Toroidal transformer for 300B - diyAudio
Go Back   Home > Forums > Commercial Sector > Vendor Forums > Tubelab

Tubelab Discussion and support of Tubelab products, prototypes and experiments

Reply
 
Thread Tools Search this Thread
Old 14th January 2014, 12:23 PM   #1
Divad89 is offline Divad89  Denmark
diyAudio Member
 
Join Date: Feb 2010
Default Toroidal transformer for 300B

I'm about to order the parts for the Tubelab SE (running 300B), and my plan is to use Edcor CXSE25-4-5K for opts and was thinking about a toroidal transformer for the PT, will this https://www.tube-town.net/ttstore/pr...9VA-Power.html be OK for the amp?

Thanks in advance

---
David
  Reply With Quote
Old 14th January 2014, 03:39 PM   #2
diyAudio Member
 
Join Date: Apr 2007
I use toroidal for my TSE PT. That example looks to be little low on section 1 and 2 (300V). I'm not sure if that's ok. Perhaps the experts can chime in on this. Here is PT recommendation on Tubelab website. "The power transformer needs to provide about 640 or 650 volts center tapped at 150 mA or more, 5 volts at 2 amps, and 6.3 volts at 4 amps. A center tap on the 6.3 volt winding is NOT required. The Hammond 276X will work. I have been using some surplus power transformers that are 660 VCT. They give me about 390 volts of B+."

Here's mine --> Tubelab SE - alternate power transformer
  Reply With Quote
Old 14th January 2014, 05:29 PM   #3
Divad89 is offline Divad89  Denmark
diyAudio Member
 
Join Date: Feb 2010
That is also my concern about the PT, but I've also tried to e-mail a bunch of companies who makes toroidal transformers in the EU, to check for alternatives.

---
David

Last edited by Divad89; 14th January 2014 at 05:32 PM.
  Reply With Quote
Old 14th January 2014, 09:09 PM   #4
rknize is offline rknize  United States
diyAudio Member
 
rknize's Avatar
 
Join Date: Feb 2009
Location: Chicagoland
Send a message via AIM to rknize Send a message via Yahoo to rknize
Yes, that one looks like it would be a bit low for an SSE but not totally out of the question. Depending on what tubes you plan to use, you could adjust the cathode resistor values and use a slightly different OPT to achieve power output levels that are close.
  Reply With Quote
Old 14th January 2014, 09:57 PM   #5
diyAudio Member
 
Join Date: Apr 2007
Quote:
Originally Posted by Divad89 View Post
but I've also tried to e-mail a bunch of companies who makes toroidal transformers in the EU, to check for alternatives.
Or you can try diy route like I did.
  Reply With Quote
Old 14th January 2014, 11:10 PM   #6
zman01 is offline zman01  Bangladesh
diyAudio Member
 
Join Date: Feb 2011
Location: Dhaka
Quote:
Originally Posted by rknize View Post
Yes, that one looks like it would be a bit low for an SSE but not totally out of the question.
Russ,

OP wants to build a TSE. Understand it is too low for an SSE, but would it be good for a TSE?

Thanks for your continued guidance to newbies on tube amp projects.
  Reply With Quote
Old 15th January 2014, 05:45 PM   #7
rknize is offline rknize  United States
diyAudio Member
 
rknize's Avatar
 
Join Date: Feb 2009
Location: Chicagoland
Send a message via AIM to rknize Send a message via Yahoo to rknize
Oops, got my threads mixed up. I would expect to see something like 360V B+ with that transformer. That is on the low end of what most 300B designs use, but it will work. You can run the bias a little hotter at lower plate voltages to get a little better dampening factor. That said, the curves for the 300B seem to suggest that they will be more linear at higher plate voltages. I run a B+ of about 410V when using 300Bs in my TSE.
  Reply With Quote
Old 16th January 2014, 12:25 AM   #8
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: South Florida
I still have my original Lexan TSE. I only get 320 volts with 300B's since the transformer is 275-0-275 volts, Hammond sourced, so it's really 300-0-300. I get about 5.5 WPC but it does sound nice. If that transformer really puts out 300 volts, expect about 5.5 to 6 watts. If it makes a bit more, you will get more power.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 22nd February 2014, 08:36 PM   #9
zman01 is offline zman01  Bangladesh
diyAudio Member
 
Join Date: Feb 2011
Location: Dhaka
Default Another transformer for 300B TSE

This one looks to meet all George's recommendations for a TSE with 300B tubes - PT being capable of providing about 640 or 650 volts center tapped at 150 mA or more, 5 volts at 2 amps, and 6.3 volts at 4 amps

http://www.classictone.net/40-18096.pdf

I see a bias tap for this PT - what is the guidance on this - should tape it up (unused)?

Exploring options beyond Hammond (high price for 300 series), Edcor (long wait times, no 220v or 230v option).
  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
Toroidal transformer help! bazmcc Power Supplies 10 17th August 2012 02:36 PM
toroidal transformer JozzaG Power Supplies 7 13th March 2010 07:16 AM
Toroidal transformer Ghianni Power Supplies 8 15th November 2006 04:44 PM
Toroidal Transformer sma Solid State 3 3rd February 2004 07:55 PM


New To Site? Need Help?

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