Clean LM386 amplifier schematic suggestions please.

[Renegadrian]

THX Mr. RG for your precious reply as always!
As you can see from the layout I used, pins 1 and 8 are tied together with nothing in between swe gain should be 20. I just plug the guitar in, straight. I tried both a fresh 9V battery and a 12V unregulated WW (so it gets +-13V)

[R.G.]

ACK! NO! OPEN pins 1 and 8 to get the gain down. No connection at all.

[Renegadrian]

Uh, I just used that layout which states CLEAN amp...There is no line break at pins 1 and 8...I'll do it in a second!

edit
ok now it works like it's supposed...L O U D!!!
Just a tad of distortion (with N1) when the 47k pot is maxed. but it's ok!!!

Swapped it with a 386 L - less loudness but it's CLEAN as it can be. and it takes so well my Zoom!

[Slade]

Nice, Adriano! I think I could be trying it soon.
That's very good info, R.G., Thank you!

[Top Top]

I have messed with the 386 a lot. Honestly, if you are going through the trouble of building a tube pre-amp, use a different chip that will get you more clean headroom. You can not give the 386 much before it distorts.

I built a TDA2005 guitar amp (dual 10W) from the datasheet that gives much more clean headroom. I designed my own solid state preamp for it to give it good tone shaping for guitar. It isn't that much more difficult to build a more substantial chip amp, again especially if you are going through the trouble of building a tube preamp.

Maybe take a look at Taylor's forum amp thread. There's lots of car audio 12V amp chips that can be built very simply.

[Renegadrian]

car audio ckts should be the solution...Let the valve preamp section be the only "to blame" for the sound and just add the cleanest power amp after that...

[PRR]

> different versions of this chip

The '386 has a special problem: you use it when you just do not care.

The last place I noticed a '386 in a non-DIY project, it was the squawker in a dialup modem. That's not "quality audio".

And from comments and measurements I have seen, some '386 makers have got real sloppy. Letting the process tolerances run wide and wild, so power stage bias current vanishes and low-level (in this case, anything below max) linearity vanishes.

NJM/JRC has a rich tradition in good cheap audio. They are probably holding the tolerances better than the shops making RS232 and relay drivers in the same vats with their '386s.

Before this quality-slide: the '386 is very respectable for how simple it is. When well made, its faults are fairly inoffensive (both in audio output and in throwing stray garbage back into the radio it might be built into). But it is at heart a cheap chip.

And not real powerful. And raising the voltage only goes so far. It only handles so much current and heat. It's really optimum for 9V and 8 or 16 ohms.

If you want an accurate expression of whatever tube color you find, there are better chips.

> what about lm384?

Can you actually buy one today? Whoah! You can!

LM384, like '386, is a variant LM380 (grandfather to them all). It's still a cheap chip, not a precision audio amp. Just bigger than 386. It won't go near 5W out unless you solder a couple square inches of copper directly on the center pins (see datasheet).

TDA2002/TDA2003/TDA2006 family is the classic better small mono power amp. CanaKits has TDA2003 amp-kits at unbeatable price. (One blurb says TBA810.... that's wrong.)
http://www.canakit.com/5w-audio-amplifier-kit-ck153-uk153.html
http://www.canakit.com/10w-audio-amplifier-kit-ck003-uk003.html

LM1875 is a fine audio amp but needs near 18V to wake-up good. LM675 is nearly the same thing, but organized to run good from 12V. Either will do 20 Watts with 35V total supply, but closer to 1 Watt at 12V supply.

[PRR]

> What distortions is has under these conditions are the small distortions of any Class AB amp - crossover and very low THD. The datasheet says it will be under 0.2%.

I suspect the current crop may not meet datasheet. Although that would be easy, I hear too much badmouth about recent '386 builds to believe it's all just bad builds.

BUT: you MUST use the 10 ohms and 0.1uFd across the output!! (Check these values.) I see these omitted on a LOT of plans. '386 is barely stable without them, at idle, but when pushed it just goes nuts.

> nah it distorts badly

Of course ANY part-Watt amp is sure to distort if pushed. As R.G. says, a '386 is very easy to slam. And a slammed '386 hardly annoys the neighbors. In musical terms, it is like raking leaves with a table-fork. Some big acoustic guitars may play louder than a '386 on a small speaker. (Will be louder through your eight-10" full stack.)

[Thugpoet]

is this amplifier use for headphone?

[deadastronaut]

Made a small 386 ckt - N1 - it distorts yeah...gotta try a N4...
I used THIS LAYOUT HERE


edit
nah it distorts badly even with a N4 - no clean amp here...

hi adriano, just a note : i made this in a box for a friend to boost his acoustic that had a pickup installed ...it works fine for him..
he was getting low levels going into his laptop/soundcard, its fine for that..and very clean i found. with a n4 too..hmmm.....

[Gurner]

he was getting low levels going into his laptop/soundcard, its fine for that..and very clean i found. with a n4 too..hmmm.....

That'll be the Zobel network ;-)

Seriously though - I'd much rather put the LM386 face up on a rotund female colleague's chair & use a TDA7052 in a circuit instead.....4x the power 'like for like' vs an LM386, no chunky output cap needed. If you really must use an LM386, be sure to wear massive flairs & sing "Everybody was Kung Fu fighting" as you solder up your circuit.....else you'll not get the right vibe coming out of it when you come to fire it up

[deadastronaut]

hi gurner..not that bloody zobel again,....
yeah ive got my flares on too lol...

i remember you saying about another chip which was clean, i cant remember the number though...4025 or something?..
but it looked good from what i remember...


@adriano..yeah the 1 - 8 pins unconnected...whoops..

[Gus]

Why not simple amps like this?

http://www.redcircuits.com/Page80.htm

Look in older transistor books 60's, 70's for more amp circuits

[slacker]

I've built that Red circuits amp and it's very nice. Needs a big heatsink on the output transistors but it's a simple build.

[Renegadrian]

@adriano..yeah the 1 - 8 pins unconnected...whoops..

Yes Robert, it's something that some like PRR didn't get - I wasn't talking about a verified ckt, I just built yours with 1 and 8 connected and it was terrible - it distorted badly because the ckt was wrong - but as suggested by the mighty RG they need to be apart - just a twist to break the line and it works flawlessly, as it should be according to the data sheet...

[deadastronaut]

yep thats how i built mine with the cut, just forgot the cut under 1-8 on the layout...i will amend it on my layouts page.....

[Earthscum]

Check out the TDA2822... [url+http://www.taydaelectronics.com/servlet/the-773/Amplifiers--dsh--Audio-DUAL/Detail]Tayda carries them[/url]

I found one of these in a cheap computer speaker setup that I tore apart for another project. They are stereo, like 1W per channel at 9V, and operate off of supplies similar to the 386. I've been digging on them. You can run a mono speaker, and with the right switching, you can plug in headphones and take advantage of stereo effects if you really wanted to go that far, or just have 2 separate amps on a single chip.

http://www.electro-dan.co.uk/electronics/TDA2822.html

http://www.electronica.ro/audio/TDA2822.shtml

[R.G.]

Actually, check out the LM3886. The LM3886 works down to +/-10V. Power that from a 24Vdc wall wart. It can run from a single supply, in which case the heat sink tab can be tied to a grounded chassis, as it is at V-.  According to the datasheet, at +/- 10V, it will put out 10W into 4 ohms, 5W into 8 ohms. It'll be a bit more with a 24Vdc supply.

[Brymus]

My 386 chips are a few years old and the NJM version.
So I can't comment on the quality being bad,actually I love these little chip amps.
But I can testify that with a 12V supply and an effecient 12" spkr my wife was having trouble listening to the T.V. at the other end of our house.
A couple of my friends swore it was my Valve Jr I was using and not that little chip on the breadboard.

(A) I really think for best results you need to leave pins 1 and 8 open like RG said.
(B) Also you need a 12V supply.
(C) You need an efficient guitar spkr, 12" is optimum.

I think alot of the bad build reports on 386's come from...
(A) Too much gain from not utilizing pins 1 and 8 properly.
(B) Slamming the input too hard or not hard enough/impedence mis matching.
(C) Using a little 1"-4" spkr that was salvaged from a toy or radio,ect with a really low spl rating like under 90 db. (I use spkrs rated 96 db or higher)

I also agree about the TDA 20** line being excellent,and easy to use.
Same for what RG said about the LM3886,they sound good and can be really loud.

[Renegadrian]

Bryan, I used the layout Robert made (link on the previous page) - it is indeed quite clean (not hi fi for sure, but clean as it can be) - pins 1 and 8 MUST BE DISCONNECTED. I left therm connected and a horrible noise came out.
I use an old salvaged speaker (more or less 4") but it sounds quite good. Guess it would be even better an a serious cab/speaker.

I just bought some 2822, gotta try them out...

btw...IT'S FUN TO BUILD THOSE "AMPS"!!!