BAMTM build thread

[savage25xtreme]

what about the screw to hold the crossover board down? far enough way from the inductors?

[ThomasW]

The 1/2 hitch knots in the red and black wires are a bigger problem. Doing that creates an inductor.

[savage25xtreme]

:cry: wish I had known that.

what should I do? I can still get them out of there.

[ThomasW]

Untie them

[savage25xtreme]

ok I hot glued them down and zip tied. I will do what I can thanks for the help :T

I will also try and move the crossover boards to the back of the cabinet to get the inductors as far as possible from the drivers.

[drab]

Use brass screws to hold down the crossovers. Then you won't have to worry about them.

Mike

[savage25xtreme]

your cabinets are lookin' very nice drab. maybe after I fix my mistakes I can start finishing mine today.

[drab]

Thanks! 8) I have been painting mine today and should have new pictures soon.

Yours are looking great too! :T Looks like we will start listening to some music at about the same time.

Mike

[savage25xtreme]

I tried using some Elmer's wood putty on a couple of the seams this weekend and it was almost like there was sand in it and I couldn't get it to go in the cracks. can anyone recommend something else? might have to try some bondo? hate to make up a batch of bondo when the cracks are really tiny, seems to me something simpler should work. drab what did you use? your seams are totally gone in your primed pics.

[ThomasW]

Siliconized latex caulk. It's the cheap stuff in the paint section

[Bill Schneider]

I wanted something like thinned Bondo for small cracks and imperfections. I also needed something quick drying so it could be sanded without waiting forever.

Lunch Money suggested 3M Acryl-Green spot putty to me, and it works very well for small gaps, etc.



http://www.amazon.com/3M-Acryl-Green-Spot-Putty-05960/dp/B000P0S0S4/ref=sr_1_5?ie=UTF8&s=automotive&qid=1239646116&sr= 8-5

[savage25xtreme]

Thomas, I didn't know that siliconized latex caulk was sandable?

Bill, have you been able to find that stuff at a local store? autozone? body shop?

[Bill Schneider]

Bill, have you been able to find that stuff at a local store? autozone? body shop?

I didn't look. I just got it through Amazon and bundled it with some other items that I had on my "wish list" so that shipping was reasonable.

It's worth trying a well-stocked auto supply store though.

[ThomasW]

My bad, I didn't realize you were talking about the outside of the box.

Problem with MDF is it's not stable in the long term, so you can patch all you want but eventually the seams/joints will show hairline cracks. Painting with a latex paint (or truck bed liner) can help a little since they form a somewhat flexible film....

If you want a 'piano black' or car-like finish, heroic measures must be taken to seal the joints.

[savage25xtreme]

I will be using this in the black and grey and putting a grey primer under... should I not worry about hair line seams if they are going to show anyways?

[ThomasW]

Seal the current cracks. Then seal the entire box with a sanding sealer or similar to make sure it's waterproof. Then apply your primer and spray paint. With that textured paint any cracks that do form won't be as obvious

[savage25xtreme]

sounds good :T , I already got some zinsser sealcoat, I will fill the cracks with bondo or the stuff bill said if I can find it then sealcoat the seams then sealcoat the entire box then sand with 220 grit then another coat of sealcoat then 360 grit then prime 360 grit and paint.... sound like a plan?

[ThomasW]

If your going to use the textured finish you don't need to spend a ton of time sanding the surface of the MDF.

[savage25xtreme]

my local NAPA had the acryli-green but wanted 28 dollars for it so I just ordered some.

[savage25xtreme]

I got my cabinets sealed and sanded and primed... now I have a question. I sanded the primer that is dark grey with 320 grit paper... now there is alot of ultra fine primer dust on the enclosure... how do I safely get it off for the finish coat of paint?

[ThomasW]

Use a tack cloth (google the term)

[ripcard]

I find using a vacuum with a dusting attachment (the one with the bristles) first to get the majority of the dust and then the tack cloth for the unseen particles makes the tack cloth last longer.

[savage25xtreme]

i blew them off with my compressor then use some tack cloth, thanks again Thomas....worked like a champ and my local evil-Mart had some for a dollar.... which is good because everywhere else in my town is closed.... my textured final coat is drying as i type.... lots of pic to be loaded tomorrow :T

[JonP]

thanks for the link Thomas, got some routering and gluing done last night... I have a new respect for you guys that build perfect cabinets

I also learned the hard way to put the pivot pin for the circle jig down into your work bench so when you cut the last of the work piece it doesnt grab the side of your brace and go crazy... atleast I figured this out before I started on the baffles.

Yeah, that's a nice surprise the first time... 8O What I do, is make the final cut depth just a 1/16 or less from all the way thru. (My router has a partial step cut gizmo) Idea is, you leave a thin layer holding the center from moving, but easy to crack off by pressing around the edge, and or punching it thru. Then, just a little sanding to remove the remains, and a clean hole.

