Bravox-TangBand Bookshelf Build - Page 2 - AVS Forum
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DIY Speakers and Subs > Bravox-TangBand Bookshelf Build
lowpolyjoe's Avatar lowpolyjoe 02:07 PM 02-07-2012
I appreciate the tips PI.

Good to hear about the solder... i was trying to avoid a trip to radio shack.

Unfortunately the pencil paths are mostly covered by the crossover components so i may need to take some off the board to do any effective erasing.

I do believe it will be overkill to go crazy erasing everything but at the same time i feel *dirty* leaving it as-is. I think there are only about 5 solder points. If i can get them freed up i'll just make a new board... is permanent marker preferred tracing medium?

The additional crossover components I ordered are shipping out from Parts Express... i got 8 emails about it today - which seemed odd. All the parts give a country of origin (Poland, China, Taiwan, etc..) on the invoice. Does PE ship these components direct from these countries? That would be a bummer since i imagine it will add a few weeks to my wait time

PassingInterest's Avatar PassingInterest 04:57 PM 02-07-2012
Like I say, you don't have to erase the entire pencil path, just create a "break" in the path and honestly, you may not even need to do that. But, for peace of mind, just break the path.

I don't use any layout markings, except to mark the input and outputs.

Were any of your PE parts on back-order?
I've never gotten a shipping message from PE stating a country of origin, or if I did, I didn't notice.

If there will be any shipping delays, you can use the two close substitutions you have until the exact-value parts arrive. You can swap them later. At least you won't be dead in the water that way.
lowpolyjoe's Avatar lowpolyjoe 10:10 AM 02-08-2012
Got my PE order this morning, which is great. Two components were on backorder but i noticed before i submitted the order so i cancelled them from PE and ordered them from Meniscus. Still not sure why i got a total of about 10 email notifications from PE, but everything seems OK with the delivery.

I think Meniscus shipped my items out yesterday but no tracking info yet.

Regarding the parts you sent me, PI, they are actually the correct values for use in the 1-woofer crossover, so that's great since i'm building those cabinets as well.

I did some work last night with a drum sander on my dremel... did a great job at giving me a bit of chamfer on the back of the baffle. Thanks for the tip. I didn't have the nerve to try using the dovetail bit in the router, but i will keep that in mind tuxedocivic... maybe for a larger speaker cutout where the dremel approach would take forever.

I cut up some veneer last night but it was too late to start gluing it up. Maybe tonight.

It seems there is a little asymmetry in my cabinets, which is a shame. The PL may not have fully dried when i took the kerf'ed panels off my bending jig and some of them lost form at slightly different rates during assembly. Woodglue might hold better but as i mentioned, it all dripped out of the kerfs so it would require using the molding jig on one piece at a time and laying it such that the panel was kerf-side-up, then waiting extra long for it to dry.
lowpolyjoe's Avatar lowpolyjoe 08:04 PM 02-08-2012
finally got the 5 cabinets ready to start veneering. here's a shot of them all together. smaller ones still need the tweeter hole 'adjusted' but i wanted to get started on veneering tonight. impatient...

preparing to hand-veneer the top and bottom of each cabinet. hide glue, veneer hammer, glue pot, measuring spoon... also need bucket of warm water, wet rag, dry rag and an iron. two-cherries veneer saw and a utility knife are good to have on hand too

measured out about 10tbsp of hide glue, added about the same amount of water. then cook it up in a double-boiler setup for 30mins to an hour at about 150degs. it looked a little thin so i added a little more glue to thicken it up. when i've had problems with this technique in the past a lot has had to do with the glue being too thin and not holding. i tend to keep it rather thick now.
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lowpolyjoe's Avatar lowpolyjoe 08:23 PM 02-08-2012
you can really make a lot of progress fast with hand veneering. no clamp setups or vacuum bags required. i bought some heat-lock glue that i might try since that is probably a lot easier and also does not require clamping, but there's something oldschool about this technique that i like. i'm not very good at it but i've been forcing myself to stick with it. seems almost like a lost art.

