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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  (System | Threads | Answers | This Thread)

10-19-02
  Responses (1-29 of 29)
Click title to read one, or click date to read all below it.

10-19-02   What you are hearing is pretty much the tradeoffs related to ...   Viridian

10-19-02   Bwhite, i personally think that you should try a slight rais ...   Twl

10-19-02   Hi twl, okay.. now.. the vta is that the adjustment i can do ...   Bwhite

10-19-02   47 kohms is the typical "correct" load for mm cart ...   Oldears

10-19-02   Okay... i messed with the vta. quite frankly i don't know i ...   Bwhite

10-19-02   As oldears notes, fixed 47k is usual for mm phonos. for mc c ...   Gregm

10-19-02   Gregm, i was looking at getting a jadis and the guy told me, ...   Bwhite

10-19-02   Bwhite, many of the better mc phono stages have plug-in resi ...   Twl

10-19-02: Zaikesman
I have found that the recommended loading can be pretty useless as a guide to what sounds best. It seems to me you would probably prefer a loading somewhat higher than the low 100 ohm setting, but not essentially unloaded like 47k ohms. The correct setting could prove to be in somewhere in the low to mid hundreds, or even up to a couple of thousand ohms, depending on both the cart and the rest of the system. Since you don't have the ability right now to easily test many values in order to find your favorite before wielding the soldering iron on your Black Cube (unless it has socketed resistors - I'm not familiar with it), you might want to try giving your cart's importer a call and see what they recommend using. BTW, if you do install custom value loading resistors, be sure to look into getting premium quality replacements - this might run you $20 instead of $2, but the improvement is well worth the small difference.
Zaikesman  (Reviews | Threads | Answers | This Thread)


10-20-02   Bwhite i, too, think that the sales rep was thinking of mm o ...   Gregm

10-20-02   Aah, twl suggests raising the vta, oldears suggests lowering ...   Viridian

10-20-02   Viridian - analog rigs seem to be a wee-bit tweeky to set u ...   Bwhite

10-20-02   Viridian, we can't help unless we post what we think, right? ...   Twl

10-20-02: Zaikesman
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! :-)
Zaikesman  (Reviews | Threads | Answers | This Thread)


10-23-02   Shelter says the loading for the 901 should be less than 100 ...   Wsin

10-27-02   The coph nia is factory set at 100 ohms, but, pop the cover ...   Consttraveler

10-27-02   Consttraveler - how is the coph nia??? i've read a bit abou ...   Bwhite

10-28-02   Bwhite: i am reservedly happy with the coph nia. i have no ...   Consttraveler

10-28-02   This is one of those "holy grail" issues that has ...   Cpdunn99

10-29-02: Zaikesman
Consttraveler, with a cart output so low as .23mv, many (most?) phono preamps will need the assistance of a phono step-up transformer to provide a sufficient amount of quiet gain, and that sounds to be the case with your system.
Zaikesman  (Reviews | Threads | Answers | This Thread)


10-29-02   Zaikesman: that's what i was afraid of, and where my next p ...   Consttraveler

10-29-02   Ortofon sells a step up transformer (it's in their website). ...   Psychicanimal

10-29-02   You have to always properly optimize input load according to ...   Mamba

10-29-02   Guys, unfortunately, i have to disagree with step up transfo ...   Mamba

10-29-02   Mamba, i don't think you are entirely correct about the step ...   Twl

10-30-02: Zaikesman
Consttraveler - Sorry, I'm not going to be of much help for specific recommendations, as I've never owned a super-low output MC that required a transformer (though I have read that Wright Sound offers a decent one for about $350). Maybe do a forum search on the topic 'phono step-up transformer' or such. The other option would be to just switch to a very high-gain capable phonostage that doesn't need transformer assistance (or has one built-in) to provide adequate gain (probably >66dB I should think), rather than keeping the one you own and also investing in a separate trannie, but I can't suggest which approach would potentially give better sound or be more cost effective for you (not forgetting the extra set of IC's you'll need for the stand-alone option). Best of luck, Z.
Zaikesman  (Reviews | Threads | Answers | This Thread)


10-30-02   Consttraveler, if you can find a used cotter mk2, that would ...   Twl

10-18-06   I just bought a denon 103r cartridge from audiocubes out of ...   Jwt

10-19-06   have you checked the shunt capacitance? is it 100mf? don't s ...   Gregm


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