200Hz CNC'd Tractrix horn starts with Altec "Giant Voice" drivers

[atilsley]

OK, thanks again guys, GM, Bear.

For starters, I'll use MiniDSP, so I can add eq anywhere to see if it sounds good with 300hz.

I understand the horn's Fs has a part to play...and the tractrix profile that Bear talks about.

At the end of the day, I'll get near 300, maybe 350....which will be a great outcome.

I want to beat Avant Garde (Trio) at their onw game, but not having to use a paper driver in the large horn.

If this 200Hz DIY model doesn't work, I'll buy an Azura 160Hz model, with 1.0meter diameter mouth, and 90cm deep....all the way to 1.4 inch throat. That should do the trick.

Like Martin sneddon's own rig (he's the owner of Azura), and uses Vitivox drivers.

 

[Pano]

Yes, the 1 meter mouth would do it.

 

[atilsley]

4 halves now completed to rough stage. Need to trim off glue, sand and paint prior to joining.

 

[atilsley]

more sanding, puttying, throat prep.

 

[Pano]

Looking BIG.

 

[djn]

Looking good!

 

[atilsley]

Good stage to get to...lots of sanding, then first coat of Stark White, flat finish.

 

[Pano]

Such a lot of work!

 

[atilsley]

Expanding foam added to cavity.

Rear ply board added near throat.

Putty added to new half circle area for smooth transition from driver.

1.4 inch to 2.0 inch horn adapters sourced from Cannonsound (P-Audio).

 

[GM]

Such a lot of work!

Yeah boy! It's why I switched to big rectangular WGs and my daughter's Play Doh to morph the throat from rectangular to round, but mine were normally behind a huge 'grill', so just needed them to be a no frills flat/matte black.

GM

 

[atilsley]

Yeah boy! It's why I switched to big rectangular WGs and my daughter's Play Doh to morph the throat from rectangular to round, but mine were normally behind a huge 'grill', so just needed them to be a no frills flat/matte black.

GM

Ha. When I woke up this morning, one of the horns had partly split open due to the expanding foam. Good one.

 

[GM]

Bummer! Great stuff, but really good at blowing assemblies apart. I use to make small three point hydroplanes and the first time I poured in the two part styrofoam, didn't heed the warning, just mixed it by 'eyeball', then watched it blow itself to pieces. Darndest mess I've ever had to clean up!

GM

 

[atilsley]

Oh well.

Tomorrow, I pick up my pristine 290 phenolic drivers...looking forward to seeing how this project comes together.

Will probably end up with xover around 350-400Hz...that's the target.

 

[Pano]

sux! there is some low expansion foam sold in the USA, but not sure if even that would have saved the day.

Fingers crossed for you drivers.

 

[atilsley]

Sanded and puttied damaged section following expanding foam blow out.

More work on the throats...now nice and smooth, with profile almost perfect to the horn flare.

Got my Altec 290 "Giant Voice" phenoloic drivers from Altec guru, Ray Pearson...ye ha.

Cut holes for horn adapter.

Tomorrow I'll join the horn sections, then finished. Happy.

 

[atilsley]

Consummation. Happy days.

 

[Pano]

OK, bolt those puppies up!

 

[atilsley]

Putty added to inside join.

 

[POOH]

Putty added to inside join.

Nice! Those look to be about the same dimensions as the CLS RH60's I have. I recently spent a few weeks evaluating a bunch of big radial horns and they came came out on top. Really sound great with Altec 288 or 299. Very hard to fault. About the same size as my 180 hz round tractrix horns but better LF loading and upper end power response.

Looking good, I think you will be rewarded.

 

[atilsley]

Great, that's encouraging.