Project #3: BAMTM's (78% done)

[Raptor550]

***Finished Pics are at the bottom of this page***

So I'm a little nuts as a beginner, I am doing two projects at the same time. Project Forum I have decided will be a Natalie P (my speakers). This will be my BAMTM build thread (my friends speakers).

I went to PE and spent about $368 and got parts for everything at once:



-along with some extra goodies to tinker with, any good ideas for the Dayton RS225's? I have two extra DA175's and one extra RS180 (im thinking center channel MT maybe?)

I started construction o the towers to Zaphs specs. I am buying wood clamps tomorrow but for now I am stacking various sized cinderblocks and placing them in interesting ways, four two by fours will be placed inside for bracing, I might do a 5th one screwed into the back oriended differntly.



I plan to glue carpet onto the back and side walls for dampening, its about 3/4 to an inch thick, anything wrong with that?

I cant wait to hear these! Zaph, if you are reading thins, thanks a ton for the fun project and all the learning materials you provide! God bless you! You get a green star!:greenstar:

[joecarrow]

The RS225 is quite a nice driver, although it doesn't stay clean high enough to cross to most tweeters. How many did you buy? The "Statement" three-ways use it, as well as Mark K's MT with the RS28a tweeter.

I think that the RS225 could be great in a big three-way tower with a narrow-ish face. It would be a step down from the three-way towers the guys around here have done with the RS270, but it could also be narrower. The driver likes a big box, though, so if you make it narrow it will need some depth to get enough volume.

Also, I don't see anything wrong with using carpet. Carpet pad might be better, but it's not likely to do anything *bad* to the sound.

[Dennis H]

Wow, nice pile o' drivers! Gotta admire a guy who jumps in like that. :T

[cjd]

I think that the RS225 could be great in a big three-way tower with a narrow-ish face. It would be a step down from the three-way towers the guys around here have done with the RS270, but it could also be narrower.

Yeah, like 11" narrow. And, uh... well, 54" tall, 14.5" deep. Couple RS225's, couple RS150's, a nice tweeter... and... oh - go check out Ryan's thread, eh? :P

[joecarrow]

Dang, I knew there was a drawback from all this gainful employment! I can't keep up with all of the projects anymore

[sprint_9]

Yea if your using particle board you will want to use the carpet. I built a sub box out of particle board instead of MDF, had it given to me for free, and I plan on only using this as somewhat of a temporary box for a few years. Anyhow it was a severe pain trying to get them finished properly, especially on the corners since it chips up so easily.

[Raptor550]

I only own two rs255's so that limits any projects with extensive buying for now. Maybe I could kill em at 80-100 hz and build them in as sidefireing subs for the natp's of mine. Or build an enclosure and make them into a small two driver powered sub. Of course I haven't a clue how to do that (properly).

I looked at Mark K's crossover and at $200 minimum I don't think thats doable in the near future, the M8ta looks even more expensive! I would like to tackle this project eventually. I am curious how the M8ta's sound next to the Modula MTM's. Does the surface and extension of two 180's beat one 255?

As for the BAMTM's I have the second enclosure halfway complete, same as the first picture. Now I am waiting to get the baffles done with a friend who has tools.
Would dampening the edges cut down on chips at all? only the bottom half's are going to be painted, the tops will be silver PE vinal to match the drivers. Some girls looked at the designs and said they looked like big sexy beasts. :T
Heres the Goal: (modeled by me in 3Ds max)

[Raptor550]

So I did allot of work last night. I finished the crossovers



I have the speakers firmly braced with 4 2x4's across



I cut the backs to size and glued and nailed carpet to the back



Cobba on here lent me his router so I routed and attached my baffles, they are such a snug fit that the speakers will stay in without screws. I am pleased. Last but not least I rounded the sides



I gave them a first listening even though the bottoms are incomplete. they sound a bit muddy on the low end but my guess is they just need some batting.



some of the boomyness will go away with an airtight seal and a proper bottom. Biggest problem right now are the interconnects. They keep free spinning, and when they do that they break the solder (that was hard to do holding up half a cabinet).
As you can see they do not yet have the seas aluminum tweeters yet, they are coming in the mail, right now I am using my silk seas just to get an idea of the sound. I can also feel a bit of air leakedge around the tweeter (!%#*@!)

[Raptor550]

Hey I was just wondering. The DA-175's are aluminum cone but have paper parts to. I hear that alum have odd order distortion and paper has even order which contribute to different sounds in drivers. The DA's definitely sound different than the RS drivers. Do you think there break up is less dramatic because they are not completely metal?

They seem to sound like small woofers whereas despite cone breakup the rs180's feel kinda like big (low) mids. Any thoughts from people who have experience with both lines?

PS. some of the muddiness I mentioned earlier may have also been (partly) due to them not being broken in yet.

[augerpro]

Nice work! What kind of finish are you using?

