couple questions about preamp design for piezo pickup

tempus fugit · 2006-12-20T15:00:33+00:00

Hey all;I am trying to design/build a preamp for a piezo pickup for my guitar, and Ijust wanted to check a couple things first. It'll just be a simple opampdesign. The output Z of the pickup is 1.3 Meg at 100 Hz, so I figure I'llneed a bifet like a TL071, with an input resistor of about 5-10 Meg. I wantto be able to control the volume from the guitar. Would a pot of 500k besuitable (this is the normal value for a guitar, but do the higherimpedances affect this value)? Also, I have seen a 100ohm resistor in serieswith the output on a few designs. Does anyone know its purpose?ThanksOh - something just occurred to me: I suppose I could also use a JFETinstead of an opamp, provided I could get sufficient gain from it. Anythoughts on that?Thanks

Dec 20, 2006 28 Replies

Rate this thread:

Phil Allison 19 years ago

"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

Vote

ChrisQuayle 19 years ago

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

Vote

tempus fugit 19 years ago

and I

I'll

want

series

Vote

ChrisQuayle 19 years ago

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

Vote

tempus fugit 19 years ago

Thanks Chris and a Merry Christmas to you too

ideas

Vote

Rich Grise 19 years ago

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

Vote

tempus fugit 19 years ago

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).

Vote

J.A. Legris 19 years ago

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

Vote