Mpp Mpp - Page 521 - diyAudio
Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

Mpp
Mpp
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 6th February 2012, 10:57 PM   #5201
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Mpp
Hmm, is the Is > Idss?
  Reply With Quote
Old 6th February 2012, 11:04 PM   #5202
Joachim Gerhard is offline Joachim Gerhard  Germany
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Very near, only degenerated by the 2,5Ohm. The stage is self conducting but also forced by the constant current sources. My sample of the FPS is quiet. When i get it back from a loan i can measure it. It simulated with -77dB against 1mV.
  Reply With Quote
Old 6th February 2012, 11:07 PM   #5203
Joachim Gerhard is offline Joachim Gerhard  Germany
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
As a young man i worked in the High Tech industry. We would have build input stages for brain scanners that way. That was between 1984 and 1989.
  Reply With Quote
Old 6th February 2012, 11:12 PM   #5204
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Mpp
I am a bit afraid about the forced current regarding the 1/f hyperinflation. Anyway, only when you will measure yours we can give hesener some solid landmark to work towards really. I like the simple concept there.
  Reply With Quote
Old 6th February 2012, 11:27 PM   #5205
Joachim Gerhard is offline Joachim Gerhard  Germany
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
The FPS is basically a Tietze-Schenk low noise input stage, interpreted as a Fet input balanced INA. You can see it in T/S, Chap. 4 or in Burkhard Vogelīs "Sound of Silence", first Edition, page 48. John Curl send me a Fax with the same circuit from the 60th, also single ended, so this idea is ages old. A guy from Canada whoīs name i have forgot made an ultra low noise single ended version although he is not a fan of the constant current sources. In praxis i found that the noise disadvantage is compensated by the gain advantage plus better PSSR. Two circuit i have in my lab prove that it is ultra low noise.
One is a single ended version with 4 x 2SK369. It is so quiet that Sam found it is more quiet then his line stage. The other is the AKSA Paris that has only one 2SK369 without source resistor at Idss. I have published measurements of both circuits before here.
I am absolutely sure that the constant current sources do no harm in noise IN THE CONFIGURATION I USE.
  Reply With Quote
Old 6th February 2012, 11:35 PM   #5206
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Mpp
Must be something in the build that hesener will debug.
  Reply With Quote
Old 6th February 2012, 11:37 PM   #5207
Joachim Gerhard is offline Joachim Gerhard  Germany
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Yes, or he has not measured both inputs in tandem, balanced.
  Reply With Quote
Old 6th February 2012, 11:41 PM   #5208
ungie is offline ungie  Canada
diyAudio Member
 
Join Date: Dec 2002
Location: Ontario, Canada
Once a GB is arranged, and I have one built up, I'll be publishing measurements using AP 2722 Cascade.
  Reply With Quote
Old 6th February 2012, 11:42 PM   #5209
Joachim Gerhard is offline Joachim Gerhard  Germany
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Great, that will show a lot.
  Reply With Quote
Old 7th February 2012, 12:58 AM   #5210
Joachim Gerhard is offline Joachim Gerhard  Germany
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
I dug out a measurement of the Paris, taken at -50dB/U.
That was at the time i posted measurements from my professional lab. The Paris is in green and the noise floor of my measurement system in blue.
You can see the single ended non NFB nature by looking at the second harmonic. That grows in proportion with the input signal and ultimately third is coming up too ( not shown ).
This is a single selected 2SK369 on Idss without source resistor. It is bipolar cascoded with a ground referenced cacode with a 470 Ohm, 470 Ohm base divider, signal going out of the base ! This is supplied by a bipolar constant current source with an RC filtered single green Led voltage reference. The SAM has 4 x 2SK369 on a 0,8 Ohm feedback resistor. The current source is referenced by two red Ledīs with RC filter so the emitter resistor can be of somewhat higher value. Sigurd simulated that a 100 Ohm resistor adds around 1dB noise, so for lowest noise it should be somewhat higher, say 220 Ohm. this is all well researched and proven in praxis. It works.
Attached Images
File Type: jpg Paris -50dB Salas.jpg (114.7 KB, 297 views)
  Reply With Quote

Reply


MppHide 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

Forum Jump


New To Site? Need Help?

All times are GMT. The time now is 07:10 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki