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

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Andrea Ciuffoli's KT88 PP
Andrea Ciuffoli's KT88 PP
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 15th January 2008, 05:28 PM   #1
blacklight is offline blacklight  Finland
diyAudio Member
 
Join Date: Feb 2006
Location: you tell me
Default Andrea Ciuffoli's KT88 PP

Hey all.

Anyone tried this one?
http://www.audiodesignguide.com/my/pp3.html
Worth building? The specs are pretty much what I'm looking for. A simple KT88 PP with about 20W output.
  Reply With Quote
Old 16th January 2008, 08:20 PM   #2
Svein_B is offline Svein_B  Norway
diyAudio Member
 
Join Date: Oct 2005
Sorry, I have not tried this design.
But I love the simplistic beauty of the circuit.

There are a couple of related threads on the K&K (Lundahl) forum:
http://www.audioasylum.com/cgi/t.mpl?f=kandk&m=4663
http://www.audioasylum.com/cgi/t.mpl?f=kandk&m=1133

SveinB
  Reply With Quote
Old 16th January 2008, 08:23 PM   #3
Wavebourn is offline Wavebourn  United States
Designer & Technologist
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Andrea Ciuffoli's KT88 PP
It's a classical 1930'th design. Results depend very much on an interstage transformer's selection.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 16th January 2008, 10:23 PM   #4
ray_moth is offline ray_moth  Indonesia
diyAudio Moderator Emeritus
 
ray_moth's Avatar
 
Join Date: Jan 2004
Location: Jakarta
Results depend very much also on the quality, condition and age of the tubes, since there is no NFB to normalize them.
  Reply With Quote
Old 17th January 2008, 11:11 AM   #5
Shoog is offline Shoog
diyAudio Member
 
Shoog's Avatar
 
Join Date: Aug 2002
Location: Eire
Experience tells me that interstage phase splitting sounds very good and it is well worth the investment in suitable quality iron (these can stay with you for multiple builds).
However the choice of KT88 as the output devices seems quite a poor one. Damping factor will be poor because of the relatively high rp of the KT88, even when triode strapped. If you can live with less power some type of high powered triode would be a much better option. Even a 300B would be a good choice.

Shoog
  Reply With Quote
Old 17th January 2008, 02:43 PM   #6
Kashmire is offline Kashmire  United States
diyAudio Member
 
Join Date: Dec 2003
Location: Midwest
Very similar to Sun Audio SV-KT88PE.

Manufacturer web site: http://www2.big.or.jp/~sunaudio/sv/svkt88pe_e.html

Schematic:
http://www.meta-gizmo.com/Tri/sunschematic.html

(actually, this is for the SV-300B MKII, but the schematic is very similar for the KT88 version).

Attached is a simplified schematic of my current project, using 6CG7 valves. Not shown are Aikido noise cancellation capacitor/resistor divider, "safety" resistors in the Aikido circuit, and the grid bias for the KT88 output valves. Also not shown is ultra-linear taps for the output stage (if desired). I'll probably build this as a Class-AB1, with about 50mA idle (each) on the output valves.

The LL1660S has about 360 Ohms of primary winding resistance, which means the transformer winding also serves as the cathode bias resistor to Aikido valve V2B (upper valve).
Attached Images
File Type: jpg smoore kt88pp.jpg (39.1 KB, 1331 views)
  Reply With Quote
Old 17th January 2008, 04:51 PM   #7
Svein_B is offline Svein_B  Norway
diyAudio Member
 
Join Date: Oct 2005
Quote:
Originally posted by Shoog
However the choice of KT88 as the output devices seems quite a poor one. Damping factor will be poor because of the relatively high rp of the KT88, even when triode strapped. Shoog
What would be a ralistic output impedance of a triode strapped PP output stage with KT88 (or EL34) ?

SveinB
  Reply With Quote
Old 17th January 2008, 05:36 PM   #8
Wavebourn is offline Wavebourn  United States
Designer & Technologist
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Andrea Ciuffoli's KT88 PP
Quote:
Originally posted by Kashmire



Attached is a simplified schematic of my current project, using 6CG7 valves. Not shown are Aikido noise cancellation capacitor/resistor divider, "safety" resistors in the Aikido circuit, and the grid bias for the KT88 output valves. Also not shown is ultra-linear taps for the output stage (if desired). I'll probably build this as a Class-AB1, with about 50mA idle (each) on the output valves.

The LL1660S has about 360 Ohms of primary winding resistance, which means the transformer winding also serves as the cathode bias resistor to Aikido valve V2B (upper valve).
No comments.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 17th January 2008, 06:36 PM   #9
Kashmire is offline Kashmire  United States
diyAudio Member
 
Join Date: Dec 2003
Location: Midwest
Cryptic response. Elaborate.
  Reply With Quote
Old 17th January 2008, 07:02 PM   #10
Wavebourn is offline Wavebourn  United States
Designer & Technologist
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Andrea Ciuffoli's KT88 PP
Quote:
Originally posted by Kashmire
Cryptic response. Elaborate.

You loose gain such a way and increase impact of oddnesses of an interstage transformer.

Try to shunt a CCS in cathode of the cathode follower by a capacitor, you'll be surprised.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote

Reply


Andrea Ciuffoli's KT88 PPHide 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

Similar Threads
Thread Thread Starter Forum Replies Last Post
Andrea Ciuffoli's power follower SteveG Solid State 11 3rd February 2014 03:53 PM
Andrea Bocelli - L'Abitudine (feat. Helena) Jean Music 13 2nd January 2010 09:57 AM
Custom designed transformer for Andrea Ciuffoli 6c33c OTL AMP.... zxcxz Tubes / Valves 2 10th July 2009 05:14 PM
Help - CFB in a KT88 SE amp Drewaudio Tubes / Valves 4 30th January 2007 05:36 AM
Andrea Ciuffoli Mosfet Amp DieterD Solid State 16 24th December 2001 06:56 AM


New To Site? Need Help?

All times are GMT. The time now is 04:55 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki