Noisy Cricket problem/question

[s22secando]

Hi there! (my first post here, sorry for my English)

I recently built my first Noisy Cricket with these schematics: http://www.beavisaudio.com/projects/NoisyCricket/Noisy_Cricket_Schematic.gif It's working, but the thing is that only when volume is low (i.e. set on less than half of max value with volume set on guitar on about 7/10 and a bit of gain). When it's going to get a bit loud it starts with squealing sound (don't know if this is good description of this sound - my English can be sometimes bad ). Here is recorded sound (with mobile phone, I tried turning volume up and using grit switch): http://www.mediafire.com/?hqi0bhoy2kbaov7

I used two ICs to check, did project three times: first with everything wired on an universal board with first LC386-N1, second using only wires with LC386L, third the same with used first time LC386-N1.

The only modifications to circuit were:
- replaced MPF102 with BF245C (which was avaliable at local shop)
- removed tone pot with cap and connection to ground
- added 100uF across pins 6 (+) and 3 (-)

What else can I check? Could it be an issue with BF245C? There aren't any loose connections (the only thing that has an impact on sound when checking connections during playing is volume pot - pin 3 is loose, because pot is quite old). Battery should be now on about 8 V.

[deadastronaut]

whoahhhh sounds nasty...

pot pin 3 is loose?....

try bypassing the volume pot for now...

[tca]

Battery should be now on about 7 V.

Hi, replace the battery with a fresh one. I've build a few lm386 amps, the amp squeezes when the volume is high  when the battery is dying.

Cheers.

[s22secando]

I tried bybassing volume pot, but it didn't helped (I think pot is OK, I checked resistance values and they're from 0 do 10k, loose pin doesn't have much impact on circuit - at least for now it won't come off pot).

Sorry for late reply, I was fixing ground connections and again checking everything.

Well, I'll go and buy new battery. Then again I'll check everything and write if this helped.

EDIT: Sorry, I made mistake with battery - it's 8V.

[s22secando]

Thanks for help! The problem was with battery - after replacing it on new one, Noisy Cricket started sounding like it should. Thanks!

BTW. The quality of sound deteriorates quite much when voltage is lower than 9V (around 8.5V)

[tca]

Thanks for help! The problem was with battery - after replacing it on new one, Noisy Cricket started sounding like it should. Thanks!

BTW. The quality of sound deteriorates quite much when voltage is lower than 9V (around 8.5V)

Hi, I'm glad you figure that out. I've never build the cricket, only variations on the ruby, and the lower voltage seemed to me like 6.5V... But ok.

Cheers.

[s22secando]

Well, about deteriorating quality of sound. For now I'm taking back my word about it (and battery voltage). I'm not sure about this - I bought the cheapest one battery from the shop and after some playing it went from 9.7 V to 8.3 V (cheap battery, not alkaline) and now it's about 9 V. When battery had 8,3 V (I checked this immediately after playing) I thought that sound really was more 'farty' than when battery was full. I'll do some other testing.

Anyway now it's working quite good. I think I'll just buy 9V adapter and then I'll stop worrying about battery.

[PRR]

LM386 into loudspeaker really needs a "good" 9V battery. The peak current is much higher than a 9V battery was designed to supply. Modern alkaline 9V batteries do OK; a low-low-price smoke-alarm battery may sag below 4V every loud strum.