DIY Sub

[kexodusc]

Building a 2nd sub would offer improvments. Mainly, your bass response would be much more full throughout the room (as nodes are circumvented a bit)...your output would also increase by about 3 dB (or more depending on which theory you use).
For sound quality, I would build 2 Quatro's over one $450 sub like the Titanic MKIII. But that's just me.
Your room isn't terribly huge, so I would first wait and see if the Quatro is strained before deciding to pull the trigger on another (unless you're bored or want more bass, bwa ha ha)..Instead, I can't recommend enough that you consider buying a Parametric Equalizer...the Behringer Feedback Destroyer is only $99 at Parts Express right now...tack it onto your order...this will make a huge night and day difference.
Consider this...nobody would buy a speaker with a frequency response measured outside +/- 3 dB. Why would allow a response of +/-12 dB for your subwoofer? The BFD will tighten that up, and yield more sound improvement than another sub.
After a Parametric Eq, if you need more output, then make your 2nd unit...

As for painting, there's many people that do so, but my understanding is it requires alot of elbow grease to sand, etc...more so than staining, so I've never gone that route.
Lots of people turn their subs into coffee tables/end tables, to make them more "room friendly"....

[hmmmm]

Kexodusc, you've spent a lot of time helping me out with this. I really appreciate it.

[kexodusc]

Kexodusc, you've spent a lot of time helping me out with this. I really appreciate it.

Not nearly as much as others have spent on me...I've only been at this for a little over a year now. That's what I love about the DIY community to most...some audiophiles get carried away with out-doing the other guy, buying high-priced gear...being typical elitist snobs...the DIY community is almost the opposite, very generous and patient with newbies.

Besides, I needed a guinea pig for the 15" Quatro...(just kidding).
You should really visit the Tech Talk forum at the Parts Express website, I'm still very much a newbie compared to some of the guys there...check out some of the amazing projects these guys have done. You'll never buy a speaker again.

[hmmmm]

what type of grill covers are you guys using?

[kexodusc]

For a sub you've got a lot of options..plastic or metal "cage style" grills, etc...I prefer the black grill fabric look. $7 gave me enough fabric for 14 bookshelf speakers, and 2 subs.
Some people use black nylon pantyhose doubled over, claiming it's less expensive and more acoustically transparent than grill fabric, but I don't buy it...
Bass signals don't really suffer much from a grill.
Build a 1" to 1.5" thich grill frame (maybe .75, but make sure the woofer has enough clearance so it doesn't touch fabric or get punctured if some kid bumps into the grill), same size as the front baffle (or smaller/larger for looks) and drill some holes in the front baffle for the grill peg kits.
I used rare-earth magnets for a "clean look" on my bookshelfs. They're counter sunk into both the MDF baffle and 1/2" grill frame, covered in veneer so no plastic holes or pegs showed, so I'll probably do the same for the sub...that grill frame will be heavy though, probably needs 8 magnets at least.
I router the edges of the grill so it's contoured back a bit...you can round them or whatever you want...adds a nice touch...


Did you have anything fancy in mind?

[bcass]

Kexo (do you have a real first name? :-), do you know where to get the grill pegs? Where to get the grill cloth? Also, what is a parametric equalizer, and can it help me grow better tomatoes this year? :-)

[kexodusc]

Kexo (do you have a real first name? :-)

What do you mean?

do you know where to get the grill pegs? Where to get the grill cloth? Also, what is a parametric equalizer, and can it help me grow better tomatoes this year? :-)

Yes. Yes. An essential tool for any system with a subwoofer. Maybe.

