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Mini amp and stereo

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Project by McLeanVA posted 05-04-2015 04:28 PM 1859 views 13 times favorited 13 comments Add to Favorites Watch

This is a little amp/stereo box I build from an inexpensive 2×25 W amplifier board. Ran RCA through the back panel, and mounted an external power jack and toggle switch. The amp powers four small full-range speakers. The smaller two center speakers have high-pass filters on them to limit their frequency to the higher range. Also, impossible to see from these photos, I drilled in a VERY tiny hole in the front which has a white LED bulb fixed behind it so show when the unit is powered on. Also looks really cool at night.

The inner body was constructed using 1/4” MDF. Then I added a wrap of poplar, which I dyed using Black Gel stain. Then I mounted the striking piece of curly/figured maple on the front using compression fittings so that I can take the speakers out in the future if needed.

It really sounds great for a small room/desk speaker set. I plug the RCA cable into my iPhone and listen to my mix of tunes. With a little more effort, this can be configured with a wireless Bluetooth receiver and battery pack to make it truly portable. I bought all the parts to do this, but decided to stay as simple as possible on my first prototype.

I am looking forward to my next speaker build. Thanks for looking and I hope it inspires.

-- Measure, cut, curse, repeat.





13 comments so far

View Dallas's profile

Dallas

3599 posts in 1954 days


#1 posted 05-04-2015 04:34 PM

Awesome in the extreme!

-- Improvise.... Adapt...... Overcome!

View ChrisK's profile

ChrisK

1809 posts in 2549 days


#2 posted 05-04-2015 04:53 PM

Very nice.

-- Chris K

View drbyte's profile

drbyte

729 posts in 3529 days


#3 posted 05-04-2015 05:27 PM

Very nice! What amp did you use? Sources? Thanks!

-- Dennis, WV

View McLeanVA's profile

McLeanVA

488 posts in 2901 days


#4 posted 05-04-2015 05:58 PM

@Dennis – I bought most of my parts from Parts Express. The specific amp I used is here http://www.parts-express.com/2x25w-at-4-ohm-tda7492-class-d-audio-amplifier-board-only--320-332

-- Measure, cut, curse, repeat.

View bobasaurus's profile

bobasaurus

2675 posts in 2651 days


#5 posted 05-04-2015 06:31 PM

That’s a very nice speaker/amp. I love the curly maple front. What did you use for cutting and chamfering the holes for the speakers?

-- Allen, Colorado

View McLeanVA's profile

McLeanVA

488 posts in 2901 days


#6 posted 05-04-2015 08:00 PM

@Allen – I used a compass and careful measurement to get the holes centered and traced onto the board. I then drilled through the center with a forstner bit. I then used a handheld jigsaw to cut just shy of my original line and then dropped the boards down onto my oscillating spindle sander. Once those holes were nice and round, I ran them over my router table with a chamfer bit using a guide bearing. I hope that all makes sense. Probably the easiest part of the entire project to screw up. If the circles aren’t round, or are off a bit it’s most likely the quickest flaw to be noted.

-- Measure, cut, curse, repeat.

View McLeanVA's profile

McLeanVA

488 posts in 2901 days


#7 posted 05-04-2015 08:05 PM

Note – I uploaded two more photos to show what the box looks like without the maple face as well as the maple face after the first coat of wipe on poly. If you look close on the 3rd photo, you can see them small compression fittings (small male/female plugs) I added to be able to access the speakers.

You can also see the LED bulb which shines through the pinhole I made on the maple front.

I have more photos and will have to retrieve them and post them of the internal guts and MDF box.

-- Measure, cut, curse, repeat.

View bobasaurus's profile

bobasaurus

2675 posts in 2651 days


#8 posted 05-04-2015 11:59 PM

Thanks for the information. Any tear-out with that curly maple on the router table?

-- Allen, Colorado

View Roger's profile

Roger

19886 posts in 2271 days


#9 posted 05-05-2015 12:12 PM

Rock on! Thnx for the link also

-- Roger from KY. Work/Play/Travel Safe. Keep your dust collector fed. Kentuk55@yahoo.com

View McLeanVA's profile

McLeanVA

488 posts in 2901 days


#10 posted 05-05-2015 12:46 PM

@Allen – Thankfully no tear out on the maple, but boy did I sweat it. I started the router bit really low in the router table and took light passes. Had to keep the wood moving fairly quickly so that it didn’t burn. Eventually scooted the bit up to the height I thought worked best. Just patience and little worry will keep you form scrapping expensive wood.

-- Measure, cut, curse, repeat.

View onehandclappin's profile

onehandclappin

6 posts in 1479 days


#11 posted 07-13-2015 12:41 AM

Great choice on the curly maple! Adds a visual element to sound waves and a nice contrast to the darker outer shell.

-- there are 10 types of people in this world, those that know binary, and those that don't.

View CiscoKid's profile

CiscoKid

335 posts in 2341 days


#12 posted 11-16-2015 09:03 PM

Holy smoke! I really need to spend more time on this forum. I really do. Hope you don’t mind me copying that.

-- Al, Culpeper VA

View McLeanVA's profile

McLeanVA

488 posts in 2901 days


#13 posted 11-16-2015 09:07 PM

@Al – Please do copy. It was a really cool project to make and my wife and I use it quite a bit. I’ve since made a more utility-grade version with a sub-woofer in it. Sounds pretty good, but not as pretty to look at.

The amps are cheap, and you can always find discounts on speakers or repurpose old speakers.

-- Measure, cut, curse, repeat.

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