Armstrong Stereo Twelve - UK Vintage Radio Repair and Restoration Discussion Forum

AvSat44 · 27th Oct 2019, 5:09 am

Hi All,

Today I purchased an Armstrong Stereo Twelve Receiver in timber cabinet at a garage sale for AU$45.00. It was a bit of an impulse buy but I was initially more interested in the turntable that was mounted in the cabinet (an Orpheus Silex). It did not come with any speakers as these were apparently discarded years ago.
When I got home I started hunting for information on the receiver and have established that it might be a circa. 1963 vintage unit. It is not a Mk.2 version. From an Australian viewpoint, it's pretty impressive for a receiver of that era with push pull output stages, nice output transformers, multi band operation, tape record facility and as a nice touch, a tuning indicator tube!
However, getting to the point, I can find very little information on the web about these receivers and I'm desperate for a copy of the circuit diagram as I don't want to spend the next couple of weeks tracing it from the chassis.
If anyone out there has a copy of the circuit and any other info. for that matter, I'd be eternally grateful.
By the way the cabinet is Queen Anne style and while not the same era, I have a pair of Wharfedale Rosedale's which should sit nicely with it. I'm a bit of a Wharfedale tragic so it just seems the way to go.
Cheers.

'LIVEWIRE?' · 27th Oct 2019, 1:15 pm

Service info. for the Stereo 12 Mark2 is available for £1.99(not sure what that is in $ Australian) from VRSD via the link in the top RH corner of this page, but I'm not sure what the difference was between the Mk1 <Mk2.

Restoration73 · 27th Oct 2019, 3:34 pm

You may like to contact this site ; http://www.audiomisc.co.uk/Armstrong/armstrong.html

Synchrodyne · 27th Oct 2019, 9:37 pm

Some information on the Armstrong Stereo Twelve, including a sales brochure and a reprint of the Gramophone magazine review is available at: http://ukhhsoc.torrens.org/makers/Armstrong/index.html. There is no schematic, but I suspect that there would not have been major differences between the Stereo Twelve and the Stereo 12 Mk II.

The Stereo Twelve was Armstrong’s first stereo model in its radiogram chassis series, and appears to have been released c. 1959 March. It was superseded by the Stereo 12 Mk II, announced at the 1961 London Audio Fair. In turn the successor to the Stereo 12 Mk II was the 227, part of the 200 range announced 1964 January. At this stage Armstrong had effectively integrated its audio component and radiogram chassis products into a single range. There may have been some overlap between the end of Stereo 12 Mk II production and the start of 227 production. I think that the 200 series range was not fully rolled out until the end of 1964.

Later, Armstrong did offer a multiplex adaptor and conversion kit for the Stereo Twelve and other models. That was mentioned in Wireless World 1966 September.

Cheers,

cosmocat · 5th Nov 2019, 10:45 pm

I restored a Stereo 12 MK2, (see my icon). Luckily mine came with the original printed manual that contained the circuit diags. I don't know what the difference is between the Mk1 and MK2, I think it was mostly cosmetic.

Mine needed a new mains transformer that I had to get custom wound because of the heater supply feeding so many valves. It also needed the usual recapping and new easy to source valves.

It currently gets a lot of use as an amplifier and sounds sweet coupled to a pair of 15ohm Rogers LS3/5As.

snowman_al · 6th Nov 2019, 1:39 pm

February 1959 Practical Wireless advert.
Looks like the output transformers are different, round, to the MkII's square.

There are better pictures of both MkI and MkII on Jim's site here: http://ukhhsoc.torrens.org/makers/Ar...tes/index.html

The link that Synchrodyne gives has pretty much everything you are asking for / would need to know if you open a few pages...

Interesting that it uses fixed bias (-16v) rather than cathode bias too.

