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Old 9th Aug 2019, 6:05 pm   #1
Guitarist28
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Default Shaftesbury 519 amplifier

I recently bought an early 60's Shaftesbury 519 amplifier to add to my ever growing valve guitar amplifier collection. I did think that 120 including postage was very good considering I have seen these for sale at stupid prices (in excess of 50 - 600??) and amazingly they do indeed sell!

To date I've not had a chance to look at it detail but I'm assuming its very early (perhaps late 50's) as its construction appears more in keeping with a portable record player of the era than a later guitar amplifier.

I don't have a schematic for it albeit I've hunted through the internet to find one. It does appear to also have the original Richard Allen 10" 3ohm speaker.
It does't have the foot switch to control the tremolo which is a pity. Equally some original speaker cloth (again more akin to a radio of the period than a guitar amp) would be good if anyone can suggest where I might purchase some?

At this stage I rather concerned about the Hunts caps and Erie resistors that can be clearly seen. The restoration of this one is a bit bewildering - do I try to keep it as original as possible OR functional as a potential usable guitar amplifier?
If anyone has any information with regards to this amp I would be most grateful.

Best Regards

Rob

PS - the pictures were taken by the seller, I certainly wouldn't power it up as it is. I'm already concerned that, as it stands, the EL84 appears overloaded!
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Old 9th Aug 2019, 10:41 pm   #2
Herald1360
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Default Re: Shaftesbury 519 amplifier

I'd be suspicious about the Hunts capacitors and any of those Plessey red-yellow-black electrolytics too. The resistors can be checked (many of them whilst still in circuit) and replaced if well out of tolerance. If appearances matter you could paint the usual yellow polyprop capacitors black though disguising modern electrolytics might be harder. I've not heard of Plesseys being restuffed but it might be possible. If you search hard, you may be able to find hi-stab resistors of the same construction (extra salmon pink band) which are normally well within their specs even 60 odd years on.

Only you can make the value judgement about repair, restore or preserve- it's yours to do with as you wish after all.

Circuit- can't help, though a single ended EL84 amp even with tremelo shouldn't be too hard to reverse engineer. Using a similar Fender or the like as a starting point could make it a bit easier.
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Old 9th Aug 2019, 11:27 pm   #3
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Default Re: Shaftesbury 519 amplifier

I have seen those pink band resistors spot on in a 70 year old amplifier.
The phase splitter was fun as I was expecting the usual cathode coupled pair of triodes.
I found my first single triode phase splitter in it.
Reverse engineering can sometimes be revealing.
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Old 10th Aug 2019, 8:25 am   #4
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Default Re: Shaftesbury 519 amplifier

Looks a single ended ECL8* amp with a high gain IP (EF86) and tremelo (ECC83) A look at Mullard's ECL86 amp schematic should give a rough idea of what's what. As they're all yellow valves and look original maybe it's later than you think, IE 1970 ish.

As to keeping it original, it's not a Marshall lead or rare USA made amp where folk go to extreme lengths to make sure every cap and bolt are original to preserve " The Sacred Tone", so why bother? There are some obvious candidates for replacement, the black 0.1 on top of the OPT looks like a replacement, these caps are usually rated at 1kv + due to the high voltages seen on an SE OPT, and obviously the others mentioned.

Start it up on a LL, check some voltages, then check resistor/caps for out of spec. Take loads of good pics first from all angles.

Andy.
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Old 10th Aug 2019, 8:50 am   #5
Edward Huggins
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Default Re: Shaftesbury 519 amplifier

The ECL86 was not introduced until 1962 and if looks as if the amp pre-dates this.
Fully driven, an EL84 will give just over 4.5 watts and I wonder how such amps sounded at small gigs?
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Old 10th Aug 2019, 12:28 pm   #6
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Default Re: Shaftesbury 519 amplifier

I fixed one of these for a school friend in about 1978. I found that the Hunts branded tone corrector capacitor across the output transformer primary was almost a dead short. Replacing this and the EL84 brought it back to life.
If I knew then what I know now, I would have replaced all of the Hunts caps.

John
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Old 10th Aug 2019, 2:58 pm   #7
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Default Re: Shaftesbury 519 amplifier

I have found the attached albeit I bit difficult to read.
Shaftesbury/Dallas was bought out by the Arbiter group who made Sound City amps so this must be from the early 60's.

My intention is to use it so I will replace components that need to be replaced e.g. Hunts caps, selenium rectifier etc.

I cant say that I'm a fan of the speaker cloth so I will replace with an older grey cloth.

Will keep you posted.

Best Regards

Rob
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Old 10th Aug 2019, 3:01 pm   #8
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Default Re: Shaftesbury 519 amplifier

I had a good look at that drawing earlier on today, it looked incomplete and with errors so far as the circuit goes.

Lawrence.
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Old 10th Aug 2019, 7:34 pm   #9
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Default Re: Shaftesbury 519 amplifier

Hello Rob,

I bagged one of these (the version less the tremolo), at the Audiojumble, Kent about 7-8 years ago for 50.

From memory it was a simple circuit, however, it had been got at and been modified, but I returned it, as best I could, to what I figured was the correct original circuit when I restored it.

