i do have a set of P audio horn for my front L and R mid-hi freq (1,2 khz to about 10 khz) they are cat as* :bigsmile: extremely efficient and clean sound love them.
I would recommend looking for Compression drivers that have 2" throat and low end cutoff of 500Hz. Horns that focus on the 1k-1.5k area can be very 'squawky' and grating. 2" throat horns with lower response like this are pretty$$$
Also take into consideration the crosssover area of the woofer you will use. Many 10''-12'' drivers will get realy muddy above 500Hz. Also, get woofers that are as efficient as possible to reduce the padding necessary for the mid horns. Many may disagree but look at Parts Express for the B&C or Eminence pro drivers. These will be very efficient and have surprisingly good sound. Selenium makes some very good drivers, too. Both for horns and woofers.
The previous post regarding padding of the compression driver/horn and baffle step compensation is spot-on. You can find a baffle step circuit calculator that will run in Excel for free. Without this you may have a hard time getting the sound you want.
If you go with 8" drivers or 10" drivers that have good mid response up to 2k you can cross over your mids around 1.8k at 12db per octave. Again, the B&C or Selenium units should be good for this. If you can find some JBL Pro 2400 series 'butt' horns,( I'm series that is what they used to be called) on eBay or from Pro Sound surplus companies for a good price, get them. They have a high end response up to 20k and sound great. I don't remember the exact model# You can look at JBL archives and high frequency drivers.
If you have the amplifiers, use an electronic crossover. Again, amps and crossovers get into more moneyof course. If using and AVReceiver this is won't work unless you have pre-amp outs.
What will you be powering the speakers with?
You may want to look at some of the Klipsh designs to give you some ideas. You would be surprised how inexpesive the drivers they use are and who makes them.
Be careful mixing 4 ohm and 8 ohm drivers. Some amps just don't like it and there is really no benefit unless run in series. Plus you will have to use larger component values for inductors and caps which will cost you more money. With two woofers in series you will obviously have an 8-ohm load.
Best of luck.