mc 47Kohms/120pF / 100 ohms/120pF
  • output voltage typically mm/mc
    300mV at 1KHz – 3mV (MM Input) / 0.3mV (MC input)
  • total harmonic distortion mm/mc <0.01 / <0.05%
  • riaa curve accuracy 20Hz-20kHz / 0.5dB
  • snr mm/mc -86dB / -68dB (-94dB / -75 dB A weighted)
  • input voltage 15V/300mA AC
  • external power supply
  • rigid extruded aluminum chassis
Just curious, how close is your amp, outlet, power strip, turntable, etc. to the preamp? Have you tried moving it?

VV
Ive tried moving the pre further from amp, further from TT. No change.

Do you know what "SNR: >70dB, A-weighted, inputs shorted" means? Specifically after the DB measure.
 
The "weighting" of measurements is used to make them more closely follow what we hear rather than a measurement in raw, absolute numbers.

Below is an example. For example, noise at 200 Hz is rolled off prior to the measurement process. Although likely rare, a device with a somewhat high level of 120 Hz power supply noise would benefit from A-weighting of the measurement, although due to the response of our hearing it may not be all that important.

upload_2018-4-4_18-30-41.png

Shorting the input helps to assure that the measured noise is the internally generated noise and not noise from an outside source.
 
IMO, that is too low an output for your phono preamp. The lower the cartridge output, the higher the noise will be.
 
The "weighting" of measurements is used to make them more closely follow what we hear rather than a measurement in raw, absolute numbers.

Below is an example. For example, noise at 200 Hz is rolled off prior to the measurement process. Although likely rare, a device with a somewhat high level of 120 Hz power supply noise would benefit from A-weighting of the measurement, although due to the response of our hearing it may not be all that important.

View attachment 1154812

Shorting the input helps to assure that the measured noise is the internally generated noise and not noise from an outside source.
Thanks
 
No. The transformer itself does not generate any noise. It is a passive device. It does need to be isolated to prevent RFI/EMI from being picked up (place away from power supply transformers).
Do you have any specific models you prefer? Is there a downside? Why aren't we all using them?
 
SUTs in general tend to be a bit pricey when compared to a MC preamp and the SUT needs to be matched to the cartridge electrical characteristics. I seem to prefer using an SUT but it will depend on your system and ultimately your preference.
 
58dB for MC (that's unbelievably bad for a modern unit)
Jeez - no kidding. :(
I am using Ortofon Quintet Blue.
Which you have not yet heard, I assure you.
Do you have any specific models you prefer? Is there a downside? Why aren't we all using them?
A 1:10 turns ratio would put you at 5 mV, right where you want to be. Slightly higher would probably work, too. Denon, Ortofon, Rothwell, K&K, Parks Audio Budgie SUT, Audio Technica, h-devices, Bob's Devices all make good models. They don't wear out, so buying used is perfectly fine.

With every MC stage I've compared with an SUT, the SUT has won. We aren't all using them because many folks think that if it says MC on their preamp, they're covered. Simple as that. Downside can be hum, but placement and/or a ground-lift switch solves that.
 
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