Value of 1972 50watt metalface.

[Halfstack]

Just curious really as I have had this amp forever and dont intend to sell. Tolex is in good condition and head box is original. Only mod is to change bulgin to the rectangular three pin 240v plug. This was done in the eighties before I bought it. Inside the red die is still on most of the posts and trannies are original. It also has english mullards all the way through. I found out it is a PA head. The only difference I can see is that both channels are the same and there is no bright cap. So can anyone tell me roughly what its worth as I have never seen another to compare it to? Should I change out the mullards for something less expensive to replace?

Heres a gut shot.

 

[Halfstack]

No one able to help a newbie out?

Heres another shot of the back

 

[bfglp]

got a pic of the front. shure its a pa and not a major?

 

[janarn]

If it's a four holer, it's not a PA. They were only made in the 60's.
Hard to see much in the pictures, and you don't have a picture of the front.

My guess is that it is a '72 JMP 50w Bass, model 1986.
They sound more like the Plexies then the '72 50w Lead 1987.

 

[Halfstack]

Its definitely a PA head, a 1985 model, and also a 4 holer. My camera is busted at the mo so I cant take a front shot right now and I can only seem to post one image at a time. (new to forum). Heres the chassis sticker.

 

[Halfstack]

Heres the trannies

 

[Halfstack]

The front looks like a standard UK 50watt head. Power switch, Standby switch, power light, pres, bass, mid, treble, then Channel 1 and 2 knobs. Next to that four input jacks. Thanks for the help so far.

One more inside.

 

[janarn]

That's a rare amp. The 1985 is the PA version of the 1987 Lead,
and was a JTM-45 amp, and a JMP amp up to '68.
According to Doyle they stopped making them in '68.
It should be only one cap that's the difference between this amp
and a 1986 Bass.
Serialnumber?

 

[Halfstack]

Ser no S/A 2033D

Does that help at all ? Sound wise its clean and warm up to about 6 or 7 and then starts to break up a bit. It responds to pedals really well. I use an early 90's Marshall Bluesbreaker pedal which gives a lovely creamy overdrive to it. Both channels sound the same but jumpering thickens up the sound nicely.

I'd really like to some feedback on value as I have not seen another one.

 

[rockinr0ll]

Wow that looks pretty clean! I'm sure you could get 1500+...

The truth is that really any old Marshall is priceless, you can't put a price on the real deal. The cost of getting these old Marshall's is basically up to the demand on the buyers.

 

[ptrickamp222]

Watch ebay for the market price. That's worth 2000.00 plus easy. If the rest of it is as clean as the inside. Try and find another one!!!! All you need to do to make it a lead head is put a .68 NOS mustard cap on V2 cathode resister. If that is a PA head it may be V3 cathode would have to look at the schematic. 50 watt 72 and older PTP heads are hard to come by clean, so you have a very nice amp. I would never sell it. I own a 72' 50 watt lead head and it kills. I am right now in the purchase of a 71' 50 watter in excellent condition from across the pond and it was not cheap. But the amp is in excellent condition and original with laydown tranny. My 72' has the upright and lower plate voltage. This way thay they will have someone to talk to.......Also not a bad investment if you buy quality gear in great shape and original.

 

[ptrickamp222]

s

Just curious really as I have had this amp forever and dont intend to sell. Tolex is in good condition and head box is original. Only mod is to change 'bulgin to the rectangular three pin 240v plug. This was done in the eighties before I bought it. Inside the red die is still on most of the posts and trannies are original. It also has english mullards all the way through. I found out it is a PA head. The only difference I can see is that both channels are the same and there is no bright cap. So can anyone tell me roughly what its worth as I have never seen another to compare it to? Should I change out the mullards for something less expensive to replace?

Heres a gut shot.

Mullard's are the tubes for that amp for it to sound original. I use the middle sixty's Mullard Xf2's w/ double getters. They will last forever if bias correctly.

 

[Halfstack]

Wow, thanks for all the info guys. I have struggled to find another to compare it with. Value is really only of interest for insurance purposes. I need to find someone to give it a sympathetic service as the tone is changing very slightly. Hard to explain how, maybe a little fizzier in the top end and a little less definition in the mids. Might just be me but I think something is drifting so I havent played it for a few weeks til its checked out.

Heres a front shot. I managed to scrounge a camera. Two of the knobs have split apart and have been put away safe. Now I have found Marshall Amp Spares thru this forum I'll have to order up some more. Also the power switch needs replacing as that broke during a house move. Other than that as you can see its pretty much all together.

Good luck with the new purchase. I'd be interested to hear if the tone between the two years varies much and how.

 

[ptrickamp222]

Very nice shape!!!!! Both amps will sound very similar. The 71' with the laydown tranny will have higher plate voltage which should give more headroom and punch. But time will tell.......all Marshall's have their own tone. Plus a Great Les Paul and Speakers will help. Rock On!!!

 

[ptrickamp222]

Wow, thanks for all the info guys. I have struggled to find another to compare it with. Value is really only of interest for insurance purposes. I need to find someone to give it a sympathetic service as the tone is changing very slightly. Hard to explain how, maybe a little fizzier in the top end and a little less definition in the mids. Might just be me but I think something is drifting so I havent played it for a few weeks til its checked out.

Sounds like you need a set of tubes and a rebias. I would start with the first preamp with a known good tube and see what happens. How old are all the tubes?????? If years old a set of NOS Mullards is well worth it. Those old amps had high plate voltages and will eat new style tubes. The Mullards will last for years more......

 

[Halfstack]

I thought the filter caps might have started to degrade. Tubes is a better starting point though. The ones in it have been in there to my knowledge since about 1985 when I bought it. It only gets played at room volumes about two or three times a week so has led a gentle life for the last twenty five years or so. Someone else once mentioned that the plate voltages on the PA were higher and that only NOS stuff would stand up to them. Perhaps I should ask a tech to rebias abit cooler?

A Lester or more likely an SG is on the wish list. For now I will have to make do with my generic hot rodded Strat with a HB in the bridge pup.

 

[Jesstaa]

Tubes will definitely be starting to go downhill, so will the caps. Transformers will hopefully still be good though, is the amp vibrating?

 

[Halfstack]

No vibration. As I said its just a very slight change in tone less mids and a bit of fizzyness when overdriven. I havent plugged it in since incase something goes pop. I might just pull the chassis and see if I can see anything wrong with the caps. Leaking or bulging perhaps. If they look ok and the valves look alright perhaps it would be safe to plug in again and see if it is still there ?

Might just be me , the more you learn the more you listen.

 

[bfglp]

talk to players in your area and find the best tube amp tech. tell him you want to use it, there are mods to make it safer; output circuit protection and a simple control grid revision, these can be easly removed to hold its value for a collector and will add value for a player. KEEP ALL YOUR OLD PARTS!

filter caps are only reliable for 10 years, so if you want to play through it i would start there.
tubes are cheep buy a new set of mullards power tubes and have it biased keep the OE tubes in there boxes. when a power tube goes it can cause damage.

if this head was in a vintage guitar shop the tag on it would be $3000.00 or better.