Announcement

Collapse
No announcement yet.

Bantams MTM Underway...

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • tomzarbo
    started a topic Bantams MTM Underway...

    Bantams MTM Underway...

    As soon as I heard the tiny "Bantams" handling demanding program material fairly loudly with no problem, I knew I wanted to explore the possibilities of an MTM version. I hadn't planned on working on it this soon, but DIY Indiana is coming up in April and the 3 Liter "Nano" theme this year seemed perfectly suited to an ND91 based MTM.

    Here is a front box drawing of what I envision:



    Side view of same:



    The design uses the same Dayton Audio AMTPOD tweeter... the one intended to go in a car: http://www.parts-express.com/dayton-...-pair--275-195

    Hey, I see they're only $35 on sale, nice!

    Woofer is the 8 ohm version of the ND-91: http://www.parts-express.com/dayton-...8-ohm--290-226

    ...and the passive radiators are the non-PE Peerless 5.25" passive radiators... a Mad deal at $12.75 There are two per cabinet opposing on the sides by the way.


    Here are a few shots of how construction as gone so far:










    The thin strips of solid wood are maple, and they will provide some additional backing material for screwing in the back panel. I need to have the back removable because I intend to do a solid hardwood baffle and I plan on fastening it from the rear, pulling it towards the cabinet. I may even rear-mount the woofers if I can pull it off.




    The maple corners and side thingy's are going to have oversized holes drilled in them to allow for some movement of the hardwood baffle as time goes on.



    As you can see from the initial sketches, I intend to round over the corners and base with probably a 3/4" roundover or so. Not sure on veneer or hardwood yet, I will have to take a closer look at what I have as time gets closer. I do now have a few pieces of decent wood to pick from, so that's nice.

    I want to try a 45 degree bevel on the front as I've never done that before and I think it will look nice and sharp with the hardwood front.

    So, internal volume is 2.9 liters not including any bracing, which there isn't any except the corner and side screw blocks. The original "Bantams" made do with about 1.2 liters, so the extra volume with the MTM version along with using two larger PR's should bring the F3 down to around 62 Hz or so... F6: 55 Hz, F10: 45 Hz. I'm anticipating these will have even more 'punch' in the bass region. Sometimes it's harder for smaller drives to have the same 'impact' as larger ones playing the same frequencies... hard to explain, but I think these will be even more satisfying to play loud.

    More to come...

    TomZ

  • imakethings
    replied
    Originally posted by tomzarbo View Post
    No, I started from scratch for these basically. These use the 8 ohm version of the ND91...I still haven't finalized the crossover for these. Not that they sounded bad last year in Indiana, but I think I may try to revisit the crossover again to see if I can possibly simplify things a bit. I think I can get the tweeter crossover parts in the base, then just have the woofer crossover bits to attach to the rear baffle. It's been awhile since I've even listened to them, gotta get back to these soon. TomZ
    Thanks! I think these will make a good portable radio that would spend most its time in a bedroom.

    Leave a comment:


  • tomzarbo
    replied
    Originally posted by imakethings View Post
    Tom did you use the same crossover from the bantam TMs?
    No, I started from scratch for these basically. These use the 8 ohm version of the ND91...I still haven't finalized the crossover for these. Not that they sounded bad last year in Indiana, but I think I may try to revisit the crossover again to see if I can possibly simplify things a bit. I think I can get the tweeter crossover parts in the base, then just have the woofer crossover bits to attach to the rear baffle. It's been awhile since I've even listened to them, gotta get back to these soon.

    TomZ

    Leave a comment:


  • Wolf
    replied
    That's a definite 'no'. The doubled up drivers will have an impedance shift, and therefore at the very least change some of the values.
    Later,
    Wolf

    Leave a comment:


  • imakethings
    replied
    Tom did you use the same crossover from the bantam TMs?

    Leave a comment:


  • MLS
    replied
    They look great Tom!!! Nice work.

    Leave a comment:


  • Wolf
    replied
    I'd like to hear the Bantam TMs as well. (In fact- they could compete as well if you wished to.) I don't think you could pack them any more full without adding sand or concrete. 'Project density' is also something that increases when dealing with the itty-bitty-booger speaker builds.

    As to PRs, yes- you've used a lot of them! I've used my fair share as well, but I don't opt to use them over a port if the port gets the job done with the results I wanted. It's that price/performance thing. $2 piece of PVC vs $80 PR in some cases...

    Later,
    Wolf

    Leave a comment:


  • tomzarbo
    replied
    Thanks an awful lot, guys.

    I haven't had a chance to take any measurements yet, but I did hook the woofers up with a small coil to calm the midrange down a bit and gave a listen to check for a good bass alignment with the PR's. Check. Sounds pretty decent and even has a 'punchyness' to the sound if you stand right in front of them close enough. Funny to see two 5" PR's in action with just a duo of 3" drivers making them go. Passive Radiators make me happy. I think I'm a weird guy.

    I think I'm for sure going to bring the original "Bantams" to Indiana also... if for nothing else than to just let the guys feel how heavy they each are for their size.

    TomZ

    Leave a comment:


  • joeybutts
    replied
    I absolutely love how these are super clean yet have an exotic flair to them..... like a Lamborghini or koeniggsegg..... so much going on but beautifully constructed and finished.

    As always Tom, great execution...

    Leave a comment:


  • djg
    replied
    Those are really nice.

    Leave a comment:


  • Wolf
    replied
    Since the Denovo boxes are stocked, and it's a 'Design Team' build, they indeed have that option.

    I think both are pretty cool anyway,
    Wolf

    Leave a comment:


  • ronk
    replied
    Maybe, parts express can sell the Bantam MT kit. They have the Denova box, so all they need is to cut the holes into the Denova box and package all the drivers and crossover. There is no readymade box for the MTMs. The front and sides of the Bantam MTM are gorgeous.

    Leave a comment:


  • tomzarbo
    replied
    Thanks guys.

    RonK, My woodworking skills preclude me from building these MTM's also to be honest... if you only knew.

    Really, I wouldn't build a set of these exact speakers again if you pointed a gun to my head. WAaaaaaaaayyyy to hard. The minutia is mind boggling for me. I was trying for a certain 'look' but within the constrains of the rules for DIY Indiana coming up in a few weeks... most notably 'nothing larger than what would fit in a 12" cube,' and 'max interior volume of 3 liters.'

    After the dust settles I'll hopefully get a box plan together for these that doesn't require removable front/back with hidden fasteners, 2 cabinet gaskets, trimming driver gaskets... heck, trimming driver frames for that matter... All this was done to 'make it fit' and get just the look I wanted.

    It can be done mostly as nice, and much easier... and I'll get to that in a few months if they are fairly well accepted or if I think they deserve it sound quality wise....Lord willing. The "non DIY Indiana" version should also dig a bit deeper probably as well, but not by much.

    TomZ

    Leave a comment:


  • ronk
    replied
    Looks fantastic. It should sound fantastic. I might try making the original Bantams but my woodworking skills preclude me from trying to make the Bantams MTMs.

    Leave a comment:


  • Navy Guy
    replied
    Looks great, Tom!

    Leave a comment:

Working...
X