working in accordance to instructions ive read and videos i've watched, i wet the mdf and score it lightly with a blade or saw edge. then wet the veneer. slop some hot hide glue on the mdf, then lay the wet veneer on top. hit it with a couple of quick passes with a hot iron to get the glue flowing. starting from the center, force the excess glue out from beneath the veneer with the veneer hammer. after it sets up a bit and is held in place and you've gotten the it sitting flat, wipe the veneer with a dry rag and then put it aside.

maybe 45mins later and i got the top and bottom on each of the 5 speakers. tomorrow i'll have to go in and do a little glue cleanup but this stuff dries rock hard and is easy to chip or sand off once it's had a day or so to firm up.

hitting the curves should be interesting. i'm optimistic but admittedly i've never tried this technique on a curve. hopefully i'll get to that soon.
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tuxedocivic's Avatar tuxedocivic 08:28 PM 02-08-2012
I've never heard of hide glue. Interesting. Where can you get it... HD??
lowpolyjoe's Avatar lowpolyjoe 09:05 PM 02-08-2012
Quote:
Originally Posted by tuxedocivic View Post

I've never heard of hide glue. Interesting. Where can you get it... HD??

I think it's fairly rare. Not sure if you'll find it in a local store. I don't think I checked many places but I was told there are only a few places to get it. I ordered some off amazon and my most recent stuff from here

http://www.toolsforworkingwood.com//...ch=Hide%20glue

I learned almost everything I know on the topic from this guy's related YouTube postings


http://www.youtube.com/watch?v=inyVp...e_gdata_player

It took me several attempts before I could get any reasonable results with the technique and I still haven't mastered it. If you're good at woodworking in general maybe you'll pick it up quicker. You can find an electric kettle on amazon for under $20. Then you just need a glass jar for your double boiler setup - that's what I use anyway... A real double boiler is expensive
lowpolyjoe's Avatar lowpolyjoe 09:52 AM 02-10-2012
Last night i trimmed the veneer overhang from the previous day. It came out surprisingly good. No bubbles that i could see and only very very small chips on one panel when trimming up the veneer on the router table.

Because of glue push-out along the edges, after the router table i sanded down the edges smooth with my random orbital. It was all looking great.... until i started the next round of veneering.

I tackled one of the curved sides on each cabinet. It was much more of a pain than i anticpated. This was mostly because the straight edge of the veneer hammer only contacts a very small patch of the curved surface when trying to push out the glue. The result was many passes with the hammer, hoping that i covered the entire surface sufficiently. Pushing the hammer cross-grain tends to move the veneer and i believe is dangerous for causing splits/cracks so i could not run the hammer the flat way due to the veneer orientation.

Secondly, i noticed at the top and bottom of the cabinets that my brilliant work with the sander did more harm than good in a few places. I must have been holding the sander at an angle and i seem to have made a very slight chamfer on many of the edges. That means the veneer did not lay flat all the way up to the edge The downside to no-clamp setups is that these small inconsistencies can leave the veneer sticking up a bit. It was hard to tell how bad it was, but i'm pretty bummed out. The good thing about hide-glue is that you can heat and repair it pretty easily. If it's really bad i'll reheat the glue and maybe wrap a strap-clamp around the edge while it re-sets. Could help i suppose.

Can anyone tell from my terrible quality iPhone pics what species this veneer is? I may have mentioned before that it was from a mixed assortment i bought online and i'm not sure what it is. I like the look tho
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lowpolyjoe's Avatar lowpolyjoe 08:10 PM 02-12-2012
Finally applied veneer to the baffle and back panel the other day. The process of trimming was a little more challenging than the other sides. The curve on the two alternate sides holds the bearing of the flush-cut router bit away from the edge of the piece. The result was a lot of extra work with the random orbital to take off the last 1/8" or so.

I think i may have stated that hide-glue sands well at some point earlier in my thread. Well, it sands well if there's a thin coating of it you need to remove or something like that. But in this case there was a thick bead of pushed out glue along my seam and and i had to attack it via sanding because of the issue mentioned above. Sanding at high speed with the d/a heats up the glue after a while and it starts to get sticky and nasty. Trick seems to be to do a little at a time so it doesn't heat up too much... work on two pieces at the same time so one cools while you sand a little on the other.

