Little amp question

[Hungeryhippie]

Little amps that use the LM386, i have now made afew of these but i have a question. theres this buzz sound when a note is played (on the attack), the buzz dies down leaving a clean signal(on the decay), I have a buffer(2N3918) before the LM386 which is set up with pins 1&8 open (least gain) and every thing else asper the data sheet. I have tryed it though different speakers/cabs, but its the same. Has any one else experienced this? Know of any cures?

Oh and i tryed out the   Ultra Class A Superdrive poweramp
its good fun i tryed it being driven by a tube driver clone, it was good fun, i used a mini audio transformer from maplins cos thats what i had lying around, it works good, very quiet with nothing driving it though. I've drifted off topic now,

[Marcos - Munky]

Maybe a new battery will cure your problem.

[Hungeryhippie]

I'm using a power supply, set to 12v.

[B Tremblay]

Are you grounding the unused input of the 386?
Have you tried an RC network at the output as used in the Little Gem?

[Hungeryhippie]

Thank you for your replies

Are you grounding the unused input of the 386?
Have you tried an RC network at the output as used in the Little Gem?

Yes and yes, I have it set up just like that,

[Hungeryhippie]

i spent more time with it last night and i cracked it! I thought its just me but its not!!
The LM386 i was using was marked up XM25AS LM386N-1, which i had got from Maplins, At the begining of the week i ordered some bits from RS including some LM386's I noticed they had written on them JR386D LM386N-1.  So i swopped them round and I couldnt belive how much difference it would make, the buzz was gone and the whole sound improved fuller and clearer. Phew  :lol:

I have it set up on bread board with the following,

Input - Buffer - Fetzer Valve Boost - Lm386 - speaker

The volume control is on the input to the LM386, and there will be a switch to turn the boost on/off,  so there is a clean and dirty setting.



Thanks to those who offered help, and i hope this will also help others.