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  • BoomBox Idea, Need Some Ideas (How to Incorporate USB)

    Folk,

    Paul Carmody's Sprite boombox inspired some ideas within me but I have run into some technical dead ends.

    Design Goals:

    1. Must be modular. Just like the boomboxes of old that had detachable speakers.

    2. Must be able to accommodate an Ipod/Iphone or Android phone.

    3. Must be able to charge phone (USB charger).

    4. Must be able to deliver 50 watts RMS minimum.

    5. Must be portable with its own power.

    There are several amps that have USB charging build in on the PE site, but they lack the power needed to power the speakers. What I need is a way to power and charge the phone while playing music.

    My first thoughts were to use the following items:

    http://www.parts-express.com/pe/show...number=320-315

    http://www.amazon.com/Charging-Charg...galaxy+s3+dock

    http://www.batterymart.com/p-12v-7ah...attery-f2.html

    http://www.parts-express.com/pe/show...number=320-301

    But the problem remains that using these items will not give me the USB requirement.

    Please let me know what you guys think...

    Kevin
    Shaken, not stirred...

    Classix II
    OS MTM's
    Digger 8 sub
    Overnight Sensations Center Channel
    Sprite Build
    Wolf's PC Speakers
    Minions III with Voxel Sub

  • #2
    Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

    http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=252-196

    and

    http://www.parts-express.com/pe/psho...number=300-383
    R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
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    • #3
      Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

      Dollar General USB AC/DC charger $3.99 or Big Lots version $1.99 (Identical... right down to Memorex branding!) If you want to feed it 100 watts, go to a Salvation Army Thrift store and snag a used stereo receiver of 50WPC. You think I'm kidding, but with everybody buying AVR's and wifey's/SO's demanding the space, I could fill the back of my pick-up with good receivers (at times) for less than $20 each in that power range. I bought 4, cleaned them up, put LED dial lights in them and more than quadrupled my money on them, with some Caig De-Oxit and lube on the controls to go along with the FREE turntables I got with them ($20 for new cartridges/stylii for them) and I sold the combos to vinylheads on one weekend. I have seen NICE Craig brand 40 WPC receivers sell for $10. Yes,they are about 40 years old, but 40 years ago, Craig and Concord both made and sold some good stuff. Goest thou forth and hunt! BTW, my sister's 1950 Zenith radio-phonograph I have paper filter cap's are still good.

      Comment


      • #4
        Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

        Thanks guys but the problem has been how to run and power USB to charge the phone or Ipod while it is in the dock. Otherwise there are many amps to choose from. The goal would be to drop the phone into the dock and start play music from it.

        The Lapai amps have USB charging on them. I am just dubious of them since seeing bad reviews on youtube.

        Any other ideas?
        Shaken, not stirred...

        Classix II
        OS MTM's
        Digger 8 sub
        Overnight Sensations Center Channel
        Sprite Build
        Wolf's PC Speakers
        Minions III with Voxel Sub

        Comment


        • #5
          Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

          These or just making something similar would work for the speaker mounting part:

          http://www.parts-express.com/pe/show...number=182-168

          or just do what they do to mount cabinets. Make similar angled cuts in wood and mount similarly. Then use a couple of neo magnets embedded in the cabinet side and speakers near the bottom to really make it 'stick' and stay put.


          Something like this or a similar cable connector would get you working with your connector:

          http://www.cooking-hacks.com/index.p...dbreakout.html

          I bought one a few years ago that powered the ipod with the ability to connect a 12v input as well as using the line-level RCA outputs for cleaner sound than using the earphone 1/8" plug.

          Something like this:

          http://www.amazon.com/Decrescent-Con.../dp/B007QTAHTC

          Just hack the USB connector and use a 5V supply.

          TomZ
          Zarbo Audio Projects Youtube Channel: https://www.youtube.com/channel/UCEZ...aFQSTl6NdOwgxQ * 320-641 Amp Review Youtube: https://youtu.be/ugjfcI5p6m0 *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
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          • #6
            Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

            You just need a 5Vdc, 1-2A power supply. You can either buy one with the connector your phone uses (most Androids are micro-USB, apple is different obviously), or spice into an existing cord ignoring the data lines and just connecting the power. Audio comes from the headphone jack to whatever kind of amp you want to run.

