How to get the best Phono Signal?

[Greg]

It has been speculated in this thread that there may be a difference in the quality / hiss level of the phono stage in various Devialet amps.

OK, with respect to preferences between different external phono stages, this is in part subjective and may be system dependant, all of which is fair enough.

However, the hiss level is easily measurable with a smart phone dB app or similar.  It looks like it might be a dull and wet weekend here in the UK, so something to try if you have some time?  I think it might be interesting if we could establish that there are significant / measurable differences between the phono stages in different amps.

This is a check I performed with an iPhone app tried a while back:

Turn the amp on, select phono, at -40dB, all is quiet.  Up the volume to 0dB and you can hear the hiss very clearly.  Using an iPhone app and the phone roughly in the listening position, it recorded about 36dB as background silence (silence is quite noisy in terms of dB's)  Upping the volume until the app reached 50dB, I checked the Dev and it was on about +2dB

Hi @Confused. Just for clarity, what App are you using to conduct this check?


David

Decibel X - I have no idea how accurate it is, but I guess it would help if we use the same app for consistency.

Hello @Confused. That’s a very smart idea especially if a few of use contribute. It has a great potential to suggest if amp performance is consistent or variable, although speaker sensitivity will surely show variations in results. Maybe contributors could include the sensitivity spec of their speakers which would make working out a result more meaningful. I have a busy weekend ahead, but I have downloaded the Pro version of the app and will give it a go when I have time.

Being in principle a subjectivist, this is (for me) when objective measuring becomes worthwhile. In this particular application, it should eliminate the variance of members preferred listening levels. I am well aware that some like to listen to music with system set to low dB and others like it loud. By implication, my hiss affected unacceptable sound is a level another member would never visit. This test has the potential to identify both that and whether there is inconsistency in our Phono stages.

Many thanks for suggesting this experiment.