My Lm386 hate me

[Prive]

Hi, you know the Little gem and the Smokey amp.
I can't meke it work right.
It sounds but terrible, like a misbiased transistor.
I try the most simple configuration, just output cap, grounded +input and the guitar to -input (reversed too).
With open pins 1/8 it gets less gain, Ok but still horrible.
All the LM386 can't be broken the same way, some are really new.
There's some output impedance issue i'm missing???
My speakers are too much god for this thing, if my Marshall MK2 sounds good thru it, this little amp can't do any harm.

Please some help.

Saludos, Marcelo.

[spongebob]

The output cap has the right polarity (negative side towards speaker)?

Otherwise re-check all the connections on the pins, maybe there is a short somewhere... there is not much you can do wrong with a 386!

[Gringo]

Como andas che!

Parece que estuvieramos sincronizados, ayer mismo termine mi hibrido entre little gem y ruby. Al principio pense que habia algo mal, pero eran los parlantes  que estaba usando (unos de computadora). Tengo que probar con el parlante de mi combo, pero por ahora donde mejor sono fue con un parlante de 2" o 3" que esta en una radio a valvulas con caja de madera de mi abuelo

I have one question: how low can i go with the output cap (220uF), as i'd like to cut some bass to see if my crappy speakers can take the punishment without breaking so early.

[David]

Hola, Prive!

Questions for you:

What is your supply voltage?  If it's 6V, use the LM386-1 chip.  If it's 9 to 12V, use the LM386-3 (not hard to find) or the LM386-4 if you can find it.  I tried using the LM386-1 in a 9V-powered headphone amp, and it was distortion city.  I switched to the LM386-3 and it's clean as a mountain breeze.  I beat on that thing, too!

[Prive]

A-HA!!!!!!!

Bingo, i think it's the 1, at last all the little devices i have says LM-386N-1, i'll give it a try with 6V and post the results.

Thanks for your posts.

Que haces Gringuet!!!!!!

Jajaja asi que estas con el 386 tambien? como va? que 386 es? decime el codigo completo asi comparo.
Como anda??? a que suena?
El otro dia estabas online pero no quise joderte con el chat.

Un saludo, Marcelo.

[Gringo]

Consegui N1 y N4 (el n1, modicos $2, el n4 me lo cobraron 5 pesos!!!). Los probe con 9 y 12v, y con 12v suenan mejor los dos, voy a probar el N1 con 6v a ver que pasa, lo estoy aporreando con el mosfet booster como buffer/booster para un poco mas de ganancia.

Tambien voy a hacer las pruebas definitivas con el parlante de mi combo, para asegurarme de que lo que distorsiona es el circuito.

Any takers on how low can i go with the 220uF output cap?

[spongebob]

Any takers on how low can i go with the 220uF output cap?

You mean decreasing the output cap to reduce the bass?

Hm, not sure, but the usual formula f = 1 / (2*Pi*R*C) should also apply here, right? That would result in 90 Hz rolloff frequency for a 8 ohm speaker with the 220uF cap, so anything smaller than that will increase the rolloff frequency I guess...

It would probably more convenient to change some other component in the circuit (RC filter at the input?), the next smaller electrolytic value is 100uF, and this will probably take out some of the mids too.

[David]

Amigos:

Ese es una idea muy mala!  Sorry for my lame Spanish...

I would strongly encourage you NOT to mess with the 220uF output cap from bitter personal experience.  It's there in the application notes for the chip -- presumably for a good reason.  It's like a John Hollis circuit:  When he specifies a 10M resistor on a Flatline, he means it.

[smoguzbenjamin]

I used 100uF output caps on all my LM386-based 'designs' and that worked fine for me. I did notice that the n1 is not happy with 9v but if you attenuate the input with a trimpot you can set it to a value where your guitar won't distort like mad. You'll lose some gain but OK... it works.