Looking for Mikael's KT88 Schematic - Page 3 - 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 19th August 2005, 09:00 PM   #21
diyAudio Member
 
porkchop61's Avatar
 
Join Date: Aug 2004
Location: Mansfield, Connecticut
Default My layout for the stereo KT88 SET

Ok, can some of you "experts" please take a look at my component layout and see if this looks to be a good arrangement?
Thanks everyone.
Glenn

KT88 Stereo layout
  Reply With Quote
Old 19th August 2005, 11:19 PM   #22
diyAudio Member
 
Join Date: Jan 2005
Location: Lisboa
Looks pretty neat!

Just don't forget to have the output trannies 180 respecting each other. Also, i think you'll have a better wiring layout (easier) if the 6N1P is rotated 180.

I wanna see photos of it finished!
__________________
"There's something organic about a happy cloud of electrons" - Neutron Bob
  Reply With Quote
Old 20th August 2005, 12:58 PM   #23
diyAudio Member
 
porkchop61's Avatar
 
Join Date: Aug 2004
Location: Mansfield, Connecticut
Thanks for that info.
I've only built guitar tube amps before (mono), so I wasn't sure about the orientation of the 2 OT's. I knew about the PT and OT laminations being 90 degrees apart, but I didn't know about the OT's, thanks!
I also didn't look carefully at the pinouts of all the tubes yet.
I also like using turret boards for ease of modifications (if needed).

I did have a question about SE amps in general. I've heard that this design tends to distort a sine wave type signal on one side, is this true? I believe transmitters use this type of design, but they use some complex RC filter network to fix this issue. Any info on this?

Thanks again.
I'll post progress pix as I go along.
If anyone would like dimensioned chassis drawings, I can also post those.
Glenn
  Reply With Quote
Old 20th August 2005, 03:36 PM   #24
diyAudio Member
 
Join Date: Jan 2005
Location: Lisboa
As only one tube is amplifying the whole wave (positive and negative parts), there is no distortion besides the one induced by the amplifying element (make that tube or transistor).
What could make that to a perfect sine wave would be a push-pull topology, where one tube takes care of each part of the wave, though most would be an "out of phase" between both cycles, on poor designs..
Bu even so, what could induce that type of distortion you mention would be the amp clipping.

I'm sure other members can explain this better, and more correctly

Cheers!
__________________
"There's something organic about a happy cloud of electrons" - Neutron Bob
  Reply With Quote
Old 21st August 2005, 01:01 PM   #25
diyAudio Member
 
porkchop61's Avatar
 
Join Date: Aug 2004
Location: Mansfield, Connecticut
Hmmmm, looks like other amp designers have their output transformers with the laminations parallel to each other:
SET design
Maybe its just as I thought, only the PT and the OT have to have their laminations 90 degrees apart?
Glenn
  Reply With Quote
Old 21st August 2005, 01:10 PM   #26
diyAudio Member
 
Join Date: Jan 2005
Location: Lisboa
Read again closely to what i've said.
Output trannies at 180 from each other and facind the output tranny at 90.
In other words, have the o/t trannies have the same side facing,i.e., one output side facing the other output side
__________________
"There's something organic about a happy cloud of electrons" - Neutron Bob
  Reply With Quote
Old 22nd August 2005, 02:24 PM   #27
Sherman is offline Sherman  United States
diyAudio Member
 
Join Date: Feb 2004
Location: Chicago area
Quote:
Originally posted by rdf
..The James 6123HS isn't currently listed though James still lists it...
http://euphoniaaudio.netfirms.com/ea...?cPath=26_1_33

And the James website (not the easiest to find, actually JIANSHIN ELECTRONICS CO):

http://jianshin.myweb.hinet.net/english_first.htm

I noticed that the other day and wondered why? It is an excellent transformer at an excellent price (or at least it was).
__________________
--Sherman
  Reply With Quote
Old 22nd August 2005, 03:36 PM   #28
Sherman is offline Sherman  United States
diyAudio Member
 
Join Date: Feb 2004
Location: Chicago area
Quote:
Originally posted by porkchop61
Hmmmm, looks like other amp designers have their output transformers with the laminations parallel to each other:
SET design
Maybe its just as I thought, only the PT and the OT have to have their laminations 90 degrees apart?
Glenn

Glenn,

As Simpleton said, most builders orient the OPTs 180 degrees from each other and 90 degrees from the PTX. Some OPTs can't be easily oriented that way (vertical mount types, such as the James) but if they can I think it would be good to do it.

I really like your layout, it keeps the dirty side away from the clean side really well. I'm assuming you will run the heater wires along the front of the chassis and then run one down the middle to the right KT88, branch off to the 6N1P and then continue to the left edge of the chassis and then down to the other KT88. That keeps things separated about as well as you can.

I think the space between the volume pots and the heater wires is sufficient but I'm far from an expert in these matters.
__________________
--Sherman
  Reply With Quote
Old 22nd August 2005, 05:13 PM   #29
diyAudio Member
 
porkchop61's Avatar
 
Join Date: Aug 2004
Location: Mansfield, Connecticut
Thanks Sherman.
Yes, I'm going to do exactly as you said with the wiring.
Do other people use DC for running heaters? It would eliminate any noise problems, and the routing of the wiring would not be as fussy.

I was actually considering laying-out this chassis with the power supply down the middle in the arrangement as it looks now, but having the preamp tube in the center, and the KT88's & OT's on each side.
Looks good to be symmetrical, but probably not for noise.

I was also going to give those oil filled motor run capacitors a try for this build.
I assume that polarity doesn't matter for those types of caps?

Thanks to everyone for the tips.
Glenn
  Reply With Quote
Old 22nd August 2005, 11:58 PM   #30
Sherman is offline Sherman  United States
diyAudio Member
 
Join Date: Feb 2004
Location: Chicago area
Quote:
Originally posted by porkchop61
Thanks Sherman.
Yes, I'm going to do exactly as you said with the wiring.
Do other people use DC for running heaters?...

I was also going to give those oil filled motor run capacitors a try for this build.
I assume that polarity doesn't matter for those types of caps?

...
Glenn,

I used AC heaters with no problems. Just keep the heater wires tucked up into the top corners of the chassis as they run around and it should be fine.

You can of course use DC if you want but then you'll have to add something like a CRC filter to that as well. Plus rectifying the 6.3V tap on the PTX will give you more than 6.3VDC so you'll need to choose the resistor value in the filter carefully to get things back to 6.3V with the heater load. I wouldn't bother.

I also used motor run caps for both my SE KT88s and the SE EL84 I just "finished" today. They do the job! They are non-polar so you can hook 'em up however works out for you. I used quick-disconnects to connect all my wires to them, HT, HT center tap, B+ to 6N1P and B+ to OPT. It makes it very easy to unplug sections for testing or to "break into" a circuit to measure current.
__________________
--Sherman
  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 03:30 AM
6CA7 Mikael Abdellah's KT88 SE amp? porkchop61 Tubes / Valves 24 20th February 2011 04:31 PM
Improvements for the Mikael Abdellah KT88??? 69CamaroSS396 Tubes / Valves 42 16th December 2009 02:58 AM
Anyone running Mikael's SE KT88 in Pentode? porkchop61 Tubes / Valves 0 4th September 2008 06:08 PM
Looking for KT88 Amplifier Schematic by Mikael Abdellah jduffy Tubes / Valves 6 5th April 2007 10:02 PM


New To Site? Need Help?

All times are GMT. The time now is 06:52 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