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Author Topic: Any plans for a phono pre-amp for moving coil cartridges?  (Read 1334 times)

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Offline denti alligator

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Any plans for a phono pre-amp for moving coil cartridges?
« on: March 04, 2012, 05:59:23 pm »
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.
- Sam

Rega P3-24 (w/AT 150MLX) w/Groovetracer upgrades / C4S Seduction / Denon 2930CI / FLAC ->J.River-> MyDAC / PJCCS Quickie / C4S S.E.X. 2.0 +Nickel MQ Iron / Klipsch Forte II w/Crites upgrades / Sennheiser HD600 w/Cardas cable

Wish list: Paramounts + BeePre / Eros / Mainline / Tode / BH DAC

Offline adastra

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Re: Any plans for a phono pre-amp for moving coil cartridges?
« Reply #1 on: March 04, 2012, 07:19:56 pm »
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.
« Last Edit: March 04, 2012, 07:22:07 pm by adastra »

Offline Grainger49

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Re: Any plans for a phono pre-amp for moving coil cartridges?
« Reply #2 on: March 05, 2012, 02:44:33 am »
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.  
« Last Edit: March 05, 2012, 10:15:56 am by Grainger49 »
Grainger Morrison, Audio Salesman 1966-1976

VPI HW-19/Souther Tri-Quartz (Grado Sonata-1)/Eros/FP-2/Paramours (1) with MQ Iron (upgrades to all), Blumenstein Orca/Dungeness Speakers - PS Audio Regenerator

Offline Wanderer

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Re: Any plans for a phono pre-amp for moving coil cartridges?
« Reply #3 on: March 05, 2012, 05:23:33 am »
......The nice thing about MM cartridges is that they all can be loaded with the same resistor.  

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.  


 
« Last Edit: March 05, 2012, 05:28:25 am by Wanderer »
Kevin R-M

Offline Grainger49

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Re: Any plans for a phono pre-amp for moving coil cartridges?
« Reply #4 on: March 05, 2012, 09:01:08 am »
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
« Last Edit: March 10, 2012, 08:06:10 am by Grainger49 »
Grainger Morrison, Audio Salesman 1966-1976

VPI HW-19/Souther Tri-Quartz (Grado Sonata-1)/Eros/FP-2/Paramours (1) with MQ Iron (upgrades to all), Blumenstein Orca/Dungeness Speakers - PS Audio Regenerator

Offline Wanderer

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Re: Any plans for a phono pre-amp for moving coil cartridges?
« Reply #5 on: March 05, 2012, 09:41:30 am »
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.


You are 100% correct of course.

We are in danger of getting to the point I find I myself with my wife all too often.

"We aren't arguing, we're agreeing...LOUDLY!!"    

 
Kevin R-M

Offline Grainger49

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Re: Any plans for a phono pre-amp for moving coil cartridges?
« Reply #6 on: March 05, 2012, 09:45:25 am »
Here, here! . . .   or Hear, Hear!

You have a tongue-in-cheek PM.
« Last Edit: March 05, 2012, 09:48:21 am by Grainger49 »
Grainger Morrison, Audio Salesman 1966-1976

VPI HW-19/Souther Tri-Quartz (Grado Sonata-1)/Eros/FP-2/Paramours (1) with MQ Iron (upgrades to all), Blumenstein Orca/Dungeness Speakers - PS Audio Regenerator

Offline Doc B.

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Re: Any plans for a phono pre-amp for moving coil cartridges?
« Reply #7 on: March 05, 2012, 09:55:29 am »
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.

We have a couple of prototype active step up preamps, but so far they have proven a little too noisy to meet my standards.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline Grainger49

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Re: Any plans for a phono pre-amp for moving coil cartridges?
« Reply #8 on: March 05, 2012, 10:15:19 am »
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.
Grainger Morrison, Audio Salesman 1966-1976

VPI HW-19/Souther Tri-Quartz (Grado Sonata-1)/Eros/FP-2/Paramours (1) with MQ Iron (upgrades to all), Blumenstein Orca/Dungeness Speakers - PS Audio Regenerator

Offline Paul Joppa

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Re: Any plans for a phono pre-amp for moving coil cartridges?
« Reply #9 on: March 10, 2012, 06:04:24 am »
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!
Paul Joppa

Offline coca

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Re: Any plans for a phono pre-amp for moving coil cartridges?
« Reply #10 on: March 11, 2012, 02:49:19 pm »
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.