LM4562NA op amp noise - is it me?
Mar 13, 2013 at 5:05 PM Thread Starter Post #1 of 2

unclematerial

New Head-Fier
Joined
Mar 4, 2013
Posts
7
Likes
0
I've only recently bought a CMoy amp to get a bit more volume out of a few things I have, but also with a view to making something similar. I ordered the amp with a second op amp to put in to try and educate my ears a bit, but then I also bought an LM4562NA on eBay from someone with 100% fb and who's been civil in email. I'd read a recommendation of it on this site during some random searching, and it was £4, new. Compared to the other two op amps when used with my Android tablet in the CMoy amp there is a horrible amount of squeaking and hissing when a browser is opened or a web page changes or a folder of music is opened. I can faintly hear this with one of the other op amps, I think it's an AD8066, but so faintly that it's not an issue and makes the 4562 seem a rogue chip to me. Should I expect noise like this? The only other time i've heard the same sound is with older IBM Thinkpad laptops, through headphones, when they've started to go bad, I think some item inside the screen lid i've forgotten the name of. I can't say I hear anything bad when used with my Sony Discman, but having a choice of three chips I wouldn't leave Mr Screechy in. The seller has said ot send it back for testing and that he'd replace it if need be. If it's normal though for that model, with a tablet it's no use so I'd ask for something else or a refund if he's willing in the instance of it being deemed non-faulty. I'd just like some rough idea as a layman and beginner in these things of whether wanting to get shot of this item is reasonable or whether its 'fault' is to be expected.
 
Thanks.
 
Mar 13, 2013 at 11:00 PM Post #2 of 2

DingoSmuggler

100+ Head-Fier
Joined
Jul 11, 2011
Posts
283
Likes
26
A number of cmoys are designed to use fet-input opamps, the LM4562 is bipolar input.
As a broad generalisation - you can usually swap a fet-input opamp into a bipolar opamp circuit without worry, but not the other way round.
So chances are the opamp is fine, but the circuit doesn't suit it.
 

Users who are viewing this thread

Top