High voltage driver for AB2 operation GU81m tubes - Page 17 - 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 30th May 2012, 12:23 PM   #161
Account disabled at member's request
 
Join Date: Jul 2009
Thanks! I really appreciate the encouragement!

Actually work is progressing much more slowly than I would like. What really helps is to think things over and over...really imagine the assembly in every aspect before even touching the screwdriver. This way when the time comes to build, every forseen problem is addressed swiftly (obviously there is a margin for error). I think the amp will work well. In any case the driver section can be redesigned and swapped for something better in a very short amount of time. I am eager to test the power section. Once that is done it will just a matter of starting the testing phase.

I think the bass response will be really exceptional. Many have described music played by large tubes as "effortless". can't wait to corroborate this idea!
  Reply With Quote
Old 30th May 2012, 12:24 PM   #162
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
go slow...haste makes waste...are you affected by the earthquake?
  Reply With Quote
Old 30th May 2012, 12:28 PM   #163
Account disabled at member's request
 
Join Date: Jul 2009
here is the video

http://youtu.be/F8Jh4s9j9rk

the filaments are sofstarted via a 4A 10ohm NTC thermistor....the main switch triggers the timer which in turn activates the softsart module. This will force the surge to flow through 4x NTC thermistors. After 1.2s the thermistors are bypassed by a relay.

Last edited by Alexontherocks; 30th May 2012 at 12:32 PM.
  Reply With Quote
Old 30th May 2012, 12:43 PM   #164
Account disabled at member's request
 
Join Date: Jul 2009
Quote:
Originally Posted by Tony View Post
go slow...haste makes waste...are you affected by the earthquake?
Very true. The best part is yet to come...for now it is just boring mechanical work. I still have to wait for the sockets to be sandblasted and powdercoated.

Thanks for the question. Very kind of you. Luckily no I live in the least sismic area of Italy and just felt the smallest amount of tremors. At 9 o'clock yesterday the tremor was noticeable but not cause for concern.

The amp is so heavy I was pretty confident nothing could happen.
  Reply With Quote
Old 31st May 2012, 04:32 PM   #165
Account disabled at member's request
 
Join Date: Jul 2009
burning tubes...

all filament transformers in the amplifier are connected to mains via a NTC thermistor (CL-60) 10ohm @ 25C

Only the rectifier filaments do not draw enough power to lower the thermistor's resistance to an acceptable value...therefore with only the rectifiers on I get 2.1v instead of 2.5v.

I hope this will solve itself when the gu81m filament transformer will draw its own current.

for now...some burn in tests

xenon
Click the image to open in full size.

mercury

Click the image to open in full size.

If anyone has any suggestions for ux4 compatibile rectifiers I am all ears (no pun intended). This will be a great testing platform for future experiments
  Reply With Quote
Old 31st May 2012, 04:36 PM   #166
Account disabled at member's request
 
Join Date: Jul 2009
Also a question...

I want to move inputs and outputs to the front of the amplifier
Click the image to open in full size.

the front plate is 10mm thick. I can get away with it as far as the outputs (since the threaded connectors are very very long) but input s going to be a problem. Can anyone point out a connector, with a round footprint, which will mount on a 10mm thick panel? I thought of 6,3mm jack or RCA but both seem too short.
  Reply With Quote
Old 31st May 2012, 06:19 PM   #167
Account disabled at member's request
 
Join Date: Jul 2009
voltage boards fitted

Click the image to open in full size.

need to dremel out a pice to allow for the bank of b+ caps.
  Reply With Quote
Old 3rd June 2012, 09:05 PM   #168
Account disabled at member's request
 
Join Date: Jul 2009
unfortunately I have very little time to post this picture...so let us say somethings work, other don't

Click the image to open in full size.
  Reply With Quote
Old 3rd June 2012, 09:13 PM   #169
djn is offline djn  United States
diyAudio Member
 
djn's Avatar
 
Join Date: Oct 2004
Location: Waterford Michigan
Wow, looks like the Genie is about to jump out of the bottle. Kind of a cool picture though.
__________________
My "Art" website http://home.comcast.net/~djnagle/site/
  Reply With Quote
Old 3rd June 2012, 10:13 PM   #170
7N7 is offline 7N7  United Kingdom
diyAudio Member
 
7N7's Avatar
 
Join Date: Jan 2003
Location: England
Quote:
Originally Posted by Alexontherocks View Post
Also a question...

I want to move inputs and outputs to the front of the amplifier
Click the image to open in full size.

the front plate is 10mm thick. I can get away with it as far as the outputs (since the threaded connectors are very very long) but input s going to be a problem. Can anyone point out a connector, with a round footprint, which will mount on a 10mm thick panel? I thought of 6,3mm jack or RCA but both seem too short.
Is the front panel removable?

If so what you need is a counterbore. A counterbore is a drill - for example that begins as say a 6mm drill further along it becomes like an end-milling cutter, so you might have say a 6mm pilot hole followed by a 22mm flat cut. With care this would enable you to reduce the thickness of your panel where needed,

Paul
__________________
Plug them in and light them up
  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
High Voltage BjT's for Pre-driver stages of High Power Amplifier - Overview tiefbassuebertr Solid State 38 30th May 2011 07:37 AM
Why high voltage Fets when low voltage types gives less distortion? Circlomanen Pass Labs 21 9th December 2009 09:43 PM
Wanted - High Power, High Voltage, Audio Frequency Transformer Manual. kimbal Tubes / Valves 4 11th May 2009 08:05 PM
A high voltage drive fully differential driver/op amp Russ White Pass Labs 21 18th July 2007 10:14 PM
gu81m ik3ssj Tubes / Valves 4 4th March 2007 03:41 PM


New To Site? Need Help?

All times are GMT. The time now is 08:52 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