Okay, I'll elaborate:

Grill hardware:
http://www.partsexpress.com/webpage....ctGroup_ID=141

Cloth:
http://www.partsexpress.com/webpage....ctGroup_ID=140

A parametric EQ is hard to explain. In any given room, the dimensions and room acoustics will cause certain frequencies to become "amplified" (louder) or diminished...I won't get into why here, just trust me when I say that after you set the level or volume on your sub to match your system, you can bet you're only hearing some of the bass you should be hearing, and too much of the bass you are hearing.
The picture attached shows the difference between a system with a PEQ and one without...the pink one is much better. It slopes downward because the sub is being blended with the speakers, which will bring the total response back up so it's ruler flat (in theory).
A P EQ lets you "equalize" the bass by adjusting how much signal is sent at certain frequencies. the result is that your bass response is much more flat and even. It sounds fuller, and more real.
IMO, a $100 PEQ is better than adding another sub, or upgrading to higher quality sub that will have the response issues.
With a parametric EQ like the Behringer Feedback Destroyer (BFD for short), you use an SPL meter ($40 radio shack unit is good) to measure the bass response in your room and adjust it.
Once you add a BFD to your system, you'll wonder how you did without it...

For a better, and much longer explanation, go here:
http://www.snapbug.ws/bfd.htm

For $100, you shouldn't think twice about it.

You wouldn't buy a pair of speakers with a frequency response greater than +/- 3dB, I don't know why people allow a subwoofer to have 8 times that. I didn't even know these things existed until a year ago, and I've just ordered mine (waiting for Parts Express to receive some back-orders on other items before shipping). I've heard the huge improvement these things make.

I hope this makes some sense...Woochifer and Sir Terrence could answer more for you in the HT forum, or do a search...these have been discussed alot recently.

[bcass]

Thank you. I mean my name is Bryan, what's yours?

OK, so I have the Radio Shack SPL meter already. Is this equalizer something that goes inline with the sub's input, or... inside the sub connected to the crossover or amp, or... ? It sounds like a reasonable thing to do, and something that I've tried to do before with my equalizer. But the equalizer I have connects into the system via the tape monitor circuit, and it adds in additional noise to the receiver.

[kexodusc]

Thank you. I mean my name is Bryan, what's yours?

My name IS Kexodusc...it's Greek...
Actually, it's Ken...but don't tell anyone.

OK, so I have the Radio Shack SPL meter already. Is this equalizer something that goes inline with the sub's input, or... inside the sub connected to the crossover or amp, or... ? It sounds like a reasonable thing to do, and something that I've tried to do before with my equalizer. But the equalizer I have connects into the system via the tape monitor circuit, and it adds in additional noise to the receiver.

Yes, you hook the BFD up in between the receiver and sub...then adjust the frequency bands as required...
Since you'll need access to all the buttons and switches (this thing is the size of a cd player, and ugly silver and black in colour) putting it inside the sub wouldn't be recommended, though I suppose if you're really creative you could...I'm just gonna try to stuff mine in my A/V rack and make it look as pretty as possible.

Theoretically there is some noise added to the signal, however, we're talking frequencies below 100Hz, so this small noise is not substantial or audible to the human ear...(long physics explanation required for why, let's not go there). Subs typically get away with 2% or even 10% distortion, your ears are less sensitive to subtle nuances of bass frequencies...the minute amount of noise added to the sub's signal is not heard in this case. If you used it to EQ the midrange or high frequencies, it could be a problem.

The funny thing is, the BFD wasn't made for P EQ'ing subs, it's actually a pro-audio peice of gear that has a P EQ in it. HT buffs recognized that for LFE effects, where the added noise would be effectively zero (just trust me on this) that the BFD is a phenomenal value at $100. Most other dedicated parametric EQ's are $200-$300, and don't do anything better than the BFD (which can actually be used to P EQ 2 different subs at the same time).
We all think Behringer realizes this, since they've recently announced they are discontinuing the current 1124P model (which is $100 at Parts Express right now) and are replacing it soon with another model that will be much more expensive (and not do anything better as far as Parametric EQ'ing is concerned).
In other words...snarff up that BFD now while it's cheap!!!

Then spend a few hours reading that website above, then spend a few hours calibrating...then thank me later.

