A little DIYMA X-mas present, a brand new DIYMA sub. :p

[mvw2]

I finally decided to try out a DIYMA sub. I've seen a lot of rave reviews as well as mixed experiences. I didn't want to stay on the sidelines forever and the DIYMAs are selling out, so I jumped on one.

The packaging is quite interesting, and I must say it's the first time I've seen this type of cardboard structure. The sub was placed in a bag, in this goofy yet very protective cardboard structure, in another box, and finally the shipping box. There's definitely a lot of care taken to make sure the sub arrives safe.



Some pics moving around the sub. The sub is definitely...substantial.







Initial impressions are favorable.

It's a hefty unit but also extremely sturdy in design. There's plenty of ventilation everywhere, and the design is quite open. It certainly looks the part of a high powered subwoofer.

The suspension feels relatively stiff out of the box. I'm sure it will loosen some after a little use. Most of the other subs I've used so far have been softer. The cone has a small amount of noticeable flex to it when pressed from one side, but it's not too bad. I'd like to see absolute rigidity, but being aluminum, I doubt it would affect the level of detail much. The cone feels extremely light to the touch. I'm sure it's quite effortless for the motor to move, and I hope (assume) creates quite a transparent sound.

From my initial impression of the stiff suspension, very light and somewhat flexible cone, and obviously very powerful motor, I can see why there is some concern over cone damage during use. I can see it happening from an unexpected high output event, but I can't see it happening during normal use and not without a material defect or perhaps fatigue over some millions of cycles. I get the perception that there is very little room for error though and buckling would be an obvious form of failure. It's the nature of the beast though when playing with (relatively) thin materials like this. I don't want to get into a big discussion over this in this thread. This is just my initial impressions/opinions. At the same time, I don't plan to use this sub timidly. I plan to use it as I do any of my subs and see what happens. I honestly expect a long, healthy life for my use.

Well, I had my 1.5 cu.ft. sealed box sitting, waiting to be converted to a ported enclosure for the DIYMA sub, however I'm quite sure I don't have the internal space for the porting, at least not how I was planning to build it. It was an obvious oversight on my part (wasn't thinking), so now I need to decide if I want to build a new box for the sub.

The problem is the box is neither wide enough to allow the port to go beside the subwoofer nor deep enough to go under the subwoofer. It's a long, narrow box, measuring I think 11"x8"x35", and I'm planning to put a 4" diameter 30" long port in there. I'm piecing together Dayton's nice do-it-yourself port parts but only have one 90 degree elbow. I could snake it around in circles if I had a bunch more, lol, but it would still be a very tight squeeze just limited to one side only. I chose 4" because that was all I needed at my power level. 400w will only see about 9mm used. A 4" diameter port is plenty at this level. If I was running 1000w, I would be using something larger.

I could do an external port for the time being, if nothing else just as a test for the enclosure design. Then I could simply build a new one in the future. That might be what I will have to do.

By the way, modeled up, ideal, flat is 1.0 cu.ft. tuned to 29Hz ported, giving a F3 of 30Hz. Ported enclosures for this sub seem to be really neglected and my car has almost no subwoofer cabin gain, so that's what I'm doing. I'm shooting, at least for my makeshift 1.5 cu.ft. box, something in the range of 1.0 to 1.2 cu.ft. (lose some sub and port volume) tuned in the range of 28Hz-29Hz. Without the port inside, I'll probably have to put something inside to take up a little of the volume.

In the mean time while I play with the DIYMA beauty, npdang's getting my pioneer PRS sub for a little while to test, so that should be fun to see.

[GlasSman]

That is a nice sub. 38 LBS of American engineered goodness.

[TJHUB]

I'm very happy with mine. However, if the sub didn't work so well in small enclosures (mine is .65cF net), I would have picked some other sub. To me, if you're going with a larger enclosure and ported, there are better subs. This is of course my opinion and I am entitled to it.

[kimokalihi]

None of your pictures are showing up for me.

[Kahooli]

keep us posted, seems like you'll do a nice job of testing and reviewing. also, which vehicle is this going in?

[tcguy85]

those look pretty sweet. let us know how you like it.

[mvw2]

It's going in my Forester, but I plan to play with it in my house too in my ghetto home audio rig consisting of a $5 receiver off Ebay, some old Cambridge Soundworks Ensemble speakers again off Ebay for $60, and borrowing my bro's 300w plate amp off Parts Express for the sub.

[GlasSman]

I'd like to see the results of this sub in a ported enclosure.

[mvw2]

Well, I've got a little update for now.

I've got my box design made up and ready to build. I bought a 4" port from Parts Express, but I ended up not really being able to use the thing. I bought only one elbow, and I really have no good build options to make use of the thing. I spend a few days just fiddling with design ideas(avoiding just using an external port), and I had a really hard time being able to build a small enough enclosure size for the sub and still fit the port without probably affecting the tune frequency. It got messy. So...I went back to the good ol' slotted port approach and whipped up a design.

The box is designed to give exactly 1 cu.ft. for the sub, takes into account woofer displacement and end correction for the slot design. I essentially made the "ideal" box for the sub, 1 cu.ft. tuned to 29Hz.

Here's what I've got for now. I plan to hopefully whip this up tomorrow(along with more pics). These are just pics of what I pieced together on Powerpoint. The pics are a little fuzzy but well enough.

