Not strictly related to the speakers themselves, but as the miniDSP is a core component in driving the speakers I’ve noted this in the “beyond-econowave” posts:
For a long time the miniDSP was sitting bolted to a lump of wood, the “temporary” test chassis, with a cardboard box sitting on top of it to cover it. But this test chassis was quite noisy.
I’ve made a simple pine enclosure that makes up in solidity what it lacks in sophistication. It still containes the miniDSP and 2 simple OPA2134 based pre-amps to give me a bit of gain over the quiet miniDSP output, but I’ve got a 4 channel stepped attenuator (actually two stereo stepped attenuators ganged together) as a master volume, plus the software volume control as a fine volume pot.
There’s also a switch to switch over to the analogue input for “guest devices” .e.g. mates dropping over with DJ mixers or synths – so the sockets are on the front for easy access.
Made with bits of pine from the local hardware warehouse, and painted with leftover stain/varnish from my big speakers so it matches.
With the woofer enclosures now looking pretty good it was time to tidy up how the compression driver is supported, and tidy away the LPAD and protection circuitry.
I got some small pine boxes of the right size (from ETSY seller HIPROGRESS. I stained this the same colour as the speaker boxes, and got some self adhesive 4.5mm neoprene sheet from Clark Rubber to act as vibration damping, and protect the finish. This acts as a nice firm bed for the compression driver.
Both before and after I went overseas I’ve been experimenting with the most excellent Active Crossover Designer spreadsheets by Charlie Laub, with a lot of input and information from the Stereo.net.Au forum users, especially henry218. It’s a lot of fun to upload some measurements and get some crossover configs and ideas from helpful people and find they work! Later I’ve gotten to grips myself with cutting and pasting miniDSP biquad settings. There is quite a bit of info posted in the relevant thread, but this remains a work in progress while I improve the measurements needed to get the best results.
Also I’m quite curious to see the improved ACD that Charli Laub has in development that will include heatmap graph capability for evaluating directivity.
It took me a while to get to adding some finish to the speakers, but I finally did using some “Cabots Satin Jarrah Water Based Stain and Varnish“.
At long last the enclosures for the Lorantz 15″ woofers are (mostly) done:
Big thanks to Col for helping with the build – his expertise gleaned from the multitude of enclosures he has created was a big help in streamlining the assembly process.
After a very long delay I’ve finally gotten around to working on better cabinets for the Lorantz woofers that will unleash their full potential. Having adequate enclosures so I could be lazy and use the speakers as is no doubt contributed to the delay, but also some non audio related stuff got in the way as well, as happens.
boards assembled to check but not glued yet
The current 139 litre volume of the cabinets I’m planning need a two 100mm diameter 24 cm bass reflex ports to tune to my proposed frequency of 33Hz.. Any of the bass reflex tube products cost quite a few bucks to send over to Australia unfortunately. Thanks to the useful suggestions of Stereo.net.au forum members, I got the idea of making my own from PVC water piping, using a heat gun to form the flares. But I’m not so handy with being able to fashion them presentably well, so I went with a combined approach of using some less expensive fixed lenth 200mm long ports (the same kind from Altronics I’ve already used), with some 90mm PVC piping to make short extensions with flaring on the end.
Lucky I still had the offcuts from the ones I had shortened for the Econowave speakers so I could use that to check the dimensions were OK:
There aren’t many constant directivity waveguides for 1.4″ compression drivers, but one I had not been aware of until Paul Spencer and SvenR on SNA forums brought it to my attention was the 18sound Xt1464.
After reading up on it I found it online for sale (inc shipping) not too expensive at www.thomann.de. It did take ages to show up though, with very detailed notifications of the first and last 2 days of shipping, and nothing for the 3 weeks inbetween.
I’ve been running through ideas for some cabinets for the Lorantz woofers.
The current fairly rough PA cabinets that came with them OK, but I’m not getting the full bass the speakers are capable of.
OK, we know that simple on axis, straight into the speaker frequency measurements aren’t the whole story – getting a range of measurements at different angles gives a better idea for speakers getting general use, not the whole glued to the magic sweetspot that a lot of hifi has.
So it was time to do some directivity measurements. I don’t have the a licensed copy of ARTA so I can’t do the heatmaps ala Gainphile’s site – but at least Room EQ Wizard is a nice free package that makes it fairly easy to overlay lots of frequency response graphs in different colours.