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 25th March 2013, 12:51 AM   #31
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: South Florida
Quote:
Here is an LTSpice simulation.....About 180mA of grid current is required from the driver circuit.
That's probably about right. I measured about 250 mA and I only had 1500 volts of B+ placing my grid just into the positive region at idle.

I have seen a "low buck" 833A amp that used an ordinary low powered tube amp for a driver with the 833A grid connected to the 16 ohm tap on the OPT.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 25th March 2013, 01:30 AM   #32
Magz is offline Magz  United States
diyAudio Member
 
Join Date: Oct 2009
Location: New Jersey, USA
Hey, now there's a product idea for someone...an "Amp Booster" module containing the 833 tubes and the power supplies and input and output jacks.

Just add an 8-10W tube amp and enjoy!
  Reply With Quote
Old 25th March 2013, 06:54 PM   #33
oshifis is offline oshifis  Hungary
diyAudio Member
 
Join Date: Mar 2004
Location: Budapest, Hungary
The late Hungarian Tungram factory used to produce the equivalent OT400 thorium cathode UHF transmitter tube for cheap... It is a pity GE took over the factory and they abandoned manufacturing vacuum tubes...
  Reply With Quote
Old 25th March 2013, 07:46 PM   #34
diyAudio Member
 
Rundmaus's Avatar
 
Join Date: Aug 2005
Damn,

I wish I had the money and space for such a mid-life crisis!

Rundmaus,
having a mid-life crisis of only EL34-PP dimensions
  Reply With Quote
Old 25th March 2013, 11:02 PM   #35
multi is offline multi  Australia
diyAudio Member
 
Join Date: Jan 2011
I have just finished a 150 watt 572b amp; just as crazy as the monster 833c amp; as i have 105db speakers, but amp only uses 650 volts. I can only just manage to lift it; I use a 500kg lifting trolley if possible.
The monster 833c will need a crane!!!
Phil
  Reply With Quote
Old 27th March 2013, 01:20 AM   #36
Magz is offline Magz  United States
diyAudio Member
 
Join Date: Oct 2009
Location: New Jersey, USA
Received more parts today...most of the power transformers (picture 1), with a Lundahl 1685 13H choke in the picture for comparison.

From left: two Hammond 369KX for the 6E5P/driver circuits, two 18V, 20A Hammond 165V18 for the 833C filaments, and one Hammond 733A for the 833C B+.

The 733A is massive, as befits a 2500V, 345mA (CCS), 50/60Hz trannie. The 2500V lines come out the TOP of the transformer through separate openings, most likely for isolation from the other lines, so it looks like I'll end up laying it on its face with all the wires inside the chassis for safety - the end bells come off very easily (see picture 2), so that should be no problem.

The 369KX is rated at 450V, 300mA. Since all the supplies will be choke input I need to use higher voltage transformers. I chose ones with AT LEAST double the current ratings I need to operate.

Still waiting on the other 733A and two 159ZL chokes for the filament PS.

I also have two little Hammond BD2E transformers coming for the cooling fan PS, if I decide to go that route. My goal is to get all this into an 18"x22" chassis...it will be tight, I think.
Attached Images
File Type: jpg 833 Amp Transformers.jpg (389.4 KB, 1106 views)
File Type: jpg 733A Transformer No End Bells.jpg (318.4 KB, 1070 views)

Last edited by Magz; 27th March 2013 at 01:24 AM.
  Reply With Quote
Old 27th March 2013, 01:43 AM   #37
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: South Florida
Quote:
The 2500V lines come out the TOP of the transformer through separate openings, most likely for isolation from the other lines
That is the way it was done in the "old days." The wires come out of the top of the transformer so they can go straight to the plate caps on the 866A's.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 27th March 2013, 01:49 AM   #38
Magz is offline Magz  United States
diyAudio Member
 
Join Date: Oct 2009
Location: New Jersey, USA
Quote:
Originally Posted by tubelab.com View Post
That is the way it was done in the "old days." The wires come out of the top of the transformer so they can go straight to the plate caps on the 866A's.
That makes sense. I thought about using Xenon rectifiers but decided that SS would be smaller, lighter, and a lot safer.
  Reply With Quote
Old 27th March 2013, 08:51 AM   #39
CV6045 is offline CV6045  United Kingdom
diyAudio Member
 
CV6045's Avatar
 
Join Date: Mar 2013
Location: Portsmouth
Default 833amp

I love the 2.5kv transformer... I did not know you could get End Bells that big. If you dont mind how much did Hammond charge you for it ? I may just order a couple if I return to my own 833 Beast later.

Quote:
Originally Posted by Magz View Post
Received more parts today...most of the power transformers (picture 1), with a Lundahl 1685 13H choke in the picture for comparison.

From left: two Hammond 369KX for the 6E5P/driver circuits, two 18V, 20A Hammond 165V18 for the 833C filaments, and one Hammond 733A for the 833C B+.

The 733A is massive, as befits a 2500V, 345mA (CCS), 50/60Hz trannie. The 2500V lines come out the TOP of the transformer through separate openings, most likely for isolation from the other lines, so it looks like I'll end up laying it on its face with all the wires inside the chassis for safety - the end bells come off very easily (see picture 2), so that should be no problem.

The 369KX is rated at 450V, 300mA. Since all the supplies will be choke input I need to use higher voltage transformers. I chose ones with AT LEAST double the current ratings I need to operate.

Still waiting on the other 733A and two 159ZL chokes for the filament PS.

I also have two little Hammond BD2E transformers coming for the cooling fan PS, if I decide to go that route. My goal is to get all this into an 18"x22" chassis...it will be tight, I think.
  Reply With Quote
Old 27th March 2013, 12:39 PM   #40
Magz is offline Magz  United States
diyAudio Member
 
Join Date: Oct 2009
Location: New Jersey, USA
Quote:
Originally Posted by CV6045 View Post
I love the 2.5kv transformer... I did not know you could get End Bells that big. If you dont mind how much did Hammond charge you for it ? I may just order a couple if I return to my own 833 Beast later.
733A Hammond Manufacturing | 733A-ND | DigiKey
  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
Good Source for Nice Analog Panel Ammeters for 833C Build? Magz Tubes / Valves 12 7th March 2013 07:49 PM
mono block amps with 2 x 833C overkill ? even possible to DIY? Thesoundmen Tubes / Valves 24 23rd March 2012 05:25 AM
Small and portable headphone amp Crisis firefart_1st Headphone Systems 15 26th May 2010 08:24 PM
Midrange + midlife crisis ronzeman Multi-Way 7 1st September 2008 02:39 PM
No More Sound Crisis john2890 Everything Else 1 23rd December 2005 06:50 AM


New To Site? Need Help?

All times are GMT. The time now is 07:29 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