Amplifier idea..

[audioguru]

Those "killer" puny speakers won't have much output level, and their frequency response graphs disagree with each other and with the printed spec's. How can a 2" speaker that resonates at 150Hz in free air, have a response to as low as 80Hz in a box?
One response curve shows probably a completely different speaker with a wide, smooth response, but the other response curve is all over the place!

I think that Maplin has things all wrong and backwards. They talk about their amplifier module that has a "peak" power of 18W into a 4 ohm speaker. That's only 9W RMS at only one frequency, and probably with a horrible amount of overdrive distortion. It might be 6W RMS or less into a 4 ohm speaker, from 20Hz to 20KHz, at reasonably low distortion.

Maplin also talks about powering the amplifier with a lower supply voltage and a higher load resistance to produce even more output power. Wouldn't that be nice. If you used no supply voltage and a very high load resistance its output power would be infinite!

 

[Dr.EM]

Yeah, I noticed that :lol:

Dunno why its like that. The thing i'm after is more or less a much better version of this sort of thing:

http://i.i.com.com/cnwk.1d/sc/20649051-2-200-0.gif

Obviously, it'd be bigger, and much heavier, but it'd sound a lot better I reckon too. Already got a seperates Hi-Fi for proper listening, this is to go in my bag, though it looks like it may cost £100 :shock: , and if you right about those amps, then it would'nt be worth it at all.

 

[David Bridgen]

Re. watts "r.m.s." again.

https://www.davidbridgen.com/watts.htm

 

[Nigel Goodwin]

Re. watts "r.m.s." again.

https://www.davidbridgen.com/watts.htm

And it's still irrelevent again!.

 

[David Bridgen]

Why?

 

[Nigel Goodwin]

Why?

Because it's commonly understood as the only accurate way of giving amplifier power ratings, it's easily checked, with very simple test equipment - and it's EASY to understand.

I read your article a while back, and it's basically a discussion of semantics, not a discussion of the actual technique - just that you disagree with the terminology!. You may very well be correct?, but the term has been used for well over half a century and is perfectly acceptable to almost all the world.

I see no point in keep posting the address of your article, learned or not?, when it's only going to confuse the issue?.

 

[David Bridgen]

Ok, Nigel, I just wondered why you objected.
I shall bear your comments in mind.

 

[joecool85]

Hi. This is a schematic for a bridge amplifier of power 16w, from the web.

It doesn't actually say what the ICs are, but I couldnt help thinking they looked like 386s.

I know they're not, but could you use 2 386 amps in a bridge like this to output more power than one by itself?

Hate to bring up an old thread, but I was on google searching for some info on bridged lm386s and came across this. The schematic the OP posted is for the lm383, I know it well.

You can easily bridge the lm386, as shown on runoffgroove.com, look at the littlegem mkII.

 

[Dr.EM]

Interesting this should come up. I did actually try my orginal arrangement with pennies as heatsinks. It worked, with a small increase in volume, the pennies got very hot, chips survived though. Not very practical, but I wanted to know what exactly would happen.

 

[audioguru]

Most audio high-power amp ICs are idiot-proof. They shutdown when they get too hot. NOT A GOOD THING TO HAPPEN IN THE MIDDLE OF DOING A GIG.

TI has a tiny little class-D power amp IC. It is rated at 240 Whats.

 

[joecool85]

Most audio high-power amp ICs are idiot-proof. They shutdown when they get too hot. NOT A GOOD THING TO HAPPEN IN THE MIDDLE OF DOING A GIG.

TI has a tiny little class-D power amp IC. It is rated at 240 Whats.

Right...but I don't see a lm383 making it to a gig lol.

 

[audioguru]

I don't see a lm383 making it to a gig lol.

It hasn't been made for 11 years, it's retired like me.

 

[joecool85]

What, the lm383? Only sort of. You can still find them at some places, and besides, you can use TDA2002 chips, they are pretty much identical.