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

help with KT88 / mikaels SE amp
help with KT88 / mikaels SE amp
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
Thread Tools Search this Thread
Old 3rd October 2007, 11:12 PM   #1
soundbadger is offline soundbadger  United Kingdom
diyAudio Member
soundbadger's Avatar
Join Date: Sep 2007
Default help with KT88 / mikaels SE amp

sorry for constantly asking questions but,
i am trying to design a kt88 based single ended amp i have been looking a lot at mikaels kt88 design which seems to have had good things said about in this here forum. however im trying to work out whats going on.

i recently posted a question asking about line level and ended up being told that it varys alot but a good place to start is about 1Vrms input .

i then checked out the curves for the 6n1p driver stage valve mikael used and found that in his setup an input voltage of 1Vrms would result in an output of about 80V pk-pk. (if anyone would care to confirm this twould be cool).

anyhow 80v pk-pk seems far to much (i was told about 40-45V pk-pk) to send in to the kt88 especially in ultra-linear mode.

is mikaels amp just designed for a lower input ?

any thoughts greatly appreciated,,,
also if im wrong in any way let me know
  Reply With Quote
Old 4th October 2007, 01:52 PM   #2
Sherman is offline Sherman  United States
diyAudio Member
Join Date: Feb 2004
Location: Chicago area
The 6N1P is capable of supplying more voltage gain than is strictly needed by the KT88. However that isn't a bad thing. Seldom do you want the driver stage in a hifi amp running at full output where distortion will be high.

Having headroom in the driver is good as is having headroom in the output stage.

I've built Mikael's schematic and really like it. I'm running things a bit hotter than the schematic calls for (424V B+, 82mA on the KT88). I'm getting between 7 and 8 watts and the sound is very good. I'm also using James 6123HS OPTs which I think are an excellent value.
  Reply With Quote
Old 30th September 2010, 10:59 PM   #3
vinodt1347 is offline vinodt1347  United Kingdom
diyAudio Member
Join Date: Aug 2010
As a follow up question, the mikeal amp would need about 200mA of DC current. I have a Hammond 374Bx rated at 175ma (375-0-375V). I think this is probably the current rating for the whole of the secondary and can probably deliver twice the current for the half. Would this transfomer be sufficient.
  Reply With Quote
Old 1st October 2010, 12:08 AM   #4
mach1 is offline mach1  Australia
Join Date: Sep 2004
Location: Brisvegas
The current rating is for 375V into a cap input psu (ie 375V x 1.4). I would not use it for this application.
  Reply With Quote


help with KT88 / mikaels SE ampHide 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
Which KT88?? Andy G Tubes / Valves 100 22nd May 2017 08:41 PM
SE KT88 Amp Cassiel Tubes / Valves 50 24th March 2011 09:33 PM
Mikaels KT88SE & VTV Octal Linestage AKlein Tubes / Valves 17 10th June 2008 04:16 AM
Stereo Build - Mikaels KT88 matthew2456 Tubes / Valves 11 24th January 2007 05:56 PM
Drd Kt88? hacknet Tubes / Valves 13 26th August 2004 04:41 PM

New To Site? Need Help?

All times are GMT. The time now is 01:26 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio