The Build

Right, time to crack on. I was getting pretty cheesed off with this vague, cloudy project, and the Quads are starting to crackle and spit as the diaphragms start to break up with age!

DSP

Interesting as the pursuit of computer-based DSP has been, and I've acquired and even read a lot of books on the subject, since this was already complicated enough, I decided to go for the originally-specified MiniDSP 2x4. 

I did consider its considerably more expensive ( >2x! )brethren, 2x4HD and 4x10HD, on the basis that a) they both allow for fully digital inputs, thereby removing a D/A/D stage b) the latter has additional channels which can be used to feed subwoofers when/if that happens. But I'm very aware of requirements creep from my past life in large-scale IT projects, and how much that can screw up the achievement of any useful results. 

So, KISS!! £93 from CPC, quite a bit but I have other projects I can use it on, and keeps it all very simple. 

Amplification

Inspired by The Rational Audiophile, and not really willing to take on the building of amplifiers in order just to get the speakers to work, I looked for a suitable 6/7 channel AV amp. Luckily, Gumtree had an old Sony STR-DB1070 with a broken volume knob (works with remote still), that has 6 channels of amplification, and the right pre-amp spec to match the MiniDSP 2x4 - £35 to you, mate, from a Polish lady who works at Reading University. Too bad I had to drive to sodding Woking to get it, on an M3-closed-for-repairs day.

Loudspeakers

Cutting a long story short, I have decided to go for the DIY route. Yes, it's nominally cheaper (£100+ on a £6-700 total with amps, DSP etc.), but it's more that I fancy the challenge! So yesterday I spent a long time online, at

• Falcon Acoustics - chassis speakers; incredibly, these arrived 24 hours later!! Nice bits of kit, and very unusually structured - the rear spider that keeps the cone in place is actually separate from the magnet assembly on both types. Gosh.
• Pipestock - purveyors of PVC and ABS pipe to the gentry and other less salubrious individuals/organisations. Should deliver my 3m apiece of 4" and 3" PVC soil pipe on Monday. Some substitution required...
• 4" Class D PVC pipe, 3m length
• 90mm 9bar PVC pipe, 3m length (for 10" requirement!)
• Studiospares - connectors and 4-way speaker cable; rather than two separate sets of of wires per speaker, one for each chassis, I've gone for 4-way cable and 4 pole Neutrik Speakon connectors, largely because they look really cool and keep it all nice and tidy.
• Wickes - MDF, and the hard-to-source 4" PVC to Clay rubber couplings so easy to get in the US but not here...
• Kay's Fasteners, via their considerably cheaper Ebay shop, for stainless fixings i.e. bolts, nuts, and "rivnuts", a kind of captive nut that is a bit of an experiment, but that's why we're doing this right? Again, some substitution of US measurements required
• M5 75mm partial threaded bolts, nuts, lock washers
• M3 grubscrews, nuts, rivnuts
• M3 socket head bolts, in case grubscrews don't work
• Cybermarket - the original specification for the damping material is AcoustaStuf, not available in the UK; Dr. Frank uses Monacor MDM-3, which has been replaced by MDM-4; that's really hard to find, I eventually emailed Monacor UK who pointed me at Lawrence at Cybermarket, who was able to come up with the goods - hurray!

Remaining Issues

I haven't sourced

• The PVC-to-Clay rubber couplings; I'm going to see how the Wickes ones fit on the pipes when they arrive, then pursue an alternative if necessary
• The ABS 4" pipe cap hubs - these don't seem to be available in the UK for less than £50 apiece, so forget that... I'll use some other approach to attach the bass pipes to the stands
• Anything to cover the rear of the full range diffuser tubes, to stop the wadding coming out; it needs some sort of grill or mesh. No idea yet, but it will have to be very coarse, to prevent any sonic effects through effectively closing off the pipe.

I realised that I have got the wrong size (diameter) of screws to hold the FR speaker in the FR diffuser tube, 3mm rather than 5mm, owing to misreading my spreadsheet. Boo. I'll see how they go, it's easy to order some alternatives at Kay's.