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Old 2nd November 2012, 01:12 PM   #1
larzman is offline larzman  United States
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Default Portable T-amp boombox - components

I've been following the Boominator thread and love all the knowledge their. However, the Boominator is simply too large for my needs and I'm doing something very different on the power side.

Anyway, I'm looking at building a portable unit with the following components:
  1. Indeed Class T Amp Tripath TA2021 25WX2 Amplifier (through eBay)
  2. Infinity Reference 6912m 6 x 9-Inch 105-Watt High-Performance 2-Way Marine Loudspeaker
  3. 1 or 2 LiPo 12VDC 6,500mAH batteries
  4. iTouch or Sansa Clip+ music source
  5. pair of 5W 12V mono-crystalline solar panels
  6. Custom MPPT solar charge controller
  7. Various power jacks, i.e. USB Type A, USB micro (both female), 12VDC socket

In order of priority, the design parameters are:
1. portability. need to be able to easily fit it in my trunk with other camping/hiking gear
2. durability. Able to withstand morning dew and light rain, this is intended primarily for outdoor use
3. sound quality/audio fidelity. not extreme loudness, this is intended to be used with camping groups up to ~20 people (early 30's to 50's age group)
4. runtime

If anyone has suggestions about component selection or mods for better sound, I'd love to hear them. The solar/power cannot be changed, as the design/parts are already in hand and it's very stable and quite potent. I chose marine speakers for longevity in the outdoors, they are 4 Ohm speakers with 96bB sensitivity. I would like a more powerful amp, but the Indeed T-amp should be ok and it's very efficient. Max power supply voltage for any amp is 24VDC (if I use a pair of 12V battery packs).

Almost forgot. The speaker box dimensions will be relatively small. 11.5" square, tapered, 5.5" at bottom, 3.125" at top, made of 22 gauge steel or 18 gauge aluminum. These boxes will be detachable from the center section that houses the batteries, amplifier, solar controller and music source. Box dimensions will be hard to change, as I'm using a commercially available backbox with custom baffle.

Last edited by larzman; 2nd November 2012 at 01:21 PM.
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Old 2nd November 2012, 01:28 PM   #2
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Quote:
Originally Posted by larzman View Post
I chose marine speakers for longevity in the outdoors, they are 4 Ohm speakers with 96bB sensitivity.
No, they are not. It's 96dB sensitivity, true, but that's at 2W, so 93dB/w/m. Like other marine/car speakers these also have the dB-shelf, where output is raised around 3dB above 1KHz. That's on top of the baffle step, so they will sound really thin and lacking bass. In reality, they compare with a standard run-of-the-mill 8" replacement speaker at around 89-90dB/w/m.

Pro drivers are the only way to go. Never use car/marine speakers outside of a car/boat. (Note: exceptions exists but they are few).
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Old 2nd November 2012, 01:37 PM   #3
larzman is offline larzman  United States
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Saturnus, thanks for the comments. From what I've seen on pro drivers, they are not going to last very long if they get wet, thus my choice of marine. Do you know of any high efficiency pieces that can withstand limited moisture?
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Old 2nd November 2012, 01:46 PM   #4
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Almost all pro drivers are made of weather-resistant treated paper that easily stands up for all the misuse you can throw at them. That's what they're designed for. Remember any pro driver has to able to be used in outdoors PA systems that works in any kind of weather.

Try to keep rain/water from hitting the speaker cone directly (with a speaker grill and speaker cloth combo) and you're fine.
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Old 2nd November 2012, 04:30 PM   #5
larzman is offline larzman  United States
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Saturnus, again, thanks for the info. Do you have any specific models in mind? I've been looking around the web and nothing really stands out, and most seem to either be <90dB or very expensive (>$100 each).
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Old 30th January 2013, 06:35 PM   #6
larzman is offline larzman  United States
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In case anyone has any further insights, I'm looking for an outdoor, high sensitivity speaker that I can put into the smallest box (or it come in a weather resistant enclosure) and drive with a small amp of around 20W. Not looking for a super loud party boombox, just something sufficiently loud enough for a patio & small yard. I'll be powering it with a pair of 12V, 6.5 AH (each) batteries and small amp board. All I need to start the final part of this project is a pair of good sounding, inexpensive (<$100) speakers. Doesn't anyone here in DIYaudio ever get into portable audio? ... and yes, I've read 95% of the Boominator thread, but that's a huge box, not really portable imho.

Any help would be greatly appreciated, as I need to finish this before springtime when work takes over life for about 3 months.
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Old 31st January 2013, 11:55 AM   #7
spwalek is offline spwalek  United States
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Have you looked at car audio speakers? I've had good luck using these for my portable SLA powered stuff. As far as under $100 Parts Express has a bunch of car and marine speakers to look at.
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Old 31st January 2013, 12:43 PM   #8
larzman is offline larzman  United States
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Spwalek - thanks for the intentions, and I too was seriously looking at those components until Saturnus left his first comment in this thread. Sounds like a pro driver is the way to go, but I don't know which one, specifically.

I want to use a 6.5" speaker, possibly coaxial, or with a separate tweeter if necessary. However, I don't know what specific brand/model will give me the best results. The reason I'm looking at a 6.5" is the backbox can be smaller and the (minimal) extra bass from an 8" is hard to justify with the increased backbox size requirement. I'll be powering it with a 2x25W Sure amp board using a pair of Li-Ion batteries, so the run time will be pretty good. I am simply looking for guidance on speaker selection.

I found these, but sound quality is unknown so I'm hesitant to buy them. New Indoor Outdoor Yard Patio 6 5" Speakers Pair TS6ODW 813282016030 | eBay

If anyone has any experience with them (particularly sound quality and power level), I'd love to hear about it.

Last edited by larzman; 31st January 2013 at 12:45 PM.
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Old 13th February 2013, 09:00 PM   #9
blossom is offline blossom  New Zealand
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Boominator MINI (development thread) - Speakerplans.com Forums - Page 1
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Old 15th February 2013, 07:42 PM   #10
larzman is offline larzman  United States
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Thanks for the link blossom. I've read a lot of the Boominator thread and found some very useful info, but the unit itself is much too big for what I want. It looks like the MINI is more in line with what I want.
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