            Alternatively, you could get a car headunit with usb ports that supports the phone you want to use. This will be expensive, and required a large 12-14Vdc power supply.
            "I have not failed. I've just found 10,000 ways that won't work." Thomas A. Edison

            Comment


            • #7
              Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

              I was actually thinking about using this Amp. But I have not seen very good write ups for Lapai. I saw some comments about using a 5 amp power supply and that fixed the problems with the amp clipping.

              Remember the boomboxes that had the detachable speakers? I was going to use a pair of OS TM's and get some clips so you could carry it with a handle and then place it where you wanted, detach the speakers and play away. With the middle box at 9" high it should match up with the same height as the OS TM's.

              The idea I had was to build a "middle box" that housed the amp and dock.

              Click image for larger version

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              I planned on the box to be 8 3/4X 9X 15 1/8 and house a TB 6 1/2 subwoofer. I had pictured the amp to be mounted on top inside its own housing. If the Lapai performs as advertised then it should rock my kids room pretty hard.

              What do you guys think?
              Shaken, not stirred...

              Classix II
              OS MTM's
              Digger 8 sub
              Overnight Sensations Center Channel
              Sprite Build
              Wolf's PC Speakers
              Minions III with Voxel Sub

              Comment


              • #8
                Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

                Hi,

                You will not get 50W rms per channel out of the amplifier with a single 12V supply (battery or otherwise). You'll need two batteries in series to get near the 50W rms per channel output. The most you can get out of a 12V battery is about 13W RMS per channel when the battery is freshly charged (and still delivering upwards of 12.7 volts). You'll need two batteries in series (24V) to get nearer the rated output of the amp (detailed amp specs on power out at specific voltage). This is why so many auto head units are rated at 14W rms per channel. The specs are for a running vehicle and the car's charging system is delivering a regulated 14.4 volts. The really high power "rattle the next car's windows" amps have voltage step up circuits to get 100s of watts rms per channel.

                Also, the 7AH capacity is low for an amp with this power output at 24V. At full volume Using two of these batteries in series (24V supply) and getting 84 W rms (42 per channel) gives you a theoretical draw of 3.5 amps - but its more like 4 amps after accounting for Ca lass D amp efficiency of 85% to 90%. You will get about one hour before the batteries are fully dischaged. Why not closer to 2 hours (1 hr 45 mins=1.75H=7AH/4A)? Because SLA batteries are rated at the "20 hour rate".

                A 1A draw from a 20AH battery will yield 20 hours of run time - the rated output. However a 10A draw will not yield 2 hours but more like 1 hour and 15 minutes. There are inefficienies when drawing high current relative to the AH rating. Think of it like this - you could walk at 3 mph for 10 hours and cover 30 miles. But how long and far can you run at full speed before needing to rest/recharge?

                But 84 W rms is at full volume. What if you're continually running at half volume? Say 42 W rms total (21 W per channel)? Which to the ear, sounds louder than half 84 W rms. That's a 1.75A (2A) draw that will yield about 3 hours from a 7AH battery. You'll need to assess your run time and weight (SLAs weigh) performance goals to make a decision.

                I have run a well tended 18AH SLA battery at its half life using an inverter and a 40W light bulb for about 3 hours. That's about 4.25 amps from the battery including the inverter ineffiencies. That performance is close to a nearly new, fully broken in battery (SLAs require about a 20 charge cycle break in period before they fully deliver their rated capacity).

                Some tips:

                Auto head units can get you 4 x 14 W rms (four - 4ohm woofers) and USB, AUX, FM, etc". But you'll pay a penalty for its class B amp inefficiencies which are way worse than digital and horrible (35% efficient) at half volume. And you'll get less than the rated power out as your not running a car at its 14.4 regulated output, but rather, discharging a battery from the high 12s to 10.5 volts.

                Get a 3-stage charger for each battery. Never let SLAs sit discharged. Charge them, then switch the chargers to a lamp timer set to run 1/2 hour every day until needed. The charge will quickly cycle to the third stage about 15 Vs - so important to battling deposits on the battery plates and keeping them like new for many years.

                You need a switching circuit to charge the batteries that takes them out of the 24V series configuration and allows a charger on each battery seperately.

                Also, the regulated power supply is only 12V (same issue as one battery) and IMHO, a little overkill for the amp at 29A output.

                All of the above comes from "Been there, done that" save for the regulated power supply comment at the end.

