Bookshelf speakers build

[Nebby]

Posted this on the other forum, but I get the feeling the audience here will probably enjoy this as well. If I'm breaking any rules by posting this here too please let me know....or just delete it. Cheers.

I've started building a pair of Zaph's Bargain Mini's (ZBM) along with Zaph's SR-71. I'll be documenting my build progress in this thread with pictures and comments. Making this thread somewhat for your entertainment and for me to use it somewhat as a log of progress (or lack thereof) as these will basically be my second and third woodworking projects to date. Hope you enjoy this thread as much as I (hopefully) will enjoy the build!

I'm planning on building the boxes with a removable front baffle and bracing. The finish will be semi-flat black paint on the front baffle and veneer on the rest of the body. I picked up a few types of veneer but haven't decided on which I want to use on which. Overall, I'm just going to follow Zaph's plans and layout to keep it simple.

I've already cut the panels for the SR-71, and the initial cuts for the ZBM.

04/01/09

Here's the SR-71 in dry-fit form:

I'll be using 5 screws per edge, in this picture I only have screws in each of the corners of the top and bottom. The back plate is not screwed in, it's held there by friction alone. Frankly speaking I could probably glue the speakers together, but where would the fun be in that?

Here's the panels of the ZBM, after sizing and cutting.

If you look carefully, you can see I wrote the length of each side and a short description of each panel. I learned the hard way that it gets confusing very quickly when working with multiple cuts if you don't have them labeled (and measure...measure....and measure again before cutting!)

Here are the ZBM's, after drilling, countersinking, and screwing:

Probably not noticable, but I left a 1/32th of an inch on each side to account for any follies I make on the positioning. Luckily it doesn't seem like I messed up anywhere. I should be able to take that edge off easily with a flush trim bit on a router.

[n_maher]

Very nice work so far, looks like you have access to a good shop. I'll be looking forward to watching the progress.

[Hopstretch]

I have that same drill. Though I haven't done anything near as useful with it.

[naamanf]

Looks like a good start. Once all the parts come in I will be building the ZD5. Curious to see what you think of the SR-71.

[Nebby]

I also plan on building the ZD5's But I may be lazy with the crossovers and have madisound build them for me. Given the complexity it doesn't seem too bad to have them build it for me for $15. Speaking of crossovers I'm not quite sure how to mount the crossovers, the SR-71 kit XO came on two boards and my initial design aimed for a stacked crossover with a horizontal platform to mount the second XO board. After deciding to do a crossbrace, I found that the XO would be in the way so I may just mount it on the side.

Nate: it's a great shop but unfortunately not everything is perfectly flat. My speakers are relatively flat to each other, but not absolutely flat. I'd like to think it's good enough though!

[naamanf]

Are you doing the dowel brace or something different?

Yeah getting things set up to cut square is an art in itself. And I find that you have to keep checking to make sure things are true.

[Nebby]

Crossbrace that will be shaped...well, like a cross. It be 3/4" plywood screwed and glued to the sides and rear, and the front portion cut to the shape of the woofer to provide support.

[Pars]

Nice work!

[Nebby]

04/02/09

Today I didn't get much done, mostly because I was inspired by seeing the picture of a dovetail jig posted by swt and asked my woodshop if they had one; turns out they did! So most of my time today was spent adjusting, testing, and readjusting this tool:

After roughly 45 minutes I had good fitting joints. I will be using this jig in the future to make some wooden enclosures for the DAC's that are mostly on temporary mounting boards right now

Quick picture to show the size difference between the ZBM and SR-71:

SR-71 Parts:

Drivers

Terminal post panel

Crossover(s)

Really didn't do much today aside from tinkering with the jig, though I spent a couple minutes with this tool:

Scriber! Saves you a LOT of time that you would otherwise spent measuring again and again. On the bottom you can see the marks I made for the screws that will secure the back panel of the ZBM's.

[riceboy]

Great work. Thanks for the pics and progress update

[Smeggy]

V nice.

[swt61]

That is a very old Porter Cable dovetail jig. They just don't build them like that anymore. Those suckers are rock solid, and highly coveted by wood junkies like me.

Any chance you could sneak that out in your lunchbox?

[Nebby]

No problem! After I'm done with it I'll just need to find a lunch box big enough I knew how strong a dovetail joint was but feeling the strength after finally making a correctly fitting one was quite impressive. Even on my test pieces of scrap mdf it held quite strong, and it's got no grain to speak of!

[Augsburger]

tool:

Crossover(s)

.

That inductor looks as big as a dinner plate!

[Nebby]

I went for the "upgraded" crossover with foil inductor. Well, I didn't realize how much larger copper foil inductors were, the inductor is 3.3mH and it is 3.6" in diameter. I won't be doing anything like that again, it's making my crossover mounting/placement quite a hassle.

