May not be DIY to some but with my lack of skills it is

[Bencat57]

Apologies in advance for this as many on this thread may not consider this really DIY but I have little electrical knowledge and even less practical skills.

This all started when I had a room at the HiFi Wigam Show in 2018 . I loved the experience and had a ball . A number of the other rooms had Active Speakers in them and the speed of the sound was quite addicitive. In most cases they had also constructed the speakers .

Well making a pair of speakers was way beyond my own skills and paying someone to make one is both costly and in my view pointless. So I then turned to the idea of why no convert a pair of current models to active ? How hard can it be ?

Next was to decide on what speakers to convert . I have a few sets at home (too many as my Wife keeps reminding me) but the ones that i listen to most are my KEF 103 reference . These are a sealed baffle Two Way made in 1975/6 and I always use them hard up against a solid wall . This has certain advantages , one they are not out in the room so less likely to get knocked by grandchildren as they run aoround , they get Wife approval for being out of the way but more important than this it beefs up the Bass no end.

So as the KEF's are only single wired I needed to open them up remove the passive cross overs create an extra pair of speaker inputs , paint the cabinets with blackboard paint and then wax them to make them look okay and more domestically acceptable.

Then comes the matter of getting an active crossover created and amplifying the units . Well this proved to be much simpler that I expected I could have done a complete measurement of each unit at 1 metre in free space (the garden) using a Umik microphone and REW software and then get the crossover points . However KEF are such a professional company that they even now print out full technical specifications for the drive units with full crossover details .

Next it was then which crossover unit to use , Behringher do one and a company called MiniDSP aslo offer. When I did a bit of research I quickly realised the the MiniDSP 24HD was a very powerful unit that not only could supply the Digtial active crossover but also Equalisation in room as well.
So apply the KEF CR points (3000 khz in the case of the bass to treble units) . Choose a slope (12db,24db,36db,48db) then using REW generate a test tone and get the software to create a complex filter for each speaker in the room . Copy and paste these directly in to the MiniDSP software and then play the first tune.

As I mentioned I have always loved these KEF speakers and I was delighted that they not only retained there original sound but the advantages of active just added to them . They were always weel intergrated and musical but now they were even more musical , stage sound and imaging was greatly improved (always something you lose with speakers against the wall) and the very addictive fast sound quality that active's seem to have . Notes start and stop much quicker giving the sound a more realistic and real sound .

All of the above was good and I was very happy , but there is a very strong temptation to just do another measurement with REW and try and refine the filter just to get a little extra . The problem is you keep thinking and trying just one more session and you always have the nagging feeling that you are almost there but not quite there. This could have gone on for weeks and months but then I looked on the MiniDSP site and found that my units could be upgraded with a firmware flash to DIRAC Live software . This is a much more sophisticated software DSP programme that offers much more powerful in room correction at $150 it changes your MiniDSP 24HD to MiniDSP DDRC 24 .

Well DIRAC as noted is much more complex and powerful option but strangely it is also much simpler to use. You retain the Digital Active settings on your unit then perform a full measurment using the UMIK mic under the DIRAC software. This takes sound measurments from nine specific points and then calclulates a full digital filter that corrects the sound based around a fully flat measurement from 10HZ to 20,000kHZ . As they then state and I have heard it so agree a flat output across the whole audio listening spectrum sound dull and lacking in any interest . So they produce what they call a house curve which is slightly tilted upwards for the bass and then dropping off slightly at the 20,000kHZ point . The differenc is not subtle. Even just using the curve suggested the sound becomes more of a whole and the bass and treble really have a life of there own in proportion to the music but also seperate so eithe can rise and fall at the same time and you can here them both moving in different directions . You can easily change the target curve and best of all you can do this on the fly while music is palying and directly hear what it is doing to the music. This gives you the ability to then tune the sound to your own taste .

I know that much of the above and what I am doing is not somehting that NVA for Dr agrees with as he feels it is just complication which makes things more difficult to get right rather than his ethos of trying to simplify things to gain synergy . I am not making any claims that what i have done is the right thing to do but for me it has produced a hugely musical outcome that i listen to almost every day . Along the way I also learnt much more than i knew when I started (along with the inevitable the more you learn the more you realise the less oyu know) and I had fun which for me was just as important.

Full system now is as follows - Logitech Squeezbox Clone front ent - Digital out - MiniDSP DDRC 24 - Pair of Fidele Audio Modified Quad 405.1 power amplifiers - Modified KEF 103 Reference speakers .

[Latteman]

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