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**djkest** · 02-11-2013, 12:17 PM

Re: Something Wicked this Way Comes (RSS460HO-18)

Using Dayton Provided T/S parameters:

Using Data-bass provided T/S parameters:

I have some interesting WinISD sims I've done too, I just don't have those on this computer right now.

I recently aquired an iNuke 3000 DSP amplifier. I like it quite a bit, although it has 3 problems for home use. 1) Rack ears not removeable 2) bright silver color 3) loud! Well, the 3rd point was easy enough to take care of. It uses an 80mm x 25mm computer fan for cooling that spins about 4000 RPM. I replaced it with a 2000 RPM fan (0.12 amps @ 12 Volts) and it's very quiet now. I also trimmed the cooling shroud very slightly to reduce airflow impedance (part of the reason for the noise). You can hear the fan from 1m away in room if there is no music playing, but it's really not bad. A 0.9 amp fan would most likely be inaudible.

**1100xxben** · 02-11-2013, 12:33 PM

Re: Something Wicked this Way Comes (RSS460HO-18)

Originally posted by djkest View Post

Powered by 1/2 of a Behringer iNuke 3000 DSP.

Why just 1/2? That amplifier has a very short thermal capacity and will start folding back after driving it to high levels for a few seconds. It might be better to have it bridged and have a lot of overhead.

Very cool project though. I'm curious to hear your impressions.

**djkest** · 02-11-2013, 12:48 PM

Re: Something Wicked this Way Comes (RSS460HO-18)

Originally posted by 1100xxben View Post

Why just 1/2? That amplifier has a very short thermal capacity and will start folding back after driving it to high levels for a few seconds. It might be better to have it bridged and have a lot of overhead.

Very cool project though. I'm curious to hear your impressions.

Even with only 1 channel at 4 ohms, it should be producing about 600 Watts RMS; 900 watts peak. I seriously doubt that it will throttle back the power unless I'm running low frequency sine waves; especially since it's 2 ohm stable per channel. You may be right though, and I intend to test the crap out of this sub after it is built.

**generic** · 02-11-2013, 12:52 PM

Re: Something Wicked this Way Comes (RSS460HO-18)

Don't forget to reinforce the foundation.

**1100xxben** · 02-11-2013, 02:18 PM

Re: Something Wicked this Way Comes (RSS460HO-18)

Originally posted by djkest View Post

Even with only 1 channel at 4 ohms, it should be producing about 600 Watts RMS; 900 watts peak. I seriously doubt that it will throttle back the power unless I'm running low frequency sine waves; especially since it's 2 ohm stable per channel. You may be right though, and I intend to test the crap out of this sub after it is built.

I understand your thought process, but I think an LFE intense movie scene will be worse than most music. Just think of the magnitude and duration when the Nebuchadnezzar flies overhead.

FYI, when it folds back, you'll only see about 55 volts peak out of the thing, which equates to a maximum potential of ~400 RMS output. Especially if you're not going to use the other channel for something, I would just bridge it. The extra overhead voltage will be great for dynamic peaks, and you're splitting the thermal and electrical stress over twice as many parts. IF you have to EQ the bottom end up at all, that extra voltage potential would also be very handy so you don't run into clipping.

**ericJ** · 02-11-2013, 03:00 PM

Re: Something Wicked this Way Comes (RSS460HO-18)

Sounds like a monster. Looking forward to pics and impressions. I keep trying to talk my wife into a fridge sized sub but keep getting "no". Fun to watch others though!

**Brian Steele** · 02-11-2013, 06:33 PM

Re: Something Wicked this Way Comes (RSS460HO-18)

Originally posted by 1100xxben View Post

Why just 1/2? That amplifier has a very short thermal capacity and will start folding back after driving it to high levels for a few seconds. It might be better to have it bridged and have a lot of overhead.

FWIW, I borrowed my brother's 3000DSP to test drive two 15" pro audio bass boxes I was building for him. I didn't detect any reduction in output when driving those speakers at high levels (test track: Danity Kane's "Showstopper") for several minutes. The bludy things were so loud that all of the cabinet doors in the my kitchen were vibrating. I'm seriously considering getting one of those amps for my own use

.

**djkest** · 02-13-2013, 09:55 AM

Re: Something Wicked this Way Comes (RSS460HO-18)

Driver is set to arrive tomorrow. I have most of the pieces cut to size already. I can screw and glue the panels or use a nailgun with finish nails. I made the front baffle oversized so I could use the flush trim bit, but now I am kind of regretting that decision because I can't use the edges to square it up either. The whole thing will get Bondo on all the seams anyway. A couple features I am planning on for this build. The front baffle is going to be 3/4" MDF over 3/4" 11-ply plywood. After the annoyance of the bolt kits, I am going to attempt to mount the driver using 1" screws into pre-drilled holes in the plywood. I want to make a recessed area on the back to mount my speakon connector, just recessed enough so that it doesn't stick out too far, and could be located close to a wall if necessary.

