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Phono stage and RME ADI-2 Pro gain settings

Chester

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May 22, 2021
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Hi

I have two questions I need some help with relating to my turntable setup. I am very much an amateur so may be Misunderstanding how these things work, so I apologise upfront!

Setup:

Technics 1210 mk2, everything is standard.
Audio Technica AT33PTG/II MC cartridge
Cambridge Duo Phono stage
RME ADI-2 Pro BE R

Q1. If I set the input gain on the RME to its lowest setting, the noise floor when nothing is playing looks to be around -76dB. If I increase the input gain it obviously increases the noise floor to around -66dB or there abouts. I have been keeping the input setting on the RME at its lowest and then just having the volume higher. Am I losing any dynamic range or anything else by doing this?

Q2. The system sounds good and I appreciate the medium is not going to produce state of the art sound but is there anything I could do to eek out anymore performance from this set up? I often hear people say the stock RCA cables on the Technics limit performance but that could just be Audiophile rubbish. I’m only really interested in relatively simple tweaks to improve things rather than get into new turntables, phone stages etc.

Any advice welcome.

Chester
 

Bob from Florida

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Hi Chester,

That sounds like a nice setup! Here is my take. Your noise floor is going to be a function of the cartridge picking up hum, your cables, grounding scheme, and phono preamp. Make sure your cables are quiet cables and the turntable is properly grounded to your phono stage. This will be added to whatever noise is inherent in your line stage. The Duo has 60 db in MC with 100 ohm load. The gain is workable for the .3 mv output of your cartridge- could be higher but that would require a different phono stage. Your other option would be to go with a good quality step up transformer to the MM input, but that would be more expensive than your current phono stage. Running your line stage on minimum gain and turning the volume up more is fine as long as you can reach your desired levels of playback. Going with higher gain settings on your line stage will raise the noise floor due to the additional gain and may inject more noise of its own - depends on the preamp. If no additional noise is injected it may be a “wash“ as your volume setting will be less for the same listening level. My recent experience with the iFi Zen Phono beat my Musical Surroundings Phonomena 2+ in the noise floor department. At $200 + another $100 for the balanced cable (if you have balanced inputs on your line stage) is a viable choice to reduce noise floor into your line stage.
Hope that helps.
 
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Chester

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May 22, 2021
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Thank you @Bob from Florida for your detailed response. I have a Pro-Ject DS-2 phone stage too which offers more configurations and will go to 65dB gain, but according to the RME analogue reading, the Cambridge Duo seemed to perform just a hair better.

I will take a look at the ifi zen phono, it sounds interesting. Balanced is a nice addition.
 

Bennyboyph

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Feb 24, 2022
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An AT630 step-up transformer into the MM input, will have a lower noise floor than using the additional gain of the MC input.
 
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