Anti-bending ? reverse engineering, upgrading

DiggyFresh · Joined: Jun 08, 2013 Posts: 1 Location: Montreal

Wassup y'all, i'm new here! i apologies for my grammar,

About Upgrading the circuits of toys ect. I've been circuit bending since 2001 because of Mr. ghazala. I don't make noise music but i always incorporated toys as sound effects ect.. But sometimes i wish there was less noise with toys for my studio.

Disclamer: i totaly understand that some people like the noise and think its part of it ect.. but i wanted more fidelity for recording as i do mostly hip-hop/house..

That's when i modified a toy Megaphone voice changer, it used a 386 opamp for amplifier to the speakers, a very poor performance chip for line level.

At first i tried upgrading the capacitors for better film caps and replace the electro's. I then studied the lm386 datasheet to try to improve the circuit for line level, then it struck me, why keep the 386?? I tried to find a simple booster schematic using a low noise 5532 opamp and simply cut the trace goin from the "Black blob" to the 386's input and just replaced the output circuitry of the toy.

Made an immense improvement! Lower noise and way more deffinition of the lo-fi effect it produces.

I'm thinking of trying the same with my Yamaha pss-270. I love it, but the noise at the output is too much, I would like to have the raw Fm tones.

What do y'all think?

noto · Joined: Nov 05, 2009 Posts: 17 Location: portland

hello! first post here for me...
this thread seems old but i would like to know more about the 5532 or other low noise opamps over the lm386. i use lm386's a lot and i have never had to much trouble eliminating unwanted noise. to my ear the sound is quite clean, but i am hardly an expert. i have always preferred the lm386 because it can drive a speaker, but also sounds good from the line out. not to mention minimal parts, no need for a heatsink, low current draw, and affordable.
these days i am building much more elaborate "circuit-bent" synths, and i am selling them to musicians. needless to say, it would be in my interest to opt for better amplification techniques. within reason.
i usually use the basic lm386 configuration. if i do ever use the gain pins, it's usually just for using the "bass-boost" configuration. i feel like the gain pins aren't really worth it since they seem to factor up the THD. i really would just like to know that my signal is as clean as possible. i have never really noticed a difference in sound quality when running the signal through a low noise opamp to my line out, so i always just go with the lm386...
anyone have some wisdom to share?
thanks in advance,
tanner

PHOBoS · Posted: Mon Feb 03, 2014 7:15 am Post subject:

noto · Joined: Nov 05, 2009 Posts: 17 Location: portland

thanks PHOBos! been looking at a lot of your builds on this site. amazing work!
anyway, i guess my real concern is with whether or not i should be using the power amp to drive my line out. i will probably always use the lm386 to drive the built in speakers, but now i'm thinking there must be a better alternative to boosting the line out signal.
most of the circuits i build are pretty lofi anyway, so i don't really need the highest fidelity option, and the lm386 has always worked well. i just want to be sure that it's safe for big PA's... is it?

PHOBoS · Posted: Thu Feb 06, 2014 12:49 pm Post subject:

I don't think it could cause any problems and with a good PA system having a bit of 'juice' is a good thing. But the NE5532 is also an excellent chip for
that.
The only problem I personally have with the LM386 is that the gain is too high and therefor any noise will get amplified a lot too.

noto · Joined: Nov 05, 2009 Posts: 17 Location: portland

makes sense to me. using the lm386 has never given me any trouble driving the line out, but it usually has to be turned down quite a bit for that. might just do it the smart way and use a low-noise amplifier to be able to set the gain myself. just found a cheapo dj mixer at the thrift store that is LOADED with M5218's.
thanks for the reply