For bracing I think I am going to do some shelf-style bracing that is about 50% voided. One brace will go from the top to bottom full length, with a cutout for the driver, which is pretty substantial. And then 2 "shelfs" to break up the top to bottom panels. I also bought some small rubber "Penn Elcom" feet that I wanted to try out. They are cheap, and I don't expect them to do much, but would make the sub suitable for hard or soft surfaces.

Unfortunately I am going to be gone this weekend so I probably won't get much if any work done.

**carlspeak** · 02-13-2013, 10:58 AM

Re: Something Wicked this Way Comes (RSS460HO-18)

Nice project, but a cautionary tale follows:

I recommend to go easy on the volume. Low freq. bass can be addictive as evidenced by the myriad of thumping car subs cruzing the streets.
Here's an article I found that supports a theory I've had about the damaging effects of high SPL low freq. has on the auditory system. A suprising revelation in the article was how other, damaging physical side effects beyond hearing can result from a steady diet of infrasonic sounds.

http://www.lowertheboom.org/links/h09_infrasound.html

**djkest** · 02-21-2013, 01:35 AM

Re: Something Wicked this Way Comes (RSS460HO-18)

I got the 18" dayton driver. It's a monster! Pics really don't do it justice. The surround is just massive. The cone is very thick and rigid. Of course, the build quality is fantastic, a Dayton Reference hallmark. Pretty excited to start playing some tones through it, although I don't have any test enclosures or easy ways to contain this thing, so I'll have to wait until the sub enclosure is nearly done before I can put some power into it.

So work has begun. Of course, it's been more work than I initially thought.

Screwed and glued. Last time I used biscuits and glue only. I think I like the screws, although they aren't without their own problems. Pre-drilling all the holes and flush-mounting all the screw heads takes time.

Internal bracing design

Dry fitting the bracing inside

Gluing up the internal braces.

Lots of work to be done. Front baffle is getting a 2nd layer. Lots of flush-trimming left. Need to cut the circular holes, make the recessed speakon jack, and of course attach the back panel. More braces too. I budgeted 600 cubic inches of bracing, I think I've used about 1/2 of that.

It's funny that this is the "small design" alternative that I considered, and it's huge. The ported one would have been significantly larger and more obtrusive. Perhaps once it's all finished and painted black it won't be such a dominating spectacle. Or maybe it will be.

It's going to be 4.0-4.2 cubic feet net internal volume. I am not entirely sure what the volume displacement of the driver is.

**johnnail** · 02-21-2013, 09:28 AM

Re: Something Wicked this Way Comes (RSS460HO-18)

If flush mounted on a 1.5" baffle, then the backside of the driver will displace about 10.23 liters of cabinet volume. Overall displacement of driver backside is 11.62 liters.
Are you planning on putting any damping material inside the box such as AcoustiStuff or Fibreglass? If so, this will lower the Qtc of the system. I played with Winisd and other free box calculators and found them to be not that accurate. I prefer minimum of either Bassbox 6 Pro or LspCAD. Either of these are more accurate. When loading this driver....accounting for use of "typical" fill (all sides, back, top, bottom lined with 3" of R-13 fiberglass or equivalent....the suggested box volume to get a finished Qtc of .707 is more like 3.27 cu.ft. net. If going for full 100% fill damping, then to retain .707 Qtc, the net volume is more like 2.5 cu.ft. Bracing is good...for stiffening the walls and reinforcing the cabinet....but when it comes to taking care of standing waves, absorption is the way to go...this gets rid of the potential "muddiness". This means using some internal damping material such as long-fiber wool, fiberglass, AcousticStuff, etc. These materials are always going to lower the system Qtc. if the box volume remains the same. This not necessarily a bad or good thing...there are always tradeoffs. A lower Qtc means less "shock absorber" control on the cone that the box will have....meaning that in the lowest frequencies, the cone will reach xmax with less power than predicted as compared with same volume with no stuffing and having a significantly stiffer shock-abosrber action. The mentioned 600 watts...in a lower Qtc system box, driver will reach beyond XMax below 20hz. As I have modeled your 4 cu.ft "net" volume box with this driver, the Qtc of .704 is with no fill in the box...with typical lining of fiberglass, the Qtc drops to .66 and with 100% fill "heavy" damping it drops to .6 . To restore the system Qtc to .707 which is maximally flat amplitude, the box volume needs to be reduced to 3.27 cu.ft for typical damping, or as small as 2.53 cu.ft. for heavy 100% fill. The F3's of each configuration change a small amount...but all stay at or below 40hz. This being said, when figuring in minimal room gain (3dB-octave at 35hz...most rooms have more than this), the F3's lower to the upper 20's or lower 30's depending on the configuration. The problem with the larger box volume, is that not only are you going to reach xmax with less power than predicted at or below 20hz, but once you bring parametric EQ into the equation, this is going to worse...since boosting the frequencies in the 20-35hz region is going to make the driver reach xmax in those regions with even less power. That is why I choose strategies like keeping the Qtc of the system a bit higher if planning on using Parametric EQ (boost) to lower the system F3. It is safer for the driver....IF you are planning on driving the unit to full output.
Just my two centavos.