27th Oct 2019, 5:09 am	#1
AvSat44 Diode Join Date: Oct 2019 Location: Box Hill, Victoria, Australia Posts: 1	Armstrong Stereo Twelve Hi All, Today I purchased an Armstrong Stereo Twelve Receiver in timber cabinet at a garage sale for AU$45.00. It was a bit of an impulse buy but I was initially more interested in the turntable that was mounted in the cabinet (an Orpheus Silex). It did not come with any speakers as these were apparently discarded years ago. When I got home I started hunting for information on the receiver and have established that it might be a circa. 1963 vintage unit. It is not a Mk.2 version. From an Australian viewpoint, it's pretty impressive for a receiver of that era with push pull output stages, nice output transformers, multi band operation, tape record facility and as a nice touch, a tuning indicator tube! However, getting to the point, I can find very little information on the web about these receivers and I'm desperate for a copy of the circuit diagram as I don't want to spend the next couple of weeks tracing it from the chassis. If anyone out there has a copy of the circuit and any other info. for that matter, I'd be eternally grateful. By the way the cabinet is Queen Anne style and while not the same era, I have a pair of Wharfedale Rosedale's which should sit nicely with it. I'm a bit of a Wharfedale tragic so it just seems the way to go. Cheers.

27th Oct 2019, 1:15 pm	#2
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Armstrong Stereo Twelve Service info. for the Stereo 12 Mark2 is available for £1.99(not sure what that is in $ Australian) from VRSD via the link in the top RH corner of this page, but I'm not sure what the difference was between the Mk1 <Mk2.

27th Oct 2019, 3:34 pm	#3
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: Armstrong Stereo Twelve You may like to contact this site ; http://www.audiomisc.co.uk/Armstrong/armstrong.html

27th Oct 2019, 9:37 pm	#4
Synchrodyne Nonode Join Date: Jan 2009 Location: Papamoa Beach, Bay of Plenty, New Zealand Posts: 2,944	Re: Armstrong Stereo Twelve Some information on the Armstrong Stereo Twelve, including a sales brochure and a reprint of the Gramophone magazine review is available at: http://ukhhsoc.torrens.org/makers/Armstrong/index.html. There is no schematic, but I suspect that there would not have been major differences between the Stereo Twelve and the Stereo 12 Mk II. The Stereo Twelve was Armstrong’s first stereo model in its radiogram chassis series, and appears to have been released c. 1959 March. It was superseded by the Stereo 12 Mk II, announced at the 1961 London Audio Fair. In turn the successor to the Stereo 12 Mk II was the 227, part of the 200 range announced 1964 January. At this stage Armstrong had effectively integrated its audio component and radiogram chassis products into a single range. There may have been some overlap between the end of Stereo 12 Mk II production and the start of 227 production. I think that the 200 series range was not fully rolled out until the end of 1964. Later, Armstrong did offer a multiplex adaptor and conversion kit for the Stereo Twelve and other models. That was mentioned in Wireless World 1966 September. Cheers,

5th Nov 2019, 10:45 pm	#5
cosmocat Triode Join Date: May 2011 Location: Bristol, UK. Posts: 35	Re: Armstrong Stereo Twelve I restored a Stereo 12 MK2, (see my icon). Luckily mine came with the original printed manual that contained the circuit diags. I don't know what the difference is between the Mk1 and MK2, I think it was mostly cosmetic. Mine needed a new mains transformer that I had to get custom wound because of the heater supply feeding so many valves. It also needed the usual recapping and new easy to source valves. It currently gets a lot of use as an amplifier and sounds sweet coupled to a pair of 15ohm Rogers LS3/5As.

6th Nov 2019, 1:39 pm	#6
snowman_al Octode Join Date: Dec 2018 Location: Llandeilo, West Wales, UK. Posts: 1,092	Re: Armstrong Stereo Twelve February 1959 Practical Wireless advert. Looks like the output transformers are different, round, to the MkII's square. There are better pictures of both MkI and MkII on Jim's site here: http://ukhhsoc.torrens.org/makers/Ar...tes/index.html The link that Synchrodyne gives has pretty much everything you are asking for / would need to know if you open a few pages... Interesting that it uses fixed bias (-16v) rather than cathode bias too. Attached Thumbnails __________________ Never Leave Well Enough Alone...