1969/70 JMP Head

[Alpesitehen]

Could you please help me guys? The selled said this is in full original condition. What do you think, was any capacitors changed before? Transformers? The serial is: S/A 6847A. Is it from '69 or '70?
He asks 3400~ eur for it. What do you think?

 

[Alpesitehen]

one more pic

 

[Dblgun]

The truly qualified folks I'm sure will weigh in but that looks like a pretty darn original bass circuit. Probably gonna need some screen-grid resistors added with those modern EL34's.

 

[Matthews Guitars]

I'm definitely not the ultimate expert on originality, but I can't see a single part in that amp that I am sure is non-original. To me it looks like an absolutely untouched original example. Other than having had tubes replaced.

I don't see any screen resistors.

 

[neikeel]

It's a 1970 (long solid fabric board with rectifier and snubbers on board).
Originally a bass amp
Very clean and original
The V2a plate resistor (the one mounted on the valve socket has been replaced with a correct spec modern xicon and one of the 0.22uF 1000v Dubilier 'snubber' caps has been removed (usually two next to the rectifer).
It looks 100% and Chris's point about lack of screen resistors is correct so those modern tubes might not last long (choice is get a set of NOS xf Mullard EL34s or fit some 1k screen resistors (3w Welwyn are neat as long as you know what you are doing).

Oh and I nearly forgot, the whit bias supply wire will need moving from switched wire on the recifier to a similar white wire off one of the PT HT lugs so the tubes see bias voltage as soon as you switch on, before you flip standby. That arrangement you see was short lived and you see a lot of cooked PTs that era too if you are to play it you will need to do both of those mods.

For an immaculate amp price (in Euros) sounds good to me, I doubt you will find a cleaner one!

 

[Seanxk]

Looks like the 2nd snubber has just been snipped out, the leg is still showing.

 

[TAZIN]

Also someone drilled a small hole near the Bulgin socket.

 

[Alpesitehen]

Also someone drilled a small hole near the Bulgin socket.

I saw this kind of holes other JMPs too, i think its original. Am I wrong?

 

[Seanxk]

one more pic

Look on the right of the bulgin of this external shot. In respect to the amp and how nice it is, that hole is a big minus.

 

[neikeel]

I can’t see a pic of the power lead from the outside. Does the hole go all the way through.
Doesn’t bother me but a collector maybe. ?

 

[TAZIN]

I can’t see a pic of the power lead from the outside. Does the hole go all the way through.
Doesn’t bother me but a collector maybe. ?

Yes, unfortunately it does go all the way through the chassis & rear panel.

 

[neikeel]

Ah yes. There is a stock hole there usually covered up. I had wondered if that was it.
Good haggling point but the rest of it is exceptional.

 

[Dblgun]

I think it can be seen here Neil, just to the right of the Bulgin. Appears to be through chassis and back plate.

 

[StuC]

Ah yes. There is a stock hole there usually covered up. I had wondered if that was it.

No, that would be too easy. They drilled a new hole right next to it.

 

[Matthews Guitars]

That hole looks like the only non-reversible alteration to the amp. Demand a thousand off the price because of it!

As Neikeel said, install two 1K ohm 3 watt Welwyn green vitreous ceramic resistors across the power tube sockets and then it'll be good to go with either new or old EL34s. Or most any other power tube type, for that matter. Plus since it's a vintage correct type part, NOBODY is going to complain.

 

[Alpesitehen]

Look on the right of the bulgin of this external shot. In respect to the amp and how nice it is, that hole is a big minus.

With this in mind, 3400 Euro is still a fair price for it? Does this hole effect the price a lot?

 

[Seanxk]

With this in mind, 3400 Euro is still a fair price for it? Does this hole effect the price a lot?

I would certainly want to haggle on the hole, at this price it's not going anywhere quickly but you never know.

 

[AndyD]

Before you buy, it would be nice to see the condition and originality of the head shell! If all is good, I would try and get nearer €3000.

 

[Ned B]

For the head shell I would expect grey feet, later narrow pin spacing logo and groove-side-up handle.

 

[Alpesitehen]

Before you buy, it would be nice to see the condition and originality of the head shell! If all is good, I would try and get nearer €3000.

I add some pictures about the shell.