Simplistic NJFET RIAA

[Salas]

You are welcome. It was hard for you to reach this result, many things first time practised, many setbacks, took you a lot of dedication. Nice.

 

[RCruz]

Hi Salas

You already know my opinion about your designs

Merlin

Your´s is really a very good implementation !!!

I also have one build that is dead silent.... but it took me a while to get there.

Hope we could hear the results over the internet

 

[NPower]

Congratulations !!

Hello Merlin

Great work, and I see that you put a tremendous effort to get the correct components !!
And if it sound great to your ears, PRICELESS !!!!!!!!!

 

[SGregory]

Okay FT-3 Interstage and Polysteyrene RIAA Caps installed.
Here is the RIAA plot and 1kHz 0dB=.3mV. FFT is growing grass again. Measurement setup isn't identical since I need to clean my bench.
THD is same as before at 0.02%


Merlin, mine does dance. If it had a pole it would be x-rated.

 

[Salas]

Do you use a correction file when doing the Riaa curve?

 

[SGregory]

Yes. I think it may be the wrong one, now that you mention it. I see a lift at the high frequencies. I can't remember now if I restarted the program after selecting it. Audiotester doesn't recognize the correct file until it starts on it. Will have to retest tomorrow.

 

[Salas]

Ok. Because you did not mention it as tipped up sounding.

 

[SGregory]

I will need to receck tomorrow. It is brighter sounding. Not offensive but there. I am not sure if it is just the new caps that havn't seen a charge in x number of years or a real artifact of the riaa. I am going to let it burn in a few hours tonight and try to test it tomorrow if I have time. Have to travel for the day

 

[Salas]

You had 15.7n PP testing caps, now 15n Polysterene. Which is the flat value, and a bit different tone from caps. Let it burn a bit, check on VTA see if you want to ''tweak'' the subjective HF. I use that flat alignment too. Never bright in my system, just alive in my perception. But its free to tweak by adding a bit on 15n in other systems. There are pF Micas for tuning.

P.S. Reminding my curve.

 

[SGregory]

I have a good collection of them from tuning GNFB on my amp. Lets see what this does over night and a confirmed correction file.
The sound is changing, The bass is starting to define itself better as time goes on.

 

[Salas]

The interstage FT-3 will flex also.

 

[SGregory]

I was attributing much of what I was hearing to the Ft-3. Funny, I never believed in cap breakin until about a year ago. My Mundorf Supreme' did he same thing on my preamp. I was sad that I spent so much and had horrible sound compared to a Solen from an old project. I left them in because I was too disguntled to have the energy to take them out. It didn't take too long and they really started to live up to their reputation. I have gone back to the solens just to make sure, but switched back to the Mundorfs in short order.

 

[Salas]

There are no measurements about that, aerospace industry would not mind.

I have this subjective experience that they settle somehow in 48H, especially NOS parts. Maybe its us adapting to new tone. Don't know.

 

[SGregory]

You are correct in your point regarding us.

 

[Salas]

Do you have a link on those NOS USSR Polysterene? Wanna see if I have ever used them. Did they measure correct value BTW?

 

[SGregory]

These were spot on. 15.03nF, They did not fluctuate that much either from piece to piece.
6800pF 250V 1% K71-7 Polystyrene capacitors Lot of 26 - eBay (item 200495668839 end time Aug-12-10 17:21:05 PDT)
They are the same make as this value. From the same guy.

My meter showed .04nF open so I used a matched pair of 15.07

 

[Salas]

Those are double metallized thick coated film, with polystyrene separators. Excellent caps. Have even used 120n ones for interstage in early MM phono. Never agressive, maybe polite even.

 

[RCruz]

That is typical with the FT-3.

You will like it even more after 48hours

 

[merlin el mago]

@Salas
Also your support, effort, time, patience, etc.

@RCruz
Thanks for sharing & let me know RIAA calculations & experience. I will post subjective opinions after the break in period needed for all changes.

@NPower
Thank you for your kind words.

 

[SGregory]

RIAA with correct file

Salas,
Little better now. My correction file was corrupted and not refreshing from previous hence the lift in the top end.
This is with a new file that is flat.