Apollo OB - ?

[Bigun]

Remember the Apollo missions, when they had something go wrong and the guys on earth had to figure out how to fix it with a few parts known to be lying around in the capsule and time was running out ?

Well this isn't at all as dramatic. But I have a small challenge for you

My friend came by with some old drivers off fleabay and thought I'd like to borrow them for a couple of weeks to try 'em out with my recently completed tube amp.

Of course, these drivers are no good to man nor beast on their own so I thought about knocking up a pair of OBs so I could at least hear them - and no, I don't have any big cardboard boxes lying around I can use.

I have two 15" Alnico full-range(?) drivers with whizzers good to 5kHz+ and a pair of horn tweeters to augment the top-end. There's a couple of dodgy looking cross-over units covered in grime but I'll worry about 'em later.

Looking in the garage there's a few pieces of old wood I can hack up for this. I've sketched out the shape and size of the wood I have on hand.

So what next - I'm thinking I should take the larger panel of MDF, cut it in half to make two 3' x 3' pieces and mount the big drivers in these ?

[Godzilla]

Maybe make this...

Open Baffle

Just a suggestion.

[Bigun]

looks nice and simple, only the drivers I have are 15" and that leaves not-a-lot of baffle.

What about this ?

[Bigun]

nope, with the big cone working up to 5kHz+ I don't want it sitting so low, I'm going to risk less bass to put it closer to the listening height. Looking at the MDF I have available I can make up two 2' x 4' panels.

not much coming from Houston so I'm going to have to wing it...

[Bigun]

progress...

[gvimhoof]

Looking good! Keep us appraised and let us know how the result works for you! Are you going to keep the unfinished look or seal/paint?

[Bigun]

Originally Posted by gvimhoof

Looking good! Keep us appraised and let us know how the result works for you! Are you going to keep the unfinished look or seal/paint?

Well, I've hooked up just the big full range cones, no horn tweeters connected yet (I'll need to look at the grimy cross over units first).

Playing SADE DVD on my HT system (sony blue ray decoder) through my TGM2 amplifiers along CAT5 speaker cables (just made). Hey, these things don't sound half bad ! In fact they sound very nice. Compared with my Fostex Moon Onkens they have real bass, but are not as crisp sounding. Compared with my PMC FB1's they sound a bit thin on both ends, but they're only just warming up. The cones were quite dusty, don't know where my friend got them from.

Since all these drivers belong to my friend it'll be up to him whether he wants my DIY baffles or not. I enjoyed making them this weekend and it's my first time ever to hear this kind of driver and my first time to hear OB.

There's a bit of work to finish them up. First off, they need to be laminated with some 1/2 Birch ply on both sides of the existing baffle to give them adequate stiffness and they need some proper plinths making up. I won't leave them unsealed, I'll use a combination of black paint and sealed plywood.

I'm going to listen to them for awhile, I may become an OB fan, although I've never heard a BLH. Nice thing about being a newbie in this hobby - so much to explore !

See attached photo of the Apollo OB's in action...

[tinitus]

[gvimhoof]

Much cleaner appearance than mine. Glad to hear you like the OB sound! I finished mine last Fall and haven't found any regrets. They still make me smile every time I listen to them after working an orchestra concert (like today). Balanced sound is so much more natural than the heavy EQ curves coming out of radios these days.

[Bigun]

Nice paint finish.

I was at the symphony last night. Took the kids, their first experience. A unique two piano concerto. Very enjoyable.