Tube/Transformer Positioning on Chassis - 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 19th April 2003, 06:43 PM   #1
diyAudio Member
 
Join Date: Apr 2003
Location: New York
Question Tube/Transformer Positioning on Chassis

When planning the positioning of Power tubes (300b's, KT88's, etc.) on the top of the chassis, is it more important to keep them as far away from the preamp tubes (12AX7 or ecc88) as possible, or the transformers (in terms of noise suppression)?

Also, what about tube rectifiers? Is it ok to place one in between 2 transformers?

One more question: Is a tube rectifier such as a 5ar4 a full-wave rectifier or do I need 2 to perform that duty? Is it important to have full-wave rectification in a class A phono preamp/headphone amp?

Thanks
  Reply With Quote
Old 20th April 2003, 12:55 AM   #2
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
You want to keep your wires short. Power valves want to be next to their output transformer, and will not mind being near to a mains transformer. Pre-amplifier valves want to as far away from mains transformers as possible (whose coils should be pointed at a right angle to these valves). Valve rectifiers should be close to their mains transformer with very short wiring to their capacitor, and should always be full-wave.

5AR4/GZ34 contains two diodes and will allow full-wave rectification with a centre-tapped transformer, or, if you add a pair of silicon diodes, you can make a bridge, which allows an ordinary transformer to be used.
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 20th April 2003, 01:11 AM   #3
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Default Hybrid Rectumfrier.

Hi,

Quote:
you can make a bridge, which allows an ordinary transformer to be used.
Works with a CT xformer as well.

Cheers,

Edit: this actually works best with a CT Xformer, people should really try this it really good.
__________________
Frank
  Reply With Quote
Old 20th April 2003, 09:36 AM   #4
SHiFTY is offline SHiFTY  New Zealand
diyAudio Member
 
SHiFTY's Avatar
 
Join Date: Jul 2002
Location: New Zealand
Another thing you might want to consider is heat. Make sure you have at least half an inch or more around the rectifier and power tubes so that air can circulate.

Re: hybrid diode/tube rectification, I plan to try this at some stage, using UF4007 high speed diodes and a 5V4, you get the benefits of slow warm up and no "switching" noise (which I have never been able to hear anyway )
  Reply With Quote
Old 20th April 2003, 11:17 AM   #5
diyAudio Member
 
Le Basseur's Avatar
 
Join Date: Apr 2003
Location: Croatia
Quote:
Originally posted by EC8010
Pre-amplifier valves want to as far away from mains transformers as possible (whose coils should be pointed at a right angle to these valves).

.

What do you mean by that? (..not the biggest possible distance between the input tubes,this is obvious!)
I mean,what's this "right angle" thing?
I know about the 90 degrees alignament of the PS trans,choke(s) and OPT,and also of aligning the anodes of output beam tetrodes to 90 degrees relative to PS,but what you said is new to me.
Did you also meant some kind of "3D" arrangement of the coils (laminations) to achieve that?
__________________
"You're smart enough not to think I'm a fool"
Ol'Romanian proverb
  Reply With Quote
Old 20th April 2003, 11:37 AM   #6
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
Default Right angles to reality

Quote:
Originally posted by Le Basseur
...and also of aligning the anodes of output beam tetrodes to 90 degrees relative to PS, but what you said is new to me.
The leakage field of a coil (transformer or choke) is strongest along its axis, so if you draw a line from the centre of the coil to your input valve, the coil should be aligned at right angles to this line.

We've both learned something here, because although I can instantly see the logic, I had not considered the relative alignment of beam tetrodes and power transformers.

It's worth bearing in mind that output transformers have far less leakage flux than mains transformers because output trnasformers are designed to minimise leakage inductance. This means that you can almost do what you like with output transformers relative to valves.
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 20th April 2003, 01:20 PM   #7
GaryB is offline GaryB  United States
diyAudio Member
 
Join Date: Sep 2002
Location: Silicon Valley
Default the empirical method

Since we are trying to minimize magnetic coupling between components, I suggest that we actually do a few measurements. For a set of monoblock SE amps I'm starting one, I mounted the power transformers on the chassis and hooked them up with AC power. Then I positioned the output transformers roughly where I wanted them on the chassis and measured the induced AC voltage on them with my DVM. Moving the output transformers around allowed almost complete cancellation of the induced voltage and the optimum position was not with the transformers at 90 degrees to one another. Instead things were better when the angle was a shifted about 10 degrees off of 90.

Theory is great but nothing beats reality.

---Gary
  Reply With Quote
Old 20th April 2003, 01:36 PM   #8
diyAudio Member
 
Le Basseur's Avatar
 
Join Date: Apr 2003
Location: Croatia
Default Re: the empirical method

Quote:
Originally posted by EC8010


The leakage field of a coil (transformer or choke) is strongest along its axis, so if you draw a line from the centre of the coil to your input valve, the coil should be aligned at right angles to this line.

OK,I knew that,but I thought it's some other "snake oil" solution...

We've both learned something here, because although I can instantly see the logic, I had not considered the relative alignment of beam tetrodes and power transformers.


OK,her's the beam tetrode issue:
As you noticed,the geometry of an anode resembles an oval or rectangle.If you look at the attached picture,you'll consider the two axis,A and B.Well,the magnetic field shouldn't be along the A axis,or intersect them in any way,because in this case the hum increases.Alike,the best position of a tetrode is with the B axis and the trannsformer's flux paralleled.
.
Attached Images
File Type: jpg tetrode.jpg (20.0 KB, 473 views)
__________________
"You're smart enough not to think I'm a fool"
Ol'Romanian proverb
  Reply With Quote
Old 20th April 2003, 01:40 PM   #9
diyAudio Member
 
Le Basseur's Avatar
 
Join Date: Apr 2003
Location: Croatia
Quote:
Originally posted by EC8010


The leakage field of a coil (transformer or choke) is strongest along its axis, so if you draw a line from the centre of the coil to your input valve, the coil should be aligned at right angles to this line.

OK,I knew that,but I thought it's some other "snake oil" solution...

We've both learned something here, because although I can instantly see the logic, I had not considered the relative alignment of beam tetrodes and power transformers.
.
OK,her's the beam tetrode issue:
As you noticed,the geometry of an anode resembles an oval or rectangle.If you look at the attached picture,you'll consider the two axis,A and B.Well,the magnetic field shouldn't be along the A axis,or intersect them in any way,because in this case the hum increases.Alike,the best position of a tetrode is with the B axis and the transformer's flux paralleled.

Sorry for the mess,something's wrong with IP!



__________________
"You're smart enough not to think I'm a fool"
Ol'Romanian proverb
  Reply With Quote
Old 20th April 2003, 01:42 PM   #10
diyAudio Member
 
Le Basseur's Avatar
 
Join Date: Apr 2003
Location: Croatia
Attached Images
File Type: jpg tetrode.jpg (31.0 KB, 449 views)
__________________
"You're smart enough not to think I'm a fool"
Ol'Romanian proverb
  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
what to do with this old chassis and transformer? BobEllis Solid State 20 20th July 2009 09:40 PM
Transformer chassis layout Richard Ellis Tubes / Valves 5 27th December 2007 02:54 PM
Amp chassis and transformer testlab Swap Meet 2 8th February 2006 03:41 AM
Mirror tube chassis Simpleton Everything Else 5 24th March 2005 02:02 PM
Question about transformer positioning. G Tubes / Valves 30 6th January 2003 10:28 PM


New To Site? Need Help?

All times are GMT. The time now is 12:36 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