My DIY sonotube sub is done. Pic and impressions inside.

[bobgpsr]

Yeah, thanks for leaving that behind. We slapped a clock on the face and called it a clock tower. The bass on campus is phenomenal.

LOL That is a really good one Jon! :alol: :rofl:

[chasw98]

Very funny. Worse than you think. :P Yup, I'm a professor here.

Now I don't know whether Steve was a student of yours or not, but I find it interesting and ironic that the student has come back to help the teacher build the biggest sub I've seen :T . By the way, Steve designed my sub, so I know you're in good hands.

Chuck

[---k---]

Yeah, thanks for leaving that behind. We slapped a clock on the face and called it a clock tower. The bass on campus is phenomenal. :T

Too funny.

[SteveCallas]

Now I don't know whether Steve was a student of yours or not

No, chemistry has always been a weak point for me.

Here's a story - my lab TA for CHEM 116 freshman year was a guy named Mahesh and he once gave my group a -3 out of 30 for a lab. We completed the two page pre-lab, showed up for the lab at 7:00 AM on a Friday, put in 3 hours, completed all the post work including a four page report, and he gave us a NEGATIVE score. He had it in for us from day one, why I don't know. Complaints to the professor about that score led nowhere, so all three of us dropped out of that class, and from that day on I swore to get my revenge on Mahesh. Unfortunately, I heard he took a job in New Jersey the semester after that.

Hear me now Mahesh - I haven't forgotten, and I will still get my revenge!

[---k---]

Oh, that is nothing compared to my calculus TA, Xu - pronounced 'chew' - or atleast that is the way we all pronounced it.... How we ever learned anything, I don't know.

[JonW]

Now I don't know whether Steve was a student of yours or not, but I find it interesting and ironic that the student has come back to help the teacher build the biggest sub I've seen :T . By the way, Steve designed my sub, so I know you're in good hands.

Chuck

Nope, we never met on campus. It was after the fact, through all this DIY sub stuff. I know Steve's education was good- and not just because it was from Purdue. His sub is very well engineered. :T

Hear me now Mahesh - I haven't forgotten, and I will still get my revenge!

I don't know the guy. Perchance, do you remember the professor's name? I'll have to razz him/her about it. That's too funny a story. :rofl:

[ssabripo]

So does that mean that Jon can pull a few strings and "re-calculate" Steve's borderline GPA?

[dyazdani]

Nope, we never met on campus. It was after the fact, through all this DIY sub stuff. I know Steve's education was good- and not just because it was from Purdue. His sub is very well engineered. :T

Since I went to a Big 10 rival school, I would have to say Steve's education was good "in spite of his attending Purdue." :lol:

[SteveCallas]

Perchance, do you remember the professor's name? I'll have to razz him/her about it

If I recall correctly, it was two women in what appeared to be their early 40's who co-taught and lectured for that course. I don't recall their names, but 116 was engineering-specific chemistry, if that helps any.

so does that mean that Jon can pull a few strings and "re-calculate" Steve's borderline GPA?

Hey now, I finished with a cumulative 3.61 and a major specific 3.90, not too shabby. Luckily we dropped out of that class and it was never reflected in our GPAs - but if Jon wants to "fix" my CHEM 115 grade of a C, that'll work

Oh, that is nothing compared to my calculus TA, Xu - pronounced 'chew' - or atleast that is the way we all pronounced it.... How we ever learned anything, I don't know

Yep. My freshman year calculus TA couldn't speak Engrish, I mean English, worth a lick. Anytime someone would ask a question that would force her to explain what she just thought she explained more clearly, or break it down a little better for us, her answer was ALWAYS "Ret's move on". It was stupifying. Though my professors and learning experiences got way better as the other years went by (freshman year was an isolated incident), I still insist that if not for the diploma with a univeristy's name on it, a student might as well just buy the books, teach themself, and save thousands of dollars. That would be the DIY way to get a higher education :T

[dyazdani]

"Ret's move on".

:laughat:

[---k---]

her answer was ALWAYS "Ret's move on".

Hum, they must teach that as the stock answer. Was it preceeded by, "Whach u meen. No important. Ret's move on."

Yeah, after you get past the freshman year and get into the engineering courses, the Professors and TAs improve a lot. Some of the best TAs I had in the engineering department were foreign. So, all the foreigner TAs aren't all bad. Of course, I know of at least one engineering department that has an unwritten rule against hiring non-native English speakers as TAs. I don’t like to admit to it, but I think probably is for the better.

Anyway, we have detoured enough, no?

[JonW]

Just an amusing update...

Yesterday, I showed this thread to my girlfriend, who helped me build the sub. She saw this photo that Steve put together:

Here is a comparison shot I threw together that should be accurate based on the Ultra's dimensions:

Image not available

Volume wise, you could fit just over 5 Ultras in this enclosure.

