[sdiy] Microphonic PCB

[Tom Bugs]

Hi all,

I'm scratching my head and wondering if anyone has some insight to help.

I have a prototype made up using mainly standard SMD parts
(the main components used are: 0805 resistors, 0805 & 1206 ceramic 
multilayer caps, MLL34 silicon diodes and some dual shottkys, and SOIC 
TL074s)

I am able to tap the PCB and hear it!
(obviously not very good)

Recently I was informed by Mr.G.Richter that SMD ceramic caps tend to be 
microphonic - you won't tend to notice it unless there is some 
amplification going on.
Well, as the first stage of the PCB offers amplification I figured I 
should swap out the current caps and solder in some poly-box ones (no, 
it doesn't look all that neat!)
The microphonics still remain..

Are other parts microphonic?

Cheers for any insight!
Tom

-- 
BugBrand LTD
UK company No. 07199808
VAT No. GB 988 2629 57
1 Ninetree Hill
BRISTOL BS1 3SB
United Kingdom
www.bugbrand.co.uk