i need an opamp suggestion

[panfilero]

can anyone suggest an op-amp for me

I need to amplify my guitar signal, which is in the milli-volt range
and swings +/-.... I just need to boost it up with a gain of... I
dunno maybe between 10-100... maybe 500 at most.... but I'm looking
for a good op-amp to boost this audio signal and that I can operate
from a 9V battery

thanks

 

[panfilero]

On Aug 21, 8:51 am, panfilero <panfil...@gmail.com> wrote:

can anyone suggest an op-amp for me

I need to amplify my guitar signal, which is in the milli-volt range
and swings +/-.... I just need to boost it up with a gain of... I
dunno maybe between 10-100... maybe 500 at most.... but I'm looking
for a good op-amp to boost this audio signal and that I can operate
from a 9V battery

thanks

I'm sorry I forgot to add... that I'm trying to do this with only a
positive rail and ground, is there a good single supply opamp for this?

 

[Rich Grise]

On Fri, 21 Aug 2009 06:52:38 -0700, panfilero wrote:

On Aug 21, 8:51 am, panfilero <panfil...@gmail.com> wrote:
can anyone suggest an op-amp for me

I need to amplify my guitar signal, which is in the milli-volt range
and swings +/-.... I just need to boost it up with a gain of... I
dunno maybe between 10-100... maybe 500 at most.... but I'm looking
for a good op-amp to boost this audio signal and that I can operate
from a 9V battery

thanks

I'm sorry I forgot to add... that I'm trying to do this with only a
positive rail and ground, is there a good single supply opamp for this?

LM324 quad, TL081 single/082 dual/084 quad.

GOod Luck!
Rich

 

[whit3rd]

On Aug 21, 6:51 am, panfilero <panfil...@gmail.com> wrote:

can anyone suggest an op-amp for me

I need to amplify my guitar signal, which is in the milli-volt range
.... a gain ofbetween 10-100... maybe 500 at most....

That means the gain-bandwidth product is 10 MHz; you will want
to cascade two garden-variety amplifiers (each with max gain of 22).
TL072 is a suitable dual op amp for audio. Connect the midpoint
of your 9V battery to your ground, so it makes a +/- 4.5V supply.

 

[David Eather]

whit3rd wrote:

On Aug 21, 6:51 am, panfilero <panfil...@gmail.com> wrote:
can anyone suggest an op-amp for me

I need to amplify my guitar signal, which is in the milli-volt range
... a gain ofbetween 10-100... maybe 500 at most....

That means the gain-bandwidth product is 10 MHz; you will want
to cascade two garden-variety amplifiers (each with max gain of 22).
TL072 is a suitable dual op amp for audio. Connect the midpoint
of your 9V battery to your ground, so it makes a +/- 4.5V supply.


The TL072 has a GBW of just 3Mhz. A LM833 or NE5534 will do the job.

 

[panfilero]

On Aug 22, 8:24 pm, David Eather <eat...@tpg.com.au> wrote:

whit3rd wrote:
On Aug 21, 6:51 am, panfilero <panfil...@gmail.com> wrote:
can anyone suggest an op-amp for me

I need to amplify my guitar signal, which is in the milli-volt range
... a gain ofbetween 10-100... maybe 500 at most....

That means the gain-bandwidth product is 10 MHz; you will want
to cascade two garden-variety amplifiers (each with max gain of 22).
TL072 is a suitable dual op amp for audio.  Connect the  midpoint
of your 9V battery to your ground, so it makes a +/- 4.5V supply.

The TL072 has a GBW of just 3Mhz. A LM833 or NE5534 will do the job.

So... in order to use an opamp with a guitar signal (or audio signal)
I will need to power one of the rails with a negative voltage... is
this right? If I have one of the rails at ground, does that mean that
I can't go lower than that with my output?

thanks

 

[whit3rd]

On Aug 24, 6:38 am, panfilero <panfil...@gmail.com> wrote:

On Aug 22, 8:24 pm, David Eather <eat...@tpg.com.au> wrote:

whit3rd wrote:
On Aug 21, 6:51 am, panfilero <panfil...@gmail.com> wrote:
can anyone suggest an op-amp for me

I need to amplify my guitar
... a gain ofbetween 10-100... maybe 500

That means the gain-bandwidth product is 10 MHz; you will want
to cascade two garden-variety amplifiers (each with max gain of 22).
TL072 is a suitable dual op amp for audio.  Connect the  midpoint
of your 9V battery to your ground, so it makes a +/- 4.5V supply.

The TL072 has a GBW of just 3Mhz. A LM833 or NE5534 will do the job.

My intention was not to get the full gain with a single amplifier

stage;
two stages of amplification (22 being the square root of 500) means
that neither stage needs get near the gain-bandwidth limit.

So... in order to use an opamp with a guitar signal (or audio signal)
I will need to power one of the rails with a negative voltage... is
this right?  

It's not a necessity, the signal can either go through a DC blocking
capacitor OR the power supply can be ground-referenced
at midpoint. It's easier to do to the power supply, though.

If I have one of the rails at ground, does that mean that
I can't go lower than that with my output?

Not lower if your output is directly coupled to the operational
amplifier; it'd take a transformer or capacitor, with some associated
low-frequency rolloff. You need some low-frequency DC rejection
in any case, with a gain as high as 500 volts out per volt in, but
it can be a small capacitor that isn't signal-critical.

 

[tempus fugit]

"panfilero" <panfilero@gmail.com> wrote in message
news:fcff9ba7-7fab-44e3-9d33-f0d07de576cf@r18g2000yqd.googlegroups.com...

can anyone suggest an op-amp for me

I need to amplify my guitar signal, which is in the milli-volt range
and swings +/-.... I just need to boost it up with a gain of... I
dunno maybe between 10-100... maybe 500 at most.... but I'm looking
for a good op-amp to boost this audio signal and that I can operate
from a 9V battery

thanks

Why do you want to boost your signal that much? A guitar poickup's ouput is
in the 100mV - 1V range. I don't think you want it to be 50V do you?

I've had good luck with a TL072 (dual) or TL071 (single) for boosting guitar
signals. You don't need a dual supply, you just need to bias the input at
1/2 your supply voltage, like this:

http://www.ecircuitcenter.com/Circuits/opinv_ss/opinv_ss.htm

What exactly are you trying to do?