(Slight topic swerve) I'd welcome any discussion on the following point.
Given the OEM decided to offer a 3-way box with passive operation - or partially passive - mode, what would govern the choice between:- Passive X-Over from LO-to-MID, vs
- Passive X-Over from MID-to-HI
In contrast to the EAW box described here, in which the LO-to-MID X-Over is passive, many other 3-way boxes that offer "bi-amp-able" operation allocate the passive network to the MID-to-HI X-Over function, and thus permit the LO band to be fed with its own amp channel.
To get the conversation started, I'll ask: Is the reason for EAW's choice in this regard connected to the OEM's pre-existing inventory of passive networks? Or is there a consideration w.r.t. a CD horn?
Thanks in advance!
Firstly, you can’t use an OEM crossover in a box like the 650. Designing a passive crossover for a box of that quality is very complex.
One of the advantages of digital crossovers is that its easy to time align the highs, mids and lows. That means you do not have to physically time align the drivers, giving you more freedom with the box design.
In the case of the 650; using a passive crossover between the lows and mids worked very well - the lows and mids summed nicely through the crossover region. Where as using, a passive crossover between the mids and highs did not work as well in terms of time alignment / crossover design - phase alignment / sound quality etc.
You may notice that the 15 and 10 are not in physical alignment, however the 15 is reflex loaded and the 10 is horn loaded operating down to about 250 hz. That results in the 15 and 10 having a different phase response. If you model all of this, the horn, the reflex enclosure and the distance between you will find it works out nicely and you can design a good passive crossover.
I’m guessing … but if they wanted to make the mid/high crossover work they would have need to make the HF horn deeper (and therefore bigger) to get the time alignment they needed … and then it would not fit inside a box the size of a 650.
FWIW in practice, I think using a low/mid crossover Vs mid/hi crossover cost them some SPL.
Peter