                Regards,

                Millstonemike
                Last edited by Millstonemike; 11-27-2012, 11:43 PM.

                Comment


                • #9
                  Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

                  Originally posted by Millstonemike View Post
                  Hi,

                  You will not get 50W rms per channel out of the amplifier with a single 12V supply (battery or otherwise). You'll need two batteries in series to get near the 50W rms per channel output. The most you can get out of a 12V battery is about 13W RMS per channel when the battery is freshly charged (and still delivering upwards of 12.7 volts). You'll need two batteries in series (24V) to get nearer the rated output of the amp (detailed amp specs on power out at specific voltage). This is why so many auto head units are rated at 14W rms per channel. The specs are for a running vehicle and the car's charging system is delivering a regulated 14.4 volts. The really high power "rattle the next car's windows" amps have voltage step up circuits to get 100s of watts rms per channel.

                  Also, the 7AH capacity is low for an amp with this power output at 24V. At full volume Using two of these batteries in series (24V supply) and getting 84 W rms (42 per channel) gives you a theoretical draw of 3.5 amps - but its more like 4 amps after accounting for Ca lass D amp efficiency of 85% to 90%. You will get about one hour before the batteries are fully dischaged. Why not closer to 2 hours (1 hr 45 mins=1.75H=7AH/4A)? Because SLA batteries are rated at the "20 hour rate".

                  A 1A draw from a 20AH battery will yield 20 hours of run time - the rated output. However a 10A draw will not yield 2 hours but more like 1 hour and 15 minutes. There are inefficienies when drawing high current relative to the AH rating. Think of it like this - you could walk at 3 mph for 10 hours and cover 30 miles. But how long and far can you run at full speed before needing to rest/recharge?

                  But 84 W rms is at full volume. What if you're continually running at half volume? Say 42 W rms total (21 W per channel)? Which to the ear, sounds louder than half 84 W rms. That's a 1.75A (2A) draw that will yield about 3 hours from a 7AH battery. You'll need to assess your run time and weight (SLAs weigh) performance goals to make a decision.

                  I have run a well tended 18AH SLA battery at its half life using an inverter and a 40W light bulb for about 3 hours. That's about 4.25 amps from the battery including the inverter ineffiencies. That performance is close to a nearly new, fully broken in battery (SLAs require about a 20 charge cycle break in period before they fully deliver their rated capacity).

                  Some tips:

                  Auto head units can get you 4 x 14 W rms (four - 4ohm woofers) and USB, AUX, FM, etc". But you'll pay a penalty for its class B amp inefficiencies which are way worse than digital and horrible (35% efficient) at half volume. And you'll get less than the rated power out as your not running a car at its 14.4 regulated output, but rather, discharging a battery from the high 12s to 10.5 volts.

                  Get a 3-stage charger for each battery. Never let SLAs sit discharged. Charge them, then switch the chargers to a lamp timer set to run 1/2 hour every day until needed. The charge will quickly cycle to the third stage about 15 Vs - so important to battling deposits on the battery plates and keeping them like new for many years.

                  You need a switching circuit to charge the batteries that takes them out of the 24V series configuration and allows a charger on each battery seperately.

                  Also, the regulated power supply is only 12V (same issue as one battery) and IMHO, a little overkill for the amp at 29A output.

                  All of the above comes from "Been there, done that" save for the regulated power supply comment at the end.

                  Regards,

                  Millstonemike
                  Milstonemike,

                  Thank you for your input. Your advise is very well taken. I have since rethought my idea to make this portable. My next thought was using something like this lapai amp. I was thinking of building the subwoofer box and make an enclosure to house the amp that would integrate the amp and woofer into one. I would envision it sitting on a shelf with the OS TM's on each side.

                  I know I will need to upgrade the power supply to most likely this one. So it will have the power to power both the speakers and subwoofer.

                  What do you think of this idea?

                  Kevin
                  Shaken, not stirred...

                  Classix II
                  OS MTM's
                  Digger 8 sub
                  Overnight Sensations Center Channel
                  Sprite Build
                  Wolf's PC Speakers
                  Minions III with Voxel Sub

                  Comment


                  • #10
                    Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

                    Originally posted by kevin007 View Post
                    Milstonemike,

                    Thank you for your input. Your advise is very well taken. I have since rethought my idea to make this portable. My next thought was using something like this lapai amp. I was thinking of building the subwoofer box and make an enclosure to house the amp that would integrate the amp and woofer into one. I would envision it sitting on a shelf with the OS TM's on each side.

