A few notes on the Sump Basins
. They are perfectly decent subwoofers when sealed, but adding a port provided such an amazing boost in efficiency - right in the most crucial range (for me) - that I converted all four to full ported before the GTG. I originally intended to test them sealed, but since I will never use them sealed I don't see the point. The sump basin works better ported.
The tuning is variable by adding pipe lengths to the port's exit. Tuning was extended downward from the default 17hz, to about 14Hz in the configuration I used at the GTG. Longer tubes = lower tune and that's the main feature of the subs, the ease with which the tuning can be changed to specific frequencies. The 'dip' at 30hz represents the beginning of the (current) port's contribution to output, which peaks at +8db (vs. sealed) right around 16hz - the effect is clearly visible in the measurements. The loss of output at 30hz has to be compensated for with EQ - which I intended to do with the Crown's DSP. I had issues connecting my laptop so I depended on Gorilla's Omnimic setup instead. I've never used it, so in the name of keeping things moving, I did a below-par job with the EQ. The subs were not positioned in any particular manner - they did not fit into Gorilla's HT setup because they are too tall. I'm sure optimizing their position within the room would yield better measurements at the LP.
The main benefits of the build are as follows - Minimal tools, locally available parts, low cost, high performance, light weight and durability. I'm especially happy with how easy the whole system was to transport. The minuses amount to the space they take up and aesthetics. I'm really glad to have independent verification they are generating strong, clean bass sound from 10hz on up. That was a crucial point in my going DIY, so that I am able to mix my music with relative accuracy in the infrasonic realm.
I learned the value of a dedicated 20 amp line. My Crown XTi-2002 flashed clipping lights a number of times but never faltered, nor did the subs. If I try the same trick at home it's now clear that I run out of juice at the wall before getting the full performance from the amp. The other surprise - how identical the EP-4000 is to the XTi-2002 in terms of power output and SQ. They are essentially identical. With the Crown you pay for lighter weight and DSP, not more or 'better' power. On the flip side, using the Crown makes the whole system self-contained and light enough where one person of modest strength (me) can move the entire system by themselves. I can imagine a hip-hop Busker in NYC bringing one of these into the subway as part of their 'street' rig.
edit - more notes
Here are the WinISD curves, the ported models have interior volume calculated as 135 liters, vs. 144 for the sealed. With four subs, the 14hz tune can hit 115db reference with 'full' power (400 watts RMS each), the 17hz tune can do it with 200 watts each. During testing, we clipped the amp and the drivers themselves never faltered. I actually have no clue what it would take for them to hit their limits, since Sony's specs are all over the place and (in my opinion) inaccurate, erring on the side of caution. It's hard to believe these subs have an xmax of only 6mm considering their output.
Edited by imagic - 12/17/12 at 11:01am
Originally Posted by Gorilla83
Mark - Thanks for posting your thoughts! Looking forward to hearing from Nathan and Adam too.
Here are a few of my own:
A few notes - This was a very informal GTG for us to just hang out and listen to a few clips on all the setups. We used my Denon 4311ci receiver, minidsp for eq, SHO-10s up front, and my PS3 / Mark's laptop for media content. My room has some basic treatments including front and rear bass traps, and side wall reflection panels. A variety of amps were used throughout the day including Mark's Crown XTI2002, my EP4000, and my LG Clone FP14000. We listened to a few popular clips from the Art of Flight Blu ray, the Scuba Steve disc (Hulk, HTTYD, WOTW, BHD Irene) as well as a few Blu Ray concert clips I'm familiar with. We also played around a bit with the 10hz to 100hz sine waves at moderate levels. In addition, Mark played a number of his own creations and even broke out the synthesizer at one point, which was pretty neat. It was amazing how quickly the day went with just a few simple setups and really no formalized process.
A few measurements - these were all matched to the same level at 20hz - with the sump basin setup in the mix this was really the only logical point. I'm aware this isn't ideal, but it was what we had to work with.
After EQ - keep in mind none of us spent an extraordinary amount of time with the eq process, we did our best with just a few simple filters.
Mark's 4 X ported Sump basin setup powered by a Crown XTI2002 - Wow, you guys have got to see the pictures when Adam gets them up. A+ for creativity for sure - we all agreed they look like they belong in a sci-fi film. We hooked these up for fun - and a lot of it we had. We listened to a majority of Mark's created music with these (house/electronic/dubstep - please correct me if I'm mislabeling!. I was impressed they had some decent impact in my room which tends to really suck up the bass! The presence of these 4 beasts in the front of my room had a dominating effect.
Check out the output at 20hz and below with these guys. The overall curve was a bit crazy, likely due to Mark's port tune. Mark experimented with various points of EQ using my minidsp to try to smooth the curve out a bit as you can see before/after EQ. Mark can probably add some additional details to the build.