Found this stereo audio amplifier on mouser (6W/channel):
The datasheet doesn't mention if it's ok to take a mono signal, feed it into the left and right inputs, and wire the outputs in parallel to run a 12W speaker.
Will this blow it up? Or is it perfectly acceptable/standard practice?
Thanks,
Michael
only had a quick look at the datasheet Generally bad practice to parallel the outputs. A more normal way would be to send the monosignal to one input and an inverted signal, by an opamp usually to the other amp input, and hang the speaker between the amp outputs, and then you may not even need a o/p coupling cap, if the DC offset is minimal.
This is called BTL, bacon tomato lettuce mode
martin
I agree with Martin. You're asking for trouble if you parallel the outputs because you cannot guarantee that the voltage of the two outputs will always
*want* to be exactly the same, and if there is any difference it will cause a huge current to flow between the two sections.If you do a true bridge (BTL - hold the mayo) then you have to watch the power dissipated by the chip. When you do bridged mode then the impedance that each amp sees is 1/2 of the true load. So, if you use 4 ohm speaker then each amp section will see a 2 ohm load. This means that the output transistors will have more volts across them when you hit the maximum current (limit) and will thus need to dissipate more power and the chip will get hotter than if used in single-ended mode. However, if your speaker is 8 ohms then there won't be any worries (the amp is rated into to 4 ohms but not 2 ohms), and as food aficionado Martin points out, you can eliminate those huge/ugly output capacitors.
Bob
Snip non gourmet stuff
Just wondering if it's worth doing a DC servo on such a cheap chip, get rid of the caps permanentally (sp?)
martin
A servo for single-ended mode? How can that work? If the amplifier is on a
12V supply then each output will sit at 6V, and the other end of the speakers will be at 0V. Unless you're talking about creating a 6V supply, there's no way to get around using a capacitor in stereo mode.Bob
mono, hamburger mode only, nah, a diff amp across the o/p, 20dB atten.ish,for fun, Big RC lpf to the inverting input of the second input
martin
Ahhhh, yes. I know of these cheesy dc offset removers called "servos".
My grandfather used to tell me, "Give me a dc servo and a quarter and I'll be able to get a cup of coffee."
He also used to say (just before sitting down with a pint of Bacardi 151), "There's nothing like something to drink when you're thirsty."
Burgers...BLTs...glasses of whiskey...it all comes out in the end.
Bob
Yeah, spent hours LTspicing them. My versions always have subaudio LF resonance that really ring in the 10's of millihurtz.
Barry Porter/Cadac( RIP) gave me a micamp design that was so excellent but with weird DC feeback but was so unstable as you swept the gain from 0 to 70dB, in the millihertz zone, chopped it all out, worked fine..... Must dig itout some day and have another go
martin
I'll bet that the servo can be embedded into the inverter with careful design.
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