120-118 power transformer substitute

tqlspec · Post by **tqlspec** » Thu Mar 31, 2011 10:26 am

I purchased a used Metroamp 50W plexi kit from someone who barely started the build and never got around to finishing it. Some of the components are missing - primarily the power transformer. The kit calls for a 1202-118. I have a Hammond 270HX from another amp that I am considering using. Is it a suitable substitute? It has secondary voltage of 275-0-275 (550 V) instead of the 345-0-345 (690 V) the 1202-118 has.

BLOOZE · Post by **BLOOZE** » Fri Apr 01, 2011 7:01 am

i use a marstran and like it very much

http://www.marstran.com/118.htm

Post by **ValveStorm** » Fri Apr 01, 2011 10:03 am

+1 on the Marstran, though it look like they are out of stock.

Might try:
http://www.classictone.net/40-18054.html

I think the Hammond's may be a little too HiFi for a plexi.

neikeel · Post by **neikeel** » Fri Apr 01, 2011 11:05 am

Don't bank on those voltages:

Vdc=2 Vmax/pi = 0.637 Vmax

in this context

so 345-0-345 gives you 440v dc

and 275-0-275 gives you a quite low 354vdc

Oh and I like the Marstran -118 too!

myfoot · Post by **myfoot** » Sat Apr 02, 2011 8:25 am

BLOOZE wrote:i use a marstran and like it very much

http://www.marstran.com/118.htm

+1 Been very happy with mine!

Mars Hall · Post by **Mars Hall** » Sat Apr 02, 2011 6:03 pm

I like my Marstran PT very much, as well. Just to add George spec transformers are available through Heyboer.

Big Mike · Post by **Big Mike** » Wed May 04, 2011 10:38 am

Answering the OP question, Im sure the hammond would probably work but the voltages seem VERY low as someone else has mentioned. Probably would break up very very early, not sure that''s really what you'd want to go for.

I'd be inclined to try it since you have one, if you hate it, check one of the other options mentioned.
Especially if you enjoy tinkering. If you want to be in the correct voltage range, then skip it and go for something with the proper voltages. PT's have less impact on the tone IMO than the OT.

George's spec Heyboar PT's are very good, Brian Wallace's and Chris M's are very good as well.
But as it's the PT, i'd probably try the classictone from triode to save some dough. Hopefully you have the stock OT with the kit, which sounds VERY good.

You might shelve the hammond for another project, the voltages on that seem better suited for a Lightning or Spitfire build.

tqlspec · Post by **tqlspec** » Thu Jun 09, 2011 9:48 am

thanks for all the input. I ended up using a Classictone PT. Worked great. I'll use the Hammond in a 18W project that's next on the plate.

Metropoulos Forum

120-118 power transformer substitute

120-118 power transformer substitute

Re: 120-118 power transformer substitute

Re: 120-118 power transformer substitute

Re: 120-118 power transformer substitute

Re: 120-118 power transformer substitute

Re: 120-118 power transformer substitute

Re: 120-118 power transformer substitute

Re: 120-118 power transformer substitute