Krill output stage + tube preamp - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 24th September 2011, 01:36 PM   #1
diyAudio Member
 
Join Date: Jan 2008
Default Krill output stage + tube preamp

Hi,

I am going to build hybrid amplifier. I want to use 100W output stage from Krill amplifier. I have several questions about the output stage.

First, how should I modify the input of the output stage to make it work with external preamp and what is the input impedance of output stage?

Second, can I substitute drivers from 2SC5200 to MJ150030?

Third, can I substitute signal transistors to BD139 and BD140 - propably worse sound, but I already have them.

Thank you.
Attached Files
File Type: pdf Krill 100W.pdf (80.9 KB, 119 views)
  Reply With Quote
Old 24th September 2011, 02:00 PM   #2
diyAudio Member
 
Steve Dunlap's Avatar
 
Join Date: Sep 2008
Location: Here
Quote:
Originally Posted by kacernator View Post
Hi,

I am going to build hybrid amplifier. I want to use 100W output stage from Krill amplifier. I have several questions about the output stage.

First, how should I modify the input of the output stage to make it work with external preamp and what is the input impedance of output stage?

Second, can I substitute drivers from 2SC5200 to MJ150030?

Third, can I substitute signal transistors to BD139 and BD140 - propably worse sound, but I already have them.

Thank you.
Are you saying you want to substitute a tube VGS for the VGS shown in your attached schematic?

The output stage will accept almost any transistor that meets the power and voltage requirements.
  Reply With Quote
Old 24th September 2011, 02:23 PM   #3
diyAudio Member
 
Join Date: Jan 2008
Just to be clear...schematics attached.
Attached Images
File Type: jpg Krill 100W - output only.jpg (127.0 KB, 255 views)
  Reply With Quote
Old 24th September 2011, 02:30 PM   #4
heinz is offline heinz  Germany
diyAudio Member
 
Join Date: Mar 2007
I tried a Tube vgs : Krill construction thread - 100W version
Not 100W but sounds very good.
__________________
(((---)))
  Reply With Quote
Old 24th September 2011, 02:43 PM   #5
diyAudio Member
 
Join Date: Jan 2008
I am curious how it will sound with aikido preamp. I too will not have 100W output power, because I will have lower voltage rails (30V), but want to use double output pairs to lower output impedance.

But how to modify the input transistors? Should I connect 1k in series and 47k to ground resistor from base of input transistors?
  Reply With Quote
Old 24th September 2011, 03:01 PM   #6
heinz is offline heinz  Germany
diyAudio Member
 
Join Date: Mar 2007
i just used two resistors to trim the base of Q7/Q10. One resistor was 680K, other one 1Meg Pot.
Tube is EF86 in Triode Connection. V=200V. All Values of Restistors and Caps are rough guesses ... :-)


Edit: Attachments
Attached Images
File Type: jpg krill_tube.jpg (73.6 KB, 236 views)
File Type: jpg tube_ef86.jpg (31.1 KB, 227 views)
__________________
(((---)))

Last edited by heinz; 24th September 2011 at 03:09 PM.
  Reply With Quote
Old 24th September 2011, 03:05 PM   #7
diyAudio Member
 
Join Date: Jan 2008
680k trimpot for DC offset?
So you have about 1M input impedance of Krill output stage?
  Reply With Quote
Old 24th September 2011, 03:27 PM   #8
Bigun is online now Bigun  Canada
diyAudio Member
 
Bigun's Avatar
 
Join Date: Jan 2009
Blog Entries: 2
You can probably get rid of one of the capacitors in the signal path - either the input cap or the inter-stage cap through a judicious choice of power rails for the tube.

Steve - correct me if I'm wrong - but I also believe you'll benefit if you can afford to add more output transistors. With no gnf the output will tend to have more distortion and lower damping factor than with gnf. Additional output devices will help you reduce the output impedance, they will also have less current variation through each one so lower distortion. And as far as I can see, the Krill output stage benefits even more from additional devices because more devices means more base-storage of minority carriers which is what is behind the distinctive non-switching / soft-switching characteristic.
__________________
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.
  Reply With Quote
Old 24th September 2011, 03:36 PM   #9
diyAudio Member
 
Join Date: Jan 2008
Can I change input transistors Q7/Q10 to BC550/BC560 ?
  Reply With Quote
Old 24th September 2011, 03:42 PM   #10
heinz is offline heinz  Germany
diyAudio Member
 
Join Date: Mar 2007
I dont know - I did use bd139/bd140 in that position
__________________
(((---)))
  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
need diy tube preamp (line-stage) recommendation and general tube advice Musiclover4 Tubes / Valves 16 18th May 2013 03:19 PM
preamp output stage resistor from output to V- ? ? Bernhard Solid State 4 19th October 2007 02:55 PM
Tube Output Stage Mighty Mouse Tubes / Valves 3 24th August 2004 08:08 PM
need help on tube output stage.. tone Digital Source 2 19th March 2003 04:52 PM
Advantage of Tube Output stage on Preamp? Rarkov Tubes / Valves 11 18th November 2002 10:32 AM


New To Site? Need Help?

All times are GMT. The time now is 07:22 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