Diary: Constructing a 3 driver open baffle W subwoofer

WerTicus · « **on:** 6 Jun 2008, 07:44 am »

I ordered the drivers and amplifier last night and bought all the wood and paint today.
So here is my thread / photo diary of the construction process

I'm hoping to have the cabs finished by Monday. Then ill paint them during the week.

885mm Would be a better height to use for the sides or the internal baffle will have zero margin for error and be a very tight fit for the top woofer.

quick note: the top will be 340 + the thickness of the wood x 2 Depending on if you use 24mm or 18mm or 16mm mdf.
pretty sure all other measurements dont get affected by wood thickness
driver recess is 17.4625mm deep! (apparently, which I find hard to believe actually that's a massively thick face plate, maybe im out by 10x here)

WerTicus · « **Reply #1 on:** 8 Jun 2008, 06:38 am »

Measuring

Cut baffles

Glueing baffles

bracing baffles further

The router bit i used for the edges.

Cabinet sides and top with nice routed edges.

Milehighguy · « **Reply #2 on:** 8 Jun 2008, 05:55 pm »

Good looking Sammy! (Sammy= Samoyed dog)

WerTicus · « **Reply #3 on:** 9 Jun 2008, 05:34 am »

Yeah i saw your avatar the other day

Awesome breed

WerTicus · « **Reply #4 on:** 9 Jun 2008, 05:37 am »

Just a quick note, it looks like my calculations were off and my sides are not really tall enough, so im going to have to stick some pretty tall spikes on the bottom to get enough clearance, id make the sides, 885mm to be safe

WerTicus · « **Reply #5 on:** 10 Jun 2008, 06:39 am »

Gluing and clamping fun.

oh dear my measurements were out

Nothing feet cant fix.

The internal baffle is slightly crooked too (probably due to uneven clamping pressure + probably didnt clamp it in the best way possible)

But it will sound fine

BrunoB · « **Reply #6 on:** 12 Jun 2008, 07:22 am »

Quote from: WerTicus on 6 Jun 2008, 07:44 am

I ordered the drivers and amplifier last night and bought all the wood and paint today.
So here is my thread / photo diary of the construction process

I'm hoping to have the cabs finished by Monday. Then ill paint them during the week.

Werticus,

thanks for sharing your diary. I have built my sub as well it was a lot of fun.

What drivers and amplifier have you ordered? How do you plan to connect the three drivers?

Bruno

WerTicus · « **Reply #7 on:** 12 Jun 2008, 02:55 pm »

One coat mdf primer, 3 coats of flat white and 2 coats of clear gloss....
so far.. not sure how many layers of gloss i will need... hopefully no more than 5.

you can see i have some feet on here too, but its not perfectly level so i might get some larger feet, or more likely a couple of marbles to sit in them and act like 'solid' points for better bass.

I will start work on a power cord soon and the speaker cabling I have already made

bruno: I have 3 of the open baffle type woofers and one plate amp coming. run them all in parallel so they are a 4ohm load.

richidoo · « **Reply #8 on:** 12 Jun 2008, 04:37 pm »

Werticus, your speaker construction precision is still better than mine.

Looking good and making good progress. Are you doing stereo pair of subwoofers, or just one 3 driver subwoofer?

WerTicus · « **Reply #9 on:** 14 Jun 2008, 08:34 am »

I'm building one 3 woofer sub and i have the wood ready for a second if i feel the need
if i dont need a 2nd ill sell someone the 'flatpack' for this box in australia since i've already done all the cuts and routed all the edges

WerTicus · « **Reply #10 on:** 19 Jun 2008, 03:40 am »

Got a package with two woofers in it today - I understand there is a second box coming... but it didnt get here at the same time

Drivers certainly look the business... and weigh the business too!
Im going to use DIY cat5 speaker cable to hook them up together and to the plate amp.

Ill post some more pics a bit later when i have these two woofers in the box.

Nick77 · « **Reply #11 on:** 19 Jun 2008, 01:35 pm »

Will be curious to hear your thoughts on 2 vs 3 drivers as for as output. Good work!

WerTicus · « **Reply #12 on:** 19 Jun 2008, 03:24 pm »

I'm not going to hook them up like that, nick, the box isn't suitable for it, and i don't have the amp yet.

I put these two drivers into the box in any case, and they fit... which is nice

Cant find my camera right now so shots will have to wait.

WerTicus · « **Reply #13 on:** 21 Jun 2008, 01:29 pm »

Okay i've got it up and running, at first it was doing nothing because i had it too close to the back wall. Now i've moved it out more into the room and its doing something. I need to tweek placement and the ton of settings on the amp itself before i can form an opinion.

