Tannoy York Speaker Cabinet Modifications
Tannoy produced a number of speaker cabinets during the 1960's, two of the more common ones being the Lancaster and the York. Both these cabinets having unsatisfactory construction, and need modification to make them usable. Many owners replace the cabinets completely.
The primary problems are:
The side panels and rear panels are approx 21mm thick, and made from a solid timber core laminated with a surface finish veneer. These panels are adequate, but benefit from some additional side-bracing and damping.
In the case of the Lancaster, this cabinet is much shorter than the York cabinet shown. As a result the driver unit is physically lower than ear-level when seated and listening- this impairs the HF performance owing to the relatively directional nature of the Tannoy Dual Concentric drive units. For this reason the Lancaster may be less suited to modifying, or it should be used raised off the floor.
Shown here are the modifications undertaken.
The cabinet was completely stripped of all the original internal damping material (but this was set aside and re-installed on completion of the modifications). This was necessary to get access to the screws holding the front escutcheon in place, and the screws holding the front panel in place. The escutcheon and original front panel was removed. Both are held in position by internal screws, screwed in from behind, through a square timber batten in each corner of the cabinet.
With the particular cabinets concerned, the original timber battens in each corner were no longer securely glued to the inside side-wall cabinet surfaces. These joints were reglued with PVA glue.
The original front panel was increased in thickness with another plywood panel of differen thickness (15mm) attached to it with screws only. It would also be possible to glue the panel, although this would probably result in a higher-Q (less damping) within the front panel. The total front panel thickness is now 27mm.
A new cut-out was made in the 27mm-thick front panel to allow for the drive unit to be mounted in from the front.
A new cut-out for the port was made that was 250mm wide.
Then another smaller baffle was attached (also with screws only) to the inside of the front panel, against which the rear-flange of the drive-unit chassis mounts. A felt gasket was used to seat the drive-unit against the baffle.
The completed new front panel was re-installed. Originally the Tannoy York did not use glue to secure the front panel to the side-panels. In my case I used screws (this time screwed in from the front, not rear) spaced at about 100mm centres. It would be fine to used glue as well here to increase stiffness.
Lead sheet was secured to the inside surface of the side and top panels with bituminous sealing compound to assist with damping panel resonance. In addition, a bracing member was screwed and glued to the middle of the side panel.
A new bracing arrangement using kiln dried hardwood was added to securely attach the front panel to the rear panel (see photos).
The new port opening in the front panel is 250mm wide by 75mm high. With
a new duct of about 180mm, this gave a cabinet tuning around 32 Hz. This
gives the classic "drooping" Tannoy LF response below 100Hz, with
a shelf down to around 30Hz (approx -5dB) and then rapid roll-off below
this. This is deemed preferable to the original tuning, which gave flatter
response down to 45 Hz, but rapid roll-off below this. Corner placement,
or tone controls easily equalises the LF-shelf in the tuning chosen.
A new grill-panel was installed, made from 3mm MDF (medium density fibre board). The grill was obtained from Falcon Acoustics in the UK. The original escutcheon holds the new grill panel in place with push (interference) fit. The escutcheon and grill-fret can be be removed from the front allowing access to the drive unit without unscrewing the back panel.
The original Monitor Gold crossover was dismantled, and the capacitors
replaced with Solen Fast-Caps. The HF control-switches were also disabled
by hard-wiring for nominally flat response.
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