[hmmmm]

Did you have anything fancy in mind?[/QUOTE]

I tried several different shapes on the front and decided I like the following, simple design.
I'm going to have the top and bottom flat and flush against the edge, and the sides will be slightly rounded. Basically, if you took a long and narrow oval and cut off the top and bottom. It will come in about 1/2" on the sides. I'll use the router to round the edges.
I received my subwoofer today and now I'm getting excited. Too bad it cut my finger when I took it out of the box!

[bcass]

Thanks Ken. It looks like the BFD is plentiful on eBay and sells for around $50-$75. So I wouldn't worry (yet) about it going away.

Still, one would think that an EQ on the *whole* spectrum would be beneficial, not just on the bass. So why wouldn't you consider an equalizer for all of the output?

[kexodusc]

Did you have anything fancy in mind?

I tried several different shapes on the front and decided I like the following, simple design.
I'm going to have the top and bottom flat and flush against the edge, and the sides will be slightly rounded. Basically, if you took a long and narrow oval and cut off the top and bottom. It will come in about 1/2" on the sides. I'll use the router to round the edges.
I received my subwoofer today and now I'm getting excited. Too bad it cut my finger when I took it out of the box![/QUOTE]
Yeah, you've got to watch those stamped frames, a little jagged...you're about 40th person I've heard who has been "bitten" by the Dayton Quatro.

A word of caution about the grills...I've made 2 different fancy grills now, and a month later both times ended up hating them, and went to something else.
It looks different when it's actually on the sub/speaker, with cloth on it and with the sub finished, than in concept or when looking at it as raw mdf. The good news is MDF and cloth are cheap!
I've actually done something similar to your long oval with flat tops and bottoms for my speakers...
If you scroll to post # 6 in the link below, you'll see pics of one of the grills that looked good on paper but just drove me nuts when it was done...I've since changed it to rounded tops and bottoms.
http://forums.audioreview.com/showth...7031#post77031

[kexodusc]

Thanks Ken. It looks like the BFD is plentiful on eBay and sells for around $50-$75. So I wouldn't worry (yet) about it going away.

Still, one would think that an EQ on the *whole* spectrum would be beneficial, not just on the bass. So why wouldn't you consider an equalizer for all of the output?

Bcass: Just make sure you're not looking at the wrong gear...make sure it's the DSP-1100P (old model) or the DSP-1124P (newer model, being discontinued)...there's lots of "feedback destroyers" that don't include the parametric EQ. A friend of mine jumped on a Behringer Shark "Destroy Feedback" unit, but that doesn't have the P EQ in it, it's a different beast altogether.
You don't care about their ability to suck out feedback unless you're playing live gigs and have way too much crosstalk or something...and we can talk about that if you want - I'd recommend Yamaha over Behringer at these price points - but that's totally different

Most of the BFD's I've seen go from $60 to no higher than $99 on ebay, plus shipping (sometimes free shipping)...not a bad deal. I wouldn't buy a $99 one on ebay when you can get it from PE who is authorized to sell Behringer (which means valid warranty), but for $80 or something go ahead.
Don't be afraid to get the old 1100P model, they both do the same thing as far as P EQing goes, other features we don't need were upgraded.

[bcass]

OK, but what about my question about equalizing the whole spectrum instead of just the bass end?

[kexodusc]

Sorry, quit reading the rest of your earlier post and forgot to go back.

I'm not opposed to eq'ing everything if needed, it's a good idea...but it's gonna be tricky, and expensive.

I'll point out, however, that once you leave the lower bass region, room acoustics have less impact in terms of boosting or diminishing the loudness of frequencies.
So in many systems, an EQ is not needed, or provides a less of an improvement than in the bass region (though some people are quit fussy and particular about their sound). My Yamaha receiver has a built in Parametric EQ, but like most Parametric EQ's, it doesn't handle the sub 120 Hz bass frequencies at all, which are the ones that get the most out of hand and are the hardest to fix. I find it makes just a small, subtle improvement over not using it at all (it'd be different if I had mixed speaker types but I have 6 identical bookshelfs and a matching center)...

