ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

Source for Plexi-style PT?

:

10/21/2000 2:17 AM

Source for Plexi-style PT?

I'm currently building a 50-watt plexi clone and I need a suitable power transformer. I already have:

* Obsolete Electronics Plexi-50 OT
* M&G PTP board
* Drake choke (for Marshall reissues)

Would a Hammond PT be a good choice? It's been suggested that I avoid the Drake-Marshall reissue PT. Would either of these Hammond PT's be suitable?

* 273BX. 350-0-350, 175 ma., 6.3V @ 5A filament.
* 272JX. 300-0-300, 250 ma., 6.3V @ 8A filament.

I plan on going with the usual setup: (2) EL34's, (3) 12AX7A's, and a solid state rectifier.

Thank you.

10/21/2000 2:56 AM
Don Symes	Doesn't OEI have the PT you need?

10/21/2000 3:47 AM
BIG Dave	Nope. Joe is only offering OT's at this time.

10/21/2000 5:36 AM

hey dave, were on the same wave length.
building a 50w plexi too. (actually laying all the parts on the turret board now. got to run to the store though out of 820ohm 10k/1w and 20k/1w)

i'm plaining on useing the hammond 272jx i don't think the bx will handle the current. rember the hammonds are rated at 115volts ac! i know my house puts more then that. the 270fx 275-0-275 gives me a B+ of ~400volts dc via a full wave rectifer.

so the 272jx should give you plently of B+.

on of the things i'm considering since the jx has 5v taps is putting a tube rec. and be able to switch between SS or tube rec. just an idea i'm kicking over since i'm ordering the irons next week.

where did you get the drake choke?

Bryan

10/21/2000 8:55 AM

quote:
"where did you get the drake choke?"

I've been looking for alternatives since Marshall stopped selling them to us

I was left with a few options... either use a pretty expensive Hammond, that is a close enough in specs, but who knows about the mountings, or have a custom one wound, but I'd be needing quantities to go that route... or 3) I found that Mercury Magnetics has one for $18 ($16.50 if you buy 5 of them, which you may want to do, since you tend to build a good number of Marshall clones and the Novembers). So far that seems to be the best price I've seen, not to knock Mercury, but their prices always seemed to be a bit high on their output trannys, and the tone wasnt 100% there, like Obsolete Electroics's were, but hey, it's just a choke, not much magic or voodoo there. I will try and contact them later this week to see what they will charge for larger quantities, and if the pricing is right, I"ll buy as many as I can squeeze out, and either resell them thru the Drifter Amps site, or I may let a few go to friends and thru the coo- at cost + shipping + reasonable fee to box up etc.(which, I may find out that the price break is not that great, that with having to sip to me, then ship to whomever, it may be cheaper to buy direct.. but we'll see)

10/21/2000 1:48 PM
BIG Dave	Drake chokes are available from http://www.marshallparts.com/ for about $40 each. Ouch! I tried emailing Drake directly a few weeks ago however they didn't return my emails. Perhaps the Mercury chokes aren't that expensive after all!!!

10/21/2000 9:00 AM

Good choice with the OT and PTP board... would have been my first choice as well

As for a power tranny, you'd want 450v on the plates or more (true plexis ran a bit higher, but most agree 450v is a sweet spot!) Doug Hoffman told me the Marshall 50W power trannys he has will get ther... dnt know if his are thru New Sensor, mojo or direct from Marshall, but they seemed to be the best deal around (a hammond that can supply the voltage and current to give you that 450v+ would cost abouy the same, I guess, but with the Marshall style Hoffman has or anyone else has, for that matter, would be a drop in fit.... Plus out of all the vnedor's carrying Marshall power trannys, I've found Doug to be the most helpful, and pleasant to deal with. He's one of those vendors that I'll buy from occasionally, even if I can get better prices somewhere else (ya know, if I need onsies/twosies of anything, and dont have the $$ to buy in quantity)... I'll just buy from him to support him, sicne he's just one of those likeable sort of guys

Page 1 of 5