Sub Attaché - slim-line 6.5" buyout sub build

[bkeane1259]

I've been wanting to build this for my son for some time now to supplement the sound bar that we built for his desktop PC setup. While I procrastinated, Johhny did a nice 2.1 system with this sub for his daughter. Then the Holiday's hit and...well, you know the story. Anyway.....

Space is an issue, so a slim-line sub enclosure is the way to go. I played around modeling the 6.5" buyout subwoofer in a small ported alignment with the Dayton SA-25 plate amp. The results look very promising for low-level applications. I stress "low-level" because running this sub solo in a small ported box makes it easy to hit xmax once you get up towards 50 watts or so. However, that won't be a problem in this application.

The completed sub will have dimensions similar to an attaché case, hence the name. It will have a 2" ID x 11.5" port, tuning the box to 31Hz. Using the active XO filter at 80hz, the modeled F3 comes in at 28.3Hz. Gonna use 3/4" MDF for the cabinet and PVC pipe for the port. Some dowel bracing and Wally World mattress topper inside. It will be painted satin black fine texture. I'm looking at around $60 all-in with paint and misc supplies.

Pictures to follow tomorrow.......

[greywarden]

Looks Good. Someone needs to design a 2.5 or 3.5-way bass monster with these guys.

[Whitneyville1]

How about a pair of them for subs? They are a bit volume hungry though. If the Peerless buy-outs in the Gila Monsters was still available, stack a Gila Monster on top of one of these subs, and grin like a Cheshire Cat.
Really dumb question time. How would I go about putting a pair of these in an isobaric alignment, and what would the advantages be, beyond lower distortion. Do I wire one up normal polarity and the other reversed? Do I need two amps? I don't have the grasp of this. (Where's the "stupid" smilie?)

[mzisserson]

Looks Good. Someone needs to design a 2.5 or 3.5-way bass monster with these guys.

I have a 3-way going with 2 per side, good' nuff?

[benhinkle711]

Really dumb question time. How would I go about putting a pair of these in an isobaric alignment, and what would the advantages be, beyond lower distortion. Do I wire one up normal polarity and the other reversed? Do I need two amps? I don't have the grasp of this. (Where's the "stupid" smilie?)

Really the only advantage would be a smaller enclosure. I modeled 4 of these in an isobaric arrangement and came up with a internal volume of .75 ft, after losses. That would get the load back to 4 ohms and should get into the mid to upper 20's. How you mount the drivers would determine how you wire the drivers. If you mount them cone to cone, what some call clamshell, the drivers would be wired out of phase so that they move together. If you mount them cone to magnet you would just wire them in phase. You would need a 2 ohm stable amp if you were to use just two of them. If you mount them in a clamshell arrangment you would just need a spacer between the drivers, a ring made from MDF is what I've seen mostly. If you went with the cone magnet arrangment you could use spacers between the drivers that are thick enough to keep the inner driver's cone from hitting the outer driver's magnet at full excursion. I was going to do it this way using MDF spacers inside the enclosure. You'll want to make sure to account for the displacement of the driver and rings when calculating the enclosure volume.

[johnnyrichards]

Bryan, I think you will be very pleased with it. They are not a "Tang Band 1139" beater by any means, but they are a cut above as a mini-subwoofer.

The more I look at mine, the more I suspect they were an early production run of an aborted Dayton Classic subwoofer. They lack the binding posts, but are otherwise remarkably similar in other aspects. Then again, form follows function so...

[greywarden]

I have a 3-way going with 2 per side, good' nuff?

I approve, you can start building now

[mzisserson]

I approve, you can start building now

Already have... Build thread coming soon... I will stop hijacking this thread now... GOOD DAY!

[tobis]

This makes me wonder about using these to replace the rear side stock speakers in my dakota club cab. Then power them (carefully) with a subwoofer amp when the real subwoofer box is out of the truck.

I don't know if there is enough mounting depth, or what volume or how un-sealed it is.

[mzisserson]

This makes me wonder about using these to replace the rear side stock speakers in my dakota club cab. Then power them (carefully) with a subwoofer amp when the real subwoofer box is out of the truck.

I don't know if there is enough mounting depth, or what volume or how un-sealed it is.

They are not mid-basses. They are true subs (in frequency coverage anyway). Not mush good above 250Hz or so.

[tobis]

They are not mid-basses. They are true subs (in frequency coverage anyway). Not mush good above 250Hz or so.

That's fine. I'd be taking out the full range speakers driven by the deck and putting in subwoofers driven by a sub amp. The sub amp would normally power the subwoofer box sitting in the seat. I could unplug the box, take it out, plug in these guys, and still have some reasonable bass. Hopefully.

[bkeane1259]

This makes me wonder about using these to replace the rear side stock speakers in my dakota club cab. Then power them (carefully) with a subwoofer amp when the real subwoofer box is out of the truck.

I don't know if there is enough mounting depth, or what volume or how un-sealed it is.

As Mike said and as Johnny has measured, these 6.5" subs fall apart quickly above 200Hz, but if you're using a sub amp with an adjustable low-pass filter, I'm sure you could experiment. The cabin gain might actually work in your favor...who knows??

I can supply any physical driver measurements you might need....just ask.

[bkeane1259]

Took advantage of today's balmy Chicago weather to get a good portion of this sub done. Here's the Dayton SA25 and the 6.5" buyout sub --



The planned layout-- The amp and sub will be mounted on the same (spacious) baffle and there will be a side-firing port. Not doing anything fancy. The sub and plate amp will be surface-mounted.



3/4" MDF panels and 2" ID PVC piping --

[bkeane1259]

After routing the woofer cutout, I did a chamfer on the backside for more breathing room.



To make the 5" square cutout for the plate amp, I used a new Christmas toy -- my Dremel Saw-Max. This is one heck of a handly little saw!!



The port hole is 2.375" and the PVC pipe fits extremely snug in it. You'll have to sand the pipe slightly and then hammer it in from behind, but it is SOLID.



I used a 1/2" roundover bit for the port exit.

[bkeane1259]

Well.....none of my projects would be fun without a mistake. Turns out I had originally modeled the sub with a 2.5" x 15" port. Well I only had 2" ID PVC and I forgot to recalculate the port length. So I had to cut down the size to 11.5"



Lucky me. I got to use another Chistmas tool, and this one is really cool. The Genesis Multi-Purpose Oscillating Tool.




I used the Genesis sanding attachment to make it pretty.



Using Wally World mattress topper to line the large panel behind the woofer and I installed four 3/4" dowels for bracing.



Front baffle glued and clamped and she's drying as we speak.

[Whitneyville1]

Bryan you got clams. And as B.C. said "Clams got LEGS!" "You can never have too many clams."-Peter Lawford or Howard Hughes

[2leftthumbs]

How are you going to implement the active filter?

[bkeane1259]

How are you going to implement the active filter?

I'm not building an active filter. Sorry if I was misleading in the OP.

Just using the variable low pass on the SA25 @ 80Hz. It will be crossing over to this sound bar on my son's workstation.

[mzisserson]

80Hz. It will be crossing over to a sound bar on my son's workstation:

Dude! That's sexy as all heck! I love cool application for things.

[BeeTL]

Really cool project!