Could use input on a 2.1 boombox

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freddi

freddi

Member
Joined 2005
#1
I'd like a big clunky low distortion/ reasonably high spl capable 2.1 boombox centered around my GRS 12PT. A 30 liter 3rd order closed box would do the "point one". I'm looking (if sufficient money comes) at the 16 ohm Eminence Alphalite 6B to reach to 200Hz (again probably cap assisted) plus a tweeter. I know it will be stupid large - perhaps "stupid" period but am having health issues and want to be entertained, It would be run by a $40 Kinter 3118 2.1 amp and a phone. The Kinter has good SQ but its tone controls offer no boost.

A more practical solution due to such close channel spacing with 2.1 in one cabinet would build a MONO boombox.

Here's "1 watt" 2pi for 30 liter with 325uF

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Alphalite 6B is a 16 ohm driver - helpful to get closer to the woofer's sensitivty. Kinter's "sub" channel says 180Hz lowpass (might be 6dB/oct ?) plus 6B weighs only 1kg. Here's 1.5 liter with a cap.

So with these drivers I'm up to needing 33 liters air-space.

Some sort of tweeter is needed







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#3
TDA 2030 based 2.1 plate amp with bass / treble / balance controls, about $4 here, plus transformer 12-2-12, 2A, plus FM module with Bluetooth function...all told about $12, 15 tops (copper prices are up).

You do have to wire up extra pots, and put it in a box.

YMMV, depends on your skill.

The chips are usually Chinese, good enough for most work, buy the amp with the biggest heat sink, and put fresh heat sink compound when assembling.
Class D, like 3118, is not familiar to me.
 
#4
That looks like fun, Freddi! 30 L, you'll need a dolly to carry it around. Throw down a cardboard box on the street corner and start breakin!

I made a small portable with a Dayton KABD amp, it has DSP. It's cool, but that's another thing to wrap your head around if you aren't familiar with it. My build is here.

Good luck with the concept!

- A
 
#5
You can make a big 'sound bar' type thing , with the sub at middle, and main speakers near the end, tweeters at extreme ends.

Portable? Go for a 12V or 24V battery powered plate amp, the FM modules run at 5 or sometimes 3.3V, or you can put a plain Bluetooth reciever, use that to feed music from your phone, my friends do it in their cars all the time.
I am slightly different, use USB stick as music store in my car.

See proper volts to module. The 2030 plate amps usually have a 7805 for FM module supply, convenient.
 
#7
Thanks for the reminder and links- 'll have to put a shunt R across the amp - what value would you suggest ? It'll have a piezo but with 20ohm shunt R. I'd assume the Kinter would be something like Dayton's DTA-100A as to reaction to different loads. At very near 75 years of age - I won' t hear the top end effects.

I could have a small resistance between the piezo's highpass and the KSN1016 (which IIRC acts like a 0.16uFcap in the Motorola device) - normally I use 56-62R in that spot.
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#11
will do - might be some time - my friend will make the cabinet - the basic box using 1/2"ply will be about 29" x 17" x 9.25" external (not including a handle.)

How much power would you say a 3118 amp running from a 20V battery would deliver into the nominal 16 ohm load of the Alphalite 6B?
 

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#13
- could wire it as a mono boombox - pad the paralleled mids - would need to find a mono 3116 amp in a case - ii would be nice to find one with Baxandall type tone controls --Amazon shows a barebones 3116 in a case sans power supply for $30
 
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