Digital Active Speakers - My experience to date

[Damian]

Thanks for sharing that.

I've made my 3-way Heybrook Sextets active using 2 miniDSP 2x4HDs. I started out with what amps I had available, initially Marantz MA22 monobloc power amps, Quad 405 and the power amp section of a vintage Marantz 2285B receiver, the control the miniDSP has on these elements is quite amazing and dealt perfectly with the various sensitivity values of both the amps and the speaker drivers.

The first part of the conversion to active (after removing the crossovers) was to work out the crossover points of the units from the crossover and then replicate this using the miniDSP which was very easy with the crossover types that are available to you. This enables you to pretty much reproduce the sound of the speaker, that's when you can really start to play. Using REW (Room Equalisation Wizard) and the UMIK-1 microphone you can get a response curve to baseline your work so you can see the effects of phasing, the cone responses, the tail off of the drivers etc and then you start to move the crossover points, taking advantages of the crossovers types.

I changed the amp set up once I became happy with the results, so now I have two Linn AV5105 (two LK240 in a single box) providing the bass and the highs, with my MA22s covering the midrange.

I'm going to make the leap to Dirac Live, what Andrew said about the REW filters etc really has helped make that decision. Whilst I enjoyed the listening, the monitoring and then using REW to model the response, it became quite tedious and you always felt the need to fiddle (well I did!) however the results are amazing, just what I was looking for and breathed further life into my Sextets.

[Bencat]

Interesting read Andrew. Thanks for that. I plan on going to to Kegworth and will look you up. I see you are also doing the suitcase challenge.

Yes I will have very minimal system which I must say I am surprised at how good it sounds. Look forward to meeting you .

[Bencat]

DIRAC Graph 1.jpgDIRAC Graph 2.jpgDIRAC Graph 3.jpg



I am putting this here because it concerns the MiniDSP DDRC 24 but it is also connected to Quad ESL57 speakers which I realise should be in Past Masters apologies if I have got this wrong . As well as the above Active system which I use in my spare room I also have a MiniDSP DDRC 24 in my main system which is SBT Clone - Toslink out , MiniDSP DDRC 24 then two analogue outs to my Krell KSA50 connected to a pair of refurbished Quad ESL57 speakers.

Now I use the MiniDSP in this instance in full bypass mode for Crossover and Equalisation but use the DIRAC Live filter to adjust the Quads in the room . However I have had a very frustrating time recently since the newly refurbished Quads have come back with issues over distortion when the volume is raised and when there is heavy bass content . I have changed the routing of my system to the MiniDSP from analogue via a Concordant Valve Pre and Metrum Quad DAC in to the analogue inputs on the MiniDSP to a direct digital in but this dod not solve the problem .

After help and advice from others that use the MiniDSP and based on the graphs I have copied in below I was made aware that the target curve that was generated (Graph 2) was asking toom much to drag the Quads dip to the required level and this was causing the over load and distortion in the MiniDSP . So instead I have set the revised target in Garap 3 and I am now able to play the Quads to a very decent level with no distortion . I have lost a little power in the Bass but what is produced is at least clean and easy to follow. I am sure the settings can be tweaked and I can get a little mor lower bass out of this without setting off the MiniDSP but at the moment I am just going to listen to the musc for a few weeks and let my ears grow used to the current settings before I try any changes.

This just shows the very different roles you can use the MiniDSP unit for and how it can make a real difference in almost any system .

[Discopants]

Very interesting read Andrew thanks for sharing. Could the bass response you are noting after the quad service , just be changes in room response ?

[andy335touring]

Thanks for sharing, i've been contemplating going active for ages but with new drive units/design rather than converting an existing speaker.

A side from not having a lot of spare cash at the moment i'm constantly changing my mind on which sort of design i want to go for but one or two things are fixed is that like you i'm going for a sealed design and it needs to be a fairly compact floor standing speaker.

If i'm not working i hope to see you at the Kegworth show

[Bencat]

Very interesting read Andrew thanks for sharing. Could the bass response you are noting after the quad service , just be changes in room response ?

@Discopants Sorry i might have misled you the problem with the distortion was there before the Quads were refurbished and in no way would I make any suggestion that the work done has been anything but excellent . Thye are miles away as plain speakers from when I bought them . All issues are with the DIRAC filter and my room and the fact that DIRAC will try to correct a problem to try and achieve the ideal house curve response even if this is nt really possible with the speaker you are using. Like lots of modern equipment and software they make much of what they do simple and easy to use we forget that they need you to still work and try and understand what they are doing . They can still get things wrong you need to be able to spot the areas and address them .

[Edward]

Andrew (bencat), yes your experience matches what I found as well (even though I have not used minidsp/Dirac). Always best to concentrate on EQing the peaks and not try to EQ the bass dips too much. So setting the target curve appropriately will be the way forward. Or just remove the big +ve bass EQ points manually (not sure if minidsp/Dirac allows that).

Generally large bass dips (assuming the amp is flat to such levels) is caused by poor room acoustics which suck out bass. Trying to EQ these dips is asking the amp to do far to much (=distortion). Best to cure the room response passively with say bass traps or diffusers as the case may be. Passive room treatment is still on my todo list so lots to learn there.

[bumpy]

Andrew (bencat), yes your experience matches what I found as well (even though I have not used minidsp/Dirac). Always best to concentrate on EQing the peaks and not try to EQ the bass dips too much. So setting the target curve appropriately will be the way forward. Or just remove the big +ve bass EQ points manually (not sure if minidsp/Dirac allows that).

Generally large bass dips (assuming the amp is flat to such levels) is caused by poor room acoustics which suck out bass. Trying to EQ these dips is asking the amp to do far to much (=distortion). Best to cure the room response passively with say bass traps or diffusers as the case may be. Passive room treatment is still on my todo list so lots to learn there.

This is my experience too. Never try to bring up a dip of more than 3dB always lower the peaks and plateaus.

[Bencat]

Right now back to an update on my active set up . I was planning this system to be a Raspberry Pi with Picore and Justboom Digihat digital out to a MiniDSP DDRC 24 then from the MiniDSP out to two Quad 405 amps upgraded and matched by Fidele Audio . Problem was when I got the Quads back one developed a problem which was complete silence . So back to Fidele which diagnosed an Speaker Protection Baord that was wrongly configured so not fast enough to turn off before damge to the boards were done (nothing to do with Fidele these were Net Audio mods) .

So while the Quad was away being repaired I used one Quad for the Bass on my KEF 103's and a Trio Basic 1 for the treble . A DIRAC Live mesaurement session and this worked very well indeed and sounded excellent .

Wednesday the repaired Quad arrived back and as I only had the evening to mess about I just did a straight switch of the Quad for the Trio still looking after the treble for both speakers. Another DIRAC measurement session and put some music on . Firstly and best result music came out and it sounded good , just good not really as good as the Quad / Trio combination which was a bit of set back . Did some adjustments with music to the filter curve and this improved things but still not better than the Quad / Trio .

Just listened to the system through Wednesday night and Thursday until this morning as i do not work on Fridays it is a great day for getting stuck in to a project . So first made up a set of longer speaker cables for both speakers as this has been just a spare rooom system in a small room and only needed short cables. In five weeks I will be taking this to Kegworth so needed a new set of longer cables in order to be able to get a wider spread for the spekers in a bigger room . While I was doing a full refit of the amplifier s seemed the ideal time. Then I set the Quad amplifiers up as a single stereo amplifier for each speaker right and left with each amp doing Bass and Treble (Right for bass Left for treble) . Once completed turn on and sigh of relief nothing , no pops no buzzes no hums everything as it should be .

The out with the tape measure and the coloured notice board pins and measure out and complete a complete new DIRAC Live session . This went as expected having done quite a number of these over the last months i now seem to be able to get everthing in sync and completed very easily . The suggested House Curve shown at the end of the session looks pretty much like all of the previous ones I have done . However I know from experience that it needs a little tweaking here and there to suit my ears and my system . applied this and then press the music play button . Smile as wide as the Mersey as msuic comes out and the sound is not just good bu excellent . Switch back to the filter page in DIRAC and i am able to make some very small adjustments on the fly and hear the improvements (or were i ahve gone too far you know how it is) .

To me supreme delight this new set up is now not only better than the Quad / Quad for Bass and Treble set up but also much better than the Qaud / Trio set up . Main areas on improvement is in the texture of instruments they sound more real with little elements like the sound of astring now being much easier to hear. Then imaging this has just snapped in to place and is so much better than the passive speakers and all my other active ones as well . These are sealed baffle design and I use them hard against a back wall which reduces the imaging ability well this now brings lots of that back but i retain the speed of notes and bass reinforcement I was gettin from placement .

I am really pleased with my finak results and will be very interested to hear any comments (good or bad) at Kegeworth . I have suddenly realised that this is a very personal system made up for my own personal use in a single space and I like what it does . If that can be tranferred to a different room and the sound I get will be enjoyed by others is a different thing. My Wife Linda has just come and said that the last track (Ladysmith Black Mambazo) sounded very good so maybe I have got on the right track at least. I am sure there are little tweaks and changes that will imrpove this but I am satisfied with how it sounds now and I think I will leave the DIRAC button alone and just enjoy the music .

[Edward]

Andrew.

Excellent write up and seems like you intuitively know what to do when adjustments are required.

I'm confused how you set up the Quad amps. Are you saying that you use one Quad amp to drive the LH speaker and the other Quad amp to drive the RH speaker splitting the stereo channel on each to drive the bass and tweeter respectively?

Do you have a picture of the house curve you use showing the full spectrum? How many EQ points is Dirac coming up with to match the target curve?

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