Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => The Newcomer's Forum => Topic started by: Maddus on February 15, 2024, 03:10:24 AM

Title: LA4282 in BTL bridge mode?
Post by: Maddus on February 15, 2024, 03:10:24 AM
I was given a LA4282 from my fathers workshop (he repaired lots of TVs in the 90s).
To use this for my guitar projects, I would like to know if I can bridge this like a LA4440 for example, and what external circuitry is needed.
The LA4282 already has input and feedback resistors for a gain of 101 integrated.


Datasheets:

LA4282:
https://www.mouser.de/datasheet/2/308/1/LA4282_D-2314539.pdf

LA4440:
https://www.electroschematics.com/wp-content/uploads/2012/07/la4440-datasheet.pdf
Title: Re: LA4282 in BTL bridge mode?
Post by: phatt on February 18, 2024, 07:38:40 PM
I guess one could mix concrete with a food blender but there are better ways.
Bridging small chip amps is counter productive,
If you want more power ,,Get a bigger Chip that is designed for higher power,
LM3886 are cheap.
Phil.
Title: Re: LA4282 in BTL bridge mode?
Post by: joecool85 on February 19, 2024, 02:53:34 PM
Quote from: Maddus on February 15, 2024, 03:10:24 AMI was given a LA4282 from my fathers workshop (he repaired lots of TVs in the 90s).
To use this for my guitar projects, I would like to know if I can bridge this like a LA4440 for example, and what external circuitry is needed.
The LA4282 already has input and feedback resistors for a gain of 101 integrated.


Datasheets:

LA4282:
https://www.mouser.de/datasheet/2/308/1/LA4282_D-2314539.pdf

LA4440:
https://www.electroschematics.com/wp-content/uploads/2012/07/la4440-datasheet.pdf

You can actually get a LOT of volume out of 10 watts.  I would consider using the chip as-is and hook it up to a quality 12" guitar speaker.
Title: Re: LA4282 in BTL bridge mode?
Post by: Loudthud on February 20, 2024, 01:18:40 AM
The LA4282 has a max load of 8 Ohms per channel so you'd have to use a 16 Ohm load in bridge mode. If you want something louder than 10W, use both channels each driving it's own speaker.
Title: Re: LA4282 in BTL bridge mode?
Post by: Maddus on February 26, 2024, 03:24:54 AM
Is it bad for the chip when only one channel is mostly used? So my idea would be to hook up one channel to an internal speaker and the other to an extension speaker jack.
Title: Re: LA4282 in BTL bridge mode?
Post by: Loudthud on February 26, 2024, 03:42:52 AM
Quote from: Maddus on February 26, 2024, 03:24:54 AMIs it bad for the chip when only one channel is mostly used? So my idea would be to hook up one channel to an internal speaker and the other to an extension speaker jack.
That's not a bad idea, it shouldn't harm the chip. The heatsink should be adequate for two channel operation.
Title: Re: LA4282 in BTL bridge mode?
Post by: joecool85 on February 27, 2024, 02:46:44 PM
Quote from: Maddus on February 26, 2024, 03:24:54 AMIs it bad for the chip when only one channel is mostly used? So my idea would be to hook up one channel to an internal speaker and the other to an extension speaker jack.

I think that is a fantastic idea.