Toroidal transformer for 300B

[Divad89]

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/product_info.php/info/p835_Toroidal-139VA-Power.html be OK for the amp?

Thanks in advance

---
David

 

[Evenharmonics]

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 --> http://www.diyaudio.com/forums/tubelab/148378-tubelab-se-alternate-power-transformer.html

 

[Divad89]

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

 

[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.

 

[Evenharmonics]

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.

 

[zman01]

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.

 

[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.

 

[Tubelab_com]

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.

 

[zman01]

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).