Phono Stage - will the Naim prefix work for me?

Posted by: John on 14 July 2001

I just purchased a Rega P9 and since it comes with RCA termination I am having a little difficulty understanding what my phono stage options are. I would like to buy the Naim prefix but I don't understand how it works with the TT having RCA. I haven't seen a prefix but I understand the connectors are BNC??? Also the prefix is designed to fit inside of an LP12. With the Rega the prefix will just sit on the counter. Are there any boxes for the prefix as I am concerned about the electronics being exposed.

Thanks
John

Posted on: 14 July 2001 by John
Thanks for the reply. I have been advised by a few people that the stageline isn't that good and there are many options at this price level that are better. The Lehmann Audio Black Cube and the Musical Surroundings "Phonomena" have been recommended above the Naim stageline. Can the stagline be powered from my Supercap? If so how much better is the prefix? I don't like the idea of RCA connectors. Is the prefix designed more specifically for the LP12?

The prefix seems to come highly recommended. I of course haven't heard any of them so I am going only with other peoples opinions. If the prefix is technically better I would like to make it work if possible. I think the Prefix needs BNC termination and if this in case I only need to change the termination. I can't imagine this being a big job but I worry about making a modification to the TT. Could I encounter problems with changing the termination?

Vuk, where are you I understand you have a P9 and a Prefix. How did you deal with this issue?

Thanks
John

Posted on: 15 July 2001 by Arthur Bye
John:

While Vuk's solution seems quite practical it is not easily reversible and you will have to cut the leads on the P9 and well as the Prefix. Maybe you can get Naim to terminate the tonearm ends of the Prefix with female RCA's. Then you can Velcro the whole thing to the bottom of the P9. If memory serves me, the other end of the Prefix goes into the #2 Din input on your 52.

If you like what you hear, and I imagine that you will, you can complete a more direct connection "a la Vuk". I think I'd want to fabricate some kind of plastic dust cover for it though in the long run.

Arthur Bye

Posted on: 15 July 2001 by Martin Payne
quote:
I think the Prefix needs BNC termination

The prefix is directly wired to the arm wires and then connects to the power supply via some sort of SNAIC-type arrangement.

No BNCs are involved.

BTW, the Stageline is available with phono sockets.

cheers, Martin

Posted on: 17 July 2001 by Arthur Bye
Vuk:

I've been considering this Prefix upgrade. How do you get past the captive cables on the RB900 arm. Did you have to take the arm apart?

Arthur Bye

Posted on: 17 July 2001 by Ron The Mon
Arthur,
There is a set screw holding the tonearm cable to the tonearm pillar. If you loosen or remove this screw and carefully pull the tonearm cable out, you'll see a mini "PCB" in which Vuk pointed out you simply unsolder old and resolder the prefix in. It is an easily reversable mod and the wires are color-coded. I also soldered a separate ground wire to the "PCB" black wire as it offers a dedicated ground (better sound) with Naim preamps.
BTW, are you still using the Grado and do you intend to use this with the Prefix?

Ron The Mon

Posted on: 17 July 2001 by John
Ron the Mon, thanks for the information. I received an e-mail from Rega that stated that any modification other than changing the RCAs will nulify the lifetime warranty. Did you enquire with Rega before you made the modification?

The P9 I purchased comes with a Benz M2 cartridge. It's output is .8mV. The prefix comes in S and K types. Do they both have the wide nband width? Which type should I buy? I am told that the K types are for specific Linn cartridges only. Is this true? I also don't want to limit my future cartridge choices. Will the S type limit my choices?

Also I have discovered the raved about Prefix is powered with a dedicated Hicap or Supercap. The 52/Supercap is inferior to the Prefix with a dedicated Hicap. Has anyone demoed these differences? Are they significant? Is the Prefix/Flatcap closer to the performance of the Prefix/52/Supercap?

John

Posted on: 17 July 2001 by Andrew L. Weekes
quote:
I received an e-mail from Rega that stated that any modification other than changing the RCAs will nulify the lifetime warranty

Only if they find out - if it's easily reversible it's no problem!

Andy.

Andrew L. Weekes

Posted on: 17 July 2001 by Arthur Bye
Ron the Mon wrote:
quote:
are you still using the Grado and do you intend to use this with the Prefix?

My Grado("Reference") is a MM, probably the best MM cartridge out there. I've been wanting to move to MC for a while, just been slow about doing it. The Grado's a pretty nice cartridge in a Round Earthy kind of way. Lots of bass and mids. Resolutions pretty good too. Gets a little bass bloat now and then and PRaT is just so-so.

I recently heard a Lyra Helikon and really liked it, now I want to hear Dynavector (probably xx2, ta ketora is a little to pricey). It all takes time........

Thanks for the info about the leads. I'll pull my tonearm this weekend and take a look see. Voiding the warranty doesn't concern me too much as I think the change is easily reversed. Heck, I probably voided the warranty when I had NANA install BNC's. The things built like a tank anyhow.

Arthur By

Posted on: 17 July 2001 by David Dever
quote:
I prefered the Prefix powered off of the 52 (well, it's really coming from the Supercap via the 52) in comparison to a dedicated Hicap for it. I know this is very much a minority view and may have had something to do with a touch of bottom heaviness in my previous cartridge, but that's what I heard and I still don't understand why a Hicap would be better than a Supercap (albeit "indirect" or doing double duty). Perhaps, Dave Dever will explain.

...SUPERCAP has better-testing regulators, but smaller available reservoir capacitance (when piggybacked off NAC 52 INPUT 2)--ends up smoother than straight HICAP, but not as dynamic as separate supply of either type (which would have larger reservoir capacitance, and a connection closer to supply regs).

I use mine off the 52, though I have a spare HICAP.

Dave Dever, NANA

Posted on: 17 July 2001 by John
Dave:

Can you PLEASE respond to my questions:

The P9 I purchased comes with a Benz M2 cartridge. It's output is .8mV. The prefix comes in S and K types. Do they both have the wide band width? Which type should I buy? I am told that the K types are for specific Linn cartridges only. Is this true? I also don't want to limit my future cartridge choices. Will the S type limit my choices?

Thanks
John

Posted on: 18 July 2001 by John
Can someone at Naim please respond to my prefix question? I would like to know the differences between the K and S prefix and what would be recommended with my setup: Rega P9, Benz M2.

John

Posted on: 20 July 2001 by John
For all of the people who have been following the thread this is what I discovered from phoning NANA.

In general the Prefix is designed for the high end cartridges such as the Clearaudio. The Prefix will fully expose the TT and they didn't recommend this with the P9 and the cartridge levels I will probably consider in the future. They said it could expose problems with the cartridge. They recommended just using the E boards for my 52 as they get powered indirectly from the Supercap anyways. In an e-mail from Naim they stated there is no sonic quality differences between the K, S & E boards. The boards are just adjusted to accomodate the different outputs of cartridges. If the cartridge output exceeds the recommended output limit the board will be overloaded and the music will sound brash and bright. So it sounds like cartridge matching becomes important because if you are on the high end of the output limit for say a K board it might sound a little bright. It would also explain sonic differences between boards with the same cartridge.

I'm sticking with the internal boards for now.

John

[This message was edited by John on FRIDAY 20 July 2001 at 16:13.]