World's Most Awesome Clock Radio

[BAM]

I am setting out on a project to build an ultimate clock radio out of a fairly recent-model Philips stereo clock radio (set up like this one but made by Philips: http://mgmt.sditech.com/FileLib/Thumbnails/T608L.jpg) that my sister does not use anymore. I am going to replace the tinny 2.5" speakers with some nice ones I got from Parts Express, and swap in a Velleman-Kit 15Wx2 amplifier kit to power them. Then I want to add a woofer module using a 5.25" Dayton woofer in a special bandpass enclosure, and I need 30 watts into 8 ohms for that. Can you direct me to a place where I might learn how to build a 30-watt mono amplifier that I can use in my project? Also, if I could power it all off a single extra wallwart it would definitely be nice.

Edit: Is the IC in the Velleman Kit (TDA1521) bridgeable? If so, I could just use that to power my woofer.

[matjans]

hi

I don't know whether it's owrth the money and time you're going to invest in it, but whatever.

i'd suggest you have a look at Nuuk's Decibel Dungeon for info on building a gainclone. This'll get ya started on chip amps and for your woofer you could just use a NS lm3875 or 3886 based chipamp. If you're only going to use it as a woofer amp add a lowpass filter to the input and some (a lot?) of capacitance.

[jean-paul]

I wouldn't bridge the TDA1521. BTW that chips sounds pretty good. Don't use higher supplies than +/- 18 V ( so use a 2 x 12 V transformer ). Ditch the original ( Gemcon ? ) 4700 uF caps that came with the kit and use better ones. Use 1 uF MKT input caps with 5 mm pitch ( Wima MKS 2 series for example ).

[BAM]

I am abandoning the clock radio project because I already have a fuller plate than I expected, but I will keep your suggestions in mind regarding any future TDA1521 plans.

[jean-paul]

You can also use better diodes if you wish. BYW95C are OK and fit on the board. I bypassed the 4700 uF ( I used Marcon types ) caps with 220 nF 5 mm pitch MKT at the underside of the board and I used MKT 22 nF for the Zobel. Nice little amp.

BG N series 4.7 uF 50 V can be used too for input cap but they seem out of context in this amp ...