If you look at the graph above, the x-axis is frequency, and it stops at 160...what you'd see is that the peaks and dips are getting smaller as the frequency gets higher, eventually around 500 Hz or so the ups and downs are probably within +/- 3dB. On good speakers, the they might be reasonably flat to 200 Hz or so...frequency wavelenghts are getting smaller, and are interacting with the room "less". Basically, an EQ at this point is just changing a subtle tonality of the system, not fixing major problems.
The problem with a regular Equalizer is that it's bands are fixed, you're stuck with 60 Hz, 1000 Hz, or whatever to adjust, and your stuck with how wide a range of frequencies moving those numbers affects...with a Parametric EQ, you can adjust the filters to whatever frequencies you need need, and make the bands as narrow or wide as necessary (to a certain point)...much more useful.

You could buy a $400 to do the bass frequencies, or a $600 P EQ to do the whole system, but I'd argue your getting 90% of the performance improvement in the first $100 from the BFD.

Looking to the future, it seems built in Parametric EQ's will be a standard or at least affordable option on receivers (my RX-V1400 was only $600 with YPAO). These will handle the midrange and highs...an outboard parametric equalizer is needed for the low frequencies (except on very high-end receivers, but why pay $1000's for something the BFD will do for $100?). So your next receiver (if your current one doesn't already have one) is likely to have a parametric eq for the rest of the spectrum anyway.

Also, keep in mind that the frequency scale of music (and all sound) isn't linear but logarithmic. The range between 20 and 80 Hz alone is like 20-25% of musical information...you wouldn't think it because it's only a 60Hz difference, but in terms of wavelengths, that 60 Hz difference is actually bigger than the difference between say 500Hz and 2000 Hz, or 4000Hz and 20,000 Hz...so you really are eq'ing a HUGE part of the entire spectrum...and the rest you don't need too worry about so much.
Long story short, you're not worried so much about fixing a peak of +4 dB at 3000 Hz and a dip of -5dB at 14000Hz, you're more worried about the +14's and -10's that shake the whole house, either overpowering the other frequencies, or forcing you to turn the volume down and miss out on a lot of the bass.

Finally, I'd argue that if you've got a problem above the bass region in your system that needs EQ'ing, I'd argue you'd be further ahead (and probably save money) to replace the problem piece (speakers, amp, whatever) than to add an external equilizer. You see them used less and less in the digital age where media is wideband and most gear is up to the task.

Hope this made some sense.

[hmmmm]

Looking to the future, it seems built in Parametric EQ's will be a standard or at least affordable option on receivers (my RX-V1400 was only $600 with YPAO). These will handle the midrange and highs...an outboard parametric equalizer is needed for the low frequencies (except on very high-end receivers, but why pay $1000's for something the BFD will do for $100?). So your next receiver (if your current one doesn't already have one) is likely to have a parametric eq for the rest of the spectrum anyway.
I have the same receiver with YPAO. I thought it covered the entire frequency. Thanks for the info.

[kexodusc]

I thought YPAO and similar offerings did too...in fact that was my biggest reason for springing for it...then I found out the bass region is pretty much left out. Oh well...love the receiver.

[bcass]

Thanks Ken, that does help a lot -- and even makes sense to boot! :-) The sub project will follow the main DIY speakers project, which isn't on the project schedule as of yet. We had a new house built 1 1/2 years ago and are still shelling out money for landscaping and now finishing the basement. Yikes! But maybe by summer I'll have the funds and time to do a good sound system for my home office.

[poneal]

You do not have to get fancy with the hole. I used a jigsaw and compass to cut and measure the hole. The Dimensions: Overall Diameter: 15-1/8", Cutout Diameter: 13-7/8", Mounting Depth: 6-5/8". I centered mine and don't bother with flush mounting. With lower frequencies it's not needed. Also buy one of these, they work great and I think they look nice: http://www.partsexpress.com/pe/showd...number=260-430

Also, if you have a router and circle jig all you need is a straight two flute 1/4" bit or a 1/4" spiral upcut bit. Just make sure to align the jig right and do a test run to make sure you have it setup right.

