1 (edited by tomsaxman 2019-11-08 17:36:17)

Topic: turntable use with ADI-2 FS / Pro FS

Hello all,

I've searched the internet and this forum about using the ADI-2 FS / Pro FS with turntables as a kind of preamp in a listening setup as opposed to using a conventional preamp but couldn't find conclusive answers so I hope somebody here could enlighten me.
I am not versed in electronics so I'm not able to ascertain if the voltages stated by the different manufacturers with regards to input and output signals make sense for this kind of setup.


I have a turntable with 2M Red Ortofon cartridge (output voltage 5.5mV) connected to a Graham Slee Gram Amp 2 special edition MM Phono Preamp with output range 224mV to 1120mV rms.
Specifications here: https://www.hifisystemcomponents.com/ph … cification

Normally this signal should go to a line-level input on a conventional preamp after which it gets sent to my active loudspeakers.

Would it make sense to use one of the ADI-2's instead of such a conventional preamp, especially with regard to the use of this turntable setup? Do output and input specifics of the products match or would I be making a mistake and better use a conventional preamp (thinking about ATC CA2)?

I know the analogue input in the Pro FS version goes through the AD before going back to the analogue output whereas in the FS version it doesn't necessarily.
My question is not about that but about the matching of levels with the turntable/preamp as to be sure no form of audible distortion would be created and I would not be left with a bad vinyl experience.

Thank you for your time.
Tom

Re: turntable use with ADI-2 FS / Pro FS

You need the special preamp for the turntable for RIAA decoding, this is not being performed by the ADI-2 Pro/*.
Once your phono preamp does RIAA decoding and brings the signal to line level you can use the ADI-2 Pro/* for i.e. recording.

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13

Re: turntable use with ADI-2 FS / Pro FS

Hi Ramses, thanks for the reply.

4 (edited by Jas0_0 2019-11-08 20:37:54)

Re: turntable use with ADI-2 FS / Pro FS

Hi Tom, I do exactly what you’re suggesting (albeit with different turntable/phono stage) and it works perfectly.  It also gives the opportunity to EQ the turntable which makes a big improvement in my system.

However,  it would be worth checking the output impedance of your phono stage.  The RME’s unbalanced input impedance is quite low at 9kohm.  The phono stage’s output impedance should be ten times less than this, and ideally lower (i.e. less than 900ohms).  Slee units tend to be quite low so you should be fine, but you might need to email the manufacturer to check your model.

I once tried a high output impedance valve phono stage and it sounded really limp into the RME.

If you haven’t already, you will also need to get (or make) some phono to XLR plugs or cables to connect the two.

Finally once it’s all connected, I’d recommend setting the analogue input of the ADI Pro to ‘auto ref level’.  This will allow it to calculate the best signal/noise ratio for the output from your phono stage. 

Hope this helps, let us know how you get on.

5 (edited by tomsaxman 2019-11-09 15:50:30)

Re: turntable use with ADI-2 FS / Pro FS

JasO,
Thanks for your reply, nice to hear from somebody who is doing the same.

I'll check the output impedance of the phono stage vs RME's input impedance by mailing to the manufacturer.
Also, am I correct in understanding that you need the RCA to XLR cables in order to use the 18kOhm balanced input?
Did you try to just connect your phono stage to the line input (9kOhm) with TS jacks?

Have a nice day.

Re: turntable use with ADI-2 FS / Pro FS

tomsaxman wrote:

JasO,
Thanks for your reply, nice to hear from somebody who is doing the same.

I'll check the output impedance of the phono stage vs RME's input impedance by mailing to the manufacturer.
Also, am I correct in understanding that you need the RCA to XLR cables in order to use the 18kOhm balanced input?
Did you try to just connect your phono stage to the line input (9kOhm) with TS jacks?

Have a nice day.

Hi Tom, glad to be of help.  I think you’ll still only get 9kohms from rca to xlr as this is still an unbalanced signal.  Think it would only be 18kohms if your phono stage had balanced outputs, though someone with more tech knowledge can hopefully confirm.

Either way, I think the output impedance from a well designed solid state phono stage  from the likes of Graham Slee should be much less than 900ohms, so you should be fine

Re: turntable use with ADI-2 FS / Pro FS

Thanks.
I've been reading into the mysteries of cartridge output and phono stages and can't say I have lowered my confusion.
I guess you have been there as well smile

Re: turntable use with ADI-2 FS / Pro FS

I haven’t done that much reading on that subject I must admit - mainly because like you I use a MM cartridge so loading and gain aren’t such an art to get right.  Though at some point I plan to venture into MC land, at which point I’ll have to bite the bullet!

If you set the ADI-2 pro’s analogue input to Auto Ref Level, it will do the maths for you on the best setting between phono stage and ADC

9 (edited by willem 2019-11-10 11:08:19)

Re: turntable use with ADI-2 FS / Pro FS

I opted for a simpler route. I use an ADI-2 DAC (not the pro) as a pre amp. As a phono pre amp with RIAA I use a Project Optical Phono Ebox. It does the RIAA equalization and then outputs an optical signal (i.e. it does the AD conversion) to be used with the ADI-2. It works fine in a very resolving system. I must admit that I do not use the turntable very often, because I far prefer the sound quality of digital sources. I only kept my Linn Sondek LP12/SME/and now Shure M97XE because my family did not allow me to ditch the turntable.

RME ADI-2 DAC fs, Quad 606-2 power amp, Quad 2805 speakers, B&W PV1d sub with Antimode 8033 Cinema

Re: turntable use with ADI-2 FS / Pro FS

smile you have a nice family

Thanks for sharing your way of doing it.

Re: turntable use with ADI-2 FS / Pro FS

I got an email back from Graham Slee stating that my Gram Amp SE has an output impedance of 820 ohms which is perfect for the ADI-2's.