Re-conditioning an original 1950’s Tannoy 12 inch Silver Monitor Canterbury
Tannoy 12″ Silver monitor in Canterbury Enclosure
“This was intended as a quick ‘spruce-up’ of an original but tired Tannoy speaker – it took a bit longer than expected and isn’t perfect but I was pleased with the results”.
If you’re interested in vintage Hi Fi then you’ve likely heard of Tannoy’s original range of concentric speakers. If you’d like to know more – have a look here.
The concentric design incorporates the tweeter cone inside the centre of the base unit and is still widely used today for studio monitors.
This range of original speakers – even ‘naked’ without cabinets, now command eye-watering prices (well in excess of £2K for example) …. and …. my father-in-law had one stashed away in his garage!
He’d bought it new, but was lucky enough to get it for a knock-down price when Cole Brothers of Sheffield were shutting down their audio department some time in the late 50’s or early 60’s.
For anyone that’s interested, it’s marked LSU/HF/12/L which is the 12 inch silver monitor, regarded by many as their best (well the 15 inch one is at least). The driver serial number is 023941 and it’s cabinet 549.
Since it was very definitely languishing away, I offered to ‘fettle’ it so we could eBay it and he could have a useful pot of money for a holiday etc.
My objective was to do a light, sympathetic improvement – I didn’t want to overdo it as some purists might consider that to reduce the value (that’s an excuse for otherwise saying I’m not a furniture restorer by any stretch of the imagination!)
Half the promise is now fulfilled. (I still have it in my living room since he was keen that someone in the family got some use out of it. When it’s fully broken in (!) I’ll get it sold – for now I’m enjoying it!
The starting point
The cabinet’s lacquer was distressed, there were a few dark ring marks from mugs being left on top, a few chips to the veneer and the grills were pretty filthy.
The ‘restore’
I rubbed the unit down with wire wool, artificial wire wool (3M) pads and various grades of wet n dry.
In some places I used spirit and a razor blade. The lacquer was caked on!
The task was made much harder by the fact the grill (a plasticised type of cloth weave) was not removeable – at least I couldn’t see how without totally taking the unit apart. Each quartered side has grilled panels separated by a small wooden detail – quite tricky.
I suppose all told I put about 30-35 hours into it over a period of a couple of weeks!
I found some veneer samples on the ‘bay. In some places such as the end corner, the match is excellent – in others it’s still pretty noticeable (in some part due to my very basic veneering skills no doubt!) but at the very least I have protected the surface.
I had a decent amount of success with the dark marks and rings using propriety ring remover (which I suspect is just Oxalic Acid).
I then looked for an oil that had more oil than varnish – a Danish Oil and slapped that on. I followed it up with Renaissance Micro Crystalline Wax – this is great stuff and I’d used it previously to give my Linn LP12 a really nice finish and I’ve used it on metal too – a proper conservator’s tool!
The grill cleaned up somewhat but as you can see not perfectly.
(The paper-y thing is actually the original paper Tannoy label, attached by screw to the rear!)
The Result – Part 1
The next problem was how to hook it up!
Being a single speaker (and back in the day they were rarely sold in pairs as this pretty much pre-dated Stereo), I needed a mono amp. So…. I went on the ‘bay and bought a Cyrus Smartpower Plus Mono/Stereo amp. ‘Course, this is a power amp so I also needed a pre-amp. I thought this would be a good time to experiment with a passive pre.
Basically, there are a band of Hi Fi aficionados who swear blind about passives.
In essence, (and being no expert) a ‘pre-amplifer’ is pretty much a misnomer anyway – for the most part the volume knob on a pre-amp actually attenuates, rather than adds gain. So a passive pre-amp usually has some input selector and and some form of potentiometer to actuate the line-level signal. No power required.
An active pre-amp by contrast can add gain, provide fancy (remotely) relay-switched inputs and can provide a preamp buffer which (as I understand it) can be useful to match impedances when the source and the output might otherwise be incompatible.
So, I bought a Tisbury Mini Passive Pre-amp!
As an experiment, I tried it in my main Hi Fi rig – replacing the active Roksan Caspian M1 Pre-amplifier. I’d recently bought this (guess where!) but back in the day (2010s etc.) this retailed for over £1,500…. Not cheap.
I don’t want to start an active/passive war but I *think* I preferred the passive!! However, I’d bought the passive for a purpose, and for me, part of the Hi Fi set-up I have is pure aesthetics – I love the Roksan Caspian’s rack look (strangely many don’t!). So the Caspian is a keeper!
So, the way the Tannoy is wired up is: FLAC (lossless) -encoded music is Roon-served to a Chromecast Audio, into the passive, and into the Cyrus, set on mono mode, powering the single Tannoy.
It sounded really good in fact. Really ‘warm’ but still distinct. Great range from high to low frequencies so I was very happy!
The Crossover
Of course, over the next few weeks, it didn’t stop me wondering about the speaker’s crossover..
Crossovers have capacitors and capacitors don’t last for ever.
So I thought I’d have a closer look.
It’s pretty simple. What’s interesting is the custom two cap configuration in a metal enclosure.
I also found the circuit diagram online:
So I decided to build a replica. I ordered a bunch of parts – including some Hi Fi-spec’ed (and priced) jumbo caps and induction coil of the correct values.
It looks pretty good assembled!
So I unmounted the original and replaced it with mine – using all original screw holes etc. to preserve as much originality as possible:
I decided to check the caps with my cheapo ESR meter (and sound like I know what I’m doing at the same time). One was good, the other not.
The Result – Part 2
In a word – amazing! Clearer, more defined. A really great speaker – just wish I had two, and that it was actually mine!
It’s currently in the corner of my living room, and I can stream all my music via Roon.
The clarity and richness of the sound has made me want to find a way to stream my Vinyl from my Linn Turntable to it too – but that might be another ‘project’!