I've attached pictures of the outside and innards of my "combiner/converter".  I bought the tin of candy for about $0.50 - candy was good, but I bought several just for the tin box!

Pictures of FrankenAmp!

Wood was scavenged from a construction site!  Chassis, switch, fuse, power cord and case hardware from the "donor" amplifier.

Good Day All!

Joe had asked about if I had tried the LM1875, and I found my schematic for one of the first successful amplifiers I built based upon an LM1875 design - I called it FrankenAmp, because I used a relatively cheap practice amp for the chassis and amplifier hardware.  It is Frankenamp 2.0, because I made a new enclosure and completely reworked the innards.

The original of the attached schematic was generated as the unit was built and evolved with a lot of "cut and try" ideas along the way.  I finally got tired of messing with it and the result is as seen below. It works good, and my son uses it regularily.

There are a few changes I will make to the below design before I create another LM1875 based amplifier, but I haven't gotten around to writing them out yet - or building a prototype.  The speakers in Frankenamp 2.0 are a 5 1/2" and a 6x9" purchased at Wal-Mart for around $10.00 each.  The tweeters were from an inexpensive "miniboombox" radio from Dollar General.

Most of the rest of the parts came from my "junk box" at the time.  I used OPA2134 op amps in the design because I had handful of them at the time.  The R19/R20 combination was an adjustment to the R20 value to get a good sound level out.

Enjoy the schematic and pics that follow!

And Finally, the schematic to the "Cube of Sound".

It sounds cool, and looks definately unusual.  You will note the side speakers are out of phase with each other- that is deliberate.  This is a standard "trick" of  mounting speakers on opposite sides of the cabinet.

The Auxilliary input control is a 10 turn potentiometer, this gives finer control of the input to the mixed signal.

More pics of the "Cube of Sound"

Good Day!

Attached are pictures of one of the most unusual builds I've done to date - a little amplifier I call the "Cube of Sound" - speakers on three sides.

It began with a TDA7053 amplifier kit, two excess computer speakers (by Boston Acoustic) and two 3.2 ohm speakers from garage sales.

I wanted to have a second input that I could run from a mic level to a line level in, and thus the Cube of Sound was born.  A drawer pull for the handle, and rubber furniture cups for the feet came from the hardware store.  With such an unusual look, I just HAD to paint the backplate rather than clear coat it!

Ive attached a schematic of a little combiner box I made up for use with interfacing a guitar or other mono input amplifier with a stereo, dvd, headphone or satellite receiver.  It can combine the signals through the RCA jacks to either a mono or stereo 1/4" jack.  The resistors in line assist with the mix, as well as keep a certain level of separtion between the channels. The can be anything from about 32 ohms to about 100 ohms.  To interface with a 1/8" headphone, I picked up a 1/8" stereo to twin RCA plug cable from radio shack.

Simple reason for the BIG caps - I got them FREE, and had the space in the case. 

Yes, I did make the enclosure.  The wood for the case came from some scrap wood from a local construction site.  The grill cloth was from the same old console record player the 8 inch speaker came from, and the corners and handle were bought online.
I used the 1875 in my firsts amp rebuild (my son uses it now), didn't keep the schematic.  Information I had showed it needed a bipolar power supply, and most of the power supply resources I find lend themselves to single ended power supplies. I would use the 1875 again if I wanted to build a "beefier" amplifier.

Good Advice from Teemuk above -- first try and see if you and your friend can T/S and repair the amp, THEN, if it can't be fixed, look into building a "new" amp in the old case!
If you decide to build new - I suggest a 3886 chip as the "heart" of the design.
Good Luck!

A pic of the "Mini". The grill and speaker from an old computer speaker and the DC power jack is located in the back of the unit.  Feet are nylon 'chair feet' from wally world.

The "innards" of the Bug Eyed Monster.  Yep, 5x7 Roadmaster speakers from Waly World (20.00 for the pair), scavenged transformer and computer grade filter capacitors.  In the second pic a closeup of the "buisiness end" of the boards - note the HOT GLUE board mounting.  (Glue Guns - not just for crafties anymore).  The heat sinks on the TDA2003 chips are anodized aluminum.

Front and back pics of the Bug Eyed Monster!

Attached are pics of the "Classy Lassy".  Behind the front grill cloth are the 8" and tweeter speakers, the round side grillcloth hides the 6" speaker.  I added the duplex outlets to the back - run fewer power strips that way!

Picture of the outside and the "innards" of the reverb box.