MC step up active device

[Cold Beer]

Hi! I have searched this forum, but found nothing similar in nearer history. At least nothing that I could relate as MC step up amp.

I would like to build a MC step up device, based on new, low noise, op amps, preferrably powered by batteries.
It should be able to drive standard MM input of my preamp (CJ Premier 3).
Cartridge has 0,45 mV output and 4 ohms internal impendance, but in future, who knows, it would be nice if it could drive even lower otput carts.
Forgive me if I missed some thread, but everything older than 2010 was considered old

Thanks

 

[analog_sa]

Step-ups based on opamps are not very popular. At these signal levels it is easy to get away with a zero nfb, single stage amp, based on single or parallel fets/transistors/valves.

At .45mV even a single ECC88 triode per channel will provide a decent S/N ratio and of course you can go for paralleled. Using opamps in front of a valve phono stage is desecration

 

[Mark Tillotson]

The go-to low voltage-noise device is something like the ZTX851/951 - should be a fair few designs for those on here, including opamp-bootstrapped designs. The ZTX851 is capable of about 0.27nV/√Hz with 1/f knee around 100Hz, loads better than any opamp.

 

[Cold Beer]

Great!
I would go around tubes, if I can. Any semiconductor device that can be driven by 18 V or less would be nice. I would like some schematic diagram. This is still DIY forum?
Thanks

 

[knutn]

LSK170 (2Sk170) can give you a very simple amp with few components, see eg:

2SK170 BL MC step up amp

 

[6L6]

Pr?ampli MC Hiraga

Le Pacific JFET Phono Preamp for MM and MC Cartridges

Moving Coil Cartridge Head Amps

Project | Muffsy MC Head Amp | Hackaday.io

Even More MC Pre-Preamps

http://mc-preamp-diy.blogspot.com/2018/04/building-mc-head-amp-for-myself.html

https://www.theanalogdept.com/sut.htm

 

[jackinnj]

The go-to low voltage-noise device is something like the ZTX851/951 - should be a fair few designs for those on here, including opamp-bootstrapped designs. The ZTX851 is capable of about 0.27nV/√Hz with 1/f knee around 100Hz, loads better than any opamp.

at 6.4mA, Horowitz and Hill have it at 0.24nV/√Hz -- see table 8.1a

 

[DNi]

You might like to also have a look at this:
Designing a universal diff-in/diff-out Head Amp

Regards,
Braca

 

[grufti]

I'm 2/3 done building Hans Polak's preamp from the thread mentioned in Braca's post. It looks very promising.

Another Hans

 

[russc]

Project 187
Worth reading even if you don't choose this design.

 

[Boydk]

Richard Lee's Ultra low Noise MC Head Amp

If this doesn´t strike something, just scroll through the "analog source" forum. There´s lot´s and lot´s of duggestions

 

[billshurv]

I also recomment the latest design By Hans that Hans is building. You may not want diff in, but it makes a lot of sense. It's horribly noisy at 310pV/rtHz . The fact that it runs off either a wall wart or a 5V USB battery booster is nice and you can build a voltage amp or current amp (or both) to compare. All parts are available from any good distro and no evil matching requirements. Very little not to like.

 

[Cold Beer]

Thank you all for contribution in this thread. I have read all the links that you submitted. Some very interesting stuff there, especially regarding that amp should do a simple task, no riaa. But yet a pretty complicated stuff regarding low level signal and low noise requirements. I have sent a message to Hans. Only board will do, but complete kit would be nicer. For start.

 

[billshurv]

Hans doesn't sell boards, but I think there is enough demand for a minimum PCB run if you want a set of bare boards.

 

[Cold Beer]

It's horribly noisy at 310pV/rtHz .

I hope that this was sarcasm?

 

[billshurv]

Oh totally . You have to go to considerable lengths to better that.

 

[Cold Beer]

After reading almost all that you all have suggested, I contacted Hans. It is something new, and he is super friendly, we already talked on private. So, this is the way I will take, and all my observations, when I start with Hanses project will be posted here.

Thank you all

 

[billshurv]

Hans is a great guy!