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Get familiar with the reaction system: Introducing the Reaction System
A slim 3-way tower build
I had the HIVI RT1.3WE tweeter, the MAC-04 as a mid and wanted to build a 3-way tower. The SB Acoustics SB15SFCR39-8 came up for sale on Madisound for black Friday and I thought it would make for a nice slim tower. The woofer needs a big enclosure. The tower will be 40" tall x 7.5" wide x 13.5 inches deep with a double front baffle. The woofer will have 1.3 cubic feet tuned to 31hz. The mid will be .065 cubic foot sealed dnclosure. I just started cutting wood.
Comments
You will not be disappointed in that mid.
. . . nor in that tweeter . . .
Nor in that woofer.
BUT- I don't think you really NEED that big of an enclosure, unless you are trying to dredge the ocean floor. They model really well in smaller volumes too.
InDIYana Event Website
Going much smaller starts to bump the bass around 60hz. It definitely can go smaller, but this size gives me the height I need to get the tweeter at ear height and give me enough depth for the port. I have dome clear tubing that is 2.75" id that I would like to use.
I'm getting popcorn, this is going to be fantastic.
That bump is 2pi. After baffle step losses it’s no bump. I’m with Wolf- smaller enclosure, or… 2 woofers per box!
Correct me if I am wrong, but my understanding is that baffle step losses (or spreading losses) only occur over a narrow band of frequencies based on the size of the baffle (7.5" in this case) and the location of the woofer with respect to the floor and other room boundaries. At 60Hz, the wavelength is too long to be affected by the approximate 6dB of baffle spreading loss, which only occurs from about 1kHz down to 100Hz or so. As a result, after the narrow band of baffle step losses are accounted for, the 60Hz bump would remain.
On this baffle, baffle step losses will start around 1800hz and below. I did think about doing 2 drivers. That would be even better, but my speaker funds are limited this time of year. This driver, if you wanted a ruler flat response, would need ~2.3 cubic foot box. If you go sealed, it will do 50 hz F3 in a ~.6 cubic foot box with a QTC of .707 if I remember correctly (modeled it sealed like a month ago).
That is a great F3 for a sealed woofer.
This is the look I am going for.
I like how you are thinking...
I like that!! And can probably do something like that.
I made one mistake that it looks like you'll avoid in your mock-up. My black faceplate is inset in the front baffle, so it sticks out about 1/4-inch and had a 1/4-inch roundover. Then there is about a 1/2-inch of veneer to the sides and a sharp edge. It wouldn't have looked quite as good, but I should have just had the faceplate span the whole width so I could use a large roundover or chamfer.
One more rendering.
I'm just going to leave this here:https://www.madisoundspeakerstore.com/approx-5-woofers/sb-acoustics-sb15sfcr39-8-5x8-paper-cone-woofer/
That is the deal I got on this pair. Great deal!
https://diy.midwestaudio.club/uploads/editor/qz/bksfcp4xqvuz.png
What are the dimensions of this cabinet btw?
I can do a model of the baffle step losses at 1m, or 3, or 10m (close to true anechoic/4pi) and it will be easy to see that in 3 way, the baffle loss will mean that the woofer is generally the limiting factor and will determine your net sensitivity. This is one reason lots of 3 ways have multiple woofers, yet can use the same mid or tweeter
Of course, all bets are off in a real room to whatever happens under ~500Hz.
But if you have the real estate for 2 woofers, and an amp that can drive a 4 own load…the higher sensitivity and dynamic range will be audible.
@a4eaudio
What woofers are you using there? I never had a need for more than a pair of twin ported 8’, but curiosity killed the cat and I went all in with a pair of 12” in a sealed 13 3/4” wide enclosure. Now I want to go back to slim and sexy.
https://www.diyaudio.com/community/attachments/1734503149803-png.1395266/
I'm going in the wrong direction. Those were dual 8"s - Dayton Classic DC200-8. My big build I took to SDC this year was dual 10"s and my next big build is dual 12"s. I think after that I'll focus on two-ways with 4" drivers
I already have the build started. 2 of the racetrack woofers would be great, but the size of these is perfect. Hopefully measuring during my Christmas break.
I have the same table saw, my condolences.
I got the midrange enclosures and bracing done. I will be working on the baffles later today or tomorrow.
I got baffles cut today. Due to the 2 part baffle, I will need to veneer prior to putting the outer baffle on. I will probably paint the baffle first also.
Here are a couple of pics of how I routered out the racetrack woofers hole if anyone is wondering.
I have some of the racetrack PRs. Might need to try that technique when I use em!
Just do 2 circles with the circle jig and a straight edge with a flush bit. Turned out pretty good.
Mark has some templates available if you want the really easy method.