[krispy71]

After running my bugle for a couple of years on 9v batteries, I decided to try upping the voltage to see if I could hear any improvement. Simply wired two 9v in series per channel.  Tested voltage at 16.4v to the socket. Btw, upgraded 16v 220uf caps to 25v first.

Result - no sound.  Low rumbling that doesn't change in strength when volume is turned up. Put single 9v in socket and full sound returns.

Any suggestions on what might be the problem?

Thanks
Tony

[hagtech]

It just means the batteries were not wired in properly.  I suspect the negative side was not right (people have habit of thinking "-" is ground).  Be careful, many opamps will not tolerate this high of a supply voltage.

jh

[krispy71]

Thanks!  I'll give it another look and verify my polarity.

BTW,  I'm using the recommended OPA2134 opamps and see that they're rated to a max of 36V.  Should I be backing off that total by a good amount?

thanks,
Tony

[hagtech]

The opamps will handle 36V.  But 9V batteries start out at 10V when fresh.

jh