Digital Phono Preamp

Does anyone have experience with converting the output of an LP pickup cartridge to a digital signal? I have recently converted to using Dutch & Dutch 8c speakers which have built in DAC and amps. These are fed from my Roon Nucleus+ with an 8Tb ssd holding all my ripped cd’s via a dCS network bridge. Leaves my LP’s out in the cold hence looking for the ability to convert the output of my MC phono cartrige into a digital signal which can be fed into the bridge too?

Hi Robert and welcome to the forum. I have some limited experience but, as a serious vinyl user, I have kept an eye on developments.

There are various options but it would help if we started from what you already have access to. It isn’t so much of turning the output of your MC cartridge into digital but the output of your phono amplifier - you will need to bring the tiny signal level of the cartridge’s output to one that is suitable as an input signal to an ADC ( analogue/digital converter). This process would also normally include RIAA eq although it is possible to apply this later in the digital domain. So, before proceeding further, what do you currently use for this?

Pete, I have a range of MC cartridges ranging from Denon DL 103 through a Lyra Olympos SL so predominantly lowish output. I tend to use a step up transformer into a MM input on the phono pre amp. Having sold my Karan Acoustics Reference phono pre as part of a move from the UK to the US I’m using my B system Monk Audio Phono Preamp as a stop gap. It obviously has a line level output. Scanning the internet a few candidates I’ve come across would be the ; Mytek ADC, the M2tech Joplin or a second hand PS Audio NuWave Phono pre - the latter two having RIAA functionality in addition to an ADC. All thought welcome.

The Korg DS-DAC-10R might be an option, it can record to both double-rate DSD as well as PCM:

Thanks Ian. You are a man after my own heart if you like MCs plus SUTs rather than headamps.

OK, I know where to start from now. Unfortunately and thanking @Paul_Bemelmans for his suggestion things do get a bit complex hereon. It is late here in the UK so please excuse me if I leave it now until I post further tomorrow ( UK time).

As I said this is going to be a little complex.

The first thing is to establish exactly what you want to do. Do you want to make files that can be stored on your server and be accessed via dCS Mosaic or Roon? Or do you want to digitise your LPs on the fly and feed that output directly to the Dutch & Dutch speakers?

The former way of doing it is far more laborious as you will need software to create tracks and insert metadata. Remember that otherwise and unless you make an individual recording of each track by manually cuing each one then starting a new file, you will create a whole LP side per file without any way of navigating it. Unfortunately this is not like ripping a CD.

So, if this is the way you want to go I would recommend using something like Vinyl Studio Pro. This means using a computer to create the files and brings us to a choice of ADC.

https://www.alpinesoft.co.uk/VinylStudio/VinylStudio_pro.aspx

I am not going to recommend using any native inbuilt computer ADC . However there are excellent converter soundcards that can be installed such as those from RME ( they also make standalone ADCs ). Even so you will still encounter issues such as providing a clean power supply.

So it may be easier to use a stand alone ADC. Many of these offered to the home user market , such as the Korg previously mentioned are really complete recorders. Here again you need to check that the dedicated software allows the flexibility to create separate tracks from a file rather than stopping and starting the recording process at each track boundary. Also establish that it does not tie you in to their proprietary record/repay world. That latter issue appears to be the case with the Korg as reading their specifications it seems at least from this that replay of the created files is only possible using their Korg AudioGate software . They make no mention of creating standard format files such as .wav .dsf or FLACs etc. Further gapless replay is not supported though this may not be a big issue with needledrops. Perhaps more importantly given their drum banging for DSD there is no DoP support.

There is another point about making digital files from LPs. Unlike ripping a CD where a bit perfect copy of the data is definitive, LP replay is a moving target as better turntables, cartridges and phonostages are always evolving. So if you digitised your vinyl collection using your current 2021 equipment yet next year find a better cartridge you may then want to re-digitise the whole lot.

So my preference would be to go for an on the fly system and not record. So you really need a pure ADC . Unfortunately dCS pulled out of the studio market some years ago but I am still going to recommend looking at pro or semi-pro equipment . For example as well as RME something like a Sonifex Redbox.
https://www.sonifex.co.uk/redbox/rbadda2_ld.shtml
However you may also want to insert a preamp before the ADC for volume control duties. This latter thought brings me to the simplest solution. Why not stick with a standard analogue vinyl replay system albeit with a preamp having balanced out and just feed that to the Dutch & Dutch speakers ( XLR input 1) using their own inbuilt ADC function? OK that doesn’t feature use of Network Bridge but is straightforward.

Unfortunately whatever route you choose the technical limits of the Dutch & Dutch digital processing will make any provision of hi-resolution PCM or DSD digitisation via any ADC redundant. The 8C supports a maximum sample rate of 48KS/s anything above being downsampled. Further DSD input is not supported.

Thanks Pete that is very usefull. To your first question digitising on the fly is the route I want to take. Your final comment re using a preamp highlights my dilemma, this is the route I initially adopted but my conrad-johnson GAT with it’s single ended outputs wasn’t optimal for feeding the D&D 8’s which ideally need balanced audio inputs otherwise, as I found, you get hum. Also my digital inputs had to go via a DAC ( Naim ND555) to derive an audio output fed via the GAT into the speakers which of course then convert the signal back to digital! Digital direct fed through the dCS with volume controlled in Roon gives both the best sound and a much simpler set up but brought me back to the LP issue :upside_down_face: