It would appear that this process is a like a juggling performance with several balls. Some would say i am clown and should not be allowed to fool about with audio reproduction equipment
The Doc (RIP) hated technical talk and i have been guilty of letting it creep in to my posts and it has certainly become more frequent since RD passed. Before i know it i will be talking complete technical talk that nobody can understand and i will get lost in my measuring and test equipment (and up my own arse if i'm not already there). Don't worry, it won't happen. I will just keep talking nonsense
.Sorry Doc
Anyway back to this juggling. There are several balls - box volume, driver Qts, number of each driver size, orientation of drivers, aperiodic holes, different efficiencies of drivers, series or parallel, high pass filter caps , padding resistors, amounts of doping. That is a lot of balls to juggle. To some degree they affect the others, change one and it leads to a change in something else.
I am just about getting my head a round it all now. Thank god i don't have to design an electrical crossover
It's not all about even frequency response
. In fact for me it's very little to do with that although annoying humps that stick up like a sore thumb are not welcome. I will not sacrifice other more important things (to me) but i will chase it when i know i can safely without ballsing anything else up.
I want an exciting listen that does not fatigue or become annoying. There is a balancing act right there. Omni directional or semi omni definitely helped with that, it's not squirted in my face although the room is filled with lovely music. I want all the detail i can get. Having no filters on the bass and mid bass has helped there but the major thing with this has been adding more tweeters and mid bass drivers. Lower distortion lets the hidden detail out. Going isobaric with the 12 inchers very much helped with bass behaviour and detail.
I want the sound to be more or the less the same everywhere one could be in the room. Sat on the carpet playing with the kids, relaxing on the sofa in the traditional sweet spot if i am alone, sat next to my wife kids slightly off axis, sat on the other sofa which is in line with the left speaker. the semi omni thing definitely helped here. But adding tweeters and mid bass drivers has really opened up this aspect. Comb filtering - i can't say i have heard it. All the drivers of the same type are on different baffles which are at 90 degrees to the next.
I want bass you can feel as well as hear and i want it to be as tight as a duck's arse in water. This has been the biggest headache with these speakers. Having big bass drivers is the only place to start (yes, even in an average sized living room) Getting near the right box volume took a while - i had no T&S parameters to start with. I finally found some for the big 12 incher and could make a big box for it. The 5 inchers are much easier to deal with . The next thing was going isobaric with the 12 inchers. Wowsers. Making the big bass cube aperiodic has helped no end here as well.
I want a box that does not take up the whole room and can be up against a wall. Unfortunately big drivers need a big box or you get a huge bass hump that trust me sounds not too good. At first i looked to isobaric loading to help with this - it did by cutting the required box volume in half. Doc suggested that to do it properly i had to have an equal box volume behind each driver, which i did. But the box is still too big. What to do ? Do what Doc told me not to (sorry Doc) and go for a clamshell arrangement where the volume enclosed between the two driver cones is as small as possible. The only thing dividing the drivers is the 20mm of crappy chipboard. I suspect this could be reduced much further as at the drivers only have a maximum excurion (xmax) of 6mm and they never look like they are moving at the volumes i need. Apparently it is only the box volume behind the rear driver which counts, the volume between the two drivers does not count. So as little volume is used up as possible by the front driver. Aperiodic venting also drops required box volume so happy days
I am currently enjoying the best bass reproduction i have ever heard. Yes my big cube is no longer sealed enclosure and my isobaric configuration is how Doc told me not to do it. The box is no longer sealed (but it's not a tuned port either
) and the clamshell arrangement is against Doc's rues but neither of these brought about any reduction in bass quality that i can hear. In fact some things are improved.
I want a speaker that works at low volumes. People complain about ATC speakers not coming alive until you have them fairly loud. None of that problem here even though the drivers aren't particularly efficient. The lack of components between amp and drive unit has probably something to do with this and the parameters of the drivers themselves. No wadding in the enclosures has an effect on this too. Probably other things as well.
I want music to sound like music, a band to sound like a band not some photocopy of it or where the band are playing in different rooms. I want to know that they were enjoying the process of recording and loved the songs. A lot of this i believe comes down to phase and not going round in circles of phase change.
All in my opinion of course
It would be interesting to hear what these speakers sound like with different sources (i can't bring myself to swap out the nva based amps). It is something i will have to do soon. Different cdp's and get the record player hooked up. I hope that even though i have been voicing these things mostly around my modified Naim CD3.5 that they will work with other stuff too.