OT Input Impedance Question 5F2A build

[AHeck]

Howdy Fellers,
I found a good deal on a package power and output transformer combo and built two 5F2A circuits using them.  So far I've been able to power up both builds and run voltages, both are a bit hot, but not alarmingly so, to my level of expertise, which is humble and small...
When making guitar sounds, both are for all intents and purposes the same.  They sound great, rich harmonic overtones, really beautiful, to my ear, but, no clean tone to speak of, seemingly no headroom.  They go from making audible sound to distorted suddenly and immediately. 
Excuses for this could be that my guitar has overwound pickups or that seems to be part of the nature of the circuit.
The anomaly that concerns me, and not something I have really understood well as I've researched the topic, is that the output transformer has an input impedance of 12K Ohms, which seems very high to me, also it is rated for much more power than I need for these amps, but that should not cause the perceived problem.
I'll include the tech sheet from the transformer and one of the voltage readouts from the amps.  If you have time to give me some advice I'd love to hear what is going on with these builds so I can learn more about the subjects. Thanks very much in advance.

[AHeck]

Here are some voltages:

[sluckey]

It's more usual to see a 5K to 8K OT used in a typical 5F2A or 5F1 amp. Try one and see if it makes a difference.

BTW, have you verified that the NFB is proper phase?

[2deaf]

So..... then.... if WHT were common, BLK/RED would be a 4 Ohm tap and BLK would be a 16 Ohm tap.  How do you have the speaker(s) connected?

[AHeck]

BTW, have you verified that the NFB is proper phase?

I thought so, but maybe you know something I don’t. I pulled from the output transformer’s black wire.  How does one confirm proper phase in feedback?

[AHeck]

So..... then.... if WHT were common, BLK/RED would be a 4 Ohm tap and BLK would be a 16 Ohm tap.  How do you have the speaker(s) connected?

If that is the case, I completely mistook the proper wiring of the speaker.  I’m running white to the shaft of the 1/4” plug and black to the tip and I was quite sure that was an 8 ohm tap, and that the other option was white to bl/wh stripe at 4 ohms.

[shooter]

typically an out of phase would cause anything from mild distortion to outright squealing tantrum.

your #'s seem close;
342.9/12k expects a current of 35mA, you're at 39mA based on;
18.3/470 = I   (342.9-18.3)* I = W (all math approximate :)

5F2 is not typically known as a twin clean sorta amp so you probably have what you built, wanna mod it, we can do that 

[2deaf]

If that is the case, I completely mistook the proper wiring of the speaker.  I’m running white to the shaft of the 1/4” plug and black to the tip and I was quite sure that was an 8 ohm tap, and that the other option was white to bl/wh stripe at 4 ohms.

They state in two different places that each half of the secondary is 4 Ohms.  Therefore, WHT to BLK has twice as many windings as WHT to BLK/WHT.  Twice the windings is four times the impedance.

[shooter]

could that 4+4 be the "designers" way to get musicians to plug an 8ohmer into a 16ohm tap so the primary ~~~6k a closer "typical" 

[AHeck]

They state in two different places that each half of the secondary is 4 Ohms.  Therefore, WHT to BLK has twice as many windings as WHT to BLK/WHT.  Twice the windings is four times the impedance.
[/quote]

Thanks for this, if I ever knew it, I had forgotten it. 

[shooter]

you might want to "try" and contact the iron maker and see, most every tranny I've ever bought didn't "assume" you to know 2x winding = 4x impedance

[punkykatt]

You should do a turns ratio test to determine what is what. There should be threads on how to do that on this forum.

[PRR]

That's a very strange OT spec.

And this lump is FAR larger than a 5F2A needs.

25 Watts sine audio at 12k suggests a 800V-900V supply and 80mA-100mA bias current.

If you are really working it at 12k in a 5F2A, you get less than the 5.7 Watt spank you should have, and it will go from clean to nasty quite quickly. With the expected 5k-7k loading the tube "strains" before gross overload, giving a range of near-overload tone of various flavor, instead of abrupt overload.

Yeah, try it with a "right" transformer.