Marshall 4150 guts

[kevania]

A couple oddball features: (some not visible in pictures)

1) fuse party,
2) parametric midrange,
3) lame compressor
4) no 16ohm speaker tap
5) 2 preamp/pi tubes rather than the usual 3
6) board mounted pots (This one is a 1980!)

See any others?

[kevania]

Oh yeah, it has 3 input jacks: Normal, Bright and "Stereo". Ha!

[TimmyP1955]

Funky, but it looks as though it would not be a PITA to repair, which is what I worry about most. How's it sound?

[Cameron]

Funky, but it looks as though it would not be a PITA to repair, which is what I worry about most. How's it sound?

Easy to fix .....the bank of fuses are usually in Canadian amps along no 16ohm tap and red silkscreen on the back....but those transformers sound very very good.

[Stevem]

Holly crap are those preamp cathode,grid and plate wires long, I can't belive that does not have some kind of oscillation issue going on?!
Not a shielded wire in sight!

Are those black metal oxide output screen resistors original?

Talk about retubing cost, how about a re-fusing cost, lol!

[kevania]

Funky, but it looks as though it would not be a PITA to repair, which is what I worry about most. How's it sound?

It sounds decent but not magical. Wide open it has a Rocky Mountain Way kind of vibe with a guitar.

[kevania]

Funky, but it looks as though it would not be a PITA to repair, which is what I worry about most. How's it sound?

Easy to fix .....the bank of fuses are usually in Canadian amps along no 16ohm tap and red silkscreen on the back....but those transformers sound very very good.

I'm glad you mentioned the Canadian angle because I hadn't been thinking about that. I am not that familiar with the Canadian variations. The factory bias circuit was set for el34's.

[kevania]

Holly crap are those preamp cathode,grid and plate wires long, I can't belive that does not have some kind of oscillation issue going on?!
Not a shielded wire in sight!

Are those black metal oxide output screen resistors original?

Talk about retubing cost, how about a re-fusing cost, lol!

It's quiet as a church mouse. On my 4104 the only shielded wire is on v1. This 4150 has a lot less preamp gain with only 2 12ax7's vs 3 on the 4104. Also, with the input jack and gain pot being pcb mounted the first gain stage connection is much shorter.

The BMOR's are factory.

Yeah, I've never seen a fuse arrangement like this and quite frankly don't see the necessity. A simple Mains and HT arrangement seems to work for every other amp! Having said that, I'll probably leave it intact when do a build.

[BIG Dave]

I do not believe Marshall used different OT's so there should be a 16 Ohm wire hiding somewhere. Probably just not hooked up. I had a JCM900 that had a two way switch labelled 8 ohms and 4 ohms. There was a 16 ohm wire inside the chassis taped off. I unsoldered the 4 ohm wire from the switch, taped it off, and soldered on the 16 ohm wire where the 4 ohm wire was attached. I then had a 8 / 16 ohm output switch which I found to be more useful. Come to think of it, I probably should have put a Dymo label over the "4 OHM" on the back of the amp before I sold it....

[Cameron]

I do not believe Marshall used different OT's so there should be a 16 Ohm wire hiding somewhere. Probably just not hooked up. I had a JCM900 that had a two way switch labelled 8 ohms and 4 ohms. There was a 16 ohm wire inside the chassis taped off. I unsoldered the 4 ohm wire from the switch, taped it off, and soldered on the 16 ohm wire where the 4 ohm wire was attached. I then had a 8 / 16 ohm output switch which I found to be more useful. Come to think of it, I probably should have put a Dymo label over the "4 OHM" on the back of the amp before I sold it....

No... its just a Canadian Marshall. Only 4 and 8 taps in these Canadian amps. Great sounding transformers though.

[kevania]

I haven't checked for an extraneous 16ohm tap and am glad you mentioned it. If it isn't there, I'll just use it as an excuse to run 2 cabs....hehe.