[AlanY]

Great choice of projects! I'm impressed you're doing two sets at the same time. I started a pair of Zaph's speakers last summer but didn't finish the baffles and then got distracted. Hope to finish them this summer.

[naamanf]

I went for the "upgraded" crossover with foil inductor. Well, I didn't realize how much larger copper foil inductors were, the inductor is 3.3mH and it is 3.6" in diameter. I won't be doing anything like that again, it's making my crossover mounting/placement quite a hassle.

IMHO I wouldn't add much more bracing than is already called for on the plans. The enclosures are pretty small and should be pretty resonance free with minimal bracing. That should help a bit in fitting the crossovers. Plus adding extra material to the box without taking it's volume into consideration might have a negative effect on the F3 point.

Also I would ditch the plastic speaker terminals. Nothing like building a solid enclosure then cutting a hole in it and inserting 1/8" plastic. Binding posts directly in the MDF or using some aluminum plates with minimal holes cut out would be a better route. There some nice Dayton ones at Parts Express which are not that expensive.

[Augsburger]

The Dayton ones are really nice and I think they still come in different colors so you aren't limited to basic silver.

[Nebby]

I've decided to simplify the bracing and will be going with a single brace made out of 1/2" plywood behind the woofer, and a T brace below the port. Given that it's a .5 cu ft enclosure it won't have too much of an effect. I've checked winisd with the woofer and box size, the effect on the freq response will be minimal.

I see your point on the plastic speaker terminals, but the enclosure is made with 3/4" MDF and as it is right now even unglued, without the front and rear panels mounted it's already quite rigid. I'll concede that I have thought has come across my mind more than once of simply putting binding posts directly in the MDF or using the very slick looking Dayton Al plates.

Thanks for the comments and feedback, gives me food for thought!

[Nebby]

^just realized half of what I typed made no sense. I apologize for the terrible grammar and wording!

[AlanY]

I see your point on the plastic speaker terminals, but the enclosure is made with 3/4" MDF and as it is right now even unglued, without the front and rear panels mounted it's already quite rigid. I'll concede that I have thought has come across my mind more than once of simply putting binding posts directly in the MDF or using the very slick looking Dayton Al plates.

The plastic doesn't matter as much as you'd think since it's at the back of the cabinet... any resonance in the plastic will be emitted to the rear and be lost.

[Nebby]

I was hoping that was the case, good to hear if I use the plastic piece it won't be detrimental.

04/03/09

More tinkering with the dovetail jig today, got some results I think are acceptable. Other than that I did more measuring and marking on the SR-71, and measured/marked/drilled/etc some more on the ZBM.

Didn't quite line up the bottom piece correctly, found out the clap tends to raise up the piece by ever so much if you're not careful.

Somewhat happy with this one, any comments?

ZBM top and bottom and sides of the rear drilled/countersunk/screwed. It's starting to be a pretty solid enclosure!

I'll be testing out veneering on a scrap piece of MDF this weekend to get a feel for how the glue and softener work.

In other news, I'll be building up a pair of TPA counterpoint boards for my buffalo DAC this weekend. I plan on building a case for the DAC out of wood, with dovetail joints. I'm thinking of making the case two parts, rear panel and bottom one piece and the top/sides/front another piece. Put a dado in the side and front and slide the bottom piece right in, with four screws in the rear securing it in.

[utilisateur]

Looks solid!

I didn't know there were special jigs to make dovetails!

I bet it's not as much fun as doing them by hand though! not that i could do that personally

Awesome idea for the DAC, i think some nice timber joints make wooden enclosures even more visually appealing

If you wanted to eliminate the screws maybe you you could make something like the french keyed joint with the key being inserted horizontally from the rearpanel.

Would mean to divide the sides though , and a lot more work (potentially fun.)

[swt61]

Nebby that bottom dovetail is damned near perfect, I doubt you could get it any closer.

A little tip for your finished product...After cutting and fitting the dovetails, take some 220 grit sandpaper and lightly go over the joint. This will fill any minor flaws or voids with fine dust the correct color. Then use a jersey rag (old T-Shirt) to lightly wipe down the area (no compressed air here obviously). Take a can of spray lacquer and very lightly spray over the joint from about 12-14 inches away. Just a very light touch, and if you have no lacquer around hair spray will substitute well as long as it's the aerosol type. Give that time to dry and very lightly sand with 400 grit. This won't interfere with your chosen finish, and will give you a perfect joint.

Your box plan seems reasonable to me.

I bet it's not as much fun as doing them by hand though! not that i could do that personally

Give me a powertool over handwork any day! As long as new tools are invented to speed up the woodworking process, guys like me will keep buying them. I have great respect for the woodworkers of the past, but we gots 'lectricity now baby!

Edited April 3, 2009 by swt61

[Dusty Chalk]

Somewhat happy with this one, any comments?

That's tight!