Simplistic NJFET RIAA - Page 128 - 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 5th March 2009, 03:58 PM   #1271
vgeorge is offline vgeorge  Greece
diyAudio Member
 
vgeorge's Avatar
 
Join Date: Mar 2004
Location: poros island
Salas,

the chokes are from Giatras and they 150ma. Why you say 20ma?
  Reply With Quote
Old 5th March 2009, 04:12 PM   #1272
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Because he just calculates them at such nominal current based on wire diameter, and then uses a hand held LCR meter at 1kHz with rudimentary current if you ask him to check the inductance, does not mean that the non gaped 50VA-100VA toroidal cores are made for any other application than AC mains transformers. Toroidal cores are notorious for hating DC and go to saturation fast. Just look around in the web and try to find many offered PSU chokes in toroidal core in the 100's of mA... If it was a valid approach, it would have been everywhere. I checked them thoroughly because I had various of his toroid types in the past, and they never filtered ripple as expected above 20mA. Their nominal inductance is just wishful thinking at nominal current, the guy is decent, don't get me wrong. He maybe misses the part that a toroid core to be good for some DC needs specially distributed gap core with Mylar or Teflon separators between layers. Those cores are special, very expensive, not usually found off the self. To the contrary, you can ask him to make EI gaped chokes for your specs and they work as a charm. He does good work.

Something like a Hammond 158s is good for passively pre filtering my shunts at 200mA CCS IMHO, without losing much voltage. You would need 2 of them, or like them. And you must have enough voltage for accommodating the drop on their 60R series. How much series resistance your now chokes have?
Attached Images
File Type: jpg 158s.jpg (58.1 KB, 364 views)
  Reply With Quote
Old 5th March 2009, 04:35 PM   #1273
vgeorge is offline vgeorge  Greece
diyAudio Member
 
vgeorge's Avatar
 
Join Date: Mar 2004
Location: poros island
Thanks for all the info.
If I remeber correct they have about 90 ohm resistance.
I get around 41 to 42 before the shunts.
I will try to find some Hammonds then.
  Reply With Quote
Old 5th March 2009, 04:44 PM   #1274
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Don't go over 43V before the shunts. Your left hand side LEDs JFET CCS has 40V max, and its voltage across is VinDC-LedsVdrop. Add some resistor in case your DCin goes over 43V with the Hammonds.
  Reply With Quote
Old 5th March 2009, 04:48 PM   #1275
vgeorge is offline vgeorge  Greece
diyAudio Member
 
vgeorge's Avatar
 
Join Date: Mar 2004
Location: poros island
Thanks for the advise again!
Any place to get the Hammonds?
Also last one!
Auricaps of Mundorf Silver?

Regards
George
  Reply With Quote
Old 5th March 2009, 04:54 PM   #1276
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally posted by vgeorge
Thanks for the advise again!
Any place to get the Hammonds?
Also last one!
Auricaps of Mundorf Silver?

Regards
George
Look online for the Hammonds, they aren't heavy so it may be best to get em off ebay or some EU online store. Ask for freight costs in advance.

Both are very good capacitors. I prefer Auricaps when there is hardness potential in the rest of the set up, especially in speakers. The Mundorf has some hyped up detail but in a liquid manner and I find it a bit skinny in the power range (200Hz-800Hz). Depends very much on your total TT tone and speaker - room interface.
  Reply With Quote
Old 5th March 2009, 07:09 PM   #1277
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
Originally posted by salas
Measurement wise, I could not see so much improvement as in the simulation, but it lowered the noise floor in the range between 5k to 20kHz. This ties with the added subjective smoothness I perceived in the highs. Waiting to know gang's opinions too.
Will do....

Just a question.... As my shunt is 10cm away from the riaa, and as I know that we should place the regs as close as possible to the circuit to be powered, I was wondering if adding 2 caps (1 per channel) in the Riaa pcb decoupling the power line would produce some beneficial results ?

As my shunt has a 470u BG std in the output, i would like to place 2 x 680u BG Nx in the Riaa.

Ricardo
__________________
RC
  Reply With Quote
Old 5th March 2009, 07:30 PM   #1278
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Do you employ local RC filters on the RIAA stages as we speak?
  Reply With Quote
Old 5th March 2009, 08:51 PM   #1279
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
The shunt and the Riaa have only the circuit you designed.

Nothing more was added.

The sound is becoming very good now and I believe I lost the startup noises also.

Ricardo
__________________
RC
  Reply With Quote
Old 5th March 2009, 08:55 PM   #1280
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Just twist the wires from shunt to RIAA and use 0.1uF good pp capacitor from the B+ to ground, exactly where your B+ cable meets the RIAA board. Use your BGNX for C5 & C10. Don't worry for they are more than 220uF. There you will hear them.
BTW did you test the shunt mod yet?
  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 08:54 PM.


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