I think I have the mod bug pretty bad.

[GoldenVulture]

Did you measure that inline ?Seems like you're reading something connected to it.
It doesn't seem right. O.P.T. trannies are usually 1K + at least, on the primary.
Has it got any Make/Model on it ? [ to look up the specs ]

[karpathion]

Did you measure that inline ?Seems like you're reading something connected to it.
It doesn't seem right. O.P.T. trannies are usually 1K + at least, on the primary.
Has it got any Make/Model on it ? [ to look up the specs ]

I have the bare transformer. Nothing is connected. Am I checking it wrong?

I get the exact same thing this guy does, just like he has it. Pretty sure it's 3.5k.

[karpathion]

I have this as well. If it helps. 5k and 8k primaries. Says it can handle 2 el84s in parallel.

http://www.classictone.net/40-18031.html

[GoldenVulture]

I have this as well. If it helps. 5k and 8k primaries. Says it can handle 2 el84s in parallel.

http://www.classictone.net/40-18031.html

That looks better.That's  intersting, the dual Primary.
That link gives all the valves and configurations it will run with, neat.
No problem going from a 6v6 to an EL84

[karpathion]

That looks better.That's  intersting, the dual Primary.
That link gives all the valves and configurations it will run with, neat.
No problem going from a 6v6 to an EL84

I don't think it can do push pull though. 

I'm about to just use the Stealth transformers and build it 2x6v6 in push pull.

[karpathion]

I've been reading my ass off this morning, and I think I can do what I want with these Stealth transformers.

From what I have learned this morning, that Stealth was fine running with the 2 outer power tubes pulled. You just had to flip the impedance switch down a notch like the rest of them. With it ran like that it's in AB1 PP configuration.

Now, let's look at the spec sheets for EL84s and 6v6s to compare.

[img]<a href=[/img]





Looking at all the info, that OT should be between 5-8k on the primary. From what I've read this morning, switching 6v6s to el84s is pretty common using the same OT.

I've sent Lee Jackson an email asking he remembers the primary impedance of that OT. Hopefully he'll get back to me on that.

I have a little transformer here that is 120V primary, and 12V-0-12V secondary. Can I use that safely to test this OT? 

[GoldenVulture]

Fuck , I typed out a post and as I posted it something went askew and the site dropped off the radar. No Post.
I might try again tomorrow.[ when I can remember what I typed out ]

and when they get the site sorted from erroring.

[GoldenVulture]

You might find this site handy
- http://www.aikenamps.com/index.php/white-papers -

and this - http://www.duncanamps.com/tsc/ - The Tone Stack calculator

[karpathion]

I did nothing but study for 12 hours yesterday. I didn't study this hard in school.

That OT is a 4k primary. I'm pretty much stuck with 4x6v6 or a pair of 6l6s. I'm just going to break down and buy an OT for an 18W TMB. That TMB seems to be what I want when I look at it on paper. Everything I do leads me right back to it.

I can handle $50 for this one.

http://www.classictone.net/40-18037.html

I have a much better understanding of the power section now. I honestly did not realize that the plate voltage on power tubes determines the output impedance. It's all clicking now.

[karpathion]

Well my PT is showing some good no load numbers. I think this is about to happen.

4 taps:

Red=310V

Blue= 28.6V

Orange= 87.9V

Yellow= 6.6V

It's starting to come together now.