Omnitop 12 build pics

 

With a larger ported rear chamber the cabs can work standalone down to a reasonable crossover point of perhaps 80-100Hz rather than cutting off at 160Hz or higher which would ideally require a kickbass and a sub cab which I dont believe very many people have room to cart around or power but of course when they do its MT122 or 102 all the way.

 

There are obvious limitations of the designs such as the shorter horns can never give as much gain and focused dispersion as a longer horn and that his DR bent horns should never work in a million years but it all comes down to what is

 

a) important from a practical sound perspective and

b) what people are willing to accept as a compromise.

 

As I have said before the plans were initially made for small bands and DIYer musicians running their own rig, since then as the popularity has grown there have become a more professional engineer following but it seems that while there may be things that you as a designer would not consider because they may be "too compromised" for your tastes, Bill has managed to make them work because he has worked out that while you might not accept that as a compromise, many people will.

 

Sure the DRs may have time domain issues and require a fair amount of EQ to get it sounding right and some wise people such as JD01 have pointed out that even EQ cant account for any phase anomalies that might occur but it goes back to the fact that nevertheless people are still satisfied with their sound. The reason I use BF cabs is because I want the efficiency of a horn even a compromised one but want the portability of a reflex. I believe many people share that view.

 

Stu

 

There are also instructions on how to construct a makeshift phase plug in the plans from styrofoam which help to get the box to cutoff higher, and also the use of a low pass filter on the woofer increases response at 2kHz with the box rolling off around 3kHz which is where the piezo array or compression driver will take over. The rest can pretty well be worked out from these pictures and the overall dimensions of the box given on bills site 22"x18"x28"

 

The main criticism I have heard about from several speakerplans forum members is that the published SPL charts dont add up. Unfortunately I have no means of testing the overall output, as I dont have SPL measuring software, what I do have however is a good ear and thats ultimately what its all about, but nevertheless the SPL of bills other plan the half size Omni 10 that I built was definitely a lot louder and sounded a lot better than the reflexes I had the drivers in before. There is a review knocking around on this site.

 

The other criticism is about the use of piezo arrays. I dont have a problem with them as I have always used piezos in my boxes with great success, and from the tests done by several forum members including myself I think we have established that 12 piezos properly cut down and arrayed actually make a better sound than a pair of compression drivers and I personally found that the 1177 dual elements give the best overall sound, with the 1005s working best for electronic music.

 

The only beef I have with bill is about his use of eminence drivers which I dont really consider to be robust enough to last and I expect to have much higher power compression figures than some other manufacturers, however they do seem to make drivers with rising responses which he seems to consider most ideal for his horns.

 

The DRs are a different ball game and from what I hear they are a bitch to make but I dont have the plans for them so I cant help you with that. A single DR250 is apparently comparable with an Omnitop 2x12, roughly the same sensitivity of 106/107dB, 1x10" vs 2x12" but the Omnitop 2x12 is louder because of the increased powerhandling and sensitivity of 2 drivers vs 1.

 

Stu

 

Stu