power transformer specs, and who makes...

[Doug H]

a decent 100w that genereates a low 400v b+ with a normal 4 diode rectifier? MM has one of their toneclones, but at $365 I
m wndering if there is a better option.

A lot of the spec sheets I pull up just have center tap voltage (I assume that's what CTV means0. SO how do I convert this to what the b+ would end up as?

Thanks
Doug

[joey]

Classic tone 40-18069 it has a 330v tap that will roughly give you 400vdc-430vdc under load depending on the load.

[Doug H]

Good tip. It's in the running.

How are you supposed to derive b+ voltage when they just give you the ###-0-### specs? I looked all over the net and only found a bunch of conflicting non comital explanations.

[joey]

The x-0-x indicates a center tapped secondary, but the math is the same. The reason why it seems to be vague is because Alot of your final loaded voltage depends on the load, losses, how efficient the tx is etc..... General rule of thumb is that the unloaded voltage will be around 1.4x the secondary tap voltage, so if you have a 350-0-350v secondary common to marshall fare, (or a 175-0-175 with full wave bridge) you might expect maybe unloaded voltage of 490vdc, which turns out to be about what you do see. However when you load the supply I.e putting the tubes in, this will drop because you now have things drawing current from the supply. Typically you can estimate your loaded voltage to be around 1.3x the secondary give or take. But that really depends on what you have weasing the juice of you catch my drift.

[Doug H]

I like how some of hte spec sheets say
350 V CT
while othes say
640 V CT

I;m huessing the latter assumes the voltage doubler style recitifer?

[Doug H]

All those trannys on the metro store page you have to order from Heybor that say "tapped", does that mean they have the 400v b+ rtap?

[Doug H]

what about something like this?

http://www.edcorusa.com/products/595-xpwr007_120.aspx" onclick="window.open(this.href);return false;

run it with a standard rectifier to get 375v.

It's not a "vintage style" replica, is there anything to that when we are taling about the power-train? And if so, is it just apples versus oranges? I might be happy with an orange...for $60

[joey]

You would probably get a little less with that one maybe 365. But if that works for you than I don't see any reason you couldn't use it, just don't throw any crazy current hog power section in it.

[Doug H]

right cause 200ma ain't gonna pony up too much. this PT stuff is starting to sink in. Some of the 100w replacements trannys only sport like 300ma on the secondaries.

I'm actually looking at some of the hammonds and running a doubler to get 600 or 700 volts on the plates, but take the screen feed from between the main filter caps like a music man. I'm not sure what my output tranny's going to think about anything North of 550v though...