                    I know I will need to upgrade the power supply to most likely this one. So it will have the power to power both the speakers and subwoofer.

                    What do you think of this idea?

                    Kevin
                    Kevin,

                    That will work nicely. I read some reviews on the amp. They mentioned the "included 12V 5A power supply".

                    Realize that the Lepai's wattage figures are suspect. I'd encourage you to read several of the amp's reviews - invaluable.

                    Remember the discussion on the most watts per channel feasible at a nominal 12V supply, 4ohm speakers - 14 Wrms. 2ohm speakers (woofers) will get you more power at 12V and 8ohm speakers will get you less. That's why virtually all car speakers are 4ohms and a fair amount of subwoofers at 2ohms. So your available speaker choices exclude many 8ohm "home" speakers or you'll sacrifice power.

                    If you want a bookshelf 2.1 system this will work. And you could always plug it into your car or add an SLA.

                    If you've already sacrificed portability, and you want power and choice, then there's a really nice 2.1 plate amp - "Dayton Audio MCA2250E 2.1 Channel Class D Plate Amplifier" (sorry, don't know how to insert the link). Once you plug into the wall, you get volts and that eliminates power issues. Read the specs. They quote power at 4 ohms for the center woofer and 8 ohms for the satellite speakers at good distortion numbers. That vastly opens up your speaker choices. Read the one review. The author built a 2.1 with the Lapai and then upgraded to the Dayton 2.1 amp.

                    How it sounds will depend on how much info you can absorb from the speaker/enclosure/OX/acoustic gurus. That's why I'm here.

                    Regards,

                    Millstonemike

                    Comment


                    • #11
                      Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

                      Originally posted by Millstonemike View Post
                      Kevin,

                      That will work nicely. I read some reviews on the amp. They mentioned the "included 12V 5A power supply".

                      Realize that the Lepai's wattage figures are suspect. I'd encourage you to read several of the amp's reviews - invaluable.

                      Remember the discussion on the most watts per channel feasible at a nominal 12V supply, 4ohm speakers - 14 Wrms. 2ohm speakers (woofers) will get you more power at 12V and 8ohm speakers will get you less. That's why virtually all car speakers are 4ohms and a fair amount of subwoofers at 2ohms. So your available speaker choices exclude many 8ohm "home" speakers or you'll sacrifice power.

                      If you want a bookshelf 2.1 system this will work. And you could always plug it into your car or add an SLA.

                      If you've already sacrificed portability, and you want power and choice, then there's a really nice 2.1 plate amp - "Dayton Audio MCA2250E 2.1 Channel Class D Plate Amplifier" (sorry, don't know how to insert the link). Once you plug into the wall, you get volts and that eliminates power issues. Read the specs. They quote power at 4 ohms for the center woofer and 8 ohms for the satellite speakers at good distortion numbers. That vastly opens up your speaker choices. Read the one review. The author built a 2.1 with the Lapai and then upgraded to the Dayton 2.1 amp.

                      How it sounds will depend on how much info you can absorb from the speaker/enclosure/OX/acoustic gurus. That's why I'm here.

                      Regards,

                      Millstonemike
                      Millstonemike,

                      Thank you for the advice. I wish I had seen the plate amp before. PE does not index their site very well. Because when I search for 2.1 amp the only thing that came up was the Lapai 2.1 amp. I was very dubious about using it since it did not have great reviews. I think the plate amp would be a much better choice than the Lapai.

                      Thanks a million!

                      Kevin
                      Shaken, not stirred...

                      Classix II
                      OS MTM's
                      Digger 8 sub
                      Overnight Sensations Center Channel
                      Sprite Build
                      Wolf's PC Speakers
                      Minions III with Voxel Sub

                      Comment


                      • #12
                        Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

                        I find it odd that there are several good 2.1 class D amps chips but few "DIY" products that use them. TI, ST and Cirrus all have some nice products that will run off of 18V-34V and provide 25W-50W per channel. These chips also have embedded DSP for implementing filters and EQ. I made a 2.1 amp several years ago from the STA328 chip, but never did anything with it. It has USB audio input and a switching regulator for 5V that could be used to charge/power other devices. It would be a good starting point for your project, although it is not easy to build (SMD and a micro to program). There is someone on this board that is interested in manufacturing a product similar to this, but I'm not sure what the status is.
                        If you are into "extreme DIY" and want to build this amp, I can send you a schematic, PCB layout and a parts list.

