Mystery late 18w amps......

London John

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As many on here will know, I've long had a particular "thing" for pinstripe 18w amps, and have been lucky enough to own more than a dozen. They date from very early with a slant logo, to very late '67 or early '68. Each has their own particular sound and they all sport RS PT (two versions) and OT (either EL84 or Heavy Duty).....except the very, very late versions.

It's these amps that are the subject of the thread. Whenever people have had a chance to A/B/C a few of these amps at the same time, everybody (and I mean everybody) has chosen one of these very late versions as easily the best sounding. Weird enough.


I've had three of these extremely late 18w amps, and they all have the same major anomalies.

First, the OT on these is unlike any other 18w. It's definitely not RS, and I don't think it's Drake (but can't be certain). What I can tell you is that it's definitely factory.



The other major anomaly is that although each of these three amps had a rectifier tube base fitted in the normal position, none was ever fitted and they are all rectified with BY127 diodes. Again, this is unquestionably factory.



Lastly, all three of these amps came from within a 100 mile radius, in the NE of the UK.

Thought it worth putting this out there, as there's no documentation around these particular very late versions of the 18w which, IMHO, are the best sounding of the lot.
 

stickyfinger

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Interesting love 18 watts. Can we see more photos of these?
 

_Steve

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Thought it worth putting this out there, as there's no documentation around these particular very late versions of the 18w which, IMHO, are the best sounding of the lot.

Are there any numbers stamped on the output transformer?
 

_Steve

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Can you perhaps take some more photos of the OT and the guts out of the headshell? Is it the same basic size OT as the earlier ones?
 

shakti

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This is interesting and I would love to see more photos.

6 or 7 years ago I bought what was allegedly a trashed 18w chassis from a guy in France(?). I think I came across it at the old Plexi Palace. I was looking for a vintage spec chassis for an 18w project and never thought an original would turn up, but out of nowhere this one came up (well, if it was genuine that is).

I can’t remember the story of how the amp came into his hands, but it was chassis only, with a cracked Plexi panel, output transformer and original preamp board although with many components missing/replaced IIRC. At the time we thought the OT was non-original since it wasn’t a Radiospares. I can’t remember what the power transformer was, but I think it was non-original.

I managed to convince him to sell me the chassis but he wanted to keep the OT and the preamp board as he loved how it sounded and was going to put it into a new chassis in a head. So I bought the chassis with panels, light and hardware including all tube sockets (all black McMurdos).

I used that to build a new “quasi-vintage” 18W 1973 model with mostly NOS parts, a pair of very early ‘66 T1220s and a Radiospares EL84 OT which kindly came from an esteemed board member.

That was a long preface to the important information; the Radiospares OT did not fit the mounting holes for the original OT! There were just one set of holes with no signs of modifications or enlarged holes. I can’t remember if the RS one had a wider or narrower spacing, but I can check. In any case, from memory I do think the OT that sat in the chassis, and which the guy in France kept, looked very much like the one in London John’s photo.

There were a few other tiny variations between this chassis and what I’ve seen on other vintage 18w chassis like the placement of the fuse holder behind the power cable. OTOH I am not more of an expert on these that it may even be a fake or something scavenged from a cheaper or later model like the Popular. But if we can see some more photos of these very late 18w amps I would be most interested!
 
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Ned B

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This one in the Hamer Ad was a later one probably well into '67. I sold it 40 years ago to Jol at Hamer where it appeared in this ad soon after. These weren't too well known over here back then. I think he may have hoped it was a Bluesbreaker. I remember EL84s didn't last long and probably contributed to me letting it go. Sadly, an easy fix by running at 220. Obviously not helping John, but this post brings up the memory of a highly regrettable sale.
 

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Crikey

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As many on here will know, I've long had a particular "thing" for pinstripe 18w amps, and have been lucky enough to own more than a dozen. They date from very early with a slant logo, to very late '67 or early '68. Each has their own particular sound and they all sport RS PT (two versions) and OT (either EL84 or Heavy Duty).....except the very, very late versions.

It's these amps that are the subject of the thread. Whenever people have had a chance to A/B/C a few of these amps at the same time, everybody (and I mean everybody) has chosen one of these very late versions as easily the best sounding. Weird enough.


I've had three of these extremely late 18w amps, and they all have the same major anomalies.

First, the OT on these is unlike any other 18w. It's definitely not RS, and I don't think it's Drake (but can't be certain). What I can tell you is that it's definitely factory.



The other major anomaly is that although each of these three amps had a rectifier tube base fitted in the normal position, none was ever fitted and they are all rectified with BY127 diodes. Again, this is unquestionably factory.



Lastly, all three of these amps came from within a 100 mile radius, in the NE of the UK.

Thought it worth putting this out there, as there's no documentation around these particular very late versions of the 18w which, IMHO, are the best sounding of the lot.
Try the Budda Twinmaster
Its LAF
Great amp
Hard to believe its only 18watts
 

playloud

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British Grove on an iphone......just so wrong, but it is what it is.

One of the mystery three, with Greeny.



That sounds a lot more aggressive than I was expecting... much closer to a 50-watter. Then again, the player, guitar and room may have something to do with it!
 

Adieu

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You sure it's factory? The wires coming off the tranny look a lot brighter and less faded than the rest.
 

London John

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You sure it's factory? The wires coming off the tranny look a lot brighter and less faded than the rest.

Absolutely certain, the OT photo is with flash, the rectifier isn't.

Three amps, all exactly the same construction and parts, all from the same period.
 

Pete Farrington

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I remember EL84s didn't last long and probably contributed to me letting it go. Sadly, an easy fix by running at 220
Assuming a 240V mains, changing the amp’s PT selector from 240V to 220V would increase the secondary voltages by x 1.091, which would increase dissipation by potentially up to x 1.19.
ie the EL84 would be more, not less, stressed.
 
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Kittyfrisk

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Hello London John.
I have recently stumbled upon a 1960's Marshall '1974' pinstripe 12" combo. From investigations so far, I'm pretty certain that it is genuine, but I'm happy to answer questions on the amp that I can.
As a member of The Fretboard UK, I asked for help on there & was told that you are the 'go to' person for detailed knowledge & advice for these amps.
So, here I am joining up & asking for your help :)
Any information that you want, please just ask & I'll do my best to comply.

Kittyfrisk
 

London John

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Hello London John.
I have recently stumbled upon a 1960's Marshall '1974' pinstripe 12" combo. From investigations so far, I'm pretty certain that it is genuine, but I'm happy to answer questions on the amp that I can.
As a member of The Fretboard UK, I asked for help on there & was told that you are the 'go to' person for detailed knowledge & advice for these amps.
So, here I am joining up & asking for your help :)
Any information that you want, please just ask & I'll do my best to comply.

Kittyfrisk

I've sent you a message.
 

Matthews Guitars

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I've only personally experienced one 18 watt Marshall, a model 1973. It's just a marvelous little amp, with a sweet and perfect tone of its own. I'd very much like to have something like it.
 

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