On the back side chamfer of the baffle... if you have worries that it's too thin for the screws, you can glue on little 45deg cut blocks to put some extra meat just at those spots. This can take less area than the scalloping approach, and offer as much or more thickness. You could even put a screw insert in them to prevent the MDF from ever stripping out.

I did some baffles for the HiVi B3N, a driver that really needs the chamfer, but there ain't much left with it being a 3" and it's frame so tiny. So I cut some tiny Baltic Birch blocks with a 45 deg face. Epoxied them on, then drilled my screw holes thru them. More thickness, and the BB is tougher than the MDF.

Ah, don't worry about the screw. I wondered about how near a piece of metal or the driver motor/body would need to be to cause problems. Tested some inductors near driver magnets, hardware, etc with a LCR meter. Bottom line, if it's 2" away, it's not causing a measurable effect. 1" was just starting to be percent or so. A screw will have a smaller effect than a large, wide hunk of iron. I'd worry more if the crossover board will buzz with the one screw.

Zinnser Sealcoat (the straight shellac type) = good stuff. Pant it on till it won't drink any more, do it again. Great for your first sealing layer before other primers or whatever. Toughens up the MDF a fair amount, too. Don't worry about it if you can't, but it's probably best if you seal INSIDE as well as out. (as Thomas said) That should help the box to not inhale and exhale moisture as much over the seasons, and the seams should move less.

And finally (man, I'm just going down the list, aren't I?) I get good results with the shop vac and my hand as an attachment, for pulling off that dust. I've noticed that one of those big bench brushes seems to get a lot of dust out of a surface as well, and I'll use both.

All this talk of project details is getting me edgy to build something... :B

Keep up the good work... you're really flying along with these!

[savage25xtreme]

Hey JonP, thanks for all the great info. I moved my crossovers to the back of my cabinet through the brace hole and hot glued them in place. I could get them out if I needed to... would just take some prying and tugging I also took the loop out of the 12ga hookup wire. My baffles are only 3/4 thick so when I put the 45 degree bevel on the inside of my driver holes the edge of that didn't come out to where my screw holes will be. the SealCoat was amazing stuff. My only regret is that I didn't put another coat. I put one heavy coat on the seams then a heavy coat on the whole thing then sanded with 220 grit. If I had it to do over again I would have put one more coat before primer. oh well lesson learned, as with many other lessons on this project good tip on the leaving 1/16 left and then chipping it out, I will have to remember that. My router has a little depth gauge on it I could use. I bet a shot of air and the vacuum going at the same time would work real well, I have one of those fuzzy attachments for my shop vac. word to the wise when building speaker cabinets, have a good shop vac or dust vac system, its a life saver. :T

here comes the boring pics
SealCoated:





First coat of primer:



Hanging apparatus:



able to paint the back at the same time:



primer done on one enclosure:







and multicolored texture paint is done:





For whatever reason the flash on the camera made the primer and textured paint look really bad, but it looked awesome to me. I will put the drivers in and take some sunlight pics today after work. Thanks to everyone for your help and support. Would not have even attempted this project without a great forum like this one to help me along. ;x( :T

[savage25xtreme]

Baaaaaamtm !

great build and great results for 350 dollars including cabinets.
I didnt get done with the final assembly til late so I only listen for about 10 minutes then moved it to the center channel on my little pioneer receiver. with my Denon 385 I was doing A/B switching between my Polk R30s and my BAMTMs. Anything 200hz and up the BAMTMs destroyed the Polks by a large margin. The sealed BAMTMs are weak in the bass department, but we already knew this. then I hooked it up as my center channel as pictured and just watched some HD American Idol (no comments) it sounded SOOOO much better than what I was using that I couldn't move it... might stay there a while haha, but I'm not even going to tell you what I had there. again thanks for all the help. I will be around the forum keeping up til I start my next build. Its nice to have a project waiting for you at home that your excited to get to every night :T ;x(

[Dean100]

Very nice!!! Now that you are finished, it won't be long until you want to build something else. :T

[savage25xtreme]

starting on my 14x18 wood workin shop this weekend.... then once I save some money back up... I will be building a room full of 7 Statements :B

[JonP]

Hey JonP, thanks for all the great info. I moved my crossovers to the back of my cabinet through the brace hole and hot glued them in place. I could get them out if I needed to... would just take some prying and tugging I also took the loop out of the 12ga hookup wire. My baffles are only 3/4 thick so when I put the 45 degree bevel on the inside of my driver holes the edge of that didn't come out to where my screw holes will be. the SealCoat was amazing stuff. My only regret is that I didn't put another coat. I put one heavy coat on the seams then a heavy coat on the whole thing then sanded with 220 grit. If I had it to do over again I would have put one more coat before primer. oh well lesson learned, as with many other lessons on this project good tip on the leaving 1/16 left and then chipping it out, I will have to remember that. My router has a little depth gauge on it I could use. I bet a shot of air and the vacuum going at the same time would work real well, I have one of those fuzzy attachments for my shop vac. word to the wise when building speaker cabinets, have a good shop vac or dust vac system, its a life saver. :T

Looking great... I'm going to have to try one of those textured paints sometime... nice granite like look. Looks like you should have made 3! :B

Yep, I usually stand in awe of the amazing, spongelike qualities of MDF... especially of the cut edges... when I start slathering the Sealcoat on. Which is good, since it soaks a ways into it, and makes a hardened layer.
I think I see your screw holes for the drivers drilled already, that's good too, it will toughen up the insides, which should make it harder for the threads to strip out.

