The Mini-Bookshelf was designed as a small speaker for the classical music enthusiast, and was used for assessment in our application to the BBC for the license to build their compact monitoring speaker, the LS3/5A (see below).

The bass/midrange was an Audax 6.5 inch unit, with an Audax fabric dome hf unit.

The Bookshelf was a scaled down version of the RAM1, using the Dalesford 8 inch bextrene bass/midrange, with an Audax fabric dome hf unit.

This, like the Compact, was very popular and sounded much larger than its size suggested.

This used the same units as the Bookshelf (both this and the Bookshelf were based on the original RAM1 design).

The RAM150 introduced our first use of ABR's instead of reflex ports, with the ABR manufactured on a Dalesford frame.

The RAM200 was a larger version of the RAM150, using a 10 inch ABR and a larger magnet on the 8 inch bass/midrange unit.

The RAM400 was a top end speaker using KEF units, including the old B139 bass unit. What was unusual about this speaker was that the bass enclosure was an infinite baffle design, which no-one had ever done before with a B139.

The bass was very tight and clean, and imagery was great.

The STL4 (this is a 3D recreation as no pictures exist) was a huge transmission line, using a pair of Daleford 13 ohm bass units in parallel to drive the line, a Dalesford 8 inch midrange (because we liked the sound of it!), and an Audax fabric dome hf unit.

When we measured it at the GEC Reseach Centre anechoic chamber it had the deepest bass of any speaker they had ever measured, remaining flat to 30HZ before rolling off.

On initial listening, it seemed bass light, until real bass appeared, 

The LS3/5A is a compact monitoring loudspeaker designed by the BBC.

RAM obtained one of only three licenses for manufacture of these speakers, which were built to a very high specification using high quality (and expensive) components. Drive units were matched in pairs to within 1dB, and the balance between bass/midrange and hf units were then adjusted in production, again within 1dB.

The drive units are the KEF B110 bass/midrange, and the KEF T27 hard dome hf unit.