increasing the power of lm3886

[ryan750]

hi, could we use a gainclone to drive pairs of output transistor to drive 2 ohm load??? is there any existing schematic like this?

[rem280]

If you are going to use it to drive an output stage why don't you just use an op amp. That's all this chip is, an op amp with an output stage capable of delivering high power to a load. If you are going to design the output yourself anyway to deliver more power you don't need a power amp to drive it. An op amp will be cheaper aswell but you will be prety much be designing an amplifier not just hooking up two transistors.

[sendler]

Originally Posted by ryan750

hi, could we use a gainclone to drive pairs of output transistor to drive 2 ohm load??? is there any existing schematic like this?

Search BPA300 or buy one of the amps based on the National Semi driver chips.
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CP Design (www.chip-pcb.cn)
.
Connexelectronic

[peranders]

Originally Posted by ryan750

hi, could we use a gainclone to drive pairs of output transistor to drive 2 ohm load??? is there any existing schematic like this?

You could use a PA150 pcb which I have, see the sig below for group buy.
PA150 - 3x LM3886 PCB assembly guide

[star882]

Why not just use a chip designed for that? The TAS5630 can output 600w to 2 ohms in single channel BTL mode. (And it's a hybrid, so it's green!)
Digital Amplifier Solutions - Analog-Input Class-D Speaker Amplifiers - TAS5630 - TI.com

[AndrewT]

or use National chip/s that are designed to do exactly this duty.

LME49810, 49811, 49830

[star882]

Originally Posted by AndrewT

or use National chip/s that are designed to do exactly this duty.

LME49810, 49811, 49830

If you're looking at any significant power output, a hybrid digital like the TI I mentioned or NXP's TDF8599A - I2C-bus controlled dual channel 135W/4 Ohm, single channel 250W/2 Ohm class-D power amplifier with load diagnostics from NXP Semiconductors would make more sense. The higher efficiency means the initial cost would be much less. http://www.tinaja.com/glib/hack86.pdf

[AndrewT]

Star,
the topic is increasing the power of a linear chipamp, the 3886.
If he wants to go digital then he can join you in the digital section.

[star882]

Nowadays, the cost for a hybrid digital is low enough that for any significant amount of power, there's no reason not to use one. As an analogy, it's possible to build a 500HP engine with a carburetor, but why if fuel injection makes it much easier?

If you still want to stick to analog, I would highly recommend water cooling if you're looking at more than 100w. Just calculate the maximum power dissipation and you'll know why.

[AndrewT]

Originally Posted by star882

If you still want to stick to analogue, I would highly recommend water cooling if you're looking at more than 100w. Just calculate the maximum power dissipation and you'll know why.

why.
I have a range of linear amplifiers from 50W to 400W and none of them need water cooling. Only one has fan assisted cooling.

A 100W into 8r0 amplifier with a quiescent current of 30mA from each supply only needs to dissipate 3W, Why does that need water cooling.
A 200W into 4r0 amplifier with a quiescent current of 50mA from each supply rail only needs to dissipate 5W. That's the whole amplifier not just the output devices.
The rectifier and the transformer will dissipate quite a bit extra.

I would expect the average output power from both these examples to be less than 1W to the speaker.