gainclone as a car amp?

[Zemo]

Hey all. I want to build a gainclone as a simple car stereo amplifier, and mount it in the dash. It will have auxilliary inputs and the like, but I just need to know how to wire it up... I get +14.5V and 0V rails to work with. To put enough power to the chip what do I need? Would just getting a DC-DC converter work? (I recently discovered DC-DC converters). I'm using BrianGT's boards.

My guess is that I'd take a 15V input +/- 12V output DC-DC converter and wire up the +12V to V+, -12V to V-, and wire the com pin to PG+, PG-, OG, and CHG....or actually any one of those, since the board ties all of those together...

Then just wire the in's and out's as normal?

Any help is much appruciated!

[li_gangyi]

hmmm...+ / - 12V would get really iffy...not sure it'll even work at this voltage though...try something higher...

[matjans]

or try a opa541 / opa549. from the datasheet:

WIDE POWER-SUPPLY RANGE:
Single Supply: +8V to +60V
Dual Supply: ±4V to ±30V

[rwaudio]

or you could steal the power supply section out of another amp... like this:

[Zemo]

Cool, thanks.

Just so I know... a DC-DC converter won't work? They are small IC's that convert one DC voltage input into another DC voltage output.

Here's the datasheet for one that I thought might work:

http://www.cdpowerelectronics.com/pr...c_hpr4xx_g.pdf

Is there some reason this won't work? To be honest, I don't really know very much about them....

-Z

[digi01]

tda1521 is a good choice.
Supply with +/-12V,in bridge mode can get 2x30W power.

[Brian Donaldson]

You'll need a little more than 30 ma to run an amp

[Zemo]

I'd rather not run bridged...how much voltage should I try to get to get a reasonable amount of watts without going bridged?
...and how many mA would be a good amount?

-Z

[mikelm]

Originally posted by Zemo
I'd rather not run bridged...how much voltage should I try to get to get a reasonable amount of watts without going bridged?
...and how many mA would be a good amount?

-Z

I did get a very nice sounding result from just 12.7 volts using 2 x tda2050 per channel with a phase splitter at the i/p to give balance working. with efficient speakers this might be a good bet.

but when experimenting later wth lm 3875 also in balanced mode the best rail voltges came out at about + / - 24V

as I increased the voltage the sound became bigger and more dynamic.

I would think you will need a power supply that can give a minimum of 3amps continuous and perhaps 5A peak.

if you use DC to DC converters I would imagine that you will need at least one C L C filter to remove HF noise.

good luck

mike

[jackinnj]

don't forget that you can use the LM3875 or LM3886 in single-supply mode -- but you will need 2X the voltage, so you will wind up using a "boost" converter anyway.

i have (not in use now) an LM3875 with a switching power supply mounted in a PC-type power supply enclosure. i retained the fan and this adds greatly to the heat-sink's ability to wick away energy. the device was in the trunk of one of my MB's so there was no fan noise. (the rear sway-bar of the MB is shot, so it only goes short distances now!)