BAMTM project & what to do for a sub?

[bobhowell]

I want to build an 8" sub with the TB 1363SB or another of similar quality using a Dayton 100-200 amp plate amp. It will be used for music along with a new build of Zaph's BAMTM in a mid size room. Small is imp for WAF.

Does anyone know of plans for such?

WAF may shift me to a 6-1/2" sub.


Thanks

Bob

EDIT BY MODERATOR, threads about this project were merged

[djg]

Parts Express has an 8" sub project in their showcase. www.rjbaudio.com has a small sub project.

[---k---]

WAF may shift me to a 6-1/2" sub.

Most around here won't call that a sub and will try and persuade you to upgrading your wife.

Small size usually requires a sealed sub. Ported will give you more extension, but the port usually is too long to fit in the box or a small diameter which will have port chuffing.

I quickly tried to model it and didn't like my results. Looking at Roman's models, I think I should spend more time on it. I would love to hear Roman's sub, because I have doubts about how well it would satisfy people - especially for big HT booms. Pay close attention to his usage. I'm not sure your BMTM's would benefit as much.

[joecarrow]

If it had been for movies instead of music, I'd have heartily recommended some bass shakers. Last night I watched Sweeny Todd with my wife (in our apartment), and the bass shakers were very dramatic.

It's hard to get away from size for a sub. If you really need a small box, you can always build it smaller than optimum and then apply equalization- but that takes a lot of amplifier power. Another option is to move the sub closer to the listening position- say behind the couch and out of sight. There have been subs that make use of multiple smaller TB's for greater output.

Here's one that I was thinking of, but there was another somewhere that I can't recall:

http://www.partsexpress.com/projectshowcase/indexn.cfm?project=Boogieman

[ThomasW]

I want to build an 8" sub with the TB 1363SB or another of similar quality using a Dayton 100-200 amp plate amp. It will be used for music along with a new build of Zaph's BAMTM in a mid size room. Small is imp for WAF.

Does anyone know of plans for such?

WAF may shift me to a 6-1/2" sub.

Doing this with a single 6.5" driver is a waste of time and money.

You'd be better off making the BAMTM as a sealed box, and using a bass bins with side firing subs instead of speaker stands.

[bobhowell]

Well, after reading Speaker Blg 201 the last weeks, I am wondering if I should look at an isobaric setup. Say two 8" of some cheaper speaker. I think I saw an 8" peerless, 8 ohms, that might double up. I don't see much of that around. Am I missing something?

I am making the BAMTM's sealed at about 1.2 cf. Won't I need a bass boost?

[ThomasW]

I am making the BAMTM's sealed at about 1.2 cf. Won't I need a bass boost?

Yes.

Where are you going to put these speakers? Are they going to sit on speaker stands?

[robfive]

I want to build an 8" sub with the TB 1363SB or another of similar quality using a Dayton 100-200 amp plate amp. It will be used for music along with a new build of Zaph's BAMTM in a mid size room. Small is imp for WAF.

Does anyone know of plans for such?

WAF may shift me to a 6-1/2" sub.


Thanks

Bob

psst...Bob... I'll try to keep it down so the others won't hear...I made a subwoofer using a TB W8-740 in a 14" cube with two 2" ports about 14" long each. I powered it with a 70 watt amp from partsexpress and it performed really well. Especially just for music I think it would be a great solution for you...

And now to restore any credenitals; I am currently running a 15" titanic in a U-frame dipole configuration with an Ep2500 and BFD until I decide on a location for the infinite baffle manifold in the ceiling.

Robert

[bobhowell]

Mods to Zaph's BAMTM Cabinets

I am planning for these cabinets to be 32" high and 12" deep, maintaining about 1.2 cf., still 9" wide. I am using 1" thick poplar. I want to dress it up with molding, dye it red, seal with shellac and then put on black stain in areas. What are the limits on molding on the sides. I will round over the baffle 3/4". Reading tells me I must keep it away from the tweeter area. How about 1-3" back from sides of the baffle and to the edge on top.

Thanks

Bob

[nmuntz]

I built Roman's Cerberus subwoofer.

http://www.rjbaudio.com/Cerberus/cerberus.html

It's a very good sounding sub. As a post above mentioned and Roman says in his notes there is quite a bit of port noise at high volumes. I noticed it especially below 38Hz. Under normal listening conditions, it's not audible. However, I use for music, not HT.

I'm using it in a room that is 14' x 20' with hardwood flooring and not much furniture.

[ThomasW]

32" high puts the tweeter at a very strange height. Where are these speakers going to be placed?

[djg]

Build the towers with subs in the base, per plans. You should respect the work Zaph puts into his designs and not mess with them.


I should tone this down a bit. I mean you should recognize the design elements of a speaker and try to limit your mods so that performance is not compromised. This forum is a great place to run ideas by some very smart and experienced people.

[ThomasW]

You should respect the work Zaph puts into his designs and not mess with them.

The OP's idea for increasing the height won't be a problem. His ideas about adding molding maybe problematic.

[bobhowell]

Yes the height is strange but the plan is to put them on a 8-10 base some day(soon). My wife sold a set of Pioneer CS 88's at a garage sale when I weakened. I am taking the stealth approach. I plan to make them look like plant stands and let her put a fern on top.

