Looking for Mikael's KT88 Schematic - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

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

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 28th June 2005, 08:54 PM   #1
diyAudio Member
 
Join Date: Jul 2004
Location: PA
Default Looking for Mikael's KT88 Schematic

Anyone out there have Mikael's KT88 schematic.

Last link I had was....
http://81.224.66.34/se_kt88.gif

Not working anymore.

Thanks.
Toyman
  Reply With Quote
Old 29th June 2005, 12:24 AM   #2
XT8510 is offline XT8510  Netherlands
diyAudio Member
 
Join Date: Dec 2004
Location: Rotterdam
lets see if this works:
Attached Images
File Type: gif se_kt88.gif (18.1 KB, 5849 views)
  Reply With Quote
Old 29th June 2005, 01:15 PM   #3
Sherman is offline Sherman  United States
diyAudio Member
 
Join Date: Feb 2004
Location: Chicago area
This is a great sounding circuit and is as simple to build as you will find! You'll be happy with it.

If you are looking for OPTs for this amp I can recommend the James 6123HS. Price from Euphonia Audio is about the same as for the Hammond 1628SE and the sound is great. (Plus they look great, finish is definitely top notch!)
__________________
--Sherman
  Reply With Quote
Old 30th June 2005, 03:39 PM   #4
diyAudio Member
 
Join Date: Jul 2004
Location: PA
Thanks Guys.

Sherman, can you recommend some caps and resistors?

I seem to be having trouble finding a 220uF/63V and the 100uF/25V caps as well as the 470Ohm/25W resistor.

Can this amp run without a pre-amp, strictly with a CD source?
What about a SS preamp?

P.S. I'm a noob.

Thanks,
Earl
  Reply With Quote
Old 30th June 2005, 04:05 PM   #5
Sherman is offline Sherman  United States
diyAudio Member
 
Join Date: Feb 2004
Location: Chicago area
Quote:
Originally posted by Toyman_PA
Thanks Guys.

...

I seem to be having trouble finding a 220uF/63V and the 100uF/25V caps as well as the 470Ohm/25W resistor.

Can this amp run without a pre-amp...

P.S. I'm a noob.

Thanks,
Earl
Earl,

I ended up using 220uF/100V and 100uF/50V caps. Both were non-polar electrolytics. With the caps you can use a higher voltage rating than specified but you should stick with the recommended capacitance.

For the power resistor 20W should be OK.

You can find suitable resistors and capacitors at Mouser.

The amp was designed to run without a pre-amp so any source such as a CD player, tuner or tape player should be fine. For phono you would need a phono pre.
__________________
--Sherman
  Reply With Quote
Old 1st July 2005, 06:56 AM   #6
diyAudio Member
 
Join Date: Jun 2005
Location: New England
Default Noob questions

Sorry for the extra-basic noob stuff, but I've only built one amp so far, and I gotta learn somehow.

1) What's a good way to design a PS for this amp? I can't decide if I think a single supply for a pair of these on one chassis to make a stereo amp would be cooler than a separate PS for each, as in a pair of monoblocks. Regardless, I know I need 400v B+ per the schem, but what about generating enough current to power all 4 tubes? How do I calculate that?

2) For a circuit like this, how does one calculate the output in watts? I've always wondered that...

Thanks for the patience!

-Jeff
  Reply With Quote
Old 1st July 2005, 11:50 AM   #7
diyAudio Member
 
Join Date: Jul 2004
Location: PA
Hey Jeff,

Here is the power supply Sherman used for his monoblocks. He would be able to better the answer the single psu question. I was thinking about going with non-tube (can't remember the proper term) psu. Don't know the pros/cons though.

http://www.diyaudio.com/forums/attac...amp=1118349787

Earl
  Reply With Quote
Old 1st July 2005, 12:20 PM   #8
diyAudio Member
 
Join Date: Jan 2005
Location: Lisboa
You would have to put some dropping resistors if using solid-state rectifiers, as the 5U4G (simulating the same circuit on Duncan's PSU) makes for a voltage dropp of around 50V comparing with SS (370V vs 425V)
I'm going for tube rectification, different sound
  Reply With Quote
Old 5th July 2005, 12:02 AM   #9
Sherman is offline Sherman  United States
diyAudio Member
 
Join Date: Feb 2004
Location: Chicago area
Default Re: Noob questions

Quote:
Originally posted by jgunn5066
...

1) What's a good way to design a PS for this amp? I can't decide if I think a single supply for a pair of these on one chassis to make a stereo amp would be cooler than a separate PS for each, as in a pair of monoblocks. Regardless, I know I need 400v B+ per the schem, but what about generating enough current to power all 4 tubes? How do I calculate that?

2) For a circuit like this, how does one calculate the output in watts? I've always wondered that...

Thanks for the patience!

-Jeff
Jeff,

Earl posted my PS so you have that. It is for a monoblock, one 6N1P and one KT88. If you are building in a stereo chassis you only need 3 tubes- one 6N1P and two KT88. The 6N1P is a dual triode (two triodes in one envelope).

Calculating the current needed from your PS is not hard. First if you are doing tube rectification you need to supply sufficient current to the rectifier heater. The 5U4-G heater takes 3A at 5V.

Next you need to supply the heaters for your other tubes. The
KT88 takes 1.6A at 6.3V and the 6N1P is probably about 1A (I forget the exact value).

Last you need to know the current draw of your tubes for the B+. The KT88 is biased at 75mA in Mikael's circuit, I don't remember what the 6N1P draws, I think about 15mA? Add those up and give yourself some headroom.

If you are doing a stereo chassis then you'll have to supply heater current to two KT88's so you'll need 3.2A for those and still need the 1A or whatever for the 6N1P.

For the B+ you'll need to double everything from the monoblock. 150mA for two KT88s and 30mA for both triodes in the 6N1P.

Pick a PTX with enough guts.

As for power output- at full-tilt a single ended KT88 might make 8-10 watts (I think the sheet value is 11 watts). In this circuit, keeping distortion reasonable and running ultralinear rather than pentode mode a good guess would be between 4 and 7 watts. I haven't put the scope on mine yet to really measure it. I think Mikael was estimating 4-5 watts on his amp.
__________________
--Sherman
  Reply With Quote
Old 14th August 2005, 01:09 PM   #10
diyAudio Member
 
porkchop61's Avatar
 
Join Date: Aug 2004
Location: Mansfield, Connecticut
Question Stereo power transformer for this amp?

Ok-
I just found this thread on this project, and I'm going to build a stereo version of this amp.

My question is, can I use a Hammond 273BX for a stereo version of this amp? It's rated for 175ma not the 180ma as calculated is the above message. Is this close enough?
Have any others built a stero version of this amp?
Thanks.
Glenn
  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
Mikael Abdellah's kt88, (LOADLINES) soundbadger Tubes / Valves 6 3rd January 2012 02:30 AM
6CA7 Mikael Abdellah's KT88 SE amp? porkchop61 Tubes / Valves 24 20th February 2011 03:31 PM
Improvements for the Mikael Abdellah KT88??? 69CamaroSS396 Tubes / Valves 42 16th December 2009 01:58 AM
Anyone running Mikael's SE KT88 in Pentode? porkchop61 Tubes / Valves 0 4th September 2008 05:08 PM
Looking for KT88 Amplifier Schematic by Mikael Abdellah jduffy Tubes / Valves 6 5th April 2007 09:02 PM


New To Site? Need Help?

All times are GMT. The time now is 09:32 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