affect of passive cross-overs on Re

now then........

....i've been sitting at work all afternoon pondering my new mid/top end set up and how its going to come together......

......i've got some of the components already and kinda know what other bits i want.....its at the planning stage at the mo coz its taking all my spare time to make the remaining high-pressure hornz, but a little advice on a couple of things would be appreciated.....

...right... in total its going to consist of.....

2x P.Audio BMD450 1" exit compression drivers 1.75" voice coil 80w (r.m.s. i assume) 108dB spl..... mounted on P.audio PH220 90x70 dispersion horn

4x phl audio 1130, 130W aes,   16ohm,  300-5k htz,  sens=96dB spl max 113dB 1.5" voice coil

these two will make up the top end, with 1 comp driver and 2 phl drivers per side, crossed over active 500htz-20K(?), then 2 way passive with eminence px2-3k5 xover (lp 12dB/oct, hp 18dB oct, 8ohm 400w) crossing to the comp drivers at 3.5K  

2x phl in parrallel require 250W at 8ohm......1x p.audio requires max power of 150W at 8?ohm(?bit of a guess?)......without the xover the combined power of all drivers required would be 400W at 4ohm (correct?).......the x over is stated as being 8ohm.....what effect on the total resistance and therefore the total power required does the cross over make? ...there is a gain +/-9dB to the trebble on the passive cross over so if this was set to  -3dB there would be half as much power going to the one comp driver as there would be to the 2 phl drivers...correct? this would power them all to the correct levels...... 

.............am i talking sh*t here?

i will use 2x 15" fane classic 200W 44Htz-4KHtz for lower mid around 120Htz to 500Htz and these will come directly from the actice x-over....

...how does that sound to people?......i have to leave work now but will be back on tomorrow....

....any advice appreciated as ever.....

cheers    

cheers martin  .......i remember you saying that it would be optimal to build my own cross-over unit........i'm not sure that i'd be able to make one without messing it up........how complex would it be to build a cross over specific to my needs? and how does it compare to the purchased ones in terms of factors such as cost and time? (which i never seem to have enough of at the moment!) ...is there a cross over unit available that would be better suited to the application?

i'll have a quick look at the b+c horns.....and be back

many thanks 

.....now then......just been speaking to proaudio parts, they couldn't think of a horn that i could use the 6.5" drivers on so i think i'm going to go for a normal direct radiating design for the 6.5's and horn load the p.audio tweeters......i want to stick 2x 6.5" and 1x 1" compression in a single cab........normally they will be used 2 cabs next to each other on top of a single stack.......

would it be better to go for......   T    or..&nbs p;  M      or....&nb sp;   T      &n bsp;   

                                                 M      ;       T           ;    M   M

                                                 M      ;        M

....( T= 1" copmpression , M= 6.5" phl audio).....to keep interference to a minimum?

many thanks as ever

Limmer do a 6,5"/1" midrange flare and IIRC there was a 6,5" mid in the works at PAP. Enquire about Limmer at www.lsv-achenbach.de . Limmer aren't cheap though.

Regards

Martin

You are catching on. if you have a horn with 60 degree horizontal dispersion (turning a 90x60 horn around) you'll end up with a trap cab with around 15degrees for a side angle. Whether it's sensible to keep the Mid-high section as close as possible to one another...I'm not sure. This would mean that you'd end up with a left and a right speaker.

With a little effort, a measurement mic, pre-amp, jig and speaker workshop, you can design your own crossovers, but crossover design is a bit of an art. One needs to be especially careful of the response characteristics off-axis if you intend on being able to stack these properly.

Martin

Basically, assuming a well designed crossover.

Due to cost I would also recommend a DR setup for now. You can play around with a horn setup at a later stage. A well designed crossover is a big boon though. In Germany you get people like Sound Klinik that design crossovers for people like yourself, but methinks you're looking at 200Euros for the design.

Do a search (perhaps on diyaudio.com) on the Edge tool. Shows you the effect of baffle diffraction on frequency response.

Regards

Martin