Yes, the Quattro is a nice subwoofer. It has a high SPL, easier to drive, and lower XMAX which I prefer. Glad your enjoying the hobby. Here is my home page in case you want to make some speakers some day. IMO that the best sounding ones so far (my opinion of course) the the Audax 5.25" and MDT20 combo. I have this in my bedroom/computer room with an 8" sub and 50 watt plate amp and it rocks the room. Of course the bedroom is a lot smaller space to fill with sound than a living room.

I'm currently working on a RS150S-8 design. These are Dayton's new low distortion aluminum cone drivers. Heres the main page link:

http://home.stx.rr.com/poneal/

[hmmmm]

Well, I finally got the time to glue the box together and start the sanding process. So far everything has gone as smooth as butter. My wife complained that she couldn't see out the car windows because of the sawdust. I forgot to pull it out of the garage.
I'm waiting for the fabric to come in but was wondering if you spray the front of the grill and back and just wrap it around. (with 3m 777 spray)
Also, I'd like to build some 2 way speakers next and wanted to know if it is possible to match the sound with speakers I already have for the center channel etc... I'm happy with my MC500 from CSW and the surrounds and don't feel like conquering an entire surround sound system.

[kexodusc]

It can get pretty tricky to build mains that are voiced to match your center channel...I'd recommend building 3 of the same speaker if you're getting into home theater or look at some existing designs.
You could sell your speakers to finance your DIY upgrade (that's what I did, got better sound and made extra money to boot!). With surrounds, it doesn't matter as much for movies as for multi-channel audio.
In the end though, you can compromise and build better main speakers which you'll love for music, and just have mismatch for home theater (which isn't really as bad as you'd think...just a bit annoying at times).
Do the upgrades in stages, a pair at a time or something.

I just used the 3m spray, sprayed the back of the grill frame, then stuck the cloth to it rather than spraying the cloth...you could do the front too, but it might make mess and look a bit funny...the stuff is pretty tacky, and holds no problem. Then I used scissors and utility knife to trim the excess fabric down. Actually, the grills were the toughest part of all the speakers I've done.

[squeegy200]

Lots of good information here.

I built mine after doing some reading. I learned a lot of different approaches and techniques from various websites on the net. The beauty of it was that I could buy the parts and build a design. Then I could test it out in my environment before finishing. If I didn't like it, reengineer the dimensions, ports or build an entirely different design without much loss in anything more than some material.

This website was very helpful
http://www.diysubwoofers.org/projects/

[kexodusc]

Just a note...the diysubwoofers.org site is the best, subwoofer only site I've found...it should be favorite link for everyone building a sub!!!

[MomurdA]

And was wondering if I could substitute a 12 or 10 inch sub for thie 15, and keep the same dimensions for the box. I cant use a 15 inch cuz i live in an apartment. I really dont know about acoustics, but it seems to me that with a smaller sub in a large box like that it would make deeper bass than in a smaller box. Is this correct?

[kexodusc]

And was wondering if I could substitute a 12 or 10 inch sub for thie 15, and keep the same dimensions for the box. I cant use a 15 inch cuz i live in an apartment. I really dont know about acoustics, but it seems to me that with a smaller sub in a large box like that it would make deeper bass than in a smaller box. Is this correct?

MomurdA: It's unlikely a 12" or 10" sub would work in such a big cabinet properly, so you'd have to shrink it down some. Too big a cabinet is bad for a sub as well, there' s a point where the bass extension is sacrificed for distortion and output...

But not to worry, easiest thing to do is find a 10" or 12" woofer you like (I recommend the DVC line at Parts Express, the Adire Shiva, or an Atlas Audio woofer for starters) and then come back here or go to the Tech Talk forums at PE and ask about cabinet sizes...if you can find and download UniBox or some software you can do it yourself if you understand T/S parameters, otherwise I'm sure someone would be happy to help you out.
In many cases there's already some cabinet ideas on these websites that work well.

Or check out some of the links here for ideas...Personally, I'd go with a 12" sub over a 10"...just do it and thank yourself later...