denti alligator
New member
Just curious if this has been talked about and what the reasons are for not pursuing this earlier. I would think there would be a high demand for such a phono pre-amp.
Any plans for a phono pre-amp for moving coil cartridges?
- Thread starter denti alligator
- Start date
I have to put in my $.02 and say that a step-up transformer is an ideal solution, with the added benefit that you can tailor it specifically to your cart. A great many MC preamps are simply adding an SUT inline anyway, and a lot of folks think trannys sound better than active preamps. Just about the simplest gadget one could build. I have a Linn Karma cart and built an SUT with Cinemag 3440AHs and it's been a huge success. FWIW.
EDIT: Whoops! I should add that my SUT feeds the Seduction with great results.
EDIT: Whoops! I should add that my SUT feeds the Seduction with great results.
Grainger49
New member
Doc has posted about first a SUT from Bottlehead then an active tubed step up device. Since neither have gone very far. The SUT was officially passed on, IIRC, because of shielding problems. You know Doc wants everything to be as quiet as possible. You will probably find these posts in General.
Right now Bottlehead has the Seduction, Eros, "Tube Phono" RIAA only and variable EQ versions. That is a pretty good line up of phono stages. It isn't clear to me if the Tube Phono have MC inputs. I don't think so.
Of course an SUT is only applicable for a small range of MC cartridges due to impedance and gain matches. An active stage would need variable gain and impedance loading to be applicable to a wider range of MC cartridges. The nice thing about MM cartridges is that they all can be loaded with the same resistor.
Right now Bottlehead has the Seduction, Eros, "Tube Phono" RIAA only and variable EQ versions. That is a pretty good line up of phono stages. It isn't clear to me if the Tube Phono have MC inputs. I don't think so.
Of course an SUT is only applicable for a small range of MC cartridges due to impedance and gain matches. An active stage would need variable gain and impedance loading to be applicable to a wider range of MC cartridges. The nice thing about MM cartridges is that they all can be loaded with the same resistor.
Grainger49 said:
Worth a search on Vinyl Engine forum on "cartridrge loading". Loading can be a factor with MMs too.
Some of us who post over there have found the Audio Technica 440MLa sounds much smoother on the top with loading changed to 32k ohms instead of the standard 47 k ohms. Adding 100 k ohm resistor in parallel across the standard phono input gets one in the ball park.
Shure MM cartridges can also be pretty fussy about the capacitve load they see. M-97 can sound overly dull if the total load capacitance it sees is not in the 200-300pF sweet spot.
There are those that view the major advantage of moving coil cartridges is there relative insensitivity to capacitive load due to the lower inductance of the coils. One could see the need for careful impedance matching as the trade off.
My appologies for being a contrary sod.
Grainger49
New member
I knew my statement would draw fire when I typed it. That is not the point and I admit that some rare MM/MI cartridges are specified at something other than 47k ohms resistive.
But getting to the heart of my point, a resistor can be changed with the greatest of ease by a kit builder. And, too, a load capacitor can be added just as easily.
Yet, only a few MM/MI cartridges show an "optimal" load other than 47k. Most affordable, to me, cartridges say 47k just like when I sold audio gear in the 60s and 70s. I even own a HO-MC cartridge that is spec'd at 47k ohms. Just like the AT you mention. I agree some like it with a different load.
The point, that was confused, is that a LO-MC requires much more matching than a MM. I stand by that statement. See PJ's post below on matching a SUT with a MC cartridge.
The background is that the output and impedance needs to be matched to the gain and transformer impedance. There is no "one size fits all" like panty hose (doesn't work there either, ask your wife). This is from Paul Joppa:
http://www.bottlehead.com/smf/index.php/topic,116.0.html
But getting to the heart of my point, a resistor can be changed with the greatest of ease by a kit builder. And, too, a load capacitor can be added just as easily.
Yet, only a few MM/MI cartridges show an "optimal" load other than 47k. Most affordable, to me, cartridges say 47k just like when I sold audio gear in the 60s and 70s. I even own a HO-MC cartridge that is spec'd at 47k ohms. Just like the AT you mention. I agree some like it with a different load.
The point, that was confused, is that a LO-MC requires much more matching than a MM. I stand by that statement. See PJ's post below on matching a SUT with a MC cartridge.
The background is that the output and impedance needs to be matched to the gain and transformer impedance. There is no "one size fits all" like panty hose (doesn't work there either, ask your wife). This is from Paul Joppa:
http://www.bottlehead.com/smf/index.php/topic,116.0.html
Grainger49
New member
Here, here! . . . or Hear, Hear!
You have a tongue-in-cheek PM.
You have a tongue-in-cheek PM.
Grainger49
New member
Didn't I just post somewhere that Doc wants his products quiet. Or was that just in my mind. A mind is a terrible thing to fool.
I wholeheartedly support low noise, even with my age and ailing ears.
I wholeheartedly support low noise, even with my age and ailing ears.
Paul Joppa
Moderator
Still on vacation, so just a quick note. I am not giving up on the tube head amp yet! The prototypes should not be as noisy as they are, so there is probably some problem other than the tube itself. Just need to figure out what it is!
PJ, I had used a D.Y.I. battery powered head amp that was great sounding, and very quiet for many years. I swapped it from time to time with an Ortofon T-20 that was super quiet, but not as lively or musical as the head amp. I am using a Pro-ject tube hybrid MC/MM head amp at the moment, until I get something different. I am also concidering an Eros phono stage, but am just a tiny bit concerned about finding a really quiet EF86 tube. Maybe this might only be some unnecessary paranoia that has set in. However, The Eros is high on my priority list, so I am trying to figure out what stepup (head amp or transformer) I will need to purchase.
