couple questions about preamp design for piezo pickup

Dec 20, 2006 28 Replies

So, is the 1200 pf reactance in parallel with the amplifier input impedance, or in series with it ?.

Your opinion..

Fet input op amps are not good in comparison to bipolar. The fact that the ceramic pickup has a fairly high output level makes it just about acceptable for the application, but in absolute terms jfets are about the worst thing you could use for low noise audio applications.

More speculation, or insults ?.

Agreed, except that I was talking about the noise of the *amplifier* input stage, or do resistors suffer from flicker (1/f) noise ?.

I think you need to explain this bit in more detail.

Equivalent noise voltage for given bandwidth and circuit impedance, no argument there, though it's best to use a quality metal film resistor if you need the best noise figure, not carbon composition or carbon film. Is this relevant to the present discussion though ?.

Well, it may be irrelevant to you, but real musicians choose a solution based on the *sound*, not some ivory tower theory, though a little can help to get you there. Have you ever done extensive work with musicians ?.

More opinion, with no supporting facts..

Except that the application requires some gain, so a source follower is not a valid solution. That is source follower, gain < 1...

Chris

"ChrisQuayle" Phil Allison

** That is * particularly asinine * of you.
** Way better than one from a know nothing lying, fool like you.
** More silly nonsense - yawn.

This pathetic fool just cannot follow a line of reason.

** Plain fact, I'm afraid.

Clueless in the extreme just what you are.

** Who knows or gives a hoot what a PITA, deceitful * context snipper * like YOU thinks ??

The voltage noise of a 1.3 Mohm resistor is WAY more than a TL071 input and only the resistor noise can be attenuated by the piezo.

Try learning some basic circuit theory one day.

** Maybe try reading what is right in front of you .

Shame if it all goes right over your thick head.

** That is UTTER BOLLOCKS !!!!

Go look up " Johnson Noise" on Goolge - maybe Mr Wiki will inform you.

BTW:

Now I know for SURE you are a know nothing, LYING piece of s*it.

** Piss off - bloody WANKER !!

** If gain is needed, the signal level must be low - hence no overload problem existed in the first place.

You are an absolute ** Quack ** - Mr Quayle.

F*ck the hell OFF !!

........ Phil

You appear to be a boorish, arrogant, authoritarian and browbeating individual who cannot stand to be disagreed with. Like a 2 year old who throws his toys out of the cot when he can't get his own way. I really feel sorry for your wife and children, but hey it's the season of goodwill, so go have a few cans of Fosters and I hope you get well soon :-)...

Chris

and I

I'll

want

series

Don't worry and don't be put off, it's a hazard of posting on the groups :-). Have a good Christmas and let us all know how you get on with the preamp...

Chris

Thanks Chris and a Merry Christmas to you too

ideas

Flame war? Are you new? ;-)

This is mild, compared to what we usually see around here, unless you're talking about being an incorrigible top-poster! >:-[

Good Luck! Rich

K people have said that to me before - how am I top posting? The last message displays as the last in the thread on my reader (OE).

Top-posting refers not to the top of the thread, but the top of your reply. Right now I am top-posting, which is what you just did. Scroll down past the quotations to the bottom of this reply...

tempus fugit wrote:

...This is bottom-posting, which is what you should be doing.

-- Joe Legris

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