[Vapor Audio]

I still have a lot of work to do on my GR MTMWW project, but am already planning the next one ... I definately have the sickness!  Anyway, how's this sound.

I have 4 Peerless 5 1/4" HDS Nomex cone mids, and a pair of Focal TC120TD5 tweeters.  I'll run them from about 300-400hz up as an open baffle MTM - their low extension will be determined by whatever baffle size I decide.  And for the low end put the open baffle on top of a GR SW-12/PR-12 enclosure. 

I have some BIG pieces of 1 1/2" thick solid curly maple that'll make a gorgeous baffle, and has been cured for about 10 years so it shouldn't warp any more.  The design I'm sure will require a lot of tweaking, and I wouldn't even consider taking it on without the necessary measuring equipment - which I have.  But mainly I just want to play with something OB - I've never even heard an OB design   One big decision will be if I want to use a plate amp on the sub section or not.

[Danny Richie]

I have 4 Peerless 5 1/4" HDS Nomex cone mids,

Not bad drivers. I don't know how low you can really play them in an open baffle though.

and a pair of Focal TC120TD5 tweeters.

I had a love/hate relationship with the Focal tweeters. With the right gear, capacitors, and a well treated room they can really shine, but with the wrong gear, wrong caps, and an overly live room they can take your head off.

I'll run them from about 300-400hz up as an open baffle MTM - their low extension will be determined by whatever baffle size I decide.  And for the low end put the open baffle on top of a GR SW-12/PR-12 enclosure.

 

300 to 400Hz is no mans land. Don't split the heart of the mid-range into dissimilar drivers with different offsets.

[Russell Dawkins]

300 to 400Hz is no mans land. Don't split the heart of the mid-range into dissimilar drivers with different offsets.

You raise an interesting point, Danny. What range do you consider the most important not to have a crossover in?

I know one designer thinks 300 - 3k is sacred ground, and from my experience I would tend to agree.

What do you think?

[Danny Richie]

What range do you consider the most important not to have a crossover in?

The 300 to 500Hz region is the heart.



You can get away with crossovers in the 200Hz region if they are similar drivers or identical drivers and kept acoustically in phase.

With dissimilar drivers I'd stick to 125Hz ranges or less.

On the top end of the scale 800 to 1000Hz is the lower limit. Crossing any lower picks up to much fundamentals. Lower order crossovers or more gradual acoustic slopes will allow the lower crossover points in those ranges to blend more easily as one driver or set of drivers plays further up into the range of the next where they gradually hand off to one another.

1,200 to 1,500Hz and up and you're in great shape.

[Vapor Audio]

Well, it'll be impossible to get those Peerless 5 1/4" drivers to play down to 200hz open baffle without some EQ'ing ... which I don't want to do.  I think I'll just build the open baffle part and see how low they'll go, and figure it out from there.