Simplistic NJFET RIAA

[nezbleu]

I have always liked the Vishay PTF series resistors -- very low noise, very low tempco, very low voltage coefficient, available in close tolerance. I have never detected a sonic problem with them. Only available up to 1/4W though, so useless for higher power applications. Readily available in 0.1%/10ppm though, and prices are reasonable.

 

[Salas]

I'll check everything

Work the DIP too if it reoccurs.

 

[Marra]

Ok will do.

 

[Turbon]

I have always liked the Vishay PTF series resistors -- very low noise, very low tempco, very low voltage coefficient, available in close tolerance. I have never detected a sonic problem with them. Only available up to 1/4W though, so useless for higher power applications. Readily available in 0.1%/10ppm though, and prices are reasonable.

Good to hear, from where? Quite happy with the BOM as a starter. But I will not buy them in batches of thousands...

Regards

 

[nezbleu]

Vishay Metal Film Resistors | Mouser

 

[nezbleu]

You can also get them in even closer tolerance, like 0.02%, but the prices start to get high.

 

[quan]

Hi Salas, proceeded as build guide. Tp1/TP2 measured 3.6V both channels, but B+ measured 32.20V, 32.11V respectively. You mentioned B+ about 33-37V. Do i need to adjust the VR2 to achieve B+ >33V?.
Quan

 

[Salas]

Its you used 10R Rs instead of 9.1R for 14mA. Normal result, bit steadier, less heat on the 9530, bit less gain but more than enough for your carts. ~62dB. Its a good result, I suggest you keep it like that.

 

[quan]

Its you used 10R Rs instead of 9.1R for 14mA. Normal result, bit steadier, less heat on the 9530, bit less gain but more than enough for your carts. ~62dB. Its a good result, I suggest you keep it like that.

Yes, i had some dale 10R ready so it went in.The initial impression is very impressive. I used with denon 103 modded/Garrard 301. Expect more refine over the next few days. Do you think is it worth to have extra RC filter prior to DC input of the phono?.
Quan.

 

[Salas]

I am not sure, it looks like its a system dependent thing regarding pollution levels at a place, and down to liking. No harm to try and decide.

Is there a picture we can see your build? After enough hours of play you will have more distinct impressions to relay, but hey, a good day is always looking good early in the morning. Well done.

 

[Salas]

Hey, Marra, did the paper noise disappear for good or it did some new phantom pass since yesterday?

 

[Marra]

I thought that I had found the cause as one of the interconnects was somewhat loose.With different cables all seemed well until 40mins of listening.The crinkling noise doesn't interfere with the listening only being noticeable when close to the speaker inbetween tracks.

 

[Salas]

Its not normal to have not even intermittently though. Look for cold joints in the signal entry and output on PCB and on the 4 LEDs exchanged. When small LEDs get worked much or see trouble they can develop noises as much as FETs for the same reasons.

 

[Marra]

Thanks Salas I'll check things out.Do you think it better to simply change the four led's.

 

[Salas]

Sure, but its just only one of the suspicious places. It could be a bad output cap c4 even. It takes a DSO with fast refresh or analog scope and look for the low level bug in all places, or various hit or miss exchanges.

 

[Salas]

Anyways, at least its not major. Could had worse with that power up in reversal.

 

[Marra]

The output cap is a nos Solen at least ten years old.As is the one on the other board of course.

 

[Salas]

There is 1meg R9 installed across the output, yes?

 

[Marra]

Yes

 

[Salas]

Rework the joints at input and output and check some other DIP positions in that channel too just in case the elusive bug is due to some silly reason.