The Midlife Crisis - My 833C Amp Build - Page 77 - 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 2014, 07:42 PM   #761
pre65 is offline pre65  United Kingdom
diyAudio Member
 
Join Date: Oct 2005
Location: Essex/Suffolk borders.UK
Hi Magz

I have my own pair of 833a (GU-48)home built monoblocks, but at the moment my HT is "only" 950v, and I drive the grid with a power interstage.

I am collecting more iron to rebuild the amps with higher HT, about 1300v as I don't need massive watts, and I may also follow your example and use Rod Coleman filament modules in parallel.

One question, the chokes you use on the raw DC supply are Hammond 159ZL ?

If so, does the 10A rating cause any problems ?

regards Philip.
  Reply With Quote
Old 29th July 2014, 09:34 PM   #762
Magz is online now Magz  United States
diyAudio Member
 
Join Date: Oct 2009
Location: New Jersey, USA
Yes Philip, those are the chokes I used. I modified the ones that go in the first position with bolts through the frames to make them a little less prone to vibration, and mounted them on Deflex bushings. There is a description with pictures somewhere in this thread. They still do vibrate, however, but it's not audible from the listening position. If you have the room, go for 20A rated chokes in the L1 position. I didn't have enough room, so I made do.
  Reply With Quote
Old 29th July 2014, 09:36 PM   #763
pre65 is offline pre65  United Kingdom
diyAudio Member
 
Join Date: Oct 2005
Location: Essex/Suffolk borders.UK
Thanks for the advice.

I'll post a picture of my version soon.
  Reply With Quote
Old 30th July 2014, 06:04 AM   #764
pre65 is offline pre65  United Kingdom
diyAudio Member
 
Join Date: Oct 2005
Location: Essex/Suffolk borders.UK
My version uses a separate amp (KT66 as a triode) to drive the power interstage into the 833a grid. The output transformers are offboard as I use them for several different amps.(like GK-71 as a triode.)

Click the image to open in full size.

These are the KT66 driver amps.

Click the image to open in full size.

Last edited by pre65; 30th July 2014 at 06:10 AM.
  Reply With Quote
Old 30th July 2014, 09:32 AM   #765
pre65 is offline pre65  United Kingdom
diyAudio Member
 
Join Date: Oct 2005
Location: Essex/Suffolk borders.UK
Looking into options for a 20A 2.5mH choke, the Hammond 195E20 seems suitable, and the mains transformer could be an Antek 500va with two 20v secondaries, ref AN-5220. I have used Antek before and like their products.

http://www.hammondmfg.com/pdf/5c0034.pdf

http://www.antekinc.com/an-5220-500va-20v-transformer/

Last edited by pre65; 30th July 2014 at 09:40 AM.
  Reply With Quote
Old 18th August 2014, 02:04 AM   #766
diyAudio Member
 
Join Date: Jan 2006
Location: hanoi
Magz,

Do you have detailed schematic for the whole PSUs in your amp? I recall you mentioned your B+ PSU is LCLC, but I didnt find details about the chokes. As I'm aware of, choke input filter demands quite a bit about the choke, both inductance and current capacity, especially when you are using very high voltage (2500VAC input), right?

Thanks,
Duong
  Reply With Quote
Old 18th August 2014, 06:02 PM   #767
Magz is online now Magz  United States
diyAudio Member
 
Join Date: Oct 2009
Location: New Jersey, USA
Quote:
Originally Posted by hoangduongo View Post
Magz,

Do you have detailed schematic for the whole PSUs in your amp? I recall you mentioned your B+ PSU is LCLC, but I didnt find details about the chokes. As I'm aware of, choke input filter demands quite a bit about the choke, both inductance and current capacity, especially when you are using very high voltage (2500VAC input), right?

Thanks,
Duong
PSUDs are on page 5 and 6 of this thread. L1 needs to be a very good choke - for the 2500VAC I had Monolith make me a custom unit (35H). For the Driver I used a Lundahl choke. For the filament I used a Hammond (see above on this page).
  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
mono block amps with 2 x 833C overkill ? even possible to DIY? Thesoundmen Tubes / Valves 25 9th June 2014 02:27 AM
Good Source for Nice Analog Panel Ammeters for 833C Build? Magz Tubes / Valves 12 7th March 2013 07:49 PM
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 02:29 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