I was able to circle back around to this project last night. I've been spending a lot of time lately getting my Mustang ready to go back to the drag strip (it's been 9 years since I last raced). Anyway I had the house to myself so I used that time to take a bunch of tweeter measurements with my different test baffles. I took on axis, 15 deg, 30 deg, and 45 deg off axis (horizontal) measurements. The measurements show the stock plastic faceplate front flush mounted was the clear winner. Those measurements were very smooth and actually improved as I moved further off axis. Second place went to the straight 45 deg chamfer, 1/2" deep guide. It looked fairly similar to the stock faceplace down low but got pretty nasty above 10kHz. Last place was the 1/2" roundover guide. It displayed a 6 dB dip at 5kHz and a wonky top end. I did not try to measure the tweeter front mounted flush with no faceplate as Ben plans to. So I can't guess how it would fare.
Router work on the poplar baffles is complete. These "test" baffles turned out nice enough I think I'll give them a good sanding and apply some sort of finish. That way I have plenty of time to take more intensive measurements and design the crossovers in time for DIY Iowa!
I'm going to attempt to stain these baffles red mahogany. I bought some wood conditioner that will hopefully stave off the blotchiness poplar supposedly has. I'll test on scrap pieces first of course.
I did some sample pieces after work. The Minwax conditioner followed with red mahogany stain didn't turn out very well at all. Still very blotchy. I blame it on the extremely marginal quality of pretty much every Minwax product I've evwr used. The straight shellac looked pretty nice but it never lays flat and requires coat-sand-coat-sand-coat..... The BLO really popped the grain and color and will look great after it fully cures and then top coated with some gloss lacquer. So I think that is what I will use on the baffles.
Boiled Linseed Oil. I just apply it right out of the can with an old white tube sock. Let it sit and soak in for 10 minutes or so, then wipe off any excess with an old t-shirt. It can be handled the next day but I wouldn't put a top coat on for at least a week. A fan helps speed the curing process. It's not a look everyone would like because it adds an amber hue to the wood. I personally like that look though and it does make the grain patern really show.
Craig are you using sealcoat as is out of the can? You can dilute it with denatured alcohol and apply thinner coats if you want it to lay a little flatter. I usually just do a quick hand sand with 320 to 600 depending in satin/semi/polished (my waterbassed gloss poly likes 600 grit). It dries so fast the streaks from the applicator usually remain.
Aha ... isn't that the stuff that catches your rags on fire? Used Danish Oil on boys Picos. The look was ok but the feel was what set the wood off. Do you also 'sand the blo in'?
I think if you did a large project like a whole set of kitchen cabinets and threw all those rags in a garbage can they could catch on fire. For a speaker/amp project I only have one small application rag that is fairly wet and two or three wipe off rags that barely have any BLO on them. Still... I'm very careful to lay all of them out flat on the concrete floor and away from anything combustable until they're dry (basically the next morning).
I don't sand the BLO in. I only sand the wood up to 220 grit, clean it well, then apply with just an old sock moving in the direction of the grain.
I like this finish. I've used this finish on a couple of speaker baffles and a couple of tube amp/preamp cases with good results. YMMV
One old time trick was to sand in BLO as a small grain filler. I've tried it twice and it's a muddy mess. First it takes forever to dry, once it does it obscures the grain and diminishes the depth.
BTW, BLO is great finish on wooden handle tools like shovels and hammers...I use it on my workbench top
Here are some cell phone pictures. Here is the same board side by side, both sanded up to 220 grit, one bare and one with a coat of boiled linseed oil. No top coat.
Here are the prototype baffles with drivers installed. If I like how they sound I will eventually make new baffles out of some nice species of wood like walnut or cherry. Still these don't look too bad in poplar. A couple coats of clear lacquer will improve their look.
Hmm, missed the disussion (if any) about the waveguide for the tweeter. What's the deal? Love those TB 1320SIF bamboo, I listened to them full range for about a year, and may use them in a new 3 way. Nice look with the poplar. I'm a big fan of all Tung finishes. I've had some problems with other finishes.
But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
Hell , keep the current baffles. There is nothing wrong with those are all. They look really sharp Craig! You do nice work. Have to come up with a fancy way to fasten them to the lower enclosure . Brass or a brushed metal look might be neat?
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I'm looking forward to hearing these in Iowa.
I don't sand the BLO in. I only sand the wood up to 220 grit, clean it well, then apply with just an old sock moving in the direction of the grain.
I like this finish. I've used this finish on a couple of speaker baffles and a couple of tube amp/preamp cases with good results. YMMV
BTW, BLO is great finish on wooden handle tools like shovels and hammers...I use it on my workbench top
What's the deal?
Love those TB 1320SIF bamboo, I listened to them full range for about a year,
and may use them in a new 3 way.
Nice look with the poplar. I'm a big fan of all Tung finishes. I've had some problems
with other finishes.
Have to come up with a fancy way to fasten them to the lower enclosure . Brass or a brushed metal look might be neat?