Metropoulos Forum

Im searching for the greatest replica of the Black Flag OT (but Im thinking on PT also) Ive found that Black Flag irons could be more than one :

OT : 784-128 vs 784-139

PT : 1202-118 vs 1202-133

which one is the right one (Im thinking that both first options are best but need experts chimin' in) and which is the best replica out there?? do I will incur in voltage issues ??
thanks for any help

Brian Wallace does the -128, -139 and -118.

http://marstran.com/JTM50-JMP50%20TRANSFORMERS.html

I do not know of a -133 clone. They are higher voltage.

My original JTM50 with -118 PT and -128 OT puts 410 volts on output plates with a NOS Mullard GZ34 but 360 with an old Russian Sovtek!

To use a really corny and much over exercised phrase it 'sounds killer!'

The 128's are in stock now.
The 133 is basically a JTM45 1202-55 PT with higher current capability.

thanks,
before I order something can you please tell the impedance difference between 128 vs 139 OTs ??

Both are 3.5k.

I believe the -128 has a bit more low end response - Brian can tell you

ps Brian if you are reading this - are you stil collecting pictorial stuff of JTM/JMP50s? Your pictorial page is not on the home page drop down - still a great resource

great, thanks, is your JTM50 with 470k or 270k res on mixer ??

Neil,

Yes, I am still accepting Marshall pictures. The page is still there but the link is missing right now. http://marstran.com/Marshall%20Pictorial%20Page.htm

antosimoni,

The JTM50 will have the 470k mix resistors.

Brian

great inf, thank, just one final request : when Marshall changed the Presence pot from 5K to 25K ?? I was thinking this change occured from the JTM to the JMP but I dont know if the JTM50 already have a 25K pot, can you please clarify ??

antosimoni wrote:great, thanks, is your JTM50 with 470k or 270k res on mixer ??

My original has 270k mixers with 556pF bypass cap, single 10k dropper on board and single 32uF filter cap on the board. I replaced the dead 32uF mains can with reformed RS 16/32 = 48uF mains, stock PI and screens. So almost a JTM45 in those respects. It has -128 OT and -118 PT. It has white rear panel with single rear fuse holder.
For this reason I suspect Brian might want pics for his site, there are other similar amps in his historical database but not the pictorial one.
http://vintageamps.com/plexiboard/viewt ... 1&t=101591

I have a half built clone in one of Dom's block end chassis with Brian's transformers on which I will use 470k mixers with 556pF cap and x2 10k droppers and dual 32uF preamp filter. The rest of the components will be identical I hope. This one will have gold rear panel and both fuses on the back.
It will be interesting to compare the two.............

great amp (added my comment ) !! did it sports a 5K or 25K Presence pot ? its nt clear to me when MArshall started with 25K ones

PS : now I need also a replica of the 3H 352-114 choke...

antosimoni wrote:great amp (added my comment ) !! did it sports a 5K or 25K Presence pot ? its nt clear to me when MArshall started with 25K ones

PS : now I need also a replica of the 3H 352-114 choke...

5k pot. I think the 25k came in around '74 or so. The C1999 does the same job!