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Advice on adding tweeters to a Sprite build (and other modifications)?

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  • Advice on adding tweeters to a Sprite build (and other modifications)?

    I've built two small boomboxes for my nephews--they aren't quite done, just shot the lacquer and need to do the final assembly--I think it's time to build something for myself, or will be come January. Doesn't need to be portable, just want it for the kitchen, so no battery, but bluetooth is good, as well as 3.5 mini jack input, and then I saw the Sprite design, which is about perfect for my needs, but I see it cuts off about 15,000 Hz and figured it needs some tweeters to bring in the high end? So I picked out these, for no other reason than I like their look! https://www.parts-express.com/goldwo...eeter--270-180 They're 8 ohm, same as the Dayton ND90-8 in the Sprite design, but I also notice they can handle a lot more power, 50 watts RMS to the ND90-8's 20 watt (40 watt peak). Is that a problem? Should I look for tweeters with 20 watt RMS, too? And here's where my lack of understanding gets in the way, and it's not for lack of trying, either: it looks like a high pass filter would serve to protect the tweeter from the low end frequencies, but is that enough, or would it also require a crossover that only lets through the higher frequencies, at least beginning at 2000 Hz (from the tweeter specs), or possibly even higher? And are the tweeters and the full range drivers connected to the same outputs on the amplifier? I can't imagine how else they would be connected. I'd also like to add some analog VU meters, just because that's what I grew up with on my dad's stereo, and I think they're cool. But those would be wired to the same amplifier outputs, too, right? How much is too much? Which brings me to the amplifier/power supply. I don't see anything on Parts Express that includes bluetooth and other inputs, like the aforementioned 3.5 mm mini jack, or even RCA. I also like the idea of an onboard volume control knob, as opposed to volume control that just affects phone/tablet volume. I've found this on Amazon, though I have no idea if it's good, bad, or downright ugly. https://www.amazon.com/dp/B016ZR7JZK

    I'm sure I could think of more questions, but I'll leave it there for now. Thanks for your time.

  • #2
    There are some real experts here who have given me some great advice recently.
    Eg, stick to a proven design, here is a nice one might suit (going to be my next build)
    I wanted to add volume too, so I'm using a KAB board and this.


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    • #3
      Originally posted by Jamesbil View Post
      There are some real experts here who have given me some great advice recently.
      Eg, stick to a proven design, here is a nice one might suit (going to be my next build)
      I wanted to add volume too, so I'm using a KAB board and this.

      Thanks for the response. I've already done some building, and a ton of reading. I feel like I would learn more if I took a proven design and added a tweeter to it. With guidance, of course. Then I get to see the elements of a speaker in motion, as it were, and better understand how they relate to one another. For instance, if I add a tweeter to a Sprite build, does it go directly into the same cabinet as the ND90-8 requiring a change to the original filter (a 2 way crossover), or can the tweeter go into its own cabinet and just get its own filter? The second option seems pretty easy, but I don't know if it's actually an option.

      Thanks for the tip on the KAB board breakout volume/power input, too!
      DIY audio projects by Paul Carmody (Undefinition)

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      • #4
        ND16 is a popular small tweeter, I would probably use that.
        Look for a build called the Helium, though I think it might use the ND91

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        • #5
          http://techtalk.parts-express.com/fo...e-micromonitor

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          • #6
            i just made my own custom boom box using the ND90-4 and the ND16FA-6. I will try to post details of my build including the crossover this weekend.

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            • #7
              Having done some more reading and question asking, it seems as though I could just put the tweeter in the same cabinet and filter it, but as someone said, that would just serve to add some sparkle on top. A two-way crossover would be the proper way to do it, but then I would have thrown the original design out the window, which wasn't my goal to start with.

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              • #8
                Originally posted by Matt Clara View Post
                Having done some more reading and question asking, it seems as though I could just put the tweeter in the same cabinet and filter it, but as someone said, that would just serve to add some sparkle on top. A two-way crossover would be the proper way to do it, but then I would have thrown the original design out the window, which wasn't my goal to start with.
                True. The worst case for this will be some response wierdness where the tweeter and mid overlap. I'd try the ND16, and filter it quite high to make sure that overlap is well above 4k and out of the critical hearing range.
                Electronics engineer, woofer enthusiast, and musician.
                Wogg Music

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                • #9
                  Originally posted by wogg View Post
                  True. The worst case for this will be some response wierdness where the tweeter and mid overlap. I'd try the ND16, and filter it quite high to make sure that overlap is well above 4k and out of the critical hearing range.
                  So you're saying just add the sparkle? Thanks for the response.
                  Last edited by Matt Clara; 12-08-2017, 11:56 AM.

