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i've caught the bug :( Want to make a small as possible BT speaker.

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  • i've caught the bug :( Want to make a small as possible BT speaker.

    Guys,

    i want to do more wood work and was thinking of making a small BT speaker after seeing the page about passive aggressives. I fully intend to kerf again and make a bar of sorts. Only real criteria is i get to bend wood and make it confuse people due to its size. after reading the PR thread, sounds like size will be the limiting factor to what can be added to it.

    Parts
    1x https://www.parts-express.com/dayton...8-ohm--290-206
    2x https://www.parts-express.com/dayton...iator--290-205

    AMP?
    DTA 2 tripath

    BT board - unsure at the moment.

    Looking at the specs on the driver, this little fella can get as low as 55Hz in a 0.05cuft box, which would be quite nice for a portable BT speaker. Sure i would like to push the envelope if possible and go lower, but depending on how much larger the box goes (remembering i want to keep it small).

    I have worked out the dimensions, but not sure as i havent made many speakers to date if a mono full range driver will be adequate and if i can covert the amp to being a mono. I didnt want to buy another amp i have this one lying around from a previous build, but depending on cost of the BT addition, may rethink and get the KAB-215 as it has the ability to add the battery board.

    configuration is either all 3x items across the front, or the driver at the front and 2x PR's at the rear. I havent modelled this yet, but would love to hear if people think something is missing, needs to be added or just think its a dumb idea. I was thinking of placing my order next weekend just so i can have a good think about what the design can be.

    Let me know the thoughts regardless if it is bad.

    Cheers

  • #2
    ND65 are really low sensitivity. This will require more power.
    DTA-2 is not bridgeable, as it's already bridged on each channel. I see you only have one active driver, so how are you doing stereo?

    Later,
    Wolf
    "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
    "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
    "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
    "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

    *InDIYana event website*

    Photobucket pages:
    http://photobucket.com/Wolf-Speakers_and_more

    My blog/writeups/thoughts here at PE:
    http://techtalk.parts-express.com/blog.php?u=4102

    Comment


    • #3
      Originally posted by Wolf View Post
      ND65 are really low sensitivity. This will require more power.
      DTA-2 is not bridgeable, as it's already bridged on each channel. I see you only have one active driver, so how are you doing stereo?

      Later,
      Wolf
      Valid point, stereo amp mono concept. I was hoping to keep the size down, but I would need to double the volume to get what i need foe stereo.

      Honestly didn't know the issue with the amp. I use them to power the tectonics and it works well, so assumed.smaller speakers would be fine...lucky I posted

      Any recommendations?

      Comment


      • #4
        The ND65-4 may be a better choice for this as it will get louder with the DTA-2 amp than the 8 ohm version you linked to. That amp may be enough amp to drive it to decent levels.
        I haven't modeled the ND65-4 with those PR's, though it loves living in a smallish vented box.

        You could always just use one channel for mono and just leave the other unused... seems strange, but it shouldn't hurt anything.

        I used this board from PE: https://www.parts-express.com/tda749...2x50w--320-606
        With a 16v input, It will have enough oomph to work out that little speaker just fine. It also has the ability (says the description) to wire it R+ and L+ for a mono mode, I can't confirm that though.

        This amp/Bluetooth combo unit might work as well: https://www.parts-express.com/dayton...th-21--325-100 The dimensions on that one 3.6" x 2.7" x 0.9" high may be too big, though, not sure how much room you have.

        Again, just use one side of the stereo output to power your speaker with. There may also be some decent choices on Aliexpress or Amazon for small amp/Bluetooth units all in one. All in one may not be a bad idea because I've tinkered with a few different little amp projects and most have suffered with some kind of noise issue.

        If you haven't already seen these, here are a few examples of uses with the ND65-4 vented. I had noise issues with the Toni Table Radio but not the sound travelers: http://projectgallery.parts-express....ound-traveler/

        http://projectgallery.parts-express....i-table-radio/

        Hope this helps a bit.

        I'd love to see you post pics as you go, I love these small radio projects.

        TomZ
        *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
        *Part 2 *Gluing multiple curved laminations of HDF *Cello's Speaker Project Page

        *Building the "Micro-B 2.1 Plate Amplifier -- Part 1 * Part 2 * Part 3 * Part 4 * * Part 5 'Review' * -- Assembly Instructions PDF

        Comment


        • #5
          Don't know if Tom has his T/S parms handy (for the ND65-4), but these are mine from a pair. (I TRIED to break in by hand, but you really can't poke anything through the backside of the frame - ESP. your FINGERs - just too tiny. I really SHOULD run them at Xmax (100Hz?) for a few hours... maybe I'll do that.)

          spec / DATS(pair)
          Qes: 0.68 / 1.02 (quite high - adds to the ripple)
          Qms: 5.6 / 4.3
          Qts: 0.61 / 0.82 (from high Qes)
          Fs: 90 / 138 (also high)
          Vas: .019 / .008 cf (sort of balanced by higher Q)

          w/WinISD, they really can NOT reach below 60Hz (per spec), they CAN do mid-60s though, w/quite a "ripple".
          I've tracked the ND series' parms over time, and it SEEMs like they've slowly slide away from their initially quite terrific parms? (in terms of low end reach - mostly)

          The -8s I DATS'd (5 y.a.) were: Qes .46, Qms 5.2, Qts .42, Fs 90, Vas .018

          Anyway - SEEMs like a PR-tuned box never models quite as low as a port tube (for ME).
          I don't get a good bottom end curve w/those ND65 PRs, but I CAN get something usable w/a pair of the ND90s.
          Thing is, it's not that hard to tune a 0.05cf box w/a 1"id port tube.
          The PRs (like in the Passive Aggresives) are needed more since the larger woof has more cone area and a reasonably size vent would be too long (IMO).