It took a while but i finally got all the sides sanded flush. Only one or two places where i got a little too aggresive and showed a hint of sand-through on the very edge.
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lowpolyjoe's Avatar lowpolyjoe 08:25 PM 02-12-2012
Next up i had to trim the veneer around the speaker cut-outs. On a bigger build with 3/4" wood or maybe just larger driver holes i guess you could use a router with the flush cut bit. In this case i used my dremel with a roto-zip blade and the router-base attachment. It came out ok, but i'd be interested to hear what others have done. Veneering before you cut the speaker holes is probably the way to go but that has some drawbacks itself.

I couldn't leave good-enough alone and decided to try to clean up the edges with a drum-sander bit in the dremel. The last picture below tells the story about what happens when you're a bit tired and in a rush. It jumped out of the hole and skidded across the baffle and put a big ugly dent one of my boxes. It's the box i built for use as a center channel - which was the best case, since i don't plan on using these for home theatre just now anyway. Still very frustrating.
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lowpolyjoe's Avatar lowpolyjoe 08:33 PM 02-12-2012
I finished up the two boards for the crossover. I'm not super confident in my crossover assembly and wanted to have access for later adjustment/replacement/repair. I'm mounting the boards with velcro and not soldering any of the i/o connections.

I added some ring connectors to connect to the terminal inputs and some female-disconnects to connect to the speakers. Parts express had a nice assortment of those female-disconnects that covered both sizes i needed in this case. Had to run to Radio Shack for the ring connectors - i spent $4 on connectors just before closing time and they still tried to sell me a cell-phone.

It's probably difficult to tell from these pics, but it is pretty tight fitting these crossovers in the cabinet. I was restricted in board width because they have to fit through the small speaker cutouts... then restricted in board length because they have to make the turn when i push them into the box. I thought i had everything covered fine with my 2-board layout until i tried to put the first mid-driver in place and it hit one of the capacitors Good thing i used velcro. I was able to shift the positioning enough to get everything to fit.

The single woofer cabinets are going to be insane - they use the same crossover design (with slightly different values) and the box is 1/2 the size. Really nervous about how everything is going to fit
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lowpolyjoe's Avatar lowpolyjoe 08:50 PM 02-12-2012
Finally the moment of truth - how are these things going to sound compared to the stock offering of an Onkyo mini-receiver.

The Onkyo's are vented so i figured they would have the edge down low, and they do. The 50-150hz range there's a sizeable loss of up to 5db. The rest of the curve shows a smoother overall performance, most significantly avoiding the Onkyo's giant dip at ~700hz and minimizing issues around the smaller problem areas at 2.5k and 6k. I believe these curves are 1/6 octave smoothed - i forgot to adjust the smoothing before i started testing or i would have used less. Also attached is a distortion curve for 2nd-5th from the Bravox. I could have sworn i had one for the Onkyo also but i can't find it.

I'm too tired to put together a the second channel tonight, but when i do i'll measure that too and check for consistency to make sure i haven't done anything wrong with the crossover wiring. If anyone sees any telltale signs of issues with these curves please let me know.

The Bravox-TangBand cabinet is slightly taller than the Onkyo's with about the same width. The depth is the shining star with this design, at only a bit over 5", perhaps half the Onkyo's depth. These would fit really nice on a shallow shelf.

I'm not sure how i'm going to finish the cabinets... stain or natural. I like the veneer, though i still don't know what it is. I'll probably do some tests on some of my leftover veneer cuttings.
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PassingInterest's Avatar PassingInterest 08:41 AM 02-13-2012
Looking good so far.
lowpolyjoe's Avatar lowpolyjoe 10:59 AM 02-15-2012
thanks PI.

i'm experiementing with finishes on scrap veneer (which turns out to be Prima Vera). i'm thinking tung oil with shellac as a top coat to avoid the horrid smell of working with some other topcoats. i'm hoping to accentuate the figure with the tung oil but would love advice if there's a better way to get the same effect.

still working on all the crossover assembly a little at a time.

have to bondo some areas around the driver cutouts that are producing leaks in some places. hope to make some progress this weekend and then re-measure.
tuxedocivic's Avatar tuxedocivic 10:22 AM 02-16-2012
Looking Good!
lowpolyjoe's Avatar lowpolyjoe 12:46 PM 02-17-2012
thanks tuxedocivic.

