First timer: select a low-budget bookshelf design?

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A few more build pics, and the drivers arrived today (hooray for being close to Wisconsin!).



After the last glue-up, now they look like speaker cabinets:
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The lower braces need holes in them. The plans have fancy, big hole saw holes or router holes sketched out, but my modest tools called for lots more holes with a 3/4" spade bit. I don't know if that's 30% holes, but I'm happy enough I guess?

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Gluing in those braces took almost all the ingenuity I have.
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It came out okay though
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That's about all there is to do on the body of the cabinets, so on to the baffles. I'm jigsawing the holes, so I marked off the circle and drilled a starter hole.
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The Pluvia Sevens arrived in the mail this morning and I've never bought speaker drivers before, but does everyone else do this with them?


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Now that I made it here, I'm pondering a few more questions.



The screws that are included are just about 3mm diameter and the holes that they go through are just over 3mm wide. I want to put threaded inserts into the back of the particle board and use machine screws through the driver into the inserts. It looks like a #4 screw is the largest one that will fit through that hole. 4-40 threaded inserts appear to be readily available, so I need to get 10 of them.


My other question is about how to fit the braces that press against the back of the drivers. I can set the drivers in place with the gasket and I measure about 5.4mm of space. Should I trim that much off of the braces and try fitting them again? How will I know that I've found the correct size?
 
frugal-phile™
Joined 2001
Paid Member
That is close enuff to 30% holes.

I don’t usually bother listening (or treating drivers) until they have at least 200 hours hooked up just as you have.

The holey/driver brace needs to brace th edriver against the back (and sides) of the box. It is tricky to get perfect, tight but not so much that it stresses the driver basket.

dave
 
Now that the drivers are here, it's hard to wait on anything. I put wires in the cabinets. All the connections are going to be on the outside, so I just ran in a piece of twisted pair through a small hole. I'll use a terminal strip or wire nuts on the outside.
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How's that for strain relief?

Next it was time to chamfer the back of the baffle away from the driver. I marked the mounting holes on the front of the baffle and drilled small pilot holes through on the drill press to get the mounting locations on the back side. Then I made the chamfer with a rasp, avoiding the areas near the mounting holes.
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Now I had wiring, a hole in the baffle, and the baffle is a tight slip fit into the cabinet, which means I got to really hear them for the first time. Is blue painters tape the recommended material for this?
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As someone who hasn't had a stereo in 15 years, that was a pretty moving experience, to be honest.

The last step is to get into town to the hardware store and buy some 4-40 threaded inserts (hopefully they have some) along with the machine screws. I think I'm supposed to stick the gasket onto the cabinet before I screw down the driver, but I can't figure out how I'm going to do that with nice concentric circles. I wish I could stick it on the driver first! Once the driver mounting is sorted I'll finalize the brace and glue it in. It's pretty close right now after some caliper and table saw work today.

I'm thinking of getting a couple pillows at the thrift store to tear open for stuffing. I have dreams of sanding and priming and painting, but it might take a few months of listening before I can stand to disassemble them for finishing.
 
frugal-phile™
Joined 2001
Paid Member
I wish I could stick it on the driver first!

I always put on the driver. A little bit of gluestick can hold well enuff until they are sandwhiched when the driver attached.

...but it might take a few months of listening before I can stand to disassemble them for finishing.

Very common. And often leading to being finished far after the it was originally planned :^)

These boxes want to be lined, not stuffed. Pillow fill probably won’t do it.
dave
 
I always put on the driver. A little bit of gluestick can hold well enuff until they are sandwhiched when the driver attached.

That's awesome. I'll gluestick them to the driver, then peel and stick that to the cabinet. That's the ticket, thanks for the good tip.

These boxes want to be lined, not stuffed. Pillow fill probably won’t do it.

I'm looking for other inexpensive options for lining these boxes. I can't find an easy source for the thick wool felt that you recommend. There' something like this 1m*1m Filler Foam White Speaker Acoustic Filler Foam Polyester Fiber Durable SH 7314217706802 | eBay that comes on the slow boat from China, but it's also 1 inch thick which seems like a lot in these little cabinets. I've got various foam scraps around the house from packages and such, but I'm not sure if they're going to do anything. I've got lots and lots of craft felt, I could think about gluing up multiple thicknesses of that.

I'm running them unlined and taped up and there is some definitely some unclarity when the music gets complicated. I wonder if that's due to the internal reflections with no lining at all in there?
 
Made a little bit more progress. I got the threaded inserts and managed to get them installed in the particle board. Dave's mention of putting in t-nuts using the bolt gave me an idea.

First, drill a through hole for the final bolt size
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Then drill the larger hole in the back for the insert and put the bolt sticking out.
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Threading the insert down the bolt keeps it straight up and down
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Then use the screwdriver to drive the insert all the way in.
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It worked okay, I only snapped off three or four of the ten before they were fully in. ;)

Then it was time to glue in the brace and line the inside. I cheaped out and used two layers of a thick craft felt that we had in the fabric scraps, mounted with hot glue
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I'm going to be listening some more before I glue on the baffles and solder on the drivers. Anything else I'm forgetting before I make it even harder to access the inside of the cabinet?
 
I got back from a trip and I'm ready to finish these off. I glued on the baffle today. It took all my clamps since it has gluing surfaces on so many sides.

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Here's a shot of them in use in the office. I've got some replacement panel lamps coming for the little receiver and a Discman for a source. I've been testing with MP3s streamed off a PC to a tablet or phone. Is lo-fi a word? I guess there's always "FrugalPhile". (Thanks again Dave.)

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After the glue is all dry, I'm going to chamfer the front corners on the table saw and solder the drivers in. There's some terminal strips in the mail for connecting "proper" speaker wires instead of a single length of twisted pair the way they are now.
 
They're pretty much done now as far as the to-do list. I cut the pretty little diagonals on the front corners so now they look like their Onken heritage. I soldered the drivers in place and the terminal strips go on the back as soon as they arrive.


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I had some concerns with audible clicks on a few tracks, but it turned out I just had the volume turned up too high on the source and it was clipping in its DAC. I discovered test tones and it appears that these little speakers can play down to 70 Hz (since I can hear that when I play the test tone) but not at all audibly at 60Hz.


I'm on to dreaming about the next project with possibilities of a little subwoofer to help them out, or smaller desktop computer speakers.


Thanks to everyone on this thread for your help and suggestions.
 
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