turntables: mm to mc cartridge requirements question.

[shedshrine]

Just got my turntable (ThorensTD125mk2) back after a checkup and new cartridge install. My first experience with a moving coil cartridge.

Before:



After:



Not experiencing a big "Wow" effect moving from a Shure mm to the Dynavector mc cartridge.

Running the tt with an old HH Scott 12 watt tube amp (222b) with high and low phono inputs.
The "high" input sounds better, but still not very vivid or powerful with this cartridge setup.
Volume knob half way up is adequate volume, but again not that involving.

Does this cartridge require a break in, or is that whole concept hooey.
Or does a mc cartridge need a different kind of phono preamp to shine?
Admittedly the cables on the tt are originals from back in the '60s if that's part of it.
Any ideas or experiences?


Thanks!
M

[Mudfoot Marshall]

Just got my turntable (ThorensTD125mk2) back after a checkup and new cartridge install. My first experience with a moving coil cartridge.


Not experiencing a big "Wow" effect moving from a Shure mm to the Dynavector mc cartridge.

Running the tt with an old HH Scott 12 watt tube amp (222b) with high and low phono inputs.
The "high" input sounds better, but still not very vivid or powerful with this cartridge setup.
Volume knob half way up is adequate volume, but again not that involving.

Does this cartridge require a break in, or is that whole concept hooey.
Or does a mc cartridge need a different kind of phono preamp to shine?
Admittedly the cables on the tt are originals from back in the '60s if that's part of it.
Any ideas or experiences?


Thanks!
M

New carts will need some break-in to open up (more bottom end and smoother mid and top range) the rubber suspension being the biggest culprit as it will become more "free flowing" over a period of about 25-50 hrs.

You would need a MC-to-MM step-up transformer to boost the low output and match the impedance. Although your Dyna is a high-output many people have skipped the step-up and been happy. I have never heard this model personally so I can't speak of what is missing sound-wise.

Have fun,
Jake

[shedshrine]

Thanks Mudfoot,
I'll see if putting a few hours on it gets the sound more "free flowing"

If not, like you said, I'll look into the step up boxes.

Found this online:

"The phono section is a 47Kohm MM stage. Use MAG low input. Optimal operation range for the Scott is 5mv so you will need to step up the your MC to 5mv."

[shedshrine]

These guys look the business for step up transformer kits..

http://www.kandkaudio.com/phonostage.html

[shedshrine]

I 've been playing discs all night and dialing in the speakers (JBL Decade 26) presence and brilliance controls, messing with the 222b's eq etc., and the Dynavector has definitely got more air and bass than my technics sporting the old Shure mm cartridge.

Currently I've got the (amplifier)222b's eq flat and Ramsey Lewis' Maiden Voyage is sounding full and open at the moment. Any "fluidity" that wants to follow a break in period is welcome however!

[Snarl 12/8]

How are you correcting for confirmation bias in your observations?

Just Kidding!

But seriously, sometimes I think our ears just need to get used to hearing something different before we can decide if it's better or not. And then, if we like what we're hearing after a while we chalk it up to rubber breaking in and caps getting more fluid and stuff. Has anyone done any measuring of a cartridge response before/after this "break in" period? I'm not saying there's not a break in period, I feel like I've experienced this myself. But I couldn't help wondering if it was just my ears that were breaking in. What's the evidence that that's not the case?

[shedshrine]

How are you correcting for confirmation bias in your observations?

Just Kidding!

Yes, the ramifications have been delineated within the perameters.

All I can say is I am enjoying my renewed love affair with this silly hobby.

[Jim Williams]

MC carts are lower impedance and output levels. I would avoid step-up transformers as those inject another low pass function and also have insertion losses that will eat a couple of db's of noise floor. Jensen makes the best model if you want that route.

Better are specific MC preamps designed with very low noise input transistors. There are plenty available including kits and DIY designs for low cost. Those will offer better transparency and noise specs.

[themagicmanmdt]

what jim said

yeah

[shedshrine]

Thanks.

Well, right channel is going out on the HH Scott's phono outputs,
so swapped in my other ancient piece, a MAC1500. It has two (high and low) phono inputs as well:

one rated at 5.6 MV and the other at 2.8 MV.

"The sensitivity is the minimum voltage you need from the cartridge to get the receiver to provide it's full output power. For any given position of the volume control, the sound will be louder if the turntable is in the more sensitive 2.8 mV input compared to the 5.6 mV input.

If the 2.8 mV is too loud and maybe a bit distorted, use the 5.6 mV input. If when using the 5.6 mV input, you have to turn the volume control way up to get the loudness you want and / or if the sound is maybe a bit noisy, use the 2.6 mV input."

In any case, what this translated to for my system was this. I've got the Technics with the Shure mm on the high, and the Thorens with the Dynavector mc on the easier to drive low.

The Thorens/Dynavector mc cartridge low input combo sounds clear and strong with amp controls flat.

The Technics/Shure mm cart high input has a strong midrange, and with the loudness engaged the added presence on top and thankfully non-muddying non-tubbifying low end even with the volume up a bit. Thicker tone though, not as resolved.


But of course now the Macintosh's left channel is making intermittent static noise in the phono modes.

[Bill @ Irie Lab]

From an Old-School audiophile turned engineer - As mentioned above moving coil cartridges have a much lower output and impedance than moving magnet cartridges.

The coil moving in a magnetic field has far less mass than a tiny magnet wiggling in a coil structure, so they are more responsive. The drawback is they need added gain to feed.a standard preamp phono section.

This is accomplished by using an outboard small signal active amplification stage (a head amp) or a transformer akin to the type used for ribbon microphones (according to Jensen, they are the exactly same winding).

Audiophile publications The Absolute Sound or Stereophile publish special equipment issues that will show what's available and give recommendations.

***WARNING - THESE SUCKERS CAN BE MUCHO EXPENSIVE and are very susceptible to hum and RF interference ***

Enjoy the vinyl!

PS I had that same Thorens model, loved it and wish I hadn't sold mine.