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 29th March 2013, 06:17 PM   #1
diyAudio Member
 
Join Date: Mar 2010
Default SIT Variations

Hoping to revive interest in the 2SK82 SIT , attached are some pics and schematic of my efforts. The circuit is by no means original, borrowing heavily from Andrea Ciuffoli's Power Follower 99 design, sans cap multiplier and active CCS. Having built a Hammond 193 inductor version of L'Amp, I was intriqued by the concept of a single stage, single device amplifier. This concept has been beaten to death (see the OTA and D'Lite threads) but as far as I can tell there hasn't been a 2SK82 implementation.
The circuit as presented is circumscribed by my self- imposed restrictions ie, only one active device per channel with a minimum of components and is not for everyone.
There is no voltage gain and efficiency is very poor - about 3 to 5 watts of usable power and a low output impedance preamp able to swing significant voltage is required. What the circuit offers is a level of transparency I have not encountered before and I have been sufficiently impressed to invest the effort to house my original breadboarded design into something half-way presentable.
For those who care of such things, there is no switch-on thump - the device ramps up nicely and input signal phase is preserved.
Attached Images
File Type: jpg DSC03317.JPG (664.2 KB, 1409 views)
File Type: jpg DSC03318.JPG (707.0 KB, 1332 views)
File Type: jpg DSC03319.JPG (679.0 KB, 1257 views)
File Type: jpg DSC03320.JPG (693.0 KB, 1121 views)
File Type: jpg DSC03321.JPG (611.3 KB, 1117 views)
  Reply With Quote
Old 29th March 2013, 07:42 PM   #2
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
me likee

also - that switch protection is so twisty twist
__________________
my Papa is smarter than your Nelson !
tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb ; Papatreasure
  Reply With Quote
Old 29th March 2013, 11:36 PM   #3
diyAudio Member
 
Join Date: Mar 2010
Hi Zen Mod,

I kinda suspected that the proliferation of chokes would appeal to you !
Having ruled out an active CCS, my only alternative was a plain old resistor acting under ideal constant voltage conditions. But then again no active voltage regulation for me so the next best thing was passive choke regulation.
You will notice that even though there is a choke preceding the first cap, this is not a traditional choke input configuration. For one thing the choke value is way too small and a properly sized choke would drop too much voltage. This first choke functions as a kind of 'shock-absorber', buffering the first cap from the charging surges - I use this often in my tube designs.
The power supply as configured performs far better than I expected with the added benefit of extremely low hum and noise level - at the lower limits of my measurement capabilities. No doubt the over-sized Antek transformer with static shield helps.
In operation there is total silence even when I stick my head into my 100db plus efficient horns !
  Reply With Quote
Old 29th March 2013, 11:46 PM   #4
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
I believe that's why he used to be called Choky...

Very cool amp.

  Reply With Quote
Old 30th March 2013, 12:38 AM   #5
diyAudio Member
 
Loudthud's Avatar
 
Join Date: Nov 2007
Location: Near Dallas Texas USA
Why are there four heatsinks? Where are the chokes mounted? I don't see 'em.
  Reply With Quote
Old 30th March 2013, 03:10 AM   #6
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Quote:
Originally Posted by audiong View Post
.......even when I stick my head into my 100db plus efficient horns !
please , don't do that too often

with every repetition of act , there is rising probability that some jerk is in the room , with fingers on start button


(been there , they done that )
__________________
my Papa is smarter than your Nelson !
tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb ; Papatreasure
  Reply With Quote
Old 30th March 2013, 04:53 AM   #7
diyAudio Member
 
Join Date: Mar 2010
Hi Zen Mod,

Regrettably, after the kind words from The Master and you , my head no longer fits.
Time to start looking for a pair of 210 cabs !
Attached Images
File Type: jpg DSC00468.JPG (621.6 KB, 543 views)
  Reply With Quote
Old 30th March 2013, 10:13 AM   #8
Dzius is offline Dzius  Poland
diyAudio Member
 
Dzius's Avatar
 
Join Date: Sep 2010
Location: Warsaw
Here is my version

SIT_SIT3.png

and one channel during tests:

DSCF1084_50.jpg
  Reply With Quote
Old 30th March 2013, 01:19 PM   #9
www.audiohobby.com
diyAudio Member
 
Join Date: May 2001
Blog Entries: 4
Really nice amps. I'd love to hear them on those big Altecs.
__________________
I'm not hanging around the forum these days but if you need help: Visit My Website | My YouTube Channel | Email Me | Wheaton's Law |
  Reply With Quote
Old 30th March 2013, 02:23 PM   #10
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Is SJDP120R085 good for a drop in test to those arrangements? How close is that type to the custom PASS SIT-1 part?
  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
My SIT - First Impressions and......... dantwomey Pass Labs 10 15th January 2013 03:40 PM
Shunt Regulator variations (Parallel voltage regulator variations) for SS Pre-Amp tiefbassuebertr Solid State 2 15th December 2012 10:09 AM
Behind SIT 2 pdyn Pass Labs 0 13th September 2012 08:54 AM
SIT-1 and SIT-2 owner manuals Nelson Pass Pass Labs 25 12th September 2012 07:16 PM
SIT-Preamp VladimirK Solid State 36 27th August 2011 08:36 PM


New To Site? Need Help?

All times are GMT. The time now is 03:18 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