6V6 line preamp - Page 61 - 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 2nd April 2012, 08:56 PM   #601
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by buzzforb View Post
I have found that creating da best universal tube and its golden bias point leads to a need for a universal cure of sorts. I was just trying to keep everyone informed, I can quit anytime.
We want you to show us the varnished PSU box and write the sonic impressions of tube rectification VS SS diode bridge before you fulfill the destiny hourglass and eventually quit your noble mission though.
  Reply With Quote
Old 2nd April 2012, 09:03 PM   #602
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
I said i could quit, not that i will. 26 or 45 or 6p15ev is next
__________________
...Shape the sound , Man!
  Reply With Quote
Old 5th April 2012, 11:46 PM   #603
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Salas,
I have my 5U4G wired like this exactly
http://www.vt52.com/info/vt52/schema..._schema_6b.gif
THe only difference is that I am using my 6.3V secondary to power it. I am taking the suggestion of putting a cl60 thermistor and .15R resistor in series with the filament to reduce it to 5V. Without tube installed, I get 6VAC on across filament pins and 310 across both diode pins and ground. Checked all connections and have good continuity. PLug the 5u4g in and nothing. I am using toroid, so neutral of dual secondaries are tied together to ground with each hot tied to tube diode.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 6th April 2012, 01:09 AM   #604
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Why you did it like that? Having a center tap in the 6.3V secondary also? Is your 5U4G a used and tested before sample? Me I had wired like that File:VacRect2E.png - Wikipedia, the free encyclopedia
  Reply With Quote
Old 6th April 2012, 01:21 AM   #605
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
I realized after posting link that it would be misleading. I got it figured out. Works great and the thermistor idea is nice, although i donr know about its affect on sound.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 7th April 2012, 02:30 PM   #606
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
The jury is still out, but i think i like SS rectification better than the tube. It seems that the smoothness, drive , and grunt i gained with this pre, especially with the RCA blackplates, is lost when using the tube rectifier. I have added motorun caps and choke, so i cant say for sure, but i know more later. Going to add the SS and switch, so i can go back and forth. Just wanted to get the tube rectifier up and running. HAven't tried SIlver in oil yet. Will do that after getting psu sorted.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 7th April 2012, 03:16 PM   #607
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
What exact type of SS diodes you use?
  Reply With Quote
Old 7th April 2012, 03:33 PM   #608
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
Simple sf4007, although i think i have some fancy stealth diodes around here somewhere. I am going to really clean up the layout(AC hum from rectifier tube), and add SS rectifer and switch before pronouncing judgement. Ill give pics of components and layout, along with opinion for clarity sake.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 7th April 2012, 06:28 PM   #609
diyAudio Member
 
triode_al's Avatar
 
Join Date: May 2004
Location: Westland
Blog Entries: 1
Quote:
Originally Posted by buzzforb View Post
- - I am going to really clean up the layout(AC hum from rectifier tube), and add SS rectifer and switch before pronouncing judgement. Ill give pics of components and layout, along with opinion for clarity sake.
a very important issue is the amount of capacitance the rectifier tube sees, and the resistance of the transformer plus the feeder resistor or choke to the next section. If wrongly dimensioned (too much) the tube will start to arc or oscillate maybe.
Trick is to get the sweet spot.
Quote:
Example: WE274B text
The peak current increases in value as the capacitance of the capacitor is increased and may be much larger than the average rectified output current, though its duration in such cases is only a short fraction of a cycle. Since for good tube performance, the anode current must be considerably less at every part of the cycle than the total emission current from the filament, the maximum permissible output current must be limited to such a value that this condition is satisfied. The permissible output current may be larger, therefore, for a choke-input filter, in which the peak anode current is only slightly larger than the output current. The choke-input filter also gives much better regulation than the capacitor-input circuit. The choke-input filter, therefore, should always be selected in preference to the capacitor-input filter wherever possible.
With a capacitor-input filter, the capacitance of the input capacitor should preferably not exceed 4 microfarads.
The same value goes for the 5R4W and similars.
__________________
DAC TDA1541 S1; Kondo post-I/V filter; MC30-Super --> two stage RIAA; Pre: Kaneda ; F5 ; 300B PP ; ESL 57
  Reply With Quote
Old 7th April 2012, 08:46 PM   #610
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
I have 100R then 4.7uF, then 68R, then 40uF, then hammond 193Q 10H 500mA choke, then 40uF, then supply umbilical into main case, then 1uF local decoupling.
__________________
...Shape the sound , Man!
  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
Help me design my DAC/Line Preamp. kuroguy Tubes / Valves 7 2nd April 2009 08:31 PM
preamp line ctt richwalters Tubes / Valves 1 7th March 2008 04:34 PM
Preamp for Line In and Mic blur Instruments and Amps 1 4th January 2007 04:02 PM
Line stage preamp, based on SY's "Heretical Unity gain line stage" Danko Tubes / Valves 23 18th July 2005 04:07 AM
Line preamp for 2A3 amp Petman Tubes / Valves 0 24th May 2002 03:11 PM


New To Site? Need Help?

All times are GMT. The time now is 09:55 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