Mpp - Page 203 - 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 8th December 2010, 08:10 PM   #2021
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Capt, that is interesting historical information. I have a Tube - Fet Arthur Loesch MC build by Jürgen Ultee that uses the 2SK147 in a Tube-Fet cascode but i myself have no experience with this part other then listening to Jürgens creation. I can not make it to CES this year so i am very sorry to miss that oportunity. Maybe i can find a friend that carries them home.
Are you the gentman that gave me historical 2SK170, 2SJ74 in the first place ?
If yes, that was much apreciated. It´s now time to reveil the Fets i use. I promisse not to hide anything here i publish. It´s the 2SK369. Look at the ID curve over UDS ( or Vds if you will ) at 10mA idle for example. Where the 2SK170 has a visible bend the plot of the 2SK369 is rather flat. That translates into a very high early voltage and that has a lot of consequences that i will try to explain.
  Reply With Quote
Old 8th December 2010, 08:54 PM   #2022
diyAudio Member
 
Join Date: Aug 2009
Default 2SK369

That is the same part as 2SK147 in standard TO92 package, it also was available in mini TO92 which allows a pair to fit in TO18 heatsink for better thermal coupling. Sorry you won't be at CES, PM your address and I will mail you a few
  Reply With Quote
Old 8th December 2010, 09:07 PM   #2023
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
You will not get there from HERE, Joachim. You are playing with fire. Syn08 can teach you a thing or two, in this case. To get to about .2nV/rt Hz in this reality, I resorted to a dedicated MC transformer, in front of my phono preamp.
  Reply With Quote
Old 8th December 2010, 09:25 PM   #2024
YWN is offline YWN  United Kingdom
Account disabled at member's request
 
Join Date: Jun 2010
Location: UK
Quote:
Originally Posted by Joachim Gerhard View Post
Back to the current source YWN, your thoughts are two steps forward from mine.
The problem with that simple circuit i see is that Ube is dependent on temperature by the formular 2mV per Kelvin devided by R3 ( aproximately, sorry that i repeat that so often). Temperature sensitivity is also in the cascode. The Fet i choose is rock solid though because it has a very high early voltage. That translates into a nearly horizontal line when you plot ID in mA against UDS in Volts, even at the rather high ID of 10mA per Fet i choose. The task now is to compensate the current source against the bipoar cascode transistor. I checked iddle current over the 0.8Ohm resistor and it was rock stable. I can do that with more resolution of cause. The trouble comes from the bipolar cascode transistor i think.
Hi Joachim, not sure I follow, but I'm positively sure the servo won't be able to fix both problems, the output offset and the voltage at the drains collector junction. Yes, I think temperature can play a major role here, it may trigger the flipping, since the gain is very large.

Re my other questions, I wrote and got an email response from SYN08 and I think I now have the answers to my early other questions (compensation and RC cell). Pretty clever ideas, I would say. BTW, don't answer if you don't feel like, but have you considered asking him for permission to use the circuit (or the original ideas included into that, as per your post #1940 and #1972)? Not to say he didn't hereby overreacted, but he seem to be a nice guy though...
  Reply With Quote
Old 8th December 2010, 09:29 PM   #2025
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Where do you think i should go ?
I continued this discussion only because i got requests. So this is all in retrospect. I already canceled the project in question and non of the circuits published here got ever into a product anyone can buy.
My assotiated whould kill me if i publish a circuit here that they financed.
I give up. Lets NEVER talk about that circuit again here please.
  Reply With Quote
Old 8th December 2010, 09:39 PM   #2026
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
See my last post YWN. If i will ever use again an idea he originally had and i am not so blind not to realise it i will ask him for permission. Reading his words though about my
non existing abilities to measure and design i am not sure if he ever will realise my aproach more then an insect trying to stitch him.
i am totally demotivated now and stop my thread.
This does not make any sense to me any more.
Good by friends.
  Reply With Quote
Old 8th December 2010, 09:43 PM   #2027
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Congratulations YWN, what a heartening move.
  Reply With Quote
Old 8th December 2010, 10:31 PM   #2028
YWN is offline YWN  United Kingdom
Account disabled at member's request
 
Join Date: Jun 2010
Location: UK
Quote:
Originally Posted by Salas View Post
Congratulations YWN, what a heartening move.
Err... must go to bed now... did i do something wrong, sorry Joachim and everbody else...
  Reply With Quote
Old 9th December 2010, 05:17 AM   #2029
masag1 is offline masag1  Germany
diyAudio Member
 
Join Date: Dec 2008
Hi Joachim,

hundreds of diy'ers will be very sad, if you will stop your thread.

Please take some hours of sleep and reconsider your decision

Sometimes there are missunderstandings, and people do not recognize that things are finished and are given to the filling basket.

The www gives us the opportunity to share and support your research, and especially for me dummkopf, to participate.

Please keep going on.

Herzliche Grüße

SAm
  Reply With Quote
Old 9th December 2010, 06:21 AM   #2030
diyAudio Member
 
Join Date: Sep 2002
Location: Germany
Blog Entries: 1
So Syn08 and YMV are pissed because of a topolgy mentioned since perhaps 1969 (1.Version Tietze-Schenk) and Joachim is to stop developing and contributing to the community? Salas is right, what a heartening move

Quote:
Originally Posted by Joachim Gerhard View Post
Hi Ingemar ! The Topology goes further back then the HPS 5.1. First there was the Self MC pre-pre back in the 90th. Then there was the Colins circuit in AudioXpress that uses a Fet.
Around the same time there was Burkhard Vogels BUVO that had a RIAA wraped around the input stage, again with bipolar input. Mr. Vogel split the gain though. His input stage has 47dB of gain and then he adds an adjustable linear gain stage. I also published a circuit in Linear Audio Volume 0 that has that kind of gain cell but set up as a symmetrical INA. Looking even further back Mr.Self must have gotten his idea somewhere and i found his basic topology in "Halbleiter Schaltungstechnik, Tietze-Schenk". I have only the latest issue 13. The basic circuit is on page 497. How old that idea is i can not say but Vogel also refers to Tietze-Schenk so i asume it has been there for many years. There is no new thing under the sun ( King Salomon ). What i claim is novel with my circuit is that i do the amplification and EQ in one stage. That saves me 2 gain stages compared to the HPS5.1 and one gain stage compared to the BUVO.
i also think that i have not lost quality in the process. There is around 77dB of feedback availlable at 20kHz so distortion should be superbly low. The Fets i use are optimised for Audio and have a very high Early Voltage for example plus low 1/F frequency plus low GR noise. I have other details in the circuit that give excellent PSU rejection and i drive the Fets at a certain operation points that avoids heating and gate current. I have published cascoded Fet stages here aplenty since the beginning of my thread 19 month ago. I must admit that i learned a lot about noise from Synn08 and Scott Wurzer, although it was not always a smooth ride.
  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 03:34 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