Buffers - Best practises

[wcampagner]

Hello,

I've read a lot of threads about buffers...
What i can sumarise is:
Basicaly you can do buffers with BJT's, FET's and AMP-OP's...

The diference between them is that FET's have more imput impedance than BJT's and BJT's have less output impedance than FET's... so some people like FET's for Input Buffers and BJT's for output buffers... both of them don't provide a 1 to 1 gain... they provide a bit less... let's say 0,96... but some people like this effect for stompboxes...

AMP-OP's can provide 1 to 1 gain and they have very high imput impedance and very low output impedance... so it is used for "transparent" buffers...

What i really want to know... in practise, if there is an audible diference between this buffers... what i want to do is design a quality buffer in terms of not generating too much noise and doesn't change the tone too much too...

Another question is about component quality... i've made an input and an output buffer using BJT's... i tested with the cheap 2N3904 transistor and the low noise 2N5089 transistor... and i couldn't hear any diference... is there a way i can test it so that i can hear the diference?? maybe putting my amp in the 10 volume???

Thanks a lot,
Wagner.

[gez]

For commercial designs the criteria for deciding what gets used seems to be based on:

Cost
Simplicity (see above)
How much space the device used (plus supporting circuitry) takes up on a PCB (see above again  )
Current consumption

I'm sure there are other considerations...