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I've been working on various active speaker projects since buying my 2X4HD, and subsequently upgrading it to DDRC-24. One of these was a pair of 2-way stand mount bass reflex speakers using Tannoy 8" Dual Concentric drivers that were salvaged from one of their "in-wall" speaker products. These sounded pretty good, but I always felt that they were lacking in bass extension and the bass always seemed "strained" and not as crisp as it could have been. So, I decided to try my hand at a 3-way design - I have a 2X4 Balanced, so I figured I could use the DDRC's crossover to separate out the HF for the tweeter, and feed the LF into the 2X4 Balanced to split the mids out from the bass.
I came across a pair of Tannoy 8" woofers used on Ebay and bid for them; turned out that the guy selling them had 2 matching sets, so I ended up with 4 bass drivers - so using a pair of them in each cab I would have a similar bass driver cone area to a 10" woofer, which seemed like a promising way to go. I spent a while modelling the bass end in Basta! to figure out cab volume and reflex port dimensions, and drew up the cabinet in CAD - all looked pretty good on paper. I had a fair amount of 12mm thick OSB board left over from lining my shed, so I decided to use that in double thickness to build the cabs, and because it is quite "friable" at the edges, used 12mm square Oak battens to finish the corners.
Much sawing, glueing and varnishing later, and I now have a pair of floorstanders - the DC driver is mounted in its own small vilume compartment at the top of the cab, with the rest of the volume being used as a bass reflex cabinet for the pair of woofers. The bas-to-mid crossover is currently set at 300 Hz and the mid-to-treble crossover at 2000 Hz.

Cabs assembled and had their first of many coats of polyurethane lacquer.


Right hand cab with drivers mounted.


Left hand cab, with one of the old stand mount cabinets in the background.


Very happy with the end result; bass much better integrated with the mid/treble and much deeper/punchier, and the imaging has also markedly improved. Upgrading the DDRC to Dirac V2.0 has been a great improvement as well.

Beautiful speakers @TonyJ! How does it sound? Send us some screenshot of your Dirac when you get a chance.

Thanks @Devteam. They sound excellent, though I say so myself - lots of detail, plenty of bass extension, and the imaging is pretty good too, so ticks all my boxes.

The Dirac plots look like this:





I am using the Harman curve, which I was using under Dirav V1 - see one of my other posts re the issues with porting them across from V1 to V2.

While on the subject of V2, when I start Dirac it encourages me to upgrade to V2.3, but there was a thread in here that suggested to stick with V2.2.3. Is that still the case, or have the V2.3 isssues been resolved now?

Hi Tony_J,

I'm impressed by your woodwork skills. It looks good. Hope that it sounds good too.

I am planning to go active with tri-amping, I currently already have one miniDSP 2x4 HD (not upgraded yet to DL), and I am using it for one box (with now three active LF/MF/HF speakers). Without Dirac I am already stunned by the improved sound quality thanks to tri-amping and REW (without the 40 year old filter). The second speaker (with the original filter still in place) is powered from the remaining fourth audio output.

So, my next step will be to go active on the both speakers.

I am really curious about more details of your experiences and your hardware miniDSP setup. I would really appreciate it if you could tell us a bit more about it.

Thx.

Hi Frits

Thanks for your kind words! They sound pretty good to my ears.

The approach you have taken (use one 2X4 HD for one box, and then a separate one for the other box) will certainly work, and as you have discovered with the one channel so far, the improvement in sound quality is quite significant. With the Dirac added to the mix, the results are even better - the imaging improves, the overall balance is better, and of course with the "target curve" approach you can tailor the speaker response to pretty much anything you like. Just for amusement value, I have made up target curves based on frequency response curves for well-known speaker brands and used then to generate filter sets - with the ability to define 4 different sets, you can then switch between them to see what kind of profile you prefer. Great fun. However, running two 2X4 HDs, one for left and one for right, is a tad cumbersome - ideally, you would start with one of the miniDSPs that offers more than 4 outputs, so you can do it all in one box. I ended up where I am because my previous projects were all 2-way and I had a spare 2X4 Balanced that I could press into service. The advantage of my "cascaded" approach is that once I have set up the 2X4 Balanced for the right crossover frequency and any gross level matching, I can leave it completely alone and do all of the fine tuning on the one DDRC-24. You could almost certainly get to the same place using two DDRC-24's but you would have to run Dirac twice (one for left, one for right) and that is a bit cumbersome, and of course expensive. The downside of my approach is that I'm going from digital in the DDRC-24 to analogue, then back to digital in the 2X4 Balanced, which I'm sure the purists would frown at.

If it helps in visualising what my setup is, I've done a crude diagram - see below (I am showing them at a HiFi enthusiasts show so had prepared this for the attendees). The amps are IcePower 50ASX2 Class D amps, 50+50W, in cases from Ghent Audio. So nominally, there are 6X50W amps driving the system. The bass drivers are 6 Ohm, wired (at the moment) in parallel, so they are presenting at best a 3 Ohm load to the amps; that is probably a bit on the low side, and I have a fourth IcePower board, so I am waiting on another case from Ghent which will then allow me to give each bass driver its own separate amp channel. It is actually running fine in its current config, so this may be a bit unnecessary, but it will make me feel more confident that I am not overloading the amps.

A brief update - just upgraded to the latest & greatest Dirac 3.0.11, plus the latest plugin and DDRC firmware, and these are sounding better than ever. Well worth the small amount of effort involved, particularly if you have not yet upgraded to Dirac V3.

Another brief update - in September last year I replaced the DDRC-24 and 2X4 Balanced with a Flex-8 - makes the plumbing a lot simpler and the setting up was easier too. It's a great product!