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50W monoblock "Engineers Amp"

6EW6 is another pin compatible input tube with high gm, and quite linear. Worth a tube roll.

I had them in my amp at one time. I remember that they were better than the 6CB6 (more gain), but I settled on the 6GU5, possibly because I had more of them.

I know, I am being conservative... but it seems like many people are a risk building these things. I don't want any electrocutions, or fires...

I was just being......UH me! Big power requires big voltage. The 125 WPC flavor needs 600 to 650 volts. I have been tinkering with a big sweep tube amp that runs on about 720 volts. Still working out the details, but it won't be any time soon.
 
I've got several Dynaco MKIII's hanging around. I wonder how well these OPT's would work in this design? Primary impedance seems to be the same.

I was looking at new mkIII transformers, comparing prices against the Hammond and what Edcor has to offer. Using existing mkIII's would save you a bundle, even thou the Edcors are quite cheap compared to the others.

jeff
 
I am looking at the pic linked below, and wondered whether Pete's mother every yelled: "You're gonna electrocute yourself!":

DCPP_MB_proto_small.jpg
 
I can better imagine it as, "Why are the lights in the house dimming? Are you making another vacuum cleaner again??"

Oh, it's even better than that. I started down this path when I was pretty young, like 8. Quite often after I rigged something up, I'd get my mom to plug it in for me. There were many sparks and blown fuses.

I do not recall ever doing this... but my dad once told me that I was wiring up something but only had one wire nut to connect the line cord to it, so I put all the wires into one wire nut. Obviously that didn't work too well...

Pete
 
I started down this path when I was pretty young, like 8.

I was about the same age. My parents were more afraid of electricity than I was so I plugged my own stuff in. I did get my father to make me a wooden box with an outlet and a light switch in it. I had to wire it.That way all of my experiments had a "kill switch" that could be engaged by terrified parents, siblings and friends......and more often ME. This practice continues today.

"Why are the lights in the house dimming?......" "Why is the TV acting up again? I told you not to play with that thing when we are watching TV." Those responses were the results of two power consuming, TV jamming projects, the ham radio transmitter and one of several Tesla coil experiments.

None of those experiments resulted in anything more useful than getting myself and some friends banned from entering the high school science fair EVER AGAIN. A middle school project involving the spark coil from a Model T Ford only resulted in that projects withdrawal from competition.
 
Gee, with the pair of George and Pete, add in all the experiments of mothers plugging in gizmos to tremble coils from Model T's somehow leads into to things like Pete's new Engineer's Amp monoblocks and George's glowing tube behind lexan shield... I am beginning to think that MAYBE I should have stuck that fork into the outlet.

Anyway... Pete, when will we be graced with a few more pictures? The suspense is killing me.
 
We must all be like minded:D

When I was 11, so first year of secondary school I made an electric shocker. Just a small backwards mains transformer a 9V battery and a micro switch. I got caught in a science class zapping my friend in the back of the neck. I really thought I was in big trouble. My teacher Mr Turner took the gadget and got everyone in the class to hold hands and gave the whole class a shock. Good times, best teacher I have ever had.

Cheers
Matt
 
"are these right Edcor OPT's for the amps: CXPP60-4.2K?"

Those CXPP60 should work fine. Might have slightly different mounting holes from the Hammond 1650N, I don't know. The Edcor OTs are good quality. They are blue. The Hammonds are black. If that makes any difference.

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Anyone able to comment on how much buzz/hum from the Hammond power xfmr 290FX versus the 291FX? I know the 300 series (373FX) are dead quiet, but they cost almost 2X.

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For 440V B+, one could use an industrial (Ebay) 120V to 480V xfmr with an inductor input DC filter. The inductor may cancel out the cost savings though.

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It might be cheaper to just use a 120V:480V industrial xfmr with a cap input (610V B+), and then up the size of the OT to 100 Watt. Rather more dangerous B+ voltage to work with then, only for the experienced builder. Expect some hum from an industrial power xfmr. however, they don't put any extra steel laminations in those.