I started joking about subs and showed her one from the 50's the size of a chifiro ( how ever you spell that French cabinet) with a nude model in side. Then I went to a 12" sub built as a table. She was crushed, as she wants to move her Mothers Victorian furniture into the same place. I have two daughters in their 20's that always side with her. I got a 50" plasma into the living room so I don't complain. Decorating is their hobby. You guys sound like a bunch of bachelors I know at work.

Thanks

Bob

[ThomasW]

If you're going to have a bases for the speakers, my suggestion is to go with the standard BAMTM box and use taller bases as your subs. The drivers can fire to the side if needed.

There maybe other stealth options depending on the layout of the room and architecture/design of the house. Do you have or can you create a graphic of the floorplan?

[djg]

Are we mice or men? Just kidding. My sub is an end table.

[bobhowell]

New Sub option

I have a 150 yr old Wardrobe in the living room with room on top for 12" high box about 14"deep. I could have a 10" woofer, or maybe down firing. would it shake the wardrobe?

Bob

[ThomasW]

I have a 150 yr old Wardrobe in the living room with room on top for 12" high box about 14"deep. I could have a 10" woofer, or maybe down firing. would it shake the wardrobe?

Bob

Yes it would probably shake the wardrobe a little. Depending on it's width you might consider a pair of 8"s. That would give you ~1/3rd more swept volume over a comparable 10"

Is there an attic space above or basement below that could be used for an IB sub? It doesn't get more stealthy that those..

[mayhem13]

I like Thomas's idea of subs in the bases. The OP could restrict the upper part to the Zaph design volume and use the rest for a sub enclosure, side firing 12's maybe with plate amp mounted in the rear. Since he hasn't built the MTM cabinets yet, plenty of time to redesign. RS315HOs love small boxes! Hey Thomas-If so could the OP put the MTM xovers in the same enclosure as the subs or would the magnetic field from the massive sub magnets effect performance, not to mention the vibration on the coils ?

[Rmaz]

Bob

If you are using those speakers for music only, you may not need a sub. I built the Zaphaudio BAMTM's a few months ago. For music, these speakers sound great to me without a sub. Good clean bass even at moderately high volume.

-Rich

[Gir]

I built some BAMTM's for/with my friend and used two W8's in the bottom of each tower. I had the port actually go through the top chamber and into the bottom one for the subs. Worked out great and the bass is pretty impressive. I'll try and take a few shots for you today or tomorrow.

[bobhowell]

I have been looking at the 10" subs Zaph mentioned in the BAMTM writeup. Dayton RSS265HF &HO. I modeled the HF in Unibox and got a sealed box size of 29 Ltrs, with 19 for heavy fill. This seemed small to me. Did I do this right? If so, I see how to make a stand with the sub in it. From what I understand, I would set the plate amp to cross over at about 80HZ. I would just have one sub.

I don't understand how to decide between sealed and vented.

Also, whats the difference between BASE and regular plate amp?

I plan to use equally for listening and HT. The writeup indicated I should get HF version.

Thanks,
Bob

[ThomasW]

Unibox and got a sealed box size of 29 Ltrs, with 19 for heavy fill. This seemed small to me. Did I do this right?

Sorry but we're not psychic, you'd need to post screen shots of your sim, since I'm way to lazy to create a from scratch model just to double check your work....

I don't understand how to decide between sealed and vented.

Port boxes are larger, and give a big boost in output at the tuning frequency. And that Fb (tuning frequency) is a function of the size of the box and the size of the port.

Also, whats the difference between BASE and regular plate amp?

I assume you mean bass not base? 99% of all plate amps are for subs (bass) there are a few plate amps design for actively crossing over the main speakers. You don't want one of those.

I plan to use equally for listening and HT. The writeup indicated I should get HF version.

Yes

If these things are going on stands follow Zaphs pdf where he shows the cabinet with the side firing subs. These can of course be built as a separate box the main speaker sits on.

[bobhowell]

I was asking about a Bash Amp vrs Plate. Got in a hurry.

Here is the Unibox graph.

I tried to get a screen shot of the Excell worksheet but no got.

I am not sure what is most helpfull in checking my work. It is showing 19 L with heavy fill added. Seems to good to be true. That is smaller than Roman has in his 6 1/2 TB sub, Cerberus.

[ThomasW]

It runs out of excursion above 30Hz. So it's more a woofer than a subwoofer.

The idea of having a 'sub' crammed in a box that's .67 cu ft isn't very realistic unless you go with a brute force design. This means using a high excursion driver, combined with a high power amp and a Linkwitz Transform circuit. Using this method you can force the driver to play lower, problem is the price of admission is $pendy... 8O

You might want to read the "Hoffman's Iron Law" section in the middle of this webpage

http://home.comcast.net/~thomasw-2/SubwooferSetupandEQpage1.html

[bobhowell]

I don't understand Unibox. It seemed to be doing what I learned in Speakerbuilding 201, But output unusable. Zaph indicates 1cft is about right for either hf or hd driver. That would be plenty small.

I will study the page you refered to.
Thanks,

Bob