How can I make a guitar fuzz effect

[nanop]

Don't use an LM386 as a pre-amp. It will be too much for your guitar amp.

MP

Try using a LF351 IC.

Nanop

 

[audioguru2]

Can you send me a circuit for this preamp with an OP-AMP?

National Semiconductor discontinued making their LF351 opamp. I have been using the Texas Instruments TL07x series of audio low noise opamps.
This guitar preamp circuit has a gain of 101, fuzz diodes and an input impedance of 1M:View attachment 39548

 

[MP1]

Sorry MP but you are wrong.
R3 is the input resistance of the inverting opamp amplifier which is 1k ohms. The 0.47uF input coupling capacitor has a reactance of 1k ohms at 340 Hz, so the load to a guitar pickup is only 2k ohms at 340Hz and less at higher frequencies.

Many experts say that a guitar pickup must be loaded with a very high impedance:

Well, I just got back from a business trip and found your post.
No. I am not wrong. Some of the guitar effects which use a 1K input resistor to the op-amp are:

Ibanez Graphic EQ
MXR Flanger
Ross Stereo Delay
Ibanez TS9 Tube Screamer
Ibanez TS-808 Tube Screamer
MXR Hot Tubes Distortion
MANY MANY more........

Also, note that you are mis-quoting the "experts" regarding the guitar pick up. All guitar pick ups have loading provided on the guitar circuitry under the plate. You do not need to add it. Guitar pickups do not connect directly to the jack.

I have actually been one of these guitar effects "experts" since the mid 70's.
Also note that the C1 and R1 combination makes for a low cut frequency calculated as C=1/ (6.28)*(Low Cut off freq in HZ)*(R1).


MP

 

[nanop]

National Semiconductor discontinued making their LF351 opamp.

Sry about that. Here's a circuit that can be built around a TL071, TL082, or LF351 if u have one. They all have the same pin connections. The gain's about 100.

 

[audioguru2]

No. I am not wrong. Some of the guitar effects which use a 1K input resistor to the op-amp are:

Ibanez Graphic EQ
MXR Flanger
Ross Stereo Delay
Ibanez TS9 Tube Screamer
Ibanez TS-808 Tube Screamer
MXR Hot Tubes Distortion
MANY MANY more........

I have actually been one of these guitar effects "experts" since the mid 70's.
MP

MP, you have shown that you don't know about the input impedance of opamp circuits.
An inverting opamp circuit has a very low input impedance provided by its input resistor. A non-inverting opamp circuit has a very high input impedance provided by its DC-reference-voltage resistor to ground.

The "MXR Flanger" circuit has a 1k resistor at its input in series with a 470k resistor. Its opamp is non-inverting and the circuit's input impedance is 471k.
The "Ibanez Tube Screamer" circuit uses a 1k resistor at its input in series with a very high input impedance emitter follower. Its input impedance is also about 470k.

Many Fender guitar preamp circuits use a vacuum tube with a 1M resistor as its input impedance.
Many other guitar preamp circuits use a 10M resistor as their input impedance.View attachment 39550

 

[MP1]

MP, you have shown that you don't know about the input impedance of opamp circuits.

yeah....whatever....  :

...guess it was just luck that got me my Engineering degree.... you technicians could teach us a lot.


MP

 

[audioguru2]

yeah....whatever....View attachment 39551

 

[MP1]

No, I did not design the fuzz circuit Jesus posted. It is a standard that has been used for many years. It works and has worked well for many. I have a similar circuit inside the plate on an older guitar that I have from the late 60's.

Again, there is nothing wrong with the design. There are much better designs, but if his circuit is not working, it is not due to the design. It is due to making it incorrectly. (That is not theory...that is fact).

MP

 

[audioguru2]

No, I did not design the fuzz circuit Jesus posted. It is a standard that has been used for many years. It works and has worked well for many. I have a similar circuit inside the plate on an older guitar that I have from the late 60's.

Again, there is nothing wrong with the design. There are much better designs, but if his circuit is not working, it is not due to the design. It is due to making it incorrectly. (That is not theory...that is fact).

MP

Have you ever seen a guitar preamp that uses an inverting opamp with a 1k input impedance?
As I said earlier, many have a non-inverting opamp circuit with a high input impedance of 1M and some have 10M.