SevenSixTwo - InDIYana 2018 Coax Design

[tomzarbo]

Is the silicone brush used to apply glue? Great idea!
TomZ

[KEtheredge87]

Is the silicone brush used to apply glue? Great idea!
TomZ

Hey Tom, Yep! That brush was living a lonely life in our kitchen drawers, so I rescued it. The brush spreads the glue around decently, and when I'm done I just let it dry. The glue doesn't stick at all, and it just pulls out of the bristles when it dries. Pretty sure I saw the idea first from the Wood Working for Mere Mortals YouTube channel. That guy has a lot of decent practical ideas.

[6thplanet]

Project is looking good man! I also wanted to try those coaxes out. I think using the same magnet for both drivers is a pretty cool idea. Hope they sound as good as they look, the FR is a bit scary looking!

[KEtheredge87]

Project is looking good man! I also wanted to try those coaxes out. I think using the same magnet for both drivers is a pretty cool idea. Hope they sound as good as they look, the FR is a bit scary looking!

Thanks man!

I'll admit I'm a bit concerned by the frequency response graphs that were published as well (Not that I have a keen eye for what to look for in those plots, my speaker building career is still young!) I did several iterations of PCD modeling to get to something that seemed like a plausible attempt at a 3-way design before deciding on the driver and placing the order.

Truth be told, my first inclination was to use the Dayton CX150, but the uncertainty in when they would be available and how they would address the design issues scared me off. Hopefully I can speed this first testing box along so I can measure with the OmniMic for my XO work. That'll be equally as exciting

[xmax]

All Coax's seem to have some compromises in the FR plot often the power response makes up for it.

[KEtheredge87]

Monday evening update - The glue-up for the top, bottom, front, and back went well. All the clamps did their jobs and held things in place. I set the newly glued cabinet pieces up for a flush trim and made the front baffle even with the top and bottom, and then made the top and bottom even with the back.

The bummer of all that was my brand new Ridgid shop vac has a problem and would not turn on! I've been using that sucker with a fine dust filter bag in place since I bought it just before Christmas and it's been a champ. I'd prefer NOT to rip this one open to look for an issue since it should still be under some kind of warranty, so I'll have to contact Ridgid directly during business hours tomorrow. I'm afraid I will get the run-around... or some garbage about shipping the thing to a service center. The whole situation really chaps me though... I bought the Ridgid to replace a ShopVac branded model from Lowes that lasted more than 5 years of my abuse. Somebody please get in their time machine and bring me a shop vac from the 1970's. Bet those still work!

Anyway... I've got the cabinet gluing up only one wall right now. I'm using the other wall as a caul to distribute the clamping force. I want to keep one wall unglued while I do my port length adjustments to hit the tuning frequency. My plan is to remove the whole MDF slot port assembly and trim it down on the table saw a little at a time until I get the right frequency. Once I'm set there, I'll glue and clamp it to the bottom of the cabinet.

Also... this is further proof that one can never have enough bar clamps!

[JavadS]

Yup! I own about 40 bar clamps and counting, fortunately they’re cheap st Harbor Freight and amazing, and they hang on the wall quite neatly. Coming along nicely!

[augerpro]

Keith, coaxes can be pretty wonky on axis. At minimum, do a set of measurements at about 40 degrees off axis and use that as check on your crossover design.

[KEtheredge87]

Keith, coaxes can be pretty wonky on axis. At minimum, do a set of measurements at about 40 degrees off axis and use that as check on your crossover design.

Thanks Brandon, I assume I should model a matching set of ~40 degree off-axis measurements in PCD to compare against? At this point I am operating more on a "model then listen" than a "model, then check with a measurement". Until I get better with using my ears to do the judging, using my eyes and some data can't hurt.

[augerpro]

I assume I should model a matching set of ~40 degree off-axis measurements in PCD to compare against?

Yep

[jhollander]

WRT to off axis measures, I design on axis and do a quick check off axis to see what's happening. Some times I end up leaving more dips as they fill in off axis. So looking off axis helps to guide my on axis design.

[KEtheredge87]

WRT to off axis measures, I design on axis and do a quick check off axis to see what's happening. Some times I end up leaving more dips as they fill in off axis. So looking off axis helps to guide my on axis design.

Thanks John! Hopefully I'll be at that stage in the design before too long.

While I'm posting... tonight I had to spend my time dissecting my brand new Ridgid shop vac to confirm the thermal fuse had tripped in there. That sucker is quite literally in the heart of the beast, wrapped up in the motor windings. While a replacement is on order, I picked up a tiny ShopVac brand vacuum to catch all the dust my router will throw. Definitely a speed bump I did not expect! Back to work tomorrow!

[marvin]

I would think you could have exchanged that vac at Home Depot if it failed within 30 days

[KEtheredge87]

I would think you could have exchanged that vac at Home Depot if it failed within 30 days

Hey Marvin, yeah... I threw away the receipt in a fit of hubris. Also bought it using a gift card, and HD claims they can't look up receipts (I believe they said they absolutely can't look up receipts from gift card transactions). I find the customer service aspect of this particular transaction sorely lacking, so I'll be making a pointed stink on their facebook page after fixing it. Those thermal fuses are only $1 each, so I'm not out loads of money, but the principle of the matter is just messed up. If Menards can print receipts right at their front door, then HD just isn't trying to help their customers.

Good thing I'm not afraid to do some research, turn a wrench, and solder some stuff! Anyway... back to MDF and wood glue this evening!

[marvin]

Agreed! Any true DIYer gets satisfaction from fixing something with an inexpensive part, even tho' it should have been warranteed. Good job.