L'Amp: A simple SIT Amp - Page 165 - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 19th March 2013, 05:39 PM   #1641
diyAudio Member
 
Join Date: May 2009
No, but I had also autoformers in mind...
This is a good solution for higher voltage curves of 2sk82 but
you wont get rid of the big elec. cap.

Quote:
Originally Posted by flg View Post
  Reply With Quote
Old 6th April 2013, 09:41 PM   #1642
generg is offline generg  Germany
diyAudio Member
 
generg's Avatar
 
Join Date: Jul 2009
Location: Near Frankfurt
I played again with the SK82 and a CCS version with a R100. The rival was a R085 instead of the SIT.

The gain with the R085 was ugly high, about 25-30x and you could already hear the hiss from the semi with my 86db Lowther.
Sound was heavy and good, but not spectacular.

The sound with SIT was much more detailed, but very thin.

ZM advised me to seek for the reason not in the CCS, but in the lower part.

First I thought that the different transconductance makes the difference.

Around 5-6 Siemens against 0.5 Siemens. Or was it the big amplification difference hat fooled me....
Later I read Mikes article again, and stopped at the 'load line' term.
Indeed I had a combination of voltage and current for the Sit that was not on the loaddline Mike showed.

I chosed the 19V/1.6A point and I have the strong impression that the sound now lost the overly bright character.

Am I fooled by my exspectations? Does anybody have similar experiences?

Or is it simply the different combination of K2 and k3 that pleases me.
What is the advantage or disadvantage to be on the loadline with the SIT?

Is it possible that the importance of loadline is less important with the R085?

Any answers welcome!
__________________
and the First Wtt is......a really First Class PSS Idea
  Reply With Quote
Old 6th April 2013, 10:05 PM   #1643
Telstar is offline Telstar  Italy
diyAudio Member
 
Join Date: Dec 2007
Location: Italy
I believe that the K82s need to be matched a bit, following the loadline in Mike's article.
I dont have a tracer for high voltage/current, but I can tell for sure that there is a lot of variance among the sony SITs. I have 4 units, two are decently close, but the other two are way off (at the extremes).
__________________
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938
  Reply With Quote
Old 6th April 2013, 10:19 PM   #1644
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
as i said - and 'twas not invented by mighty moi - THD spectra is explanation for everything

The Class-A Amplifier Site - Jean Hiraga Index , just few general remarks , but these will maybe lead you further

there are more papers on French , but I will must wait to meet my fave Froggy Yoda for clarification ....
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM
  Reply With Quote
Old 7th April 2013, 12:06 AM   #1645
diyAudio Member
 
Join Date: May 2001
Blog Entries: 5
The R085 is more pentodey than a 2SK82 so there's less opportunity for working the loadline in OTL territory. Interestingly, the R085 (I posted some curves somewhere recently) is probably more well suited to an SET coupled design as it's more triodey at low-current high voltage. You probably couldn't go real high on the primary impedance, but a 64-150 Ohm transformer is probably workable, e.g. NP's Arch Nemesis.

You might also want to try a bit of degeneration with the R085, if the f-word doesn't bother you.

For the second part of your question: with a SIT, working the loadline to get the harmonic flavor you like best is where all the fun is. In my experience when the second and third harmonics are about the same magnitude things start to sound more threadbare.
  Reply With Quote
Old 7th April 2013, 12:29 AM   #1646
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by Michael Rothacher View Post
The R085 is more pentodey than a 2SK82 so there's less opportunity for working the loadline in OTL territory. Interestingly, the R085 (I posted some curves somewhere recently)
Here your traces again, annotated.
Attached Images
File Type: png R085_Id_Vds.png (41.5 KB, 283 views)
  Reply With Quote
Old 7th April 2013, 12:31 AM   #1647
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
ACA upper part is interesting , as load

ya didn't hear that from moi


btw. Mr. MR ....... where are you lately ....... Buzz iz having all the buzz for himself , without us
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM
  Reply With Quote
Old 7th April 2013, 12:39 AM   #1648
Telstar is offline Telstar  Italy
diyAudio Member
 
Join Date: Dec 2007
Location: Italy
Quote:
Originally Posted by Michael Rothacher View Post
In my experience when the second and third harmonics are about the same magnitude things start to sound more threadbare.
threadbare - what does this word mean?
I tend to prefer the 2nd bout 33% higher but you surely got more experience than I.
__________________
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938
  Reply With Quote
Old 7th April 2013, 12:51 AM   #1649
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Quote:
Originally Posted by Zen Mod View Post
ACA upper part is interesting , as load

ya didn't hear that from moi


btw. Mr. MR ....... where are you lately ....... Buzz iz having all the buzz for himself , without us
ACA is perfect, in fact. No degeneration, more for feedback if you want it. Its in my R085 thread ramblings. Nelson answered in fairly direct way, as matter of fact.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 7th April 2013, 01:04 AM   #1650
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
you're like squirrel , jumping all the time

I can't follow ya ....... so - from now - you must put a link to everything you mention

wakoosquirrelyank

__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM
  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


Similar Threads
Thread Thread Starter Forum Replies Last Post
L’Amp: A Simple SIT Amp: Part 1 Michael Rothacher diyAudio.com Articles 22 5th October 2013 09:25 AM
SIT Amp Article Out Now Variac Site Announcements 0 2nd December 2011 07:55 AM
Srajan has the 1st SIT amp for Une dégustation vizion Pass Labs 131 14th November 2011 11:41 PM
SIT-Preamp VladimirK Solid State 36 27th August 2011 08:36 PM
New SIT - old problem StevenOH Parts 2 13th June 2008 10:46 AM


New To Site? Need Help?

All times are GMT. The time now is 06:03 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