                        Click image for larger version

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                        Free Passive Speaker Designer Lite (PSD-Lite) -- http://www.audiodevelopers.com/Softw...Lite/setup.exe

                        Comment


                        • #13
                          Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

                          Originally posted by neildavis View Post
                          I find it odd that there are several good 2.1 class D amps chips but few "DIY" products that use them. TI, ST and Cirrus all have some nice products that will run off of 18V-34V and provide 25W-50W per channel. These chips also have embedded DSP for implementing filters and EQ. I made a 2.1 amp several years ago from the STA328 chip, but never did anything with it. It has USB audio input and a switching regulator for 5V that could be used to charge/power other devices. It would be a good starting point for your project, although it is not easy to build (SMD and a micro to program). There is someone on this board that is interested in manufacturing a product similar to this, but I'm not sure what the status is.
                          If you are into "extreme DIY" and want to build this amp, I can send you a schematic, PCB layout and a parts list.

                          [ATTACH=CONFIG]31198[/ATTACH]
                          Wow, what a great little project! I was just thinking that it would be cool to build a nice little system for each of my kids. I would be interested in your offer. I have not attempted such a project. But my oldest son might be interested in taking on such a thing. Maybe he could use it for a science project for school?

                          Kevin
                          Shaken, not stirred...

                          Classix II
                          OS MTM's
                          Digger 8 sub
                          Overnight Sensations Center Channel
                          Sprite Build
                          Wolf's PC Speakers
                          Minions III with Voxel Sub

                          Comment


                          • #14
                            Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

                            Hey,

                            I'm thinking about the 2.1 plate amp for a "luggable" 2.1 system. The benefit would be all the power I need and great speaker choice. The drawback is the ineffiency introduced by a 12V DC to 120AC power inverter (10%-15%?). However, the plate amp is Class D digital so if you running at low volumes you will draw proportionally less amps from the battery through the inverter.

                            In 2009, I purchased a nice little, single enclosure, 60W rms 2.1 speaker-amp unit (Parrrot Boombox). I run it off a battery with an inverter. The Parrot is light at 12lbs - a requirement as I lug 300lbs over a half mile to the site. It has a warm, wonderful sound and sufficient output for my needs. I use this at a US national park with friends from Sun-up to Sun-down (some 12 hours during Late June and July). The 18AH battery will not run it that long so mornings are quiet time.

                            The unit is crystal clear at full voulme but the woofer overheats in the summer. The problem with the Parrot is it keeps blowing its woofer (reapired once under warranty in 2010) and currently failed. You can't replace the woofer as the cabinet is sealed closed at the factory and you get a replacement box anymore as it's out of production.

                            Hence, DYI may be necessary becuase I've had upteen boomboxes for this and non of them gives decent sound.

                            Regards,

                            Millstonemike

                            Comment


                            • #15
                              Re: BoomBox Idea, Need Some Ideas (How to Incorporate USB)

                              In my mind, the key to a battery powered system is speaker sensitivity; 10dB is a factor of 10 less power needed, so smaller amp, smaller battery and longer playing time. The ONS use the HiVi B4N, a [email protected] sensitivity driver. I did a similar project, sans subwoofer, based on the PS180 driver at [email protected] sensitivity for this very reason. Even if the amp only makes 10W/ch, it's still pushing 105dB at 1M. You need 100W into an ONS MTM to match that output.
                              http://techtalk.parts-express.com/sh...ciency-speaker

                              Next, we wary of the power ratings of small 12V Chinese amps, I've yet to see a 2.1 that delivered. If you're interested in the little Sure chip amps, research the chip set as well as the specific board. Some implementations fail to follow the chip set input/output filtering properly, with resulting nonlinearities in response. I recently got this amp based on favorable reviews of the TK2050 chip set. Works very well at 12v or 24V (1 or 2 batteries).
                              http://www.parts-express.com/pe/psho...number=320-334

                              Finally, re-read Neils post, especially the part about his amp being "not easy to build (SMD and a micro to program)." If you've yet to work with surface mount devices, you will find them extremely challenging. Neil does not seem to work at the level of mortal hobbyists...

                              Have fun,
                              Frank

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