          Comment


          • #6
            I looked and couldn't find my DATS data for that driver. I often just jot down the specs or copy/paste a screen shot, but nothing turned up ... so I don't actually have any of my data from using it in the two projects I did. Also, my BassBox Pro files are all borked up, every single one, so I can't draw specs from those either. The last update did a number on my stuff.

            TomZ
            *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
            *Part 2 *Gluing multiple curved laminations of HDF *Cello's Speaker Project Page

            *Building the "Micro-B 2.1 Plate Amplifier -- Part 1 * Part 2 * Part 3 * Part 4 * * Part 5 'Review' * -- Assembly Instructions PDF

            Comment


            • #7
              The issue with an integrated BT receiver/amp module is that the speaker output will be split as a L channel signal and a R-channel signal. Use only one, and you will be missing content only in the other channel of the stereo material. With a separate amp and BT receiver, you can easily sum the L-R signal output of the receiver to a combined mono signal to feed the amp (two resistors).

              You can use an integrated BT-amp if your BT source has a mono mode (but that seems rare nowadays).

              If I had a project like this, I'd perform some surgery on the integrated BT/amp module to sum the signal to mono between the BT section's output and the amp section's input (but that requires massaging SMD components on the board).

              Comment


              • #8
                I noticed a sure board BRB1 AA-AB41151 that was similar to the one most have seen before, just without the RCA outs and probably some other things, but thought it might be a suitable pair to the DTA. I have the KAB 230 v3 in the bigger boombox which is geeat and side by side with the newer PC speakers is very similar in output ( that I can test with my head tilted listening intently).

                As I already had it's big brother I really wanted to have a box of no greater than an interapi volume of 0.04-0.05 cu.ft. it sounds like I've fallen victim of taking that bassbox vented calc for granted. Might need to go back to the drawing board and model Chris's actual measurements and see what I would be happy to accept. 60hz from a tiny driver would be cool. Another potential is the 4in Peerless PR and try to have two enclosures, I have to look and see what xmax and sd are on those, but considering I would have to increase the height to get more volume. I would say if I can get a small size and what I have in my head, this might have to make it to the scrap pile pre construction.

                When I was typing this original post I actually thought Chris would suggest port over PR, which was great advice with my last build. I think I might have got caught up with this slave bass idea after seeing what mass produced items on the market have, where they claim to have 5 drivers (two being a PR and two small tweeters and one mid range).

                Random idea and may sound like total crap......would it be better to have two of

                https://www.parts-express.com/dayton...4-ohm--285-103

                And one ND65 or larger to act as a mini sub/mid? Then I could keep that small box and mount in on the base or top and use a port, Guessing it could be done on one channel as a x over? Like I said feel free to say "go home you're drunk"

                Comment


                • #9
                  check this out

                  front has two ND65-4 drivers. each side has two ND65 PRs (total of 4 PRs)

                  simple contour filter for some BSC (but this will likely sit near a wall / on a desk, so not aiming for stand-mounted +6 dB of BSC)


                  Attached Files

                  Comment


                  • #10
                    Looks cool, what size enclosure you using? Or have you got a write up of this one in the project section

                    Comment


                    • #11
                      Originally posted by 3rutu5 View Post
                      Looks cool, what size enclosure you using? Or have you got a write up of this one in the project section
                      don't recall exact dimensions at the moment. no write-up of this one. about 0.05 cubic foot volume. tuning about 70 Hz
                      box is a repurposed cigar box.

                      Comment


                      • #12
                        if you want great bass -- use the self-contained Tang Band micro-sub with passive radiator
                        https://www.parts-express.com/tang-b...3-5-8--264-942

                        I used it in my Bourbon box build

                        Comment


                        • #13
                          I just finished a little BT speaker.. I'm calling it the lunchbox. Two ND65-8's with an ND140 passive. roughly 8x8x5 external dimensions. Using a KAB-60M mono bluetooth amp for power.

                          Comment


                          • #14
                            Originally posted by Parts Express Patrick View Post
                            I just finished a little BT speaker.. I'm calling it the lunchbox. Two ND65-8's with an ND140 passive. roughly 8x8x5 external dimensions. Using a KAB-60M mono bluetooth amp for power.
                            i like it. What was the reason behind having 2 drivers but using a mono over a stereo amp? does the PR provide a little extra umphhh

                            Comment


                            • #15
                              Originally posted by ceiol View Post

                              don't recall exact dimensions at the moment. no write-up of this one. about 0.05 cubic foot volume. tuning about 70 Hz
                              box is a repurposed cigar box.
                              hmmmm....thats an idea, i have two spare cigar boxes floating around, but wouldnt help with the woodworking itch

                              Comment

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