Simplistic NJFET RIAA

alexkosha · 2013-09-22 5:04 pm

to minimise the loop area of that long loop

AndrewT said:
if one connects the returns at the Source and one also has the returns connected somewhere downstream, then one has created a very long loop. That loop is very likely to have problems with picking up interference.
Recently I can across a dual coax with the screens in contact. That would be one way to minimise the loop area of that long loop.
I have never seen any project describe how to avoid this stereo source to stereo receiver loop.
There are a couple of papers that describe methods of reducing the current in these loops.

This is what I made for my BHL Phono amp. Please correct my drawing if you see something wrong in it.

Please note, this is not a Folded Simplistic.

haishaul · 2013-09-23 11:31 am

Hi ,
just bought the kit , and working on the PSU.
Does anyone can recommend on boxes for PSU and PCBs (where to order ?)

AndrewT · 2013-09-23 11:40 am

Build your PSU, then add on your amplifier. Only after you see how big it is and how you can package all the bits can you decide on the shape and size of the box.

haishaul · 2013-09-23 12:46 pm

off course I will do that.
The question is , is there a vendor the produce certain boxes that are recommended ?
Can the PSU box be made of Plastic (I guess the PCB need an Aluminium case) ?

TNX

Salas · 2013-09-23 2:41 pm

The DIYA store has many adequate boxes lately:
Compact with Quasi Heatsinks - Chassis

skouliki · 2013-09-23 3:09 pm

Hi Salas.
I will be using your phonostage with a Myref RevC amp through a passive 10k attenuator. Is the 2.2uf value of the output capacitor enough? Or should i use a 4.7uf output cap?

Salas · 2013-09-23 3:21 pm

0.1uF C3 and 3.3uF C4 will do well for 10K preamp input Z.
(Keeping near to the original integrated subsonic roll off curve)

skouliki · 2013-09-23 3:32 pm

Thanks Salas

chokesrule · 2013-09-27 8:20 pm

Salas I put your stage as in the pdf on nelson b1 buffer .All credit to you :its fantastic .

Salas · 2013-09-27 8:23 pm

The folded one? For MM or MC? Any pics?

alexkosha · 2013-09-29 5:36 pm

Salas said:
The folded one? For MM or MC? Any pics?

I see you placed 7809 regulator with BC550C NPN transistor for MC PCU in your yearly manual. Do you prefer 78XX over LM317T? Why? LM317 has lower noise and higher ripple rejection. Please let me know.

Salas · 2013-09-29 6:11 pm

I did not care since a capacitance multiplier followed in that pre-pre case, so the 78xx was chosen for simplicity. LM317 with adj. pin AC decoupling cap is superior to 78xx when alone. But what it has to do with the quoted post?

RCruz · 2013-09-29 7:57 pm

Some difficulties making the kmultiplier work with the usual 4 pole smoothing caps (oscilations maybe)... I tryed with "normal" Elna 10000uF and found no gains relative to my "normal" RC concept.... the V12R are quite good in psrr so I will keep it simple now

alexkosha · 2013-09-29 9:17 pm

Salas said:
I did not care since a capacitance multiplier followed in that pre-pre case, so the 78xx was chosen for simplicity. LM317 with adj. pin AC decoupling cap is superior to 78xx when alone. But what it has to do with the quoted post?

It was my mistake to include that quote.
Can you explain what BC550C is doing there. What it is for?
If I use LM317T, then do I need to add that transistor to the circuit?
If yes, can I use BC547C instead (I do not have BC550C)? It is the same beside noise is little higher.
Thank you.

Salas · 2013-09-29 9:53 pm

RCruz said:
Some difficulties making the kmultiplier work with the usual 4 pole smoothing caps (oscilations maybe)... I tryed with "normal" Elna 10000uF and found no gains relative to my "normal" RC concept.... the V12R are quite good in psrr so I will keep it simple now

The less circuitry the better if making no audible contribution.
I will make one such raw rail active filter to test it myself with other reg versions at a point too maybe.

Salas · 2013-09-29 10:10 pm

alexkosha said:
It was my mistake to include that quote.
Can you explain what BC550C is doing there. What it is for?
If I use LM317T, then do I need to add that transistor to the circuit?
If yes, can I use BC547C instead (I do not have BC550C)? It is the same beside noise is little higher.
Thank you.

Its a pre-pre and that transistor has a capacitor there that multiplies its value by the gain so to filter the regulator's noise because its a very sensitive signal level and there is no cascode. BC547C will do fine.

There was a short thread with builds even for that pre-pre from the older pdf.
http://www.diyaudio.com/forums/analogue-source/188730-2sk170-bl-mc-step-up-amp-5.html#post2606756
http://www.diyaudio.com/forums/analogue-source/188730-2sk170-bl-mc-step-up-amp-6.html#post2723587

alexkosha · 2013-09-29 10:26 pm

Thank you a lot.

Salas · 2013-09-29 10:47 pm

The pre pre can be made in stand alone version too. Used like an external step up transformer.

RCruz · 2013-09-30 6:48 am

Very nice build.... where can I find the circuit ?

alexkosha · 2013-09-30 8:33 am

Salas said:
Its a pre-pre and that transistor has a capacitor there that multiplies its value by the gain so to filter the regulator's noise because its a very sensitive signal level and there is no cascode. BC547C will do fine.

There was a short thread with builds even for that pre-pre from the older pdf.
http://www.diyaudio.com/forums/analogue-source/188730-2sk170-bl-mc-step-up-amp-5.html#post2606756
http://www.diyaudio.com/forums/analogue-source/188730-2sk170-bl-mc-step-up-amp-6.html#post2723587

I made BC547C addition to my LM317T PSU with 2 Elna RFS caps, but noise got increased. Please see attached schematics. Did I make mistake somewhere there?

Simplistic NJFET RIAA

Member

Attachments

Member

R.I.P.

Member

diyAudio Chief Moderator

Member

diyAudio Chief Moderator

Member

Member

diyAudio Chief Moderator

Member

diyAudio Chief Moderator

Member

Member

diyAudio Chief Moderator

diyAudio Chief Moderator

Member

diyAudio Chief Moderator

Member

Member

Attachments