The JE Labs/ Angela SE 2A3 amplifier, revisited

paulbottlehead said:
Remember that magnetic field radiation is related to voltage. Your 2.5V filament lines aren't going to do much there. I would just twist them up.
Since you have two metal enclosures, you can put a metal braid over the whole umbilical and let that be your shield and the connection between the enclosures. That is always how I have done it. Of course be sure to get stranded wire for this and small heatshrink with adhesive to slip over each solder joint.

2A3 filament voltage drop could be an issue with what you're doing. If you switch to a 6.3V CT/4A transformer for each tube, you can full wave rectify that with a small resistor, then a cap. This resistor can be tuned to bring your filament voltage back up if the umbilical is driving you nuts. DC on the filaments will also lower the noise floor of the amp a bit, though honestly 2A3s are reasonably quiet as it is.
Click to expand...
Thanks Paul, this is exactly the kind of input I was hoping for. I’ll give it a whirl with AC fils to start, and hope for the best!
 
If you end up with Hammond 2.5V transformers, they are usually wound with a 117V primary, so you'll have a little more than 2.5V coming out anyway.
 
paulbottlehead said:
If you end up with Hammond 2.5V transformers, they are usually wound with a 117V primary, so you'll have a little more than 2.5V coming out anyway.
Click to expand...
Yes, I'm using the 166L2 which are spec'd for 2.5A output, but I also have some 166M2 which are good for 3A... Seems like one of those might be just the ticket!
 
124V is only 3% high from 120V. 124V on a 117V transformer primary winding can make some other issues though, and your 2.5V winding would end up being more like 2.65V.
 
It's been freakin' cold in MN, and my garage shop is equally frigid. My wife has graciously let me move the build operation indoors to the laundry room table. I know full well that this is a big deal, and now I owe her big time...

It ain't pretty! :)

49102918402_eead077291_k.jpg
 
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two words, Benjamin.
Heated.
Garage.

:smoke

In all seriousness, that is very nice of her. My wife's tolerance of my eccentricities is one of the things I love about her (and that, frankly, I don't understand nor deserve). The woman's a saint!
 
I am curious about the chassis you are using. Is it aluminum or steel? And assuming it's a stock item, where did you get it?
 
Thanks. I guess I need to look over the Hammond offerings more carefully because that looks like a very solid chassis.
 
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