Simplistic NJFET RIAA - Page 883 - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 10th December 2012, 10:32 AM   #8821
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Can the folded cascode be implemented with a 28V PSU ?
__________________
RC
  Reply With Quote
Old 10th December 2012, 10:38 AM   #8822
diyAudio Member
 
The Space Egg Corp's Avatar
 
Join Date: Sep 2010
Location: London & Miami
Blog Entries: 13
Goldfinger ! 00 Salas.

Obviously 24crt sound !
N I C E !

Thanks... I'll order the proper GR's...eBay seller screw-up !
( Ricardo, the GR's are for the BIB reg....I have 50 2SK170-BL for amp boards x4 )

Top experimenting BTW chaps !
Tally Ho !!!

Si.

PS...Ricardo, dunno if you understood...
...I can make low AND hi Ohms now...2 different resistance-wire types.
Let me know if you would like a set...
...can make & mail.
ie...4x low's & 2x highs...right ? for your build.
Also possible to make 'un-equal-sets for 'gain-matching'.
Can send some resistance wire as well...
...good 60s' stuff ( my Dad's ).
  Reply With Quote
Old 10th December 2012, 11:37 AM   #8823
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by RCruz View Post
Can the folded cascode be implemented with a 28V PSU ?
By making R13 1K, R10 5.6K, R11 1.6K in your 2xK170 build. But losing 2-3dB gain AND 5V pk-pk headroom.
  Reply With Quote
Old 10th December 2012, 12:04 PM   #8824
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by xiaox2k View Post
thanks!
For what?
  Reply With Quote
Old 10th December 2012, 12:06 PM   #8825
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
Originally Posted by Salas View Post
By making R13 1K, R10 5.6K, R11 1.6K in your 2xK170 build. But losing 2-3dB gain AND 5V pk-pk headroom.
Thank you I have a "normal" simplistic, 48dB running at 28V that needs some work than !!!
__________________
RC
  Reply With Quote
Old 10th December 2012, 12:08 PM   #8826
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
You should watch it ain't overloading with a given cart if you will convert it. 28V B+ is rather little.
  Reply With Quote
Old 10th December 2012, 12:19 PM   #8827
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
I am using a 30VAC TX, so I have 42VDC before the shunts.

Maybe I could stretch shunts output to 32V....
__________________
RC
  Reply With Quote
Old 10th December 2012, 12:27 PM   #8828
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
That would take R13 1.2K 1W, R10 6K (12K//12K?), R11 1.5K for 57.4dB and better headroom.
  Reply With Quote
Old 10th December 2012, 12:45 PM   #8829
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
Originally Posted by Salas View Post
That would take R13 1.2K 1W, R10 6K (12K//12K?), R11 1.5K for 57.4dB and better headroom.
Perfect for a chrstmas present... thank you again Salas
__________________
RC
  Reply With Quote
Old 11th December 2012, 08:09 PM   #8830
diyAudio Member
 
The Space Egg Corp's Avatar
 
Join Date: Sep 2010
Location: London & Miami
Blog Entries: 13
Hi Peoples

Strange...
...just measured my 47n & 15n Ruskie K72's again today...
...and with same meter, same temp & same desk, leads & cup of coffee next to meter...
...they don't seem to 'drift' as before !
Today, they appear WAY more stable !
( must be thawing-out from Siberian cold-storage ! )

-------

Bit of advice please Gentlemen !
Miller/stray capacitance & RIAA values.
OK...got the 'official figures' 47k, 6.8k, 47n, 15.5n.
I guess some allowance for Miller/stray capacitance has been made here.

Just asking...
...as have been using a typical 'on-line RIAA calculator' ( mh-audio.nl )...
...to see if I can 'slightly tweek' the values to better match & suit the C's & R's I have to use.

On entering...47k I get...6834r, 15.95n & 46.52n
Just playing with the combinations really.
I had always thought to use 'fixed resistors', & adjust using 'small caps'...
...but...
...If I shift the 47k down a tad, to about 45.3k...both my cap values 'sync'...
...which could be good.
Just need a 45.3k resistor, which is no problem, I think.

Question is...
...what amount of Miller/stray capacitance, should I be factoring in to this calc. ?

I am def. a subjectivist with sound...
...perhaps it will need some adjustment later...
...but a good 'calced' value to start with, would be helpfull.

Not trying to change 'massively' from 'official values'...
...just trying to get best parts match etc...
...and possibly avoid buying more caps to try.

Will try a few different ones, I'm sure...
...a good match between the 2 R's & 2 C's, will help.

---------

JFET testing went OK...
...I think a good range to match position/channel from...
...slightly low, on average, for BL's...
...but majority, within the same 'low BL range'.
Good news ! ( I think )

Cheers.

Si.

( actualy turned the iron on today !!!...NOT eBay !!! )
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 11:59 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2