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Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Preamps and Effects => Topic started by: critter01 on January 19, 2009, 09:39:55 PM

Title: TL071 pre amp from "the Guitar Handbook"
Post by: critter01 on January 19, 2009, 09:39:55 PM
Hi Guys,one of threads in this forum discussed improving the design of this preamp,apparently there were some problems with the original design.as i am about to attempt building one of these,can someone please explain what the problems were and what has been done to "improve" this preamp. ???cheers guys i look forward to your replies.
Title: Re: TL071 pre amp from "the Guitar Handbook"
Post by: critter01 on February 24, 2009, 09:58:42 PM
Awww!! come on guys, some one must be able help me??? PLEASE  !!!.cheers.
Title: Re: TL071 pre amp from "the Guitar Handbook"
Post by: J M Fahey on February 24, 2009, 11:41:58 PM
Hi Critter, please post the link (or at least the schematic).
Thanks
J M Fahey
Title: Re: TL071 pre amp from "the Guitar Handbook"
Post by: critter01 on February 25, 2009, 10:33:57 PM
SSGuitar Friend


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     Improved 'Guitar Handbook' TL071 preamp
« on: September 12, 2007, 07:55:09 AM » Quote 

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I have had a go at redesigning the circuit using the TI single supply handbook.
It avoids most of the pitfalls of the original though i am not expert.
If anyone in the know can comment that would be good.

I will try it with both a TL071 and a OPA134.
The OPA134 should sound better since it is a very high spec opamp btu you never know!


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Title: Re: TL071 pre amp from "the Guitar Handbook"
Post by: critter01 on February 26, 2009, 03:35:40 PM
http://www.ssguitar.com/index.php?topic=562.msg3915#msg3915
:loco sorry guys - heres the link to the thread i was refering to.(hope this works) looking forward to your replies.cheers
Title: Re: TL071 pre amp from "the Guitar Handbook"
Post by: armstrom on February 27, 2009, 10:46:07 AM
It's been a while since I've read that thread but without going back and re-reading it all I believe the improvements were as follows:

-increased input impedance and reduce noise by using a separate voltage divider network to generate the bias voltage and then use a higher impedance resistor to reference the non-inverting input to the bias voltage

-additional power supply filtering

There are probably other improvements that's I'm missing, but those are the ones that stand-out in my memory.


Keep in mind that the schematic attached to the first post of that thread is not "the most improved" design that is presented in the thread. Based on discussions within the thread the design was further refined and updated schematics were presented.
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