Something I forgot to mention, I usually cut the first coat 50% with alcohol, goes in deeper and faster. The Sealcoat is a "2lb cut" (amount of shellac dissolved in a gallon of alcohol) The second, I usually do straight 2lb, unless it's really sponging it up. Maybe a third, maybe not. "Regular" shellac is usually 3lb cut, BTW.

A dust tip... for those of us who don't have a serious woodshop dust collection setup, get a 20" window fan and a 20x20" furnace filter. I don't even bother to tape it on, just turn the fan on and put it up to it... the suction holds it in place. I sit in front of it while hand sanding, put it nearby when routing, etc. Don't expect it to get all the tiny, dangerous stuff, so still use personal dust protection and keep the garage open and it blowing out. But it really gathers up a lot of stuff that you'd be vacuming later. Vac off the filter, and you'll use one for a long time. I also invest in 1 micron filter bags for the shop vac...

[savage25xtreme]

great tips :T

I have a filter bag but forgot to put it on, would have been nice when the vac was hooked to my sander... those particles are tiny.

I read your postings you made maybe a few years ago about SealCoat and that's why I decided to try it. I was just not confident about how to dilute it with alcohol so I left it along, plus I only got a little quart of it. BTW I searched high and low for it on the internet and finally figured out Lowe's had it, but all of theirs had expired... then I found it right in my home town at an Ace hardware and the can was less than 2 months old. Thanks again for the help JonP ;x(

[savage25xtreme]

last night I hooked these up to my little pioneer 514, which did surprisingly well for not being rated into 4 ohm speakers. I had them crossed at 100 hz (mostly because that's the lowest xover my receiver will do :huh: ) to my PB12-NDS/2 and fed through my PS3 with an optical cable. right when the first track started in Tool Lateralus the droning of the bass guitar was really bass heavy so I had to get out my rat shack meter and got the sub back in line with the BAMTMs... so then I started over. the dynamics of this CD are awesome it goes from soft guitar solos to all out pounding of the drums and Maynard screaming. by far my favorite rock CD. in the second track I could close my eyes and hear Maynerd picking at his guitar and moving around in front of me. In the 4th (maybe) track the symbols are absolutely amazing you could here every little tick the drum stick hit the symbol , not just the initial crash. awesome is all I can say. these BAMTMs really came to life when I took the 100hz and below off of their shoulders. These are also the first set of speakers I have had that I can listen to at a reasonable level and still hear all the clarity and detail. I could sit there and have a conversation and hear every little detail of the CD. ;x( I only got to listen for about 30 minutes before the girlfriend deemed it American Idol time... but I am VERY impressed. I cant wait to get home and listen to some more tonight. For the ~360 dollars I have in this build, the BAMTMs after phenomenal. :drool:

[fuschnik]

L8 inductor?

Savage,

I followed your build with interest as I am currently in the process of building my own Zaph BAMTM. I do have a question, where did you source the L8 inductor (L8 - .30 mH .2 ohm MB Standard 19ga). I have been shopping for it, but have been unable to find an air coil at 19gauge with that low a DCR. Madisound has one with a DCR of .3 ohms. Could I substitute the .30mH 16gauge with DCR of .16 ohms without screwing things up too badly?

[PoorboyMike]

Savage,

I followed your build with interest as I am currently in the process of building my own Zaph BAMTM. I do have a question, where did you source the L8 inductor (L8 - .30 mH .2 ohm MB Standard 19ga). I have been shopping for it, but have been unable to find an air coil at 19gauge with that low a DCR. Madisound has one with a DCR of .3 ohms. Could I substitute the .30mH 16gauge with DCR of .16 ohms without screwing things up too badly?

Parts Express has an 18ga Jantzen, .30 mH .26 ohm DCR. Plenty close as far as I'm concerned. :T

http://www.parts-express.com/pe/pshowdetl.cfm?PartNumber=255-218&DID=7

[69Stingray]

Excellent build. I am glad you are happy with the results.

Did you run into any issues with paint buildup on the inside edge of the driver cutouts (no allowing the drivers to fit in)?

Excellent painting technique by he way, I am going to have to use that.

[savage25xtreme]

sorry I have been away on business, Mike is correct about the inductor, however if you read the notes on Zaphs website he says if you get an inductor with a lower DCR is makes the woofer circuit more efficient, which I see as a good thing.

I absolutely love these speakers BTW :T

I put 2 coats of primer on the cabinates (black primer) then taped off the driver cut outs then shot the textured paint.... turned out awesome, I would and still plan to clear coat the textured paint to make it tougher. If you set a cup or anything on the texture you can see it.