Metropoulos Forum

Starting my first 12 series build. Got most everything from valve storm. Got the heater wires done. Waiting on transformers from ****** audio. May need some guidance.

Good to see a new build taking shape! At this point you should consider using the Larry ground scheme. You will need to drill five holes in the chassis and use the medium size brass bolts with two solder lugs each. Lots more info if you poke around in this section before going forward with that. Pretty sure Chris's PT has the 100v tap for Japan. Maybe consider not doing the mod5 and getting an Alex attenuator or at least the Lar/Mar without cascading the preamp. It's always nice to hear a 12series in it's pure form!

Strat78 wrote:Good to see a new build taking shape! At this point you should consider using the Larry ground scheme. You will need to drill five holes in the chassis and use the medium size brass bolts with two solder lugs each. Lots more info if you poke around in this section before going forward with that. Pretty sure Chris's PT has the 100v tap for Japan. Maybe consider not doing the mod5 and getting an Alex attenuator or at least the Lar/Mar without cascading the preamp. It's always nice to hear a 12series in it's pure form!

I second All of the above

The Larry ground scheme is something I'm gonna try on my up and coming build. A 12xxx ESPECIALLY seems to be hummy/noisy when you crank it(with factory busswire/pot grounds), so this Larry/Star grounding scheme is gonna be great when slamming it (vol. on 10) into an attenuator or load/reamp type scenario.

Its going to stock, atleast for a while. I cant wait to get this thing going. Hopefully I will get the transformers today.

Just arrived. Looks like I need some mount hardware for the PT. Any one have a wiring diagram for M E R R E N audio?

The T2562 PT wire color codes...
PRIMARY:
ORANGE = common nuetral
WHITE/red = 100V Japan...
RED= 120V
BROWN= 220V
BLUE = 230V
PURPLE = 240V

SECONDARY:
Black & Blue= High Voltage to diodes or stand-by....
Yellow = High Voltage Center-Tap....connect between first group of caps...
Thick BLACK wire = Heaters
Green wires go to ground...
White = bias

Thanks Strat78. Im thinking that the OT is the same as other brand OTs.

Edit, I think this is correct, but I would double check with Chris:
Wire hook-ups for M e r r e ' 1998
PRIMARY:
WHITE= Center-Tap (goes to the B+)
RED= plates (pin#3 for V4 and V5)
BROWN= plates (pin#3 for V6 and V7)


SECONDARY:
brown= GROUND
black= 4 Ohms
yellow= 8 Ohms
green= 16 Ohms

I shot him an email last night. Hopefully i will here back soon. Should have them mounted after work today then start wiring them up.

So, by using the 100v tap on the PT, what does that give one on the plates? around 400v and what about the heaters? Would it still be at 3.15v or so?

Ill let you know when i get it up and running. Having a 100 volt tap is one reason i went with m e r r e n. Great when living in Japan.

Great choice; M e r r e n and 12 000!

Lar/Mar has done me good for years. Prefer it to the Ultimate attentuator...

I have lar/mars in every one of my marshalls. They are awesome. Im going to try the thd hotplate for a while with this amp.

Got the trannies mounted in. Took the middle screws out of the PT and put screws in the corners so i could mount it in the chassis without drilling new holes. Finding things like simple mounting hardware over here is akways an adventure. Its starting to look like a 12 series now. Hopefully ill hear back from Chris to make sure i wire them up correctly.

Before you wire the OT, measure the resistance between the primary center tap (white) and the brown and then the red wire. It should be around 16ohms for the brown wire and 17 for the red.