Simplistic NJFET RIAA

Due to the repetitive unlock / lock procedure needed to fine tune the SME3009 VTA, and because I was using a 1.5mm hex key instead of the 1/16" (1.59mm), I managed to kill the locking screw.:hot:

Three days after a short e-mail exchange with SME, I got a splendid mail package with not one but three replacement screws.

I did not even have the oportunity to ask for the cost and now I got the parts free of charge...!!!

That is what I call Customer Care. :worship:

Ricardo
 
Jensen mod

Just finished replacing the nichicon (marantz model) gold pins... (This is a first for me as I had never seen caps with gold pins before :apathic: ), by the 15000u 4pole Jensen.

It took a while because of the different connections but it was a smooth operation.

Healing from the organ transfer, the riaa sings all the same...😀

First impressions are a much better high freq detail ... (somehow I detect more distortion but maybe it was there before and I can only hear it now)
The nichicon deep bass is now missing but it is better defined and with more grip.

I also detect lower transient compression so these caps can deliver faster at high freq.

I was hoping to get rid of the 100Hz I hear before lowering the pick-up (sounds like a live concert PA idle sound), but it remains the same so these caps can not replace a snubber circuit.

I must leave it burning for a while so I can report correctly.

Ricardo:smash: :smash: :smash:
 
I though that you reported zero buzz after your latest grounding scheme... Or is it some buzz the cart pics up and then goes away?

Nichicons are no kids, listen carefully after burn in so to know if Jensen will prove really better overall...
 
The buzz is low volume compared with the music... When I lower the pick-up, the surface noise blends with the PA sound and it is not easy to hear.... sometimes I hear it on very good and silent pressings, between musics.... or worst, during low level passages.

I noticed the riaa is very susceptible to magnetic fields... my table lamp has a transformer in the base (12v bulb) and the riaa starts to pick it up at 30 cm or more... the sound is very similar to the existing buzz... maybe I should shield the TX as it is only 25cm away from the ria circuit... or put it sideways ??
 
Your grounding scheme does not allow for hum, so naturally the buzz must be a field. I would see about the TX orientation first, and if it changes anything, that means measures to be taken.😉

P.S. That is why I use shielded cable. Kill the field (?) buzz and expect smoother highs. If you resort to shielding, make sure that you will not close the magnetic circuit from chassis to central bolt of the toroid, you can even kill it. A full peripheral copper band is OK, with connection to chassis GND. Toroids mainly offend with stronger field around the secondary cable exits.
 
Marginally better due to the already very low reg's output impedance that does not blend the stages much. Of course I am sure that you are going to hear it, and depends on what the definition of ''marginally'' can mean for you and your system.
 
I guess that I will have to visit you at a point to hear my RIAA in ultra version. How long a return day trip from Athens to island of Poros can take in time? I visited Poros as a kid. Has it changed a lot from late 70s?
 
With a hydrofoil it is one hour from Piraeus, 2,5 hours with the normal boats. From the 70s many things have changed, but not as bad as in other places. You are welcome any time! You can PM if you want.
As far as ultra, I do not know!
I try to do my best, but I am getting slow now, as the summer is approaching.
Hope to finish everything when it gets cold again!
 
I have made some basszilla speakers. F5 is driving the top. Woofers are Lambda TD15X driven either by DNA-1 or some gainclones I have.
I use a passive pre for the time. I will built your 12b4a after the summer.
 

Attachments

  • img_0480.jpg
    img_0480.jpg
    36 KB · Views: 612
Nice stuff, it would be cool to listen to it before you start then, so to decide the version better. I will see if I can make Mikvous to come along. Nice TT BTW. I have designed a multi triode front end integrated gainclone that Michael uses for his Paros house. Very well dialed in with snubbers, maidas, etc. Sounds much better than the average GC.
 
Salas said:
If you resort to shielding, make sure that you will not close the magnetic circuit from chassis to central bolt of the toroid, you can even kill it. A full peripheral copper band is OK, with connection to chassis GND. Toroids mainly offend with stronger field around the secondary cable exits.

Hi Salas

What do you mean by closing the magnetic circuit and killing the TX ? :scared:

Ricardo

PS:
After 24 hours burning, low end bass appeared again but with much better nuances, grip and detail (particularly in the attack / decay area) Jensens are def better than the Nichicon for this aplication.
 
Now I am sure the hum is due to a field. breaking the AC switch on the riaa, imediately kills all the hum. 😉

The shunt + riaa keeps working for 2 seconds just using the caps voltage and it is dead silent.

Can the noise be originated by the diodes ?!
 
If a toroid is closed with a metal or wire from chassis that sits on to its axial bolt, then, this is called shorted turn. It can even melt enough.

I would orient the toroid differently to hear if the buzz changes or goes away. Your experiment with the switch points firstly to the transformer field.