I feel it's de rigueur to replace all the coupling and bypass capacitors and to check/re-form the smoothing and filter capacitors.

Sadly, mine is in storage at present in preparation for the move to my late parents’ house in Rayleigh, Essex....

Regards
Terry

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Old 11th Aug 2019, 7:49 am   #10
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Default Re: Shaftesbury 519 amplifier

"The ECL86 was not introduced until 1962 and if looks as if the amp pre-dates this" Maybe, but all the valves have yellow print, which AFAIK were issued for the Mullard Golden Jubilee in 1970, so maybe all the valves were replaced in one go if the amp was made earlier. Thought i saw a C on the valve near the OPT, could be mistaken and it would make more sense if a EL84.

A..
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Old 11th Aug 2019, 10:19 am   #11
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Default Re: Shaftesbury 519 amplifier

Yes, the valves could easily have been replaced. I will check to see if there is any numbering.
Rob

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Old 11th Aug 2019, 10:22 am   #12
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Default Re: Shaftesbury 519 amplifier

The output valve is definitely an EL84! An ECL would look different from any angle.

Re: dates and valve changes... get the etch codes off the valves, and the 3-letter codes off the Hunts caps, and you can tell when they were made and therefore whether the valves are likely to be original.

Quote:
Originally Posted by Diabolical Artificer View Post
As to keeping it original, it's not a Marshall lead or rare USA made amp where folk go to extreme lengths to make sure every cap and bolt are original to preserve " The Sacred Tone", so why bother?
Why bother with keeping anything original then? Are Marshalls the only things in the world with some historic interest? I find musical instrument amplifiers interesting as far as originality is concerned, because unlike vintage radios and TVs, they fulfil their original role exactly as they did when new. Whilst radios and TVs are usable, they do not receive the same range of broadcasts and are not the sole source of such content today; but the stand-alone guitar amp is still the conventional way of making an electric guitar audible and customising its tone. In use, exactly the same sounds can be made to issue from the speaker, for the same purpose of entertaining the listeners, as ever. Therefore, I personally feel that a considerable amount of the originality value of a music amp is in the music, and would rather have one that works like new, moreso than with a 1950s AM radio.

I would not stuff the components. I would take a few high resolution pictures of the chassis and components as-found, then change whatever needs changing to restore performance to a level that would be acceptable to a competent serviceman in its heyday. Store the removed parts with the pictures in a jiffy bag identifying what they belong to. That way the functionalilty will have been conserved first and foremost, without destroying any of the evidence of its original construction should that be of interest in the future (for example, using the Hunts 3-letter date codes as evidence of the likely manufacture date.)
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Old 11th Aug 2019, 11:11 am   #13
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Default Re: Shaftesbury 519 amplifier

Quote:
Originally Posted by Diabolical Artificer View Post
but all the valves have yellow print, which AFAIK were issued for the Mullard Golden Jubilee in 1970
Yellow print Mullard valves were around in the 1960's, I remember them well.

Lawrence.
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Old 11th Aug 2019, 12:30 pm   #14
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Default Re: Shaftesbury 519 amplifier

1969/70 apparently: https://www.vintage-radio.net/forum/...ad.php?t=61944
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Old 11th Aug 2019, 12:41 pm   #15
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Default Re: Shaftesbury 519 amplifier

I'm sure I pulled original fit PC86/PC86 yellow print valves from UHF tuners back in the 1960's.

https://www.vintage-radio.net/forum/...ad.php?t=53211

Lawrence.

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Old 11th Aug 2019, 3:19 pm   #16
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Default Re: Shaftesbury 519 amplifier

Initial work indicates that amp is possibly early 60s as the UCC smoothing cap is dated Aug 63.
The EL84 Mullard valve has ‘Made in Canada’ the others are all Great Britain.
I’m having some difficulty removing the lower chassis as the front 1/4” nuts are very difficult to get to.

Regards
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Old 11th Aug 2019, 3:25 pm   #17
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Default Re: Shaftesbury 519 amplifier

Is it bad that I know an EL84 when I see one, just from the electrode structure?
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Old 11th Aug 2019, 5:00 pm   #18
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Default Re: Shaftesbury 519 amplifier

''Is it bad that I know an EL84 when I see one'' - No it is a good thing...

From my understanding 1963 also corresponds to the 'K' (if it is a K the picture is fuzzy) letter date code on the EZ80 too.
Alan
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Old 11th Aug 2019, 5:07 pm   #19
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Default Re: Shaftesbury 519 amplifier

Good spot. All of the valves begin with a K.
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Old 11th Aug 2019, 5:14 pm   #20
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Default Re: Shaftesbury 519 amplifier

As a guitarist who has owned and restored many vintage guitar amps, I would definitely get it working reliably. Yes, I'd change those dodgy caps. It won't affect the value in my opinion, but try to sell an amp that's not working properly and it would. Also, if you did sell it as 'original', the buyer may attempt to use it and blame you for selling him a faulty amp! Yes, I realise that to the moderate, understanding, intelligent people on here that seems wrong, but those, sadly are the kind of people you meet up with.
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