Progress has slowed a bit but last night i was doing some prep work before trying to get the finish applied. I noticed there were dents along the sides of some of the boxes from where the bearing of the flush-trim router bit was running along... clearly i was pushing too hard I tried the 'sweat-out-a-dent' approach that i've seen used in various places, including a PI build i think?

Instead of trying to sand out the dent - which might be impossible or lead to sanding through the veneer, you wet the dent with some water then apply a hot steamy iron to the surface. Even though i've seen it done in several different woodworking videos and threads, i was amazed at how well it worked. +1000 for that technique. If i can make it work, it's foolproof
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PassingInterest's Avatar PassingInterest 02:52 PM 02-17-2012
Quote:
Originally Posted by lowpolyjoe View Post

I tried the 'sweat-out-a-dent' approach that i've seen used in various places, including a PI build i think?

Instead of trying to sand out the dent - which might be impossible or lead to sanding through the veneer, you wet the dent with some water then apply a hot steamy iron to the surface. Even though i've seen it done in several different woodworking videos and threads, i was amazed at how well it worked. +1000 for that technique. it i can make it work, it's foolproof

I'm glad it worked out.
lowpolyjoe's Avatar lowpolyjoe 08:20 PM 02-17-2012
I thought i would try to make the most of the finish work on these speakers. I read about using Tung oil to get a nice look before the final top coat. I bought some (expensive at home depot) and tried it on some scrap. Didn't impress me too much. I later noticed that the can says "Tung Oil Finish". Is that different than straight Tung Oil? Like... "Grape Drink"... is not the same as "Grape Juice". Anyone know?

In any case, i tried another approach designed to accentuate the figure. I put on a light coat of a pale tinted mixture of shellac and stain. The following day i sanded off the majority of the stain. The idea is (if i understand it correctly) that the figure is actually end grain and it will soak up more stain than the flat part of the grain. Then when you sand, the figure will remain highlighted.

I'm not sure i got the effect i was looking for. But i also didn't use the exact products recommended. I used some stain i had laying around - i belive trans-tint dye was suggested.

I don't think i'll try this again on veneer. The amount of sanding i needed to do to get most of the stain off was enough to warrant worry of sanding through the veneer. Prior to staining i cleaned up and prepped with ~100grit, to get rid of the stain color i used ~220grit.

The last pics show the current stats... one layer of shellac applied after sanding off the color. These pics don't show too much... i'll have to break out the good camera when all is said and done.
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PassingInterest's Avatar PassingInterest 02:25 AM 02-18-2012
Looking good, Joe.
Dyes tend to accentuate the figure in the wood, while pigment stains tend to enhance the grain.
It can get confusing though, because some products labeled as wood stain are actually dyes and it varies within a product line.
You can tell by stirring the contents of the can. Some pigments will settle to the bottom of the can and some will be stuck to the end of your stir-stick. If no gunk is on the end of your stir-stick after stirring, it is a dye.

So, use a dye to augment the figure.
Use a pigment stain to enhance the grain.
Use both if you want to accentuate both the figure and the grain.

As for Tung Oil--I don't believe the word "finish" was a clue, but beyond that it can get confusing as to which products are pure Tung Oil and which are even true Tung Oil. You might try googling it for more information. True Tung Oil tends to be pretty pricy, so you may have bought the real deal.
Waterlox is a Tung Oil and Resin blend to make it more durable than pure Tung Oil. People generally really like Waterlox.

Make sure you lay out any rags used with Tung Oil or Boiled Linseed Oil and allow them to fully air-dry before disposing them, to avoid Spontaneous Combustion. Google it if you don't believe me, folks. It is a risk you don't need to take. Play it safe.

Hope this helps.
lowpolyjoe's Avatar lowpolyjoe 11:55 AM 02-18-2012
Excellent info as always.

I think you nailed the diagnosis. After stiring my stain and seeing some gunk on the end of the stick, i think i have a pigment based product. That would explain why my finishing treatment did the exact opposite of what i was looking for.... you can't really see the figure at all. While it did provide a bit of a unique finish, it's not the finish i was interested in so i'm a little bummed.