This is the box as well as a few specs for the design:


This is basically the parts list, using 3/4" MDF. The subwoofer cutout hole is 11" even and the port is simply a sum of the parts in their correct locations.


More pics to come as I get to building the enclosure.

An interesting note of the design is the heavy port to enclosure volume ratio. This is a difficult fact to work around when placing small box subwoofers in a ported configuration. It's essentially all port. My setup isn't even that bad as I'm not using a lot of excursion. If I was putting 1kw to the sub and made a bit more use of the excursion range, I would see a design that's dominantly port versus the intended enclosure volume. I'm glad slotted designs are easy to work with in this reguard. For this, I'm simply wrapping the port around the outside. It gets a bit challenging with the PVC pipe type of design. At least I've still got my Sonicraft sitting around waiting to be placed in a ported box. I'll still be able to make use of the port I bought and have a large 6 cu.ft. box to easily place it in.

[internecine]

good luck with that front baffle, it does not look like it will be too sturdy

[BassBaller5]

agreed. Should make getting a nice seal interesting

[tcguy85]

cool, i'll be watching.

[mvw2]

Well, the sub actually overlays 3 walls. The face, although goofy like that will be screwed and glued first, making a solid piece with the side walls. Then the hole will be cut out. The small piece isn't going to do a whole lot really since the sub will rest on 3 vertical walls anyways. This makes the large side the only side that's really free. I really don't expect any problems with the design. Just don't think of that piece as having the hole initially. Think of it as a finished piece, then cutting the hole. I can't imagine trying to cut that out without it as part of the rest of the enclosure.

[npdang]

It's all where you put your priorities....

Stiff suspension = small vas = small box size

Heavy coil = low fs = improved low end extension

Light straight profile cone = increased rigidity, improved efficiency, much higher frequency/milder breakup mode, better transient response

[mvw2]

Yeah, I'm looking forward to listening to it. I'm part way done. I've got all the pieces cut and ready to screw/glue together.

[jrouter76]

Originally Posted by mvw2

Well, I've got a little update for now.

I've got my box design made up and ready to build. I bought a 4" port from Parts Express, but I ended up not really being able to use the thing. I bought only one elbow, and I really have no good build options to make use of the thing. I spend a few days just fiddling with design ideas(avoiding just using an external port), and I had a really hard time being able to build a small enough enclosure size for the sub and still fit the port without probably affecting the tune frequency. It got messy. So...I went back to the good ol' slotted port approach and whipped up a design.

The box is designed to give exactly 1 cu.ft. for the sub, takes into account woofer displacement and end correction for the slot design. I essentially made the "ideal" box for the sub, 1 cu.ft. tuned to 29Hz.

Here's what I've got for now. I plan to hopefully whip this up tomorrow(along with more pics). These are just pics of what I pieced together on Powerpoint. The pics are a little fuzzy but well enough.

This is the box as well as a few specs for the design:


This is basically the parts list, using 3/4" MDF. The subwoofer cutout hole is 11" even and the port is simply a sum of the parts in their correct locations.


More pics to come as I get to building the enclosure.

An interesting note of the design is the heavy port to enclosure volume ratio. This is a difficult fact to work around when placing small box subwoofers in a ported configuration. It's essentially all port. My setup isn't even that bad as I'm not using a lot of excursion. If I was putting 1kw to the sub and made a bit more use of the excursion range, I would see a design that's dominantly port versus the intended enclosure volume. I'm glad slotted designs are easy to work with in this reguard. For this, I'm simply wrapping the port around the outside. It gets a bit challenging with the PVC pipe type of design. At least I've still got my Sonicraft sitting around waiting to be placed in a ported box. I'll still be able to make use of the port I bought and have a large 6 cu.ft. box to easily place it in.

what did you use to get your cut-sheets for the board measurements is that a program?

[mvw2]

Just Powerpoint. I put the grid on and set to 0.25", max out page size to have room to work with, and worked with that. I put in the numbering by hand(just insert text/line stuff). It's really just simple drawing.

I need to revise the sheet though. I did end up doing two different things. One, I'm using two 2' x 4' boards and I couldn't fit all the patterns on two sheets without cutting up one of the long pieces. I ended up taking 4" off the 24.5" long piece, so I have the 20.5" and a separate 4" piece to make up that section. As well, I don't have two 8" wide pieces but rather one 8" wide one and one 6.5" wide one. I didn't notice that till after I made these pics.

[mvw2]

Small update,
the box is now in one piece.

I still have a few things to do like cut out woofer hole, seal with silicon, carpet, and run wire into the box.

I've got a bunch of pics so far, just not uploading them as of yet.

The build went pretty smoothly. I had to trim a few pieces slightly to get to exact length. The port was a little tricky getting centered in the box. I ended up tossing spare MDF around it to take up the gap and get my the 1.5" spacing I needed all around. A bunch of drilling, glueing, and 70 or so screws later, it's in one piece and looking good. I'll tackle the rest tomorrow and should have a bunch of pics up soon. Then I get to finally listen to the thing.

[Mano_X]

Like that ass

Only have seen a "similar" motor design on Focal Be Sub's




Mvw2 get that review done.

[a$$hole]

Show that ass !!

[mvw2]

Lol, getting there.

[GlasSman]

Finish already!

[a$$hole]

I really like the design of the port on your box !

[mvw2]

Got the hole cut and a bead of silicon around everything. Now I've got to wait for that to cure a bit so I can carpet.

[a$$hole]

you like your Z series amp?