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                  • #10
                    here you go

                    http://techtalk.parts-express.com/fo...pepper-boombox

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                    • #11
                      Originally posted by ceiol View Post
                      Cool, man, thanks!

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                      • #12
                        If you look at Paul's frequency response for the Sprite, it looks like it goes pretty high. I think adding a tweeter may be counterproductive (may become too bright). I have heard adding a 1 uf cap adds a bit to top end. For a design using the ND-90-8 and a tweeter, see this link: http://techtalk.parts-express.com/fo...rs-the-dadiels

                        The Dadiels. I have never heard them.

                        I personally would use Sprite filter as is, with maybe the addition of a 1 uf cap to add a bit of top end. I have built a non boom box speaker using the ND-90-8 and Paul's filter, and the top end sounds pretty good.

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                        • #13
                          Originally posted by michaelmoran View Post

                          The Dadiels.
                          Great design -- I've built them and I enjoy them a lot. I did make one change: I used the Sprite box tuning instead of the sealed box of the Dadiels.

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                          • #14
                            Hi Matt... I too had been toying with the idea of a Sprite box with a tweeter. I had built a Sprite last year with a slight deviation from the original. The BSC contour filter I used was 0.9mH coil and 16 ohm resistor. The port tubes were Jantzen Audio tapered tubes with 26.33 inside dia and 35mm outside dia. The total port length was 165mm with 155mm usable because of the flares. There was no divider between the L-R speakers. The sound was much improved by using the filter compared to running it filter free. The bass was good as usual, the mids were reasonably good and much better than boombox type while the highs were there but a little lacking though.

                            So, this time I decided to add some AMT-8 tweeters (Sounderlink AMT tweeters from Aliexpress) and make it into a 2-way with a divider between L-R speakers. I did a lot of reading, asked a lot of stupid newbie questions and finally had a plan. The plan was to make the woofer dip -3db around 4000Hz to take over from the BSC coil which starts losing out to the BSC resistor around this point and also avoid the rise in frequency around 5000Hz. The tweeter would dip -3db around 9000Hz and both would have a crossing around 6000Hz. I got hold of my last year's Sprite build, took out its guts (BSC and amp) and added the tweeters with the crossover to test it out before I set out to build the new one. I added a 0.3mH LPF coil before the BSC on the ND90-8 and a 2.2 uF HPF cap on the AMT-8. This is 1st order Solen Split filter with a proposed -6db dip around 6000Hz. It mimics a 2LR filter but with something like 1st order Butterworth slopes. The tweeter was padded down with a 12 db L-Pad (6 ohm resistor in series and 2.7 ohm shunt parallel after the HPF cap and before the tweeter) to compensate for about 7.5db of lower sensitivity of the ND90-8 and approximately 4.5db loss of the BSC. Since, this is a boombox project and I would be listening to it at a minimum of 6-8 feet distance, I was only interested on how this would sound at these or greater distances. I went with 1st order filter because from what i have read, they are the most easy to incorporate without being as power hungry as the higher order filters and any phase issues are sorted out when you listen to them at a distance of more than 6-8 feet.

                            The sound has improved drastically. The bass is now more defined, the mids are cleaner and smooth sounding and there is dramatic improvement in the treble which sound extremely clear and spacious. I am extremely satisfied with the outcome. The whole process of adding a tweeter has added on to the cost of the original Sprite build, but its worth it. I read somewhere that Paul did not add tweeters because he wanted to keep the part nos. down and he even suggested somewhere that if you wanted tweeters, he already has the OS build and we can follow that. Its just that the Sprite has been a carrot for a lot of first timers and Mr. Carmody is responsible for spreading the DIY bug amongst a lot of newbies. Once you get infected, it makes you want to tweak and the virus starts mutating.........

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