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Phono Preamp Help - 47K Ohms - 100 Ohms .. Huh?

I am relatively new to analog and therefore have little experience matching a cartridge with a phono preamp. I currently have a Shelter 901 which the user manual specs at "within 100 Ohms" as the recommended load impedance for the head amp. I've been shopping for a new phono pre and find that many top phono pre's are all rated at 47K Ohms and are not switchable.

This got me thinking that maybe 47K Ohms was the right setting for ALL phono stages and sounds the best... So since I currently use a Black Cube which IS switchable between 47K Ohms and 100 Ohms I decided to play around.

When in the 100 Ohm setting, I feel the sound is crystal clear - nearly perfect - yet the midrange seems recessed ever so slightly causing some recordings which I know should have heft and body to be somewhat recessed sounding and maybe thin. Also, at 100 Ohms, the sound is not quite as involving as I like. It's not exactly bright but quite close.... really close - in fact, as extended as I've ever heard a system be without being able to confirm it as being bright.

Switching das cube over to 47K Ohms gives a dynamite midrange. Very impressive vocals. Solo instruments seem incredibly lifelike - highs are ever-so-slightly rolled when compared to the 100 Ohm but during complex music, and even not-so-complex music the mids seem somehow congested as if the notes are bumping into one another slightly - perhaps muddy - more or less "confused". This sucks because everything else seems to be close to perfect.

Each setting has its virtues but I feel the 47K Ohm setting would be ideal without the midrange confusion.

Now for the questions...

If my Shelter 901 is designed for "within 100 Ohms" what the heck does that mean? Within? Does this mean I need to stay at 100 Ohms for the best match to the cartridge?

When switching to 47K as I said above, there are some advantages and clearly a few disadvantages. Are the downfalls more related to the phono preamp, the cartridge or even the impedance match? I mean, could the congestion be a result of the black cube itself vs. a direct result of the impedance settings?

What's more important - the preamp or the impedance setting?
bwhite
twl
3,251 posts
 
Viridian, we can't help unless we post what we think, right? There are conflicting posts on just about every thread on the forum, including the Digital page. It's not just analog that is suffering from this problem of conflicting answers.

Bwhite, at least with the TT, you CAN adjust something to change the sound. With a CD player all you can do is buy a new one.
zaikesman
3,017 posts
 
Agree with Twl, except I wouldn't even call 'conflicting' answers a 'problem' (unless they're posted by the same individual!). If there was no sincere difference of opinion or experience to be found in this hobby, we wouldn't really need this forum, would we? Vive la variety! :-)
wsin
12 posts
 
Shelter says the loading for the 901 should be less than 100 Ohm, with different phonos I had good experience with 100, 150 and 1000 Ohm so it depends on the phono amps. VTA for the 901 is also important that different settings produce different presentation, I ended up slightly tail up. I have heard other users spent up to 3 months in getting the right VTA. I don't think tracking force is as critical, I am tracking at 1.65g.
I have had various vintage of LP12s over the last 20 years, I feel it is paramount to have proper support for the LP12, the best result I had is a Sicomin platform and I think other light and rigid platforms will also do.
consttraveler
250 posts
 
The Coph Nia is factory set at 100 ohms, but, pop the cover off and there are a series of dip switches that allow adjustment from 40 to 47k Ohms. I found that 100 Ohms is the "best" setting for my Dynavector 17 D-II, Karat. Any higher and the upper registers become progressively more "pinched."
bwhite OP
807 posts
 
Consttraveler - how is the Coph Nia??? I've read a bit about them and I'm curious to know what you've compared it to. Care to share?
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