Guitar Buffer OpAmp Question

[aortizjr]

Hi...

I am looking into buliding a guitar buffer to run before and possibly after my pedal board. The schematic I am using is from Craig Andertons Projects for Guitarist. Here is a link to the basic idea:

http://www.freeinfosociety.com/electronics/schematics/pictures/craigandertonbuffer.gif

The modifications to this are mainly a two battery powersupply, split outputs, and an extra input to bypass the input filter cap.

Basically I am trying to decide on what OpAmp to use. The schem says you can use any 741. I was thinking of using a TL071 or TL072.

Any other suggestions for an opamp or to the total design?

Thanks!

[cd]

Do you have the actual Projects for Guitarists book?  There's a whole chapter in there on designing your own guitar preamp, it goes into exact detail on exactly what you want to do.

The buffer you have posted is fine, there's no gain though - what you put in, you get out, no cut, no boost.  I would use an NE5532 opamp.

[petemoore]

For discussion:
 Switchoutable, it will change the way the guitar rolls of the gain. a FF for instance will not respond the same to guitar vol rolloff.
 Jfet, if you have one of these they make good buffers, very easy to try  buffers outside the guitar, look at the circuit section of the TS buffer sectioin at GEO.
 Mosfet
 I dont use buffers much, don't know the differences, Jfet could probably be made smaller, [or less current?], and well suited to the application.
 Battery switch.

[aortizjr]

what comes in is what comes out is mostly what I am after.  I will probably make it switchoutable and add an external power supply. Since it is + - 9V, I will try and put in that capability as well from a single regular 9V supply.

I read somewhere that the OpAmp versions were better than the JFet or just plain transistors....

Battery switch, will definitely be there.

I actually do have the Projects for Guitarists book, I will read the pre-amp part, thanks for the tip!!

[puretube]

TL071 will give you far less noise than the 741.
As well as the 5532 mentioned before.
Also TL061 will have less noise than the 741, and save
battery current.

[mikeb]

Pre pedalboard a TL072 would work fine; post pedalboard a NE5532 might be a good choice as it has good drive characteristics.

Make sure you check out Jack's info here (if you haven't done so already)....

http://www.muzique.com/lab/buffers.htm

Mike

[Brett Sinclair]

If you are using a dual opamp like a NE5532, i read it is a good idea to 'terminate' the opamp you don't use...
more info here: http://www.maxim-ic.com/appnotes.cfm/appnote_number/1957

I've built my buffer like this based on the Jack Orman schematics:

[petemoore]

741's...I used many of them, and have a pile of at least 10.
 I prefer 'better' IC's, on the record "For low noise".
 Off the record, there are more precise amplifier IC's. NE5534 [single] NE5532 [Dual], 4558's, TL072's...

[aortizjr]

If you are using a dual opamp like a NE5532, i read it is a good idea to 'terminate' the opamp you don't use...
more info here: http://www.maxim-ic.com/appnotes.cfm/appnote_number/1957

I've built my buffer like this based on the Jack Orman schematics:

I have more experience with digital logic IC's than analog stuff. So Orman's designs use a single battery +9V source that goes in with the signal input. Will this work? Or does it really need a -9V as well?

Also I noticed there is no output resistor, isn't that necessary as well to set the low Z ouput impedance.

http://www.generalguitargadgets.com/v2/diagrams/buffer.jpg

Which way works better?

[Kent S.]

Hi...

I am looking into buliding a guitar buffer to run before and possibly after my pedal board. The schematic I am using is from Craig Andertons Projects for Guitarist. Here is a link to the basic idea:

http://www.freeinfosociety.com/electronics/schematics/pictures/craigandertonbuffer.gif

The modifications to this are mainly a two battery powersupply, split outputs, and an extra input to bypass the input filter cap.

Basically I am trying to decide on what OpAmp to use. The schem says you can use any 741. I was thinking of using a TL071 or TL072.

Any other suggestions for an opamp or to the total design?

Thanks!

For a simple JFet preamp buffer, look at Don Tillman's and read his reasons for using it instead of an opamp ...also the TL071,TL072 ... I thought the 71 was a single opamp, the 72 a dual opamp, and the 74 a quad opamp. Check out the preamp ... you have to sift thru the site to find it ... //www.till.com

[bwanasonic]

Jack's Mosfet Booster works well both *pre* and *post* pedalboard, and lends a very *musical* touch to the buffering. Haven't compared it with an equivalently elegant  opamp design though. Would be interested in trying out one those spiffy TI/ Burr Brown samples I have in such a circuit. Right now I use a Mosfet boost *pre*, and a Fetzer *post*.

Kerry M

[Mark Hammer]

My advice is this:  You DO NOT want to have to dive into the electronics of your guitar very often.  If you have a Strat-type guitar and need to mess up the tremolo to be able to loosen the strings to take off the pickguard to get in and change the battery...probably never.

So, whatever uses the least current will be one of the best candidates.  For this reason alone, the FET units are good.

Please note that the 741-based design makes use of what we had to build with in 1976.  We have a MUCH bigger choice now, including many op-amps that will work extremely well off much lower supply voltages, many that have much higher input impedances, lower output impedances, lower noise, and better signal handling.

I currently have a 2N5089-based preamp in one of my guitars, and it sounds good and goes for months and months and months on a single 9v battery.  I used to have a TL071-based preamp in the same instrument years ago.  It also sounded good and tended to have a bit better high end, as I remember it.  Both are pretty quiet.

Unless you plan to use the second op-amp for something (and remember, two op-amps in use is more current drain which is more frequent battery-changing), stick with either a single op-amp or a transistor-based design.  Yes, I realize it may require buying something you don't already have in your parts bin.

Finally, check out the onboard preamp Craig published in DEVICE over at my site (http://hammer.ampage.org ....scroll wayyyyyyyyy down).  It is a bit of an improvement over the one in the book.  I realize you want a buffer, not a booster.  Just set the gain to 1 and you're done.

[R.G.]

Nota Bene: you can use a 12V camera battery that's half the size of a PP3/9V transistor battery. It's tubular, and could be adapted to slipping into a hole with a cover in the same manner as a AAA battery if you were mechanically inclined.

[David]

Hi...

I am looking into buliding a guitar buffer to run before and possibly after my pedal board. The schematic I am using is from Craig Andertons Projects for Guitarist. Here is a link to the basic idea:

http://www.freeinfosociety.com/electronics/schematics/pictures/craigandertonbuffer.gif

The modifications to this are mainly a two battery powersupply, split outputs, and an extra input to bypass the input filter cap.

Basically I am trying to decide on what OpAmp to use. The schem says you can use any 741. I was thinking of using a TL071 or TL072.

Any other suggestions for an opamp or to the total design?

Thanks!

Odd.  That's not JD's site...  Do they have his permission to post that?