And she asked me "What's that little trash can in the photo?"

I told her it's another subwoofer, one that is very highly regarded, and in the $1,000 range.

And she said "Oh, so it's a baby subwoofer."

[SteveCallas]

Let's not be too hard on them - had it not been for SVS, I doubt there would currently be as much interest in high output, low extension, low distortion subwoofers as there currently is. They kinda shook things up.

[ssabripo]

Let's not be too hard on them - had it not been for SVS, I doubt there would currently be as much interest in high output, low extension, low distortion subwoofers as there currently is. They kinda shook things up.

hear hear!! :T

[FlashJim]

And she said "Oh, so it's a baby subwoofer."

Ok ... see, that's the problem right there. If a woman has a large one early on in her life, she assumes that's the norm.

You've ruined it for her and small subbed guys that follow you.

[JonW]

Let's not be too hard on them - had it not been for SVS, I doubt there would currently be as much interest in high output, low extension, low distortion subwoofers as there currently is. They kinda shook things up.

Really? I didn't know that. Interesting. I'm pretty new to this whole subwoofer thing. When I started looking into buying or building subs (and other stereo gear) about a year ago, SVS was already the raging craze on boards I started to read, like avsforum. If they paved the way, then I'm thankful to them. Certainly they have made many people happy with their products. :T

You've ruined it for her and small subbed guys that follow you.

:rofl:

[steve nn]

Certainly they have made many people happy with their products.

Most definitely! I think I have had no fewer than a dozen or so of their subs, some in triplicate. If a guy is going to buy a vented sub, they should be considered in the top echelon of offerings for the $$ IMO. I still have the 22 Hz tuned PCi in the den though.

[Nichol1997]

I just purchased a pair of re-coned Avalanche 18's and I am planning on mimicking Steve's design. I have a few questions before I order the Sonotube and amplifier.

Steve,
1) Would you do anything different from your original design?
2) Do you have any port chuffing or resonances from the port being so long?
3) Are you using a rumble filter to eliminate frequencies below port tuning?


I plan on buying a Behringer Europower 2500 and some sort of Behringer crossover or equalizer.

4) Do you have any suggestions for the crossover and/ or equalizer?

[Midnite Mick]

Holy Crap :E

I can't fully make it out but is that the edges of 103 inch plasma behind there? :B

In a word...Awesome
Makes my sealed Tumult look like a lego block

Mike

[SteveCallas]

1) Would you do anything different from your original design?
2) Do you have any port chuffing or resonances from the port being so long?
3) Are you using a rumble filter to eliminate frequencies below port tuning?

1) Not really. Had I known I would have three of these in the end and not two, I would have tuned even lower, maybe 12hz.

2) Definitely not - nothing even close. The port in this design, compared to others, is actually quite short at ~22".

3) Nope, no need. The low tune, amp limiting, and typical electronics rolloff keep it very well protected.

4) Do you have any suggestions for the crossover and/ or equalizer?

I wouldn't assume you absolutely need EQ in the first place. I'm pretty darn flat without any. As for crossover, I use a typical 80hz and it works well - no localization going on. Sub is in the front left corner, but bass in music comes from directly in center. Behringer EP2500 will work well, but be sure to consider fan noise.

Feel free to contact me if you want specifics.

[ThomasW]

3) Nope, no need. The low tune, amp limiting, and typical electronics rolloff keep it very well protected.

This assumption is incorrect . Some drivers are designed to be 'bottomless'. However even those types of designs don't prevent 'oil-canning' or other destructive behavior when/if the driver unloads. Much better to be save than sorry in this situation.

4) Do you have any suggestions for the crossover and/ or equalizer?

The vast majority of installations benefit from EQ. The EQ of choice depends on your budget.

[SteveCallas]

This assumption is incorrect . Some drivers are designed to be 'bottomless'. However even those types of designs don't prevent 'oil-canning' or other destructive behavior when/if the driver unloads. Much better to be save than sorry in this situation.

Let me attempt to provide some proof - here is some measured low end rolloff of common electronics.



A pro amp will likely have an earlier or steeper rolloff than the amps measured - the EP2500 is rated at -3db at 5hz at 10db below max output for instance. The design in question models to not reach max excursion at full rated power until ~11.7hz, it is amp limited above that frequency. The rolloff and tuning alone should already keep it protected, but if one is seeing signals hot enough to approach any potential "danger zone", they have amp clipping lights as another layer of protection - a signal to turn it down a bit. Add this all up and I think one would have to purposefully be trying to bottom this sub to get it to happen - just shoudn't happen with normal material.

[ThomasW]

There are too many variables in amps, drivers, rooms, use of EQ, people's expectations, etc., to make that kind of generalization.