Lining the walls properly and adding fill will tighten up the bass. You can experiment with the amount of fill you like. Also if these are vented you can double check the volume adn port dimensions just to make sure everything is correct. Other than that you may just be hearing the difference between two very different quality drivers.

What's up with the chipboard man?

[speedle]

Just a little correction note here. As far as I can tell, there is no particle board or chipboard in any of your photos. There is, however, OSB, which has a totally different sonic profile and doesn't "chip" like particle board. It might be what's making your speakers sound muddy.

I've made small subs for cars out of OSB before, covered with carpet they worked just fine for years, until my kids cat did his duty on them!

[Raptor550]

OSB huh? that is interesting, It probably is, it has a nice coating of stuff so that it cuts fairly smooth, I have to watch which direction I grind it however. I would definitely guess it sounds different than MDF, I did brace it with solid wood however pretty well. the OSB did not give me as much pain as the pine I used for the tops. that wood is a nightmare! I put some padding on the walls, but I don't have as much as I want in em. I have lots of batting though.

To answer your question Auger I went cheap because I figure none of the surface texture will be seen. I am going to paint these first with regular eggshell paint pretty thickly and then sand the dickens out of them. after that I will spray paint on black and the tops will be all silver veneer witch should cover over a multitude of sins. however the top wood may challenge that, it chipped pretty ragged so I will have to deal with that.


On a different note the h1212's came in the mail. I am listening to them side by side with the silks. I have to say its hard to say an outright preference. the h1212 seems to be less "rounded" then the silk if that makes any sense, more sting maybe. It seems to have a bit more airiness which is good on classical but I preferred the silk on a few songs. Its weird looking at all the graphs and gee-wiz stuff on zaphaudio and then seeing for yourself what those lines actually sound like. To me, so far, the h1212 seems crisper yet less forward.

I actually like the hex cover because it's idiot retarded: I was using a different electric screwdriver and it did not have variable speed, (I was not aware of this) and it plowed into the silks surround. I was not pleased but the damaged as near as I can tell is thankfully cosmetic ops:

[ThomasW]

OSB = oriented strand board = flake board

Boom is primarily a function of speaker interaction with the room, or a mistuned box.

There is no such thing as a 'completely metal driver'.

You can't compare tweeters unless you have an optimal crossover in place for each.

[Raptor550]

AHH its the ghosts of speakers past coming back from the dead!



I am putting a few thick layers of paint on to seal any missed air leaks and flatten out the OSB texture, when it is done drying I will sand, paint another thick layer, sand and then spray paint the bottom half black, and put silver vinyl on the top.

Things left to do:

• Find nuts to keep the terminals from spinning
• Solder all remaining connections
• Inset the bottom piece

[dblotii]

Nat P vs BAMTM opinions solicited

Trying to decide between the 2 projects (ported tower versions). After extensive reviews of the postings it seems to me that the basic sonic difference will be that the Nat's bass extends a little bit deeper. Is that it? Is either design an easier load to drive?

Dave

[ThomasW]

The NatP is a much more sophisticated speaker....

[Raptor550]

They Are Alive!!

Okay, I finished them. My friend is really excited after hearing them, currently he is re-orienting his room to accommodate them.

Women have now christened them "Tom's Sexy Beasts".

The OSB was a B@$% to work with but now I kind of enjoy the texture with Silver. It looks like beat up metal. The owner has warmed up to it too. it makes them interesting, more to look at. Here are the pictures:



and the Concept art for comparison:



They sound really good. They are not fatiguing at all, and have quite pleasant imaging. The crossover was so easy it was a joy. I am tickled by how inexpensive it was. Especially in light of the other two projects I have done.

ThomasW is correct. I have had several weeks now to compare them with the NatP's and Raptor MT's I will post a thread getting into the details but for now, because I know some are yearning in their bones for a subjective review. I will say this:
You totally get what you pay for, in a good way. I love both the NatP's and the BAMTMs. HIGHLY PLEASED. I feel dollar for dollar you cant ask for any better from either.

Tonally, the BAMTM's have been described as "more subdued", "warmer" and "easy" by guests I have had over for a listen, half of the people like the nats, half prefer Zaphs. The Nats are louder per watt. I think the Zaphs speakers are more forgiving on lower quality recordings, and are excellent at rock and roll. But I prefer the Nats with money no object. Again I will go further in depth later.

The BAMTM's are the perfect first time project, people who build it should be satisfied. You needn't have all those n00b audiophile insecurities. Yes Its cheap but it will be fine, so ease your troubled mind.

Time for the dancing nanner. :dancenana:

[jkrutke]

the BAMTM's have been described as "more subdued", "warmer" and "easy"

Sounds like some of my dates from my college days. :B

Nice color scheme. I like two tone silver and black also. I was thinking of doing a speaker to match the silver and black sub on my archives page.