SQ3 Project

The SQ3 Project? OK, even more “chutzpah” - the ‘SQ3’ stands for Stacked Quad 3, and so this is the third generation of stacked Quads at my place. I have included a number of photographs on these pages, with annotations, of the various stages the construction of the new stacked Quads.

As I've said before, without a complete rebuild of the basic speaker, you can't improve the fundamentals of an original Quad very much. You can't add an extra octave between 20 and 40 Hz for example, by re-arranging the parts. If you own and keep on owning Quads, then you're probably not interested in that sort of diarrhoea-inducing bass anyway. However, there are things you can do. The philosophy behind stacking in the first place was to produce a line source with no degradation in the quality of the sound, and to gain around 3 dB in the treble and 6 dB in the bass. The latter being caused by room effects as much as anything, when you introduce an extra 8 square feet of bass radiators. You can, naturally, achieve this by taking the factory units, removing the banana-shaped side cheeks (decorative ones), inverting one speaker and mounting them "bottom-to-bottom" in a rigid frame. It takes a pretty stout frame too, because these things are not 'lightweight'; at least not when they're a metre in the air, and you're trying to hang on to one!!

The SQ3 frame is entirely made from anodised aluminium and acrylic plates. The frame is riveted together, and the insulation held in place with Silastic 732 used as an adhesive. Special cannisters were made for the EHT units because it suited the aesthetic of the design, no other reason. They are somewhat acoustically isolated in there, so if you had a little noisy mains transformer then you could lock the little bugger up!


Design Aims of SQ3

The basic design aims then, were the following:

  1. Remove a lot of the mass from the top of the standard stack as much as possible, as per the SQ2 build. - i.e. move the transformers to the base of the stack.
  2. Mount the panels in the same configuration but clamp them even more tightly at the top, bottom, and sides with adjustable nylon bolts.
  3. Secondary to 2 above - improve bass, mid-bass and consequently mid range clarity by transferring frame vibrations into a massive, non-reflecting (acoustically, that is!) resin coated base - also making it look pretty in the process :).
  4. Reduce actual mass and acoustic mass of the speaker to a minimum at the panel assembly.


Overall the design aims were achieved (I would say that wouldn't I?), and a significant improvement was heard in the areas specified above. This was achieved in "one shot" this time!!! The whole thing has been done before, and the only (extra) mistakes that could be made this time were insulating the 6kV from the metal frame - thankfully, this was adequately achieved with strips of 3mm acrylic. This structure also has the desirable (from my point of view) feature that it is easy to change a panel ( < 10 minutes) but the structure remains an extremely rigid one.


SQ3 Construction Gallery(click to enlarge)