I had to zoom in on the image as I thought it said “Amstrad”
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admittedly I have taken out my contact lenses…
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Apologies for the pants photographs taken during my vintage Marantz phase.
Lit up and running are a pair of Model 2 mono blocks next to a pair of Model 5’s with an Model 8a front and centre.
I still have the Model 2’s which look cool of an evening session with the lights down low.
Specifications
Power output: 20 watts triode mode, 40 watts U/L into 8Ω (mono)
Frequency response: 20Hz to 20kHz
Total harmonic distortion: 0.1%
Damping factor: 20
Input sensitivity: 0.7V
Signal to noise ratio: 90dB
Speaker load impedance: 4Ω to 16Ω
Valve complement: 1 x 12AX7, 1 x 6CG7, 2 x EL34, 2 x 6AU4GTA
Dimensions: 15 x 9.5 x 6.5 inches
Weight: 47lbs
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Some of my favourite vintage amplifiers in my hoard.
Based on the classic Mullard 5-20 circuit, Audiomaster 11A mono amplifiers manufactured by W & N Electronics Ltd in London W13 circa 1957. At the time of manufacture they were rather expensive, the mono amplifier retailing at £29-10s-00 and associated control amplifier for £28-15s-00.
In the main W & N utilized expensive meaty Partridge Mains, choke and meaty Partridge double C Core Output transformers housed in anodised silver square cans and occasionally Black enamelled square cans.
W&N occasionally make use of slightly less expensive Haddon transformers housed in more rounded anodised cans.
Valves / Tubes 5: EF86, ECC83, EL34 EL34, GZ34.
Distortion 0.1% at 25 watts. Response 15 - 30000 c/s ± 1 dB. 25 dB feedback. Noise Level -90 dB. Output impedance 4, 8 or 16 ohms. Output 2 x EL34 in push-pull.
I made a simple reversible conversion on one of my pair of 11A’s utilizing socket adapters and bias resistors enabling the amps to run SIEMENS F2a11 valves in the output stage.
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@murrayjohnson…I seem to recall you having an 11a in for service a while back, did you ever get it up n running…If so what were your impressions of it Guy ?
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If I recall it belonged to Matt or Stuart but didn’t they pass it on to you?
I think it was powering up ok although it might’ve needed a cathode resistor replacing. Must be 12 years ago now.
(Just checked, we did exchange emails about them) 
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I had Totaly forgotten 
Its a shame that you never got to hear it sing…I’m sure that you would have liked its weighty presentation.
Found a nice image of 11a’s ( not mine) illustrating the slight difference between the Partridge and Haddon transformers.
I’d like to hear them, mine are the same circuit I think but with smaller transformers
They aren’t normally naked like that
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GZ37 / CV378 rectifier ?
That gz number rings a bell, I believe they are super foo mil-spec valves too
Not sure about the other one you mention, but when I had them refurbed I was told they were based on the 5-20 circuit. They were mono-integrated originally but we had the preamp but removed
CV378
They are the same thing
Two sides of the same rectifier from one of my amps
Also interchangeable with GZ33
Yup…CV designated GZ 37’s tested and measured to tighter tolerances for the military…yours looks nice and fresh…NOS? be interested in some shots of your amp/amps Kevin.
Nice what iron does it sport
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Thanks Simon,
Interstage are nickel core and output transformers are amorphous mumetal all wound by Dave Slagel of Intact Audio.
The amps were built by @Coco of this parish some years ago now, 3 stage DHT PP monoblocks, about 18Wpc
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Lightweight prototypes for his later creations ?
Quality all round