MC step up active device

Cold Beer

Member
2017-01-07 6:49 am
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 :D

Thanks
 

analog_sa

Member
Paid Member
2002-08-14 1:47 pm
Cascais
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 :)
 
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
 

billshurv

Member
Paid Member
2014-03-01 11:53 pm
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

Member
2017-01-07 6:49 am
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.
:D
 

Cold Beer

Member
2017-01-07 6:49 am
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 :D