Small SS poweramp

[earthtonesaudio]

I recently used an LM380 for a project and can attest to its loudness.  Louder than an LM386 anyway.  Two in bridged mode would get you to almost 4W.

[mistahead]

I recently used an LM380 for a project and can attest to its loudness.  Louder than an LM386 anyway.  Two in bridged mode would get you to almost 4W.

Louder than WHICH LM386 - there are at least variations of that chip with various power in/out ratings. Apples to a variety of pomme fruits yet determined is hard to compare.

The Noisy Cricket II was based on 1xLM386n-1 for instance, but you can put an LM386n-2 in it and will work with decent increase in output with a tweak or two... not suggesting this is your solution amp (could be though its not horrible).

[earthtonesaudio]

LM380 is 2W.
LM386 in any version is less power than that, typically 0.5W.

The other main difference between the chips is the input impedance of the LM380 is 150k compared to 50k in the LM386. 

[mistahead]

2W - not shabby, better impedance is a plus too.

Correct me here if I'm wrong however - but go actually have a glance over the LM386N datasheet and see the roughly 300% difference between key values on the *-1 and the *-4, am I missing something mate?

LM3886 kit-amp is on my shopping list for another application where I actually need to have an amp built by a date - also a choice for SS guitar amps and (a bit) bigger again.

[tca]

Go old school and learn some interesting fundamentals...
(...)
So why not build a discreet AB transistor amp?

That is easier said than done! Can you point one?

[mistahead]

No... The smartare in me is two steps ahead all the time...

I do however want to play with some discreet solid component amps alongside my current attempts at learning, which is reasonably on topic...

[PRR]

> have a glance over the LM386N datasheet and see the roughly 300% difference between key values on the *-1 and the *-4, am I missing something mate?

-1 -3 are rated 12V operating (15V max)
-4 is rated 18V operating (22V max)

But for whatever reason, the Characteristics are specified as 6V and 9V for the 12V parts. Power claimed is of course way down at 6V. This same -1 part could be jazzed to 12V and *may* give 4X the 0.325W quoted.

The -4 part is rated at 16V (a hair below its limit) and for a bizarre 32 ohm load. Fact is that none of these '386 chips are real efficient at low impedances. If you do happen to have a 32 ohm load, the -4 at higher voltage will do a whole Watt.

(FWIW: headphones tend to be 32 ohms, but if you put A Whole Watt into headphones, you end up like me: pretty darn deaf.)

The '380 has much fatter output devices, and a bigger package, and is much more suitable to lower impedances and higher powers. Also get a higher input impedance, not so much need for an input buffer between axe and amp. If you want something stronger than an answering machine or a modem (remember them?), go '380.

For higher power on low supply voltages, such as 12V car-audio, the Bridge Mode is like having double supply voltage. It also eliminates a big speaker capacitor. It does need an additional amplifier, but amps are now cheaper than big caps; also you buy a dual-amp chip for not much more than a single-amp chip.


> want to play with some discreet solid component amps

POWER amplifiers are "too much fun". By their nature, if you screw-up the least bit, they blow-up. Often with unclear symptoms. That's why small power amps were among the *first* linear ICs offered: economy of scale allows intensive design, low cost per transistor allows many extra transistors for protection, and the pre-made pre-tested product means far fewer slip-ups on the assembly line (or workbench). Play if you must! But after my first few years of power amp design and maintenance, I became willing to "cheat" every chance I got.

[tca]

POWER amplifiers are "too much fun".

+1

[mistahead]

Cheating is what I do now, and will again, but I've learned that sooner or later you need to know what you're cheating!

Thanks for the clarification on how I was interpreting that datasheet too PRR.

[chromesphere]

Hey, this thread got me all enthuasatic to build up something with those tda7052a's so i had another crack at the punch amp.  I'm not sure if i was drunk prehaps when i built it last time (or an error on my layout?  I think we know which ones more likely), but this time around, yeah, its got some decent output!  I also only tested it with 9v.  I'm planning to use a dedicated 12v adapter for it.  I noticed with my last (possible incorrect) test of the punch, 12v's gave a significant volume increase.  So it could be even louder with the 12v adapater!  Looking forward to testing it out tonight.

So yeah anyway, the punch is really easy to put together, definitely want to consider it out!

Paul

[zedsnotdead]

think Ive made my mind: punch it is

I'll keep you posted.

And again thank you all!

[chromesphere]

I think it took me about...15 mins to assemble on vero lol 
Good luck with it zed!
Paul