Another KT-88 - Page 2 - 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 29th July 2008, 05:33 PM   #11
poynton is offline poynton  United Kingdom
diyAudio Member
 
poynton's Avatar
 
Join Date: Mar 2005
Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)
Default Re: Another KT-88

Quote:
Originally posted by cryo
................ This is my version of Michael's KT-88 single ended circuit. .............


Beautiful.................

pardon my ignorance, but please supply a diagram or link.

Thanks
Andy
__________________
If it ain't broke, break it !! Then fix it again. It's called DIY !
  Reply With Quote
Old 29th July 2008, 05:47 PM   #12
cryo is offline cryo  United States
diyAudio Member
 
Join Date: Nov 2004
Location: CA
Sorry, I misspelled Mikael's name. I think this gif image should show the schematic I used.
Attached Images
File Type: gif se_kt88.gif (18.1 KB, 823 views)
  Reply With Quote
Old 29th July 2008, 05:57 PM   #13
cryo is offline cryo  United States
diyAudio Member
 
Join Date: Nov 2004
Location: CA
I should really thank Mikael for his schematic, it was great. And I should also thank Sherman, because I think it was his power supply design that I used. Here is the drawing for that also.
Attached Images
File Type: jpeg kt88 power supply.jpeg (19.5 KB, 743 views)
  Reply With Quote
Old 30th July 2008, 02:04 AM   #14
alexg is offline alexg  Philippines
diyAudio Member
 
alexg's Avatar
 
Join Date: Jan 2005
Location: Philippines
Cryo, nice job!

I built a few of this amp using Mikael's circuit, and after finishing each one and hearing how it sounds, the sound does not fail to amaze me!

Though, I can't build it as pretty as cryo's.
  Reply With Quote
Old 30th July 2008, 03:16 AM   #15
chrish is offline chrish  Australia
diyAudio Member
 
chrish's Avatar
 
Join Date: Oct 2003
Location: Sydney
Nice job.

How did you get such nice neat holes for the caps, especially the oval cross section one? I see you appear to have used some little clips to hold them in (requiring precision holes so the lip holds them in?). Did you make these yourself? looks like a better solution than can clamps.

Chris
  Reply With Quote
Old 30th July 2008, 03:32 AM   #16
diyAudio Member
 
Sal Brisindi's Avatar
 
Join Date: Nov 2006
Wow, absolutely a beautiful job, I am thinking building the EL34 version of that amp as I pretty much have all the parts on hand.

Regards,
Sal
  Reply With Quote
Old 30th July 2008, 03:35 PM   #17
cryo is offline cryo  United States
diyAudio Member
 
Join Date: Nov 2004
Location: CA
I will try and answer a few questions. Rodmunch asked how much this cost to build. Probably about $500 is my guess. The biggest expense being the James transformers and power supply. Lots of little stuff.

Chrish asked about the capacitor holes. The round ones were made with hole saws, drill very slow with a drill press and use lubricant. Now I must say that my technique worked, but I could not get the exact size hole I wanted. So I have a small mill that I used to clean up a smaller diameter hole and enlarge it to the exact size I wanted. I know a milling machine is a big expense, but a used bench top model is not much compared to what we drop in parts for these guys.

The oval hole was made with two holes that were then connected, I at first filed them. But I ended up now cleaning up the holes with the mill, and then connecting them on the milling machine. Hole saws can work very nicely, you just have to be very patient, and they would be tough to control without a drill press. I just had the small milling machine, and with 1/4" aluminum plate it machines like butter.

The hold downs for the caps are actually small cable clamps. I flattened them just a bit. After the caps were fitted into the holes, I placed the clamps where I wanted them. Holes were marked, then drilled on the drill press, and things work great.

I used countersunk flat-head bolts with a hex drive throughout. They just look nice and work great. I was going to use chrome, but they are really expensive. I found stainless was a lot cheaper, and a quick polish with a rag wheel and some polishing compound makes them look just like chrome.

Last thing was for the output tube vent holes. I tried to lay them out by hand and it was next to impossible. So I used a simple CAD program and laid them out precisely. Then I printed off the template, used a spray adhesive to attatch it to the plate in the exact position. Then I just drilled through the template and all of my holes were dead on.
Attached Images
File Type: jpg kt88 & 5u4g templates1.jpg (67.9 KB, 588 views)
  Reply With Quote
Old 29th September 2008, 04:59 AM   #18
John L is offline John L  United States
diyAudio Member
 
John L's Avatar
 
Join Date: Oct 2001
Location: Cary NC
Has the mistake, in Alex's rendition of Mikeal's KT88 amp been corrected yet? I was also getting ready to work on this unit, and this is the very first I have heard about there being something wrong with the diagram.

Help needed.
  Reply With Quote
Old 30th September 2008, 03:10 AM   #19
cryo is offline cryo  United States
diyAudio Member
 
Join Date: Nov 2004
Location: CA
John:

I'm sorry, I don't know what mistake you are referring to. Did Alex have something amiss in his own KT-88 build? I would be happy to help if possible, but am a bit confused as to the problem.
  Reply With Quote
Old 30th September 2008, 03:21 AM   #20
John L is offline John L  United States
diyAudio Member
 
John L's Avatar
 
Join Date: Oct 2001
Location: Cary NC
Quote:
Originally posted by cryo
John:

I'm sorry, I don't know what mistake you are referring to. Did Alex have something amiss in his own KT-88 build? I would be happy to help if possible, but am a bit confused as to the problem.
Someone mentioned this on one of the KT88 threads. It's not this one, but another. I can't remember who made it, but I think I heard it somewhere else. Maybe Porkchop, but I'm not certain. I'll try to go through and find it, ok?
  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



New To Site? Need Help?

All times are GMT. The time now is 01:51 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