Tannoy Lancaster 12R refurb.

[cooky1257]

Over my 50 years of Tannoy fandom I've found a few favourites amongst the various iterations of the Dual Concentric and my favourite Monitor Gold is the first Tannoy DC I ever heard, the Monitor Gold 12R, the appreciation has never left me, I was hooked from the off.
My first pair of Tannoys were home build 12R corner Lancaster's, they were double thickness, had cement plinths were painted Fiat red with a 1" brushed aluminium frame around black Tigan grills they looked fantastic.
They were incredible, if a little bass heavy at times.
I've had lots of reminiscences/ fun listening to a pair of rectangular 12R Lancaster's over the past 4 months or so while I tidied them up.
They'd already benefitted from a rewire with OFC , a much needed shelf brace had been added and the port had been 'modified' to take account of the Lancaster tuning being for the HE version of the 12" DC...
The work: They needed new plinths- the originals had delaminated beyond repair, the 'Lytic cap in the crossovers was way out of spec, the original grill was torn and had been removed from the baffles leaving the old hard glue behind(a sod of a job to remove), the veneer was ok given their age, barring a plant pot water ring and a fag burn to one top(the 70's!). The new shelf wasn't parallel to the back panel and prevented it screwing down properly, the drivers needed a bit of a refresh and a service.
I'll post a series of pics with a few comments regards the construction/mods/quirks etc over the next few days.

 

[myles]

I love a Tannoy thread.....apart from being tempted to spend more money!

 

[calorgas]

Uh-oh, these are my previous pair I think. Hoping that the thread doesn't reveal too much ineptitude on my part (though certainly don't hold back if so).

 

[canonman]

Over my 50 years of Tannoy fandom I've found a few favourites amongst the various iterations of the Dual Concentric and my favourite Monitor Gold is the first Tannoy DC I ever heard, the Monitor Gold 12R, the appreciation has never left me, I was hooked from the off.

My first Tannoys, a mere 22 years ago, were rectangular Lancasters. One with a 12 in Red and the other a 12 in Gold. Both supplied directly from West Norwood to the one and only previous owner.

 

[cooky1257]

Grills off, it's not pretty.

Thankfully the port mod is only secured with sealant so wasn't difficult to remove but the glue Tannoy spread all over the baffle resisted every solvent known to man ;-)

 

[cooky1257]

The project took forever mainly due to poor weather, I can't recall so much rain for weeks on end.
Finally got a chance to work outside and proceeded to mechanically remove the glue.

Tannoy probably never intend for this ply to see light of day and surface wise it's not exactly A grade so would require plenty of work.

A day or so later..

Despite the ridiculous number of those staples to secure the port and it's battens? this particular one went in slightly on the p1ss(the staple man must've said "sod it" and just kept going!)

 

[cooky1257]

After checking over the crossovers and finding both the electrolytic caps on the LF sections to be way out of spec it was a quick and easy job to replace.Other than that the crossovers are in great condition.

 

[cooky1257]

Body filler in a couple of staple dints....

 

[calorgas]

The hundreds of staples were actually holding on some black mesh fabric that a previous owner had put over the port opening - no idea why they'd used so many, took me a while to remove them all. I painted the baffle with blackboard paint before I put those separate grille boards on.

 

[cooky1257]

The hundreds of staples were actually holding on some black mesh fabric that a previous owner had put over the port opening - no idea why they'd used so many, took me a while to remove them all.

Ah good, that's the staples mystery solved, bit mad that, why not just cover the white damping with some black foam/cloth? (as I have done) though must say -I had to hammer in about fifty of them before then filling with U-pol so you might have missed a few
After the job I had removing the glue I don't blame you just painting them over either.

 

[cooky1257]

Salvage and apply rust eater to the metal feet

New 50mm plinths

Spray, re fit old feet then re-attach to enclosures using original hardware.

 

[cooky1257]

Baffles primed ready for spraying but as it happened the paint I had intended to use wasn't available so I later had to remove it as my second choice of paint can react with some primers..ho hum.

 

[cooky1257]

The shelf brace had a bit of a high spot that just needed a bit of a plane to get it flush with the rear panel. The light 12mm mdf shelf had ample cut outs and was given a layer of 4mm kill mat sound deadening. To conceal the off white lining through the port I've added a loose u -shaped curtain of 4mm open cell black grill foam behind the duct.

 

[ToTo Man]

The shelf brace had a bit of a high spot that just needed a bit of a plane to get it flush with the rear panel. The light 12mm mdf shelf had ample cut outs and was given a layer of 4mm kill mat sound deadening.

I'm curious whether the circular cutouts in the shelf have a measurable effect on the flow of air between the two partitions and hence the enclosure tuning?

 

[cooky1257]

I'm curious whether the circular cutouts in the shelf have a measurable effect on the flow of air between the two partitions and hence the enclosure tuning?

If you were to cover the shelf with a layer of felt then there'd be sufficient restriction to the pressure variations passing through the shelf( strictly speaking it isn't a flow of air rather waves of compression and rarefaction) to change the tuning (vented aperiodic loading as utilised in the York and some Lockwood monitors) but as they are, the circular cut outs in the shelf actually have a 20% more surface area than the cut outs in the driver basket, the volume of the shelf is also negligible in terms of Vb- changes to be revealed later in the thread will actually claim more than that back in any case. So no, DATS2 confirms tuning is correct.
If I get a chance, to see just how far you can push things, I'll block 2 or 3 of these shelf cut outs and run DATS to see at what point the tuning freq or Q changes.

 

[cooky1257]

Sub baffle removal, not glued, no sealant, secured with 4 bolts and the finest 12mm ply money can buy...not really, prone to splintering but hey ho it was the early 70's and no one cared.

I have a cunning plan..

 

[cooky1257]

Its not that unusual to see the odd minor ripple/irregularity in roll surrounds under certain lighting and these 12Rs were no different, in all probability they'd been like this since leaving the factory in 1973-2 small soft dimples on the outer edge of the rubber surround near a bolt lug. I suspected it was due to some slight pinching where the outer steel clamps and the surround cut-outs meet the frame. No doubt fixed in place after 50 years but I had to see if I could improve the appearance. Important to note this is a cosmetic thing for an obsessive and has no effect of performance. On the removal of the clamps I could see the lug cut-out needed trimming so I treated the rubber with some rubber reviver(hence the nice deep shine),then cleared away that thin line of dirt and left the surround to relax for a few days....

 

[cooky1257]

Lovely all original 12Rs with crackle cap HF drivers.

Tannoy were aware of the cavity resonances caused by rear mounting, ie driver bolted to the inside face of the baffle, their DC's as early as the Monitor Silver and designed the basket to accommodate both mounting methods and as the Lancaster has a main baffle cut for a 15" this is an ideal opportunity to front mount the 12R.
Sub baffle cut-out widened by 2m to accept driver front mounting.

 

[cooky1257]

Gasket and covers on.

Sub baffles glued .

Filled, flipped, corners taken off and re-bolted up.

 

[fraserking]

Looking forward to the big reveal Frank