The only realistic way to protect the driver in a ported sub is with the use of a proper highpass filter.

[JonW]

Congrats on finding some Avalanche 18's. This big sonosub is lots of fun to have around. Heck, even without playing it, it's fun to watch people's reaction when they see it for the first time. A couple friends visited a few weeks ago. The husband is really into audio. Not DIY but he has some Avalon speakers of some sort. When they walked into the room, the wife imemdiately said "Don't even think about it" while the husband had a huge, devious grin on his face.

1) Would you do anything different from your original design?

There's only one thing I don't like about the design (sorry Steve) and that's the dowels that hold the whole thing up on the bottom plate. I'm a woodworking newbie, so my dowels came out a bit crooked. And the sub slightly rests on the screws. There is a slight wobble around the dowels. I don't think it's a real problem. But it's the only aspect of the sub that doesn't seem overengineered to me, so it bugs me a little bit. If I were to build it again, I'd use something stronger than the dowels. Maybe pieces of 2x4 or something, Idunno. And I'd connect it all differently, somehow. To avoid any chance of the sub resting on the screws of the dowels. Maybe even allow access to the screws through the bottom cap (they're glued over now). Steve has no problems with any of this, so it's all my lack of ability that led to any potential problem.

2) Do you have any port chuffing or resonances from the port being so long?

None at all that I've noticed.

3) Are you using a rumble filter to eliminate frequencies below port tuning?

Nope.

I plan on buying a Behringer Europower 2500 and some sort of Behringer crossover or equalizer.

Careful with the fan noise there. I went with a Crown K1 to avoid the fan noise.

4) Do you have any suggestions for the crossover and/ or equalizer?

I haven't had a chance to look into this yet. But by my ears, there might be a "hole" between the mids of the main speakers and the sub. It sounds like the mains and the sub don't integrate perfectly. So I've got to look into EQ's and such.

Have fun with your Avalanche 18's!

[Nichol1997]

Thank you everyone for all the input.

I was real fortunate of finding the 18's. I had to wait 3 months before I could get them from the seller (long story).

Anyway, I called Sonotube today and apparently the 28" tube is a non-standard size. I had to call a bunch of places before I located a store that had them in stock. I will probably pick them up sometime this week and get started building them this weekend. I can't wait to hear them. I have been staring at the drivers for two weeks now, they are so massive!

I have thought about the fan noise of the amp and I will probably do a fan modification to make it quieter. I know this has been mentioned on the forums.

JonW,
Thanks for the pointers on the dowels. I will pay extra attention when I cut them.

I forgot to ask in my first post if anyone has experience in using two smaller ports instead of a single big one? I was hoping to use two 4" diameter ports instead of one 8" diameter port. This would allow me to have the ports firing down as well as the driver. But, if this might lead to port noise then I won't do it.

[derekbannatyne]

Two 4" ports probably wouldn't work, you'd need something like 3-4 4" ports to equal the area of one 8" port.

[SteveCallas]

I'd look into the Carvin hd1800 for amplification, what I'm using. 600 watts (which is all this design needs) with naturally quiter fans. Also, stick with the single larger port - more advantages.

[JonW]

I'd look into the Carvin hd1800 for amplification, what I'm using. 600 watts (which is all this design needs) with naturally quiter fans. Also, stick with the single larger port - more advantages.

:agree:

I used a Carvin hd1800 for my sub for a little while. It worked quite well and the fan is much quieter than the 2500, so I'm told- no personal experience with the 2500. I think the hd1800 even gave a tiny little more punch to the sub than my Crown K1. (Maybe it's the 600 verus 550 W.)

[Nichol1997]

I went to the store that said they had the 28" diameter tube in stock but of course they didn't. I am trying to get them to order it, apparently the store has to order a minimum of 72'.

Steve,
How tall are the dowels that hold the tube up off the ground?

[SteveCallas]

I'm using 8" dowels.

[JonW]

I went to the store that said they had the 28" diameter tube in stock but of course they didn't. I am trying to get them to order it, apparently the store has to order a minimum of 72'.

If it makes you feel any better, I had a heck of a time trying to find 28" tube anywhere. The minimum I could get was one 12 foot long section. Rather than doing the minimum 72' order, I just had the place wait until they were already placing another order. Then add on one 12' piece of 28" for me. That slowed things down 1-3 weeks (I forget). But building the sub took me 3 full months once I got started, so it was no real delay for me.

Yup, 8" long dowels.

[Nichol1997]

Did you guys consider standing waves inside the enclosure during the design phase?


Now that I think about, the worst sounding woofers I have ever heard were those Bazooka tubes that were really popular in car audio.

I sure hope my Avalanche's don't sound like them. If I can, I want to try to avoid standing waves, any suggestions?

[Nichol1997]

What stuffing material are you guys using and how much?

