'69 style JMP50 1987 build with lots of NOS parts

[syscokid]

That is such excellent work. Very inspiring and a 1000 times better than anything I have done.

But...

IMO: I would use shorter mounting bolts for the Imp Switch and the IEC...

Capture.JPG (24.65 KiB) Viewed 3483 times

[neikeel]

Ah he used the 6BA board stand offs I sent!!

Do you want some shorter 4BA (correct size )?

[shakti]

Actually I used some US thread stuff on this one, but thanks for the offer Neil! I've taken to using board mounting bolts for the impedance switch and IEC inlet, just got tired of struggling with the very short bolts I typically used before. I've been meaning to cut them down, just haven't got around to it.

Thanks for the kind words everyone! I recently finished a '66 style JTM45 as well. Will do photos eventually. Also need to finish up the block logo clone which is now power transformerless...need to get the proper one. Nudge, nudge Neil...

[neikeel]

I have pictures as it arrived, but need to cut the selector hole and silver hammerite the cover

[shakti]

A photo as it came will do!

[neikeel]

A photo as it came will do!

http://i76.photobucket.com/albums/j2/ne ... G_2448.jpg
http://i76.photobucket.com/albums/j2/ne ... G_2447.jpg

Here it is in situ with it painted and the selector plumbed in

[beaulieu]

nice amp..Im gathering parts do do one just like this. Me..n trannies,NOS RS board,McMurdo sockets,China hats,Belling lee fuse holder,Original switches,Iskras,Mustards. I love to build a "New" Vintage amp with the correct parts.

[shakti]

This amp is now for sale. I was going to keep it, but something has come up and this one has to go. It's brand new, dead mint with a gorgeous authentic headbox from Chris Uff in the UK. Comes with NOS Tesla, RFT and Philips Heerlen tubes (both pre- and power tubes).

Price is NOK 12000 or USD 2000, which reflects all the NOS parts and tubes as well as M e r r e n output transformer. The NOS parts and the transformers is what bumps this amp from a mere clone into the realm of amps worthy of standing side by side with an original IMHO. For comparison, a Germino Lead 55LV is $2200, without all the NOS parts/tubes and M e r r e n transformer.

[ams1aw]

PM sent!

[page361]

Great build Shakti! How do you have the Castelco switches wired? Would like to do the same but not sure how the larger DPST switch is wired - Thanks!

[page361]

Great build Shatki! How do you have the Castelco switches wired? Would like to do the same but not sure how specifically the larger DPST switch is wired - Thanks!

[shakti]

I've actually put this amp up for sale again. Too much overlap between all these Marshalls (also have a 1986, a 12-series and parts for a 69SL).

OTOH I'm also considering doing the 2204/1987 2-in1 mod. Anyone want to talk me into or out of it? I have very little experience with master volume Marshalls. I'm also not much of a heavy metal fan, but I love some variety in my amps.

- IIRC, a stock 2204 does not have the .68 on V2a, right? So to get 100% 2204 specs I will have to remove it. How does a 2204 sound with this cap intact?
- 50+50 or 32+32 for the preamp?
- 0.022 or 0.0022 for the coupling cap? What is stock for a 2204?
- I usually blend in the normal channel to make it not so spiky in 1987 mode, so I'm hesitant to lose that. Has anyone put in a 2-in1 mod which keeps the normal channel as well? May not be possible?
- is there any use for the low input on a 2204?
- what's the correct voltage for a 2204? 385ish or higher?
- would you add a PPIMV as well, or is the master volume of the 2204 "good enough"? Or does it sound better with the master cranked, and PPIMV to take it down?

It would be sort of fun to have one amp that's tricked out... Perhaps even (gasp!) an FX loop!!? I've alway been a purist, but this could be a fun project to try.

[neikeel]

I have a 2in 1 as per my original pics on SDMs site.

Easy mod to your amp without ruining it, noise is not an issue even with channel 2 as the pre-master.

I kept 47k/8 NFB and the 0.68uF on V2a, very versatile gigging amp, you keep 0.022 for 2204 and 0.0022 for 1987.

On mine that I use and keep I did not put the PPIMV on the back but for ultimate versatilty that and loop would be ideal. I like mine just how it is so have not wanted to meddle. At the moment I take my 67 JTM and this amp to gigs with a 69 1960 spec A cab and the Alex. Sound check both and depending on the room etc choose the amp and put the spare round the back (bit pretentious to have more than a half stack on show IMHO!).

[shakti]

Bump for more opinions.

I am going to try the lower B+ and see how I like that along with stock 1987 specs. I am trying to make this amp even fatter, gainier and darker. Since I have NFB on the speaker jack, it's usually 47k@16ohm. I will move it to the 8 ohm tap so I always get 47k@8ohm. Those two should probably take it where I want it for stock 1987 sounds. Wall voltage frequently shoots well over 240V here, so last time I measured plate voltage was up at 450! It's a little hard sounding and a touch screechy at that voltage, with not enough of the touch sensitive type of gain.

A few more questions:

- when did the PT change to the lower B+? In the 70s sometime, but when approximately?
- has anyone tried 0.68 on V2a + NFB 47k@8ohm vs. no bypass cap on V2a + NFB 100k@4ohm? Seems those two things changed at the same time in the early 70s
- anyone have photos of how they wired up their 1987/2204 2-in-1 mods?