I did some research, and while i found a few people saying good things about the Tung Oil Finish i used, i later found this site that suggests that it is indeed, NOT true Tung oil. Another bummer since it was about $20 for a relatively small amount.

Just finished up the last crossover assembly this morning and put on a few coats of shellac. I'm hoping to do some final assembly in the next day or two. Very curious to measure the single-woofer vs dual-woofer builds.

Thanks for the help!
lowpolyjoe's Avatar lowpolyjoe 05:09 PM 02-19-2012
When i dry-fit the drivers in one of the dual-woofer cabinets a week or so ago, i sort of eyeballed the speaker placement and drilled pilot holes. Afterwards i realized that my head must be crooked. Nothing was quite straight... the mids and tweeters are not circular so you can tell if they're not lined up perfect.

Today i was getting ready for final assembly and decided to make a little cardboard cutout to help me keep the speaker aligned when drilling the pilot holes. I think it helped. The edge of the tweeter was flat so i used that as a straight edge directly.

To rub out the shellac top coat i used some 2000 and 4000 abralon pads to wetsand with some soapy water. I've seen videos of this work amazingly well. I still don't have the technique just right, but the finish came out alright. Still bummed that i was not able to accentuate the figure. But thanks to PI's input i know what i did wrong.

This afternoon i was ready for final assembly. My hands are too big for these cabinets so it was a long and tedious process.
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lowpolyjoe's Avatar lowpolyjoe 05:17 PM 02-19-2012
I broke out the nice camera to try to get some quality shots of final product. My Bravox/TangBand 5.0 system courtesy of PI/garciab. Next i get to work on the .1


I came up a few screws short so the center channel is not quite done. Speaking of which... where do you guys get black pan-head or socket-head screws? In the past i've built mostly kits and gotten the screws with the kits. Or way back in the car-audio days i just used drywall screws I was amazed that Home Depot didn't seem to have anything fitting in the fastner aisle. I ended up finding some 'shelf screws' in an unrelated aisle and they did the trick but i had to buy all they had and i still ran out. For the future, who's the best bulk supplier for those type of driver-securing screws of various beefy-ness for various driver sizes?
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lowpolyjoe's Avatar lowpolyjoe 05:42 PM 02-19-2012
Some response measurements at about 1M on axis.

All channels are fairly consistent except the center - which doesn't really count because it only had 2 screws holding in each driver. Just included it to see what would happen.

I was very curious what the single-woofer would look like compared to the dual-woofer design. Pretty similar... more linear in fact, just a little less sensitive (both runs taken with same volume setting).

The final curve adds in the Onkyo these guys were supposed to replace. The previous response curves i posted a little while back were a bit skewed - i didn't realize my wife had fiddled with the bass/trebble controls on the receiver. These new curves are with flat settings. I was hoping for some improvements since i patched up some holes in the cabinets between last run and this run, but the ported Onkyo's still go quite a bit deeper.

I was forewarned that these little guys would need a small sub to round out the response and i'm looking forward to getting started on that in the coming weeks.

Joe
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PassingInterest's Avatar PassingInterest 08:34 PM 02-19-2012
They look great, Joe. Fine job!

About the black screws--there are several places that sell them. PE isn't bad, but there are others. There was a thread at PE recently asking about where to get screws and there were places I hadn't heard of that might be worth trying. I didn't save a link, so try a search for the thread at PE.

I sometimes paint screws black myself. Just poke a hundred or so into some cardboard and spray them.

Here's a tip--keep some water-based artist's paint on hand (small plastic bottles at craft stores) and dab a little with a small paintbrush in the center of the black Phillips screw head where some of the paint came off when you used the screwdriver on it. Looks better than shiny metal in the center of your black screws.

Edit: Found the PE screw discussion thread here.
lowpolyjoe's Avatar lowpolyjoe 09:00 AM 02-20-2012
Thanks. And that's a great link to the fastner thread. I'll have to check out some suppliers and stock up. It's annoying to make it all the way to final assembly and then realize you need to find some appropriate screws.

Hadn't thought of spraying my own but sounds like a good plan too.
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