[ThomasW]

Did you guys consider standing waves inside the enclosure during the design phase?


Now that I think about, the worst sounding woofers I have ever heard were those Bazooka tubes that were really popular in car audio.

I sure hope my Avalanche's don't sound like them. If I can, I want to try to avoid standing waves, any suggestions?

There's no such thing as a standwave in a tube sub of a length people are using for home audio.

I wouldn't spend too much time or much energy worrying about this design sounding bad. The Bazooka was a enclosure that was meant to BOOM. The sub you're building will 'roar', not boom... :T

[Nichol1997]

There's no such thing as a standwave in a tube sub of a length people are using for home audio.

I wouldn't spend too much time or much energy worrying about this design sounding bad. The Bazooka was a enclosure that was meant to BOOM. The sub you're building will 'roar', not boom... :T

I put one of the subwoofers together this weekend and one thing I noticed is that it is ringing. You can really hear it ringing when someone is speaking in movies. I have the sub crossed over at 100 Hertz with a 24 dB per octave slope.

I really don't want to use fiberglass, simply beacause I don't want to deal with it. At the same time I don't want to spend too much money. I found this stuff: http://www.mcminone.com/product.asp?...&info=warranty But I would need about $130 dollars worth. Has anybody found a cheaper alternative?

[ThomasW]

The MCM stuff will work fine, seems a bit silly though since $10 worth of fiberglass will do a better job.

[SteveCallas]

I put one of the subwoofers together this weekend and one thing I noticed is that it is ringing. You can really hear it ringing when someone is speaking in movies. I have the sub crossed over at 100 Hertz with a 24 dB per octave slope

Aside from adding stuffing, I have to ask, how thick are your end caps and what diameter sonotube did you end up using?

[Nichol1997]

Aside from adding stuffing, I have to ask, how thick are your end caps and what diameter sonotube did you end up using?

I am using 28" diameter tube. For the end caps, I laminated two 3/4" mdf together, making a total of an inch an half. These end caps fit inside the tube. I am still painting a third laminate (another 3/4" mdf) which will be screwed onto the end caps. On the driver side, I made the circle larger than the driver itself so that the driver will be recessed 3/4". I am making this part detachable so that I can fit it through my doorways.

They are definately ringing, even at low volumes. I am thinking I might try Polyfill from the Fabric store.

[SteveCallas]

They are definately ringing, even at low volumes.

What would you describe this as - enclosure resonance or just higher frequencies getting past your low pass filter?

Jon and I are using 1" poly batting. Two layers along the walls and several layers around the port.

[JonW]

Yup, what Steve said. Here are some pics I dug up. A couple layers of 1" poly batting in the tube. Many layers around the port.

Images not available

[---k---]

...I noticed is that it is ringing. You can really hear it ringing when someone is speaking in movies. ...

This sounds to me more like a cross-over issue.

[Nichol1997]

I would say it sounds more like enclosure resonances. It really sounds like the sound you get when you speak into a tube, like an echo sound.

I just listened to it again. One thing I noticed while listening to music is that if you pause it you can hear the tube ring a little.

I bought some PolyFill from the fabric store and I will try to put it in the tube sometime this week. I will keep you guys posted.

Did you use 3M spray adhesive to attach it to the walls?

[SteveCallas]

If it's an enclosure resonance issue, lining won't solve it. I asked about your endcaps becaue the end caps are responsible for maintaining a rigid circle shape - they are essentially all the bracing you need. Sorry for the grilling, but answering these might lead to solving the problem.

It seems you are only using two layers flush mounted - how is the sub standing up? How are the legs attached if the third, outer bottom cap layer isn't attached? How are the end caps held in place? Do the end caps create an air tight seal? What diameter and how long of a port are you using? If you are using a port grill cover, is it screwed down really tight? Did you use a layer of weatherstripping underneath it to prevent any accidental chatterting? Finally, if you put your hand on the sub while it's playing, are you feeling significant vibrations?

Pictures would speak a thousand words.

[Nichol1997]

I have them 95% complete, the only thing left to do is sew the fabric together for the covers. I put 5.5 yards of 1 inch polyfil on the inside walls of the tube and this cured the ringing problem that I was having before.

These things are ridiculous! I was watching the depth charge scene in U-571 and my floors and walls were shaking. The funny part is that the speakers were only turned up half way. They definitely add more realism to movies. I don't think I have ever heard or felt bass this low from any speaker before and I have heard a lot of different speakers.

I am currently running this amp: http://www.musiciansfriend.com/produ...Amp?sku=481218
at 500 watts per channel at 4 ohms. It plays plenty loud but I will eventually upgrade to a Behringer Europower 2500 or maybe even a Crown K2.

Thanks everyone for the help.

[Nichol1997]

One more.