Simplistic NJFET RIAA - Page 111 - 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 20th February 2009, 07:56 PM   #1101
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally posted by guglielmope
but I where I can find info about matching fets or buy matched ones?
Thanks a lot for your help and interest
Grazie
Guglielmo
Idss matching
  Reply With Quote
Old 20th February 2009, 08:37 PM   #1102
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
Originally posted by salas

The standard 28V LED shunt that Rcruz made, he reported it dead silent. That is all I can personally know.
The shunt is really silent and ultra fast.

Just did the 330pF mod and now everything is getting into the right place.

Now I will play with the cart loading.

Amazing !

Ricardo
__________________
RC
  Reply With Quote
Old 20th February 2009, 09:51 PM   #1103
diyAudio Member
 
Join Date: Nov 2004
Location: Udine
Hello Riccardo,
There isn' t any330p on the schematic, where I can find this update?
Do you had any problem with pcb?they was ok?
Thanks a lot
Guglielmo
  Reply With Quote
Old 20th February 2009, 11:31 PM   #1104
iko is offline iko  Canada
diyAudio Moderator
 
iko's Avatar
 
Join Date: May 2008
Location: Toronto
The only difference I noticed between the two versions of the regulator is that the power mosfets of the non-buffered one get very hot, even with a significant heat sink. The buffered version you mentioned above has cold mosfets; the darlington gets a little warm (I measured a 27 mA collector-emitor current). On the oscilloscope both show a nice regulated trace, and sound wise I could not notice any difference. The reason I mentioned it to salas was partly theoretical, furthermore, I like tweaking everything, no offense intended.
  Reply With Quote
Old 21st February 2009, 01:03 AM   #1105
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Rather odd to have cold Mosfets if the CCS is running same current in both versions. I would expect the shunt Mosfet to be somewhat colder since the driver and the idss buffer would consume about 37mA above load consumption VS the standard one, lightening its constant burden. But I don't see how the CCS Mosfet running at same current and same Vin - Vout can show such a thermal difference. Plus if they share the same heatshink they would eventually come to about the same centigrade.
  Reply With Quote
Old 21st February 2009, 12:48 PM   #1106
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
Originally posted by guglielmope
Hello Riccardo,
There isn' t any330p on the schematic, where I can find this update?
Do you had any problem with pcb?they was ok?
Hi Guglielmo

The original 46dB schematic indicates 16nF for C3 on the riaa circuit.

As I was using 15.72nF, I added 330pF so I got 16.05nF.

The result is very noticeable... I lost the frontal presentation of sax and trumpet, voices became less boxy and piano has a natural presentation. the 330p silver micas are burning nicely and the trebble is regaining its fluidity.

The pcb is very good indeed... everything worked at the first time !

Now I will replace some resistors and work on a propper case with good connectors.

Ricardo
__________________
RC
  Reply With Quote
Old 21st February 2009, 01:33 PM   #1107
diyAudio Member
 
nicoch58's Avatar
 
Join Date: Oct 2004
Ricardo
__________________
Sic58
  Reply With Quote
Old 21st February 2009, 01:36 PM   #1108
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
Originally posted by nicoch46
Ricardo
Thank you nicoch46
__________________
RC
  Reply With Quote
Old 21st February 2009, 03:00 PM   #1109
iko is offline iko  Canada
diyAudio Moderator
 
iko's Avatar
 
Join Date: May 2008
Location: Toronto
Quote:
Originally posted by salas
Rather odd to have cold Mosfets if the CCS is running same current in both versions. I would expect the shunt Mosfet to be somewhat colder since the driver and the idss buffer would consume about 37mA above load consumption VS the standard one, lightening its constant burden. But I don't see how the CCS Mosfet running at same current and same Vin - Vout can show such a thermal difference. Plus if they share the same heatshink they would eventually come to about the same centigrade.
Yes, it puzzle me too. I did some digging yesterday; my suspicion was that the bjt did all the work in the second stage of regulation, the shunt stage, and thus the second mosfet did no more work. I measured the current through the first mosfet, at about 97 mA, and that seems sane. The current through the second mosfet was less than 1 mA. Logically, next I removed the entire buffer+second mosfet. Right now I am running the attached configuration with great results I might say. The darlington can be replaced with other medium power transistor, I use it because it's what I had around in the junk box. I can say this with certainty, because I did compare yesterday with a lm317, and a lm338t. The shunt regulator is much better, both versions yours, salas, and the one that I slightly modified.

salas, so have you formed an opinion about the ruskie ft-3s?
Attached Images
File Type: jpg regdarlngt1.jpg (46.1 KB, 500 views)
  Reply With Quote
Old 21st February 2009, 05:59 PM   #1110
iko is offline iko  Canada
diyAudio Moderator
 
iko's Avatar
 
Join Date: May 2008
Location: Toronto
However, I would like say that I am just exploring some of these variations, and to recommend to everyone to run the salas shunt regulator.
  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 11:06 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