Help needed with EQ...Econowave-ish build

[MunkeyQ]

Hello all, I'm in need of a bit of help regarding my latest build. It's a sort of Econowave, using the Celestion CDX1-1745 (used in QSC HPR152i) on the conical HPR122i waveguide. Note to anyone else trying this combo - it's not a straight bolt-together build as unlike most waveguides, the holes are tapped since the 1425 bolts through from the other side. I drilled the threaded brass inserts out and had to use studs +nuts to attach the driver, after cutting away some bracing plastic fillets to get pliers in there to tighten the nuts.

It's biamped with a DBX Driverack, which makes playing around with crossover and EQ goodness a lot easier.

Since apparently this combination hasn't been used before (and I lack any measuring gear!), I'm having trouble dialing in the CD EQ. I'm basing it on the 1425/HPR122i here. However, it sounds very nasal with a harsh hump at about 4khz, making vocals sound unnatural and electric guitar harsh...Metallica and Guns n' Roses (the less compressed albums) are almost unlistenable. Wonderful on bluegrass and anything acoustic though! I've been fiddling for a couple of days with no luck, so I'm wondering if anyone here can offer anything. Oh yep, here's the datasheets for the CDX1-1425 and CDX1-1745.

By ear, I'd guess it's peaky at 5-6khz and a hole at xover point.

I'm using it with a Beyma 8BR40 woofer, which plays nice up until about 2khz and gets seriously nasty after that. It's tameable with a high Q notch filter, but I'd like to keep it playing <2khz if possible. I don't think the waveguide will load down that low though... Otherwise, it's a very nice woofer in a medium sized sealed cabinet - lots of smooth bass, low Fs and oodles of linear excursion. Seems to be the same cast basket as many Beyma midranges...smaller motor though.

However, I've got a niggling feeling that the nasal-ness is due to the woofer's HF limitations. Would be nice to get rid of the harshness though.

If anyone's wondering why I didn't go for the conventional E'wave build, it's because Selenium parts are unobtainable in the UK, and JBL charge a fortune for the waveguide. £7 for the part, £45 each for shipping! Over $160 just for the base-level waveguides...that's 18sound money. QSC are much more reasonable, although shipping is very slow. Screw-on drivers are also uncommon over here, but Celestion parts are plentiful. I understand the 1745 uses the same diaphragm as the 1731, albeit on a ceramic motor.

Thanks in advance. Any replies will be much appreciated!