Initial impressions are... that it is invisible and maybe not quite loud enough... need to play like i said though.

rythmik · « **Reply #14 on:** 21 Jun 2008, 06:06 pm »

Quote from: WerTicus on 21 Jun 2008, 01:29 pm

Okay i've got it up and running, at first it was doing nothing because i had it too close to the back wall. Now i've moved it out more into the room and its doing something. I need to tweek placement and the ton of settings on the amp itself before i can form an opinion.

Initial impressions are... that it is invisible and maybe not quite loud enough... need to play like i said though.

What to make sure you get the correct version of servo amp. Do you set the extension to 14hz, damping setting to med or low? xover frequency? Sorry for too many questions.

WerTicus · « **Reply #15 on:** 22 Jun 2008, 12:55 pm »

I have set..

the xo to 40hz
the low pass to 50/24
the extension to 20hz
and the damping to hi

also the peq is on +3
20% bandwidth
at 25hz.

if i set the extension to 14hz the woofers just seem to move a hell of a lot more for no audible result.

Over all I am disappointed with the result so far, the sub seems to add almost nothing that my mains are not already capable of on their own... in fact below the 35hz that my mains work to already, there seems to be nothing but large cone motion.
from 35hz up to 55hz the sub does add something however I don't even need it working in this range.

I still have more 'playing' with regards to settings, but as for room placement there is really no other options for it.

Plan B will be a large sealed box, though i'm not sure how large it will need to be with these woofers being made for a OB.

Of course if i have the wrong version of the amp please tell me what to look for so I can confirm, I should have no problems identifying capacitor or resistor values or what not on the circuit.

nodiak · « **Reply #16 on:** 22 Jun 2008, 05:38 pm »

Hang in there until Danny or Brian can help figure out your set up. Might be an out of phase problem somewhere - all drivers in phase?
Don

Danny Richie · « **Reply #17 on:** 22 Jun 2008, 05:43 pm »

Quote

Might be an out of phase problem somewhere - all drivers in phase?

That is what I thought too, especially since a pair of them can really rock the house with output.

The ones facing the opposite way have to be wired out of phase (flip the positive and negative) to keep them in phase.

All the drivers coils must also be in parallel while all of the servo coils have to be wired in series, and correct polarity needs to be maintained on all of them.

TRADERXFAN · « **Reply #18 on:** 22 Jun 2008, 05:52 pm »

I got mine up and running last night. I had them wired wrong at first... had driver coils red to red, black to back on both of the drivers which had the cones moving a bit and no bass output unless i stuck my head right up by the cabinet opening... then i realized it and switched one.

good way to break em in without bothering the neighbors if you live in an apartment though

sounding deep. very different texture than the svs since it is without some of the room gain. When I play some familiar tracks, I keep expecting the room to get energized like I am used to, but it doesn't. Still need to dial them in better and let the cones loosen up more but sounding very good so far. -actually, it just now playing this bassline on michael buble... very nice!

The box is so small compared to what I am used to. It definitely looks bigger in the pictures.

-Tony

rythmik · « **Reply #19 on:** 22 Jun 2008, 07:27 pm »

Quote from: WerTicus on 22 Jun 2008, 12:55 pm

I have set..

the xo to 40hz
the low pass to 50/24
the extension to 20hz
and the damping to hi

also the peq is on +3
20% bandwidth
at 25hz.

Please check wiring. The driver that you have inverted should also invert the polarity of connections on that driver. That is, you treat red (black) terminals as black (red) terminals and this applies to both driver and sensing coil. And then all driver coils in parallel and sensing coil in series.

Also, if you haven't done any filtering on your front speakers, we need to use phase control to get phase alignment as well. The L-R filtering assumes you have a net 4th order roll-off to get to phase alignment. If you haven't put a high pass filter, most likely it is still a 2nd order and you need 90degrees phase shift to the sub. Let us say you xover at 50hz. A full cycle is 20ms. To get a 90 degrees phase shift, you need about an 11 o'clock position on the phase control. Please also try 20hz/low damping for your extension, instead of 14hz.

BTW, if we further the 6db/oct slope of OB cancellation, the sub is more like 3rd order, and that needs an additional 45 degrees (on top of the 90 degrees phase mentioned above) which brings the total requied phase shift to 135 degrees. So Please try 1 o'clock position also to see if you can hear the difference. Without the phase control adjustment, what you have heard is very likely a broad dip due to the phase inversion.