John

**djkest** · 02-21-2013, 02:34 PM

Re: Something Wicked this Way Comes (RSS460HO-18)

John, what value are you using for XMAX? A practical limit is most likely 20mm, and Xmech is very close to 30mm.

Yeah, I am going to stuff the box, at least the back wall and some on the sides. I have a bunch of white R13 sitting around, so I might use that, it IS free after all. I will probably be testing this sub with RINNAVs woofer tester to see if we can get some individual T/S parameters. I didn't intend for this sub to have such a low Qtc, I was shooting for about 0.74 or so. I guess if it ends up being in the 0.6x range that just means it doesn't need as much power!

Note 1: got the through-hole made for the woofer. Darn thing is 1/8" off-center from side to side! It's barely noticeable, but I notice it. I will probably end up laminating a 1/4" sheet of MDF to the "short" side to even things out. so I guess one side will have 1" thick walls. :/

Note 2: Hooked it up to my little 75W emotiva amp (1 side) to see if it works. It does. As a fullrange speaker, this 18 is lacking. Absent is the "sparkle" on the high-end, and the vocals are very "dark" and "recessed". Note to prospective buyers- this won't replace your fostex driver.

I suppose I should have expected this, but playing the bassline in Norah Jones songs, with all the amp can give it, BARELY moves the cone at all; and it's pretty loud. And it's open-baffle right now. I'm almost scared to see how capable it will be when I get it hooked up to the iNuke.

**djkest** · 02-24-2013, 08:04 PM

Re: Something Wicked this Way Comes (RSS460HO-18)

Less talk more action.

Think I have enough braces?

The whole thing needs a pass with the flush-trim bit.

Spent almost 2 hours making the 4 triangular braces and getting them fit in very snug. Had to pound them in place.

I actually made a 2nd baffle for the front. The first one is trash. I was rushing too much and it was about 1/8" too short on one dimension and the cutout was 1/16" too small- sub wouldn't even go in.

I really wanted to get it done fast, but when I rush things I do crappy work. So I forced myself to slow down and just do what I can to the standard it should be done.

I was going to solder the speakon terminal to my speaker wire and then I realized I suck at soldering and I'm going to use some spade terminals.

Notes:
*The front baffle is 1.5" thick plywood. 22 plies! The driver is recessed 3/16" so that it's possible to remove the sub while the box is on it's back.

*I added 1/4" MDF sheet to one side, since the first through-hole was off-center by 1/8". It's now within 1/32", easy. That means one side is 1" thick.

**djkest** · 02-26-2013, 01:32 AM

Re: Something Wicked this Way Comes (RSS460HO-18)

Listening to it right now! I had a list of 10 "tasks" to complete when I got home from work and I just flew through them. However, when I hooked it up, no sound. I pulled the driver and sure enough, I had hooked up the Neutrik Speakon terminal wrong. Re-installing the driver I stripped one of the screw holes. Note to self, do not use impact driver to install subwoofer screws, it's too powerful. It's OK though, I'm getting bigger and longer screws soon enough to mount the driver.

It seemed really quiet at first but appears to be getting louder as we speak. A couple first sound observations- feels very effortless and plays very deep. Also seems to have "punch" or "attack" reproducing my favorite upright basses on Jazz tunes. I know, all useless subjective comments. I've got one of four clip lights flickering and I'm occasionally making stuff rattle in the room. Can't really unleash the fury right now as my wife just went to bed.

Air Leak! Turns out there was a continuous void in the 2nd baffle piece, pressing on the cone revealed a small leak on the side of the front baffle. Easily solved with some wood glue in the void. I did have to wait 2 hours before I could listen to it though.

Back Panel with 14 screws + speakon terminal:

DIY family... that's a 12" on top, 6" to the right...

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Something Wicked this Way Comes (RSS460HO-4 18" Subwoofer)

Something Wicked this Way Comes (RSS460HO-4 18" Subwoofer)

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