Thursday, September 18, 2014

Does it pound?!?! DIY Home Depot Bucket Subwoofer using a Peerless 8 inch driver and BASH 300S amp

Here is my bucket subwoofer. While being bored during some down time at work, I looked for new DIY project and stumbled up this:

A small subwoofer using a 5 gallon bucket as an enclosure, awesome right?

So I gave it a shot; made some adjustments along the way and learned a good bit. Overall it was fun, but not without a few frustrations. I might have to try the sump sub next.:

Full album of step by step creation.

I started off with just a $3 Home Depot bucket and a dream.

I then cut the hole for the Peerless SLS 830667 Paper Cone Subwoofer and glued the hell of our the top and hammer it on to the bucket with a rubber mallet.

I decided to try and port this one, but I also wanted to give myself an easy out just in case I totally screwed up. So I integrated a way to close off the port and seal up the enclosure. 

Porting it seems to have worked well enough. From my fuzzy math it should be tuned to about 30hz. Did that actually happen? Probably not. See the test results at the end.

Concrete is poured in, about 1.5 inches deep and left to dry for a few days

Attaching the wood baffle for the driver, this is where I learned that these types of buckets are near impossible to actual glue anything to.  Polypropylene and Polyethylene low energy or inert or something else all sciency so 3M made an expensive magic glue to work on them. Thank God for screws then. When the cut out was made for the woofer, a lot of tension was taken off the bottom of the bucket which caused the left over "lip" that I was trying to mount the baffle to, to angle into the bucket. The glue and screws were an attempt to pull that lip back up and get a secure mounting surface. 

Painting time. I used truck bed liner, which also doesn't stick very well. But once it cures its tough enough to not flake off immediately. Never mind the nearly dead grass, this is California and if you have green grass right now then F you. 

Cheap, crappy speaker terminals form Radio Shack. Never again.

Mounting the woofer and putting some stuffing in. A whole bunch more as added just after this picture


Since the subwoofer enclosure is made of a bucket, I needed some where or someway to mount the BASH 300S plate amp. So since we are working with plastics, I found a handing file box at Staples that suited the amp well enough.

The future amp box

Drilling some pretty pretty air vent holes. I used a checker board pattern to make them nice and even-ish

Cut out for the amp done


So how did this thing actually turn out?

From just listening to music and watching a few movies, it definitely provides some kick and sounds pretty alright to me. Much louder than the Dayton Sub-800 that I normally have on all the time; and I think it might be darn close to besting the Dayton Sub-1200. Getting into more technical understanding on how well it blends or transient response and all that, Im not the best judge. I'm a car audio bass head who rolls around with an 18 in the back of my Ford Fusion so you can see where my priorities lie.

But I did take some in room responses so at least we can see a little bit of the technical results. So check these out. As a note, I'm still having trouble with REW, Dayton UMM 6 and my PC getting a consistent overall volume. You'll note that the graphs are centered around the 100 db mark, just prior to these testings, I was getting results centered around 80 db. Graphs look identical, just centered at the wrong point. 

Ported vs Sealed response. Not a huge difference, but audible for sure. Ported open is louder accross the usable spectrum. My room has clean peak at 100hz and that showed in all subs tested.

Bucket Sub vs Dayton Sub-1200. This was most supriseing. The bucket sub is louder than the Dayton from 50hz to 100hz and equal from 50hz to 35hz where the Bucket sub gets louder again. 

A few addition images of other sub tests can be seen below

Monday, September 8, 2014

My recent adventure down Phase Lane: In Phase or Out of Phase?

Over the last month or so I have been listening to a few different set up and trying to pin point what set I wanted to build my home theater around. One set is from a well known manufacturer that that people tend to love or hate and the other from a lesser known manufacturer who has had some significant online sales of the past year or so. However, this entry isn't about a comparison between the two. This is about my experience in messing around with the phase of one of these two sets of speakers.

I found one of the pairs of speakers to be VERY muddy sounding, which when reading other professional reviews, was never a criticism of the speakers. So I wanted to start some technical tests and investigate what was going on. All of the following graphs and experience comes from an real world, untreated room. So there will be reflections and some natural room issues.

Below (graph #1) is the in room frequency response of a single of the speaker @ 1 meter. Right away the results seem to correspond to what I was hearing, a big ugly wide hump @ 150hz with everything else being acceptably flat.

Next up (in graph #2 below) was the 2.0 set up at the listening position. This is where it got really ugly, like WTF kinda ugly. This graph was unlike any that I have seen with other speakers in the same room, under essentially the same testing condition. I huge sharp dip @ 90hz; with a peak at 250hz that gradually trails off at we reach 20khz. This is were I realized I was seeing and hearing something not right. But it better explained why these speakers sounded muddy and without an detail; and absolutely not harsh or bright like they sometimes are criticized for being. I didn't know what was going on, so for nothing more than shits and giggles I switched phase on just one speaker. I remember my time in car audio and people expounding on the virtues of switching the phase on a tweeter in a component set, so I thought, maybe just maybe it will makes a difference.

This (below in graph #3) was the result. With one speaker out of phase the graph changed yet again, and this time for the better. Still a little more wavy than I would like, but finally they didn't sound so muddy and the detail and brightness came back. They sounded much more like they should have.

My first worries were it either a speaker was internally wired out of phase or that my amp was crossed some how. I triple and quadruple checked that I hadn't crossed my wires when I put on the terminal ends and that were good. Having 3 of these speakers already (used as the front 3 in a 5.1 system) I round robin tested them all. Both rotating them into position and rotating them in and out of phase and amp output A or B, the graphs always returned something very near identical. If both speakers were in the same phase, it looked and sounded like graph #2, if either speaker was out of phase with the other it looks like graph #3. 

That being the case, to the best that I can gather, this is just very weird situation that seems to be isolated to this set of speakers as they are set up in my room. At some point later I will continue my complete technical and listening review of these speakers.

Anyone got any ideas? I tried to do a little googling about phase issues, and I didn't really see anything about switching the phase on just one speaker.

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