Electric Guitar Amplifier to XLR Audio Signal
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- Опубліковано 24 сер 2024
- An Electric Guitar Amplifier to XLR Audio output is explained in this amplifier circuit video. The Pickups on Guitar converts the string vibration into electric signal Vin that is then applied as the single-ended input to the first op amp stage in this circuit. This first operational amplifier combined with capacitors, resistors and a potentiometer constructs a non-inverting variable gain high-pass amplifier to minimize the unwanted DC offset of Op Amp and undesired low frequencies below say 100 or 50 Hz. The second op amp stage is cascaded at the output of the first stage and acts as an inverting amplifier with a constant gain of negative one to generate the differential output voltage so that the overall amplifier operates as a single-ended to differential programmable gain amplifier for electronic guitar and other audio instruments if need be. A combination of Kirchhoff Circuit Laws including KCL (current law) at negative input terminals of the two OpAmps and also Virtual short of the op amps enforced by negative feedback are used to compute the variable gain of the electric guitar amplifier that can vary from 6dB to ~40dB in this design.
Yet more useful video. Thank you sir. I'd only like to mention that if you limit an upper freq to let's say 5kHz, you'll get a better sound from an electric guitar in almost all cases. They don't like high frequencies. They very much like distortions, but these must be soft ones )
And a guitar has no ground. A coil which generates +- is connected to a plug after some simple RC circuitry, but this is a symmetrical signal by it's nature, and a cable can have a 6.3 jack at one side, and XLR at another side, if I'm not mistaken.
Electric guitar pickup coils are "floating" with two terminals that could go directly to the two hot pins of a differential input - but in practice one of the two pickup wires is attached to metal shielding that lines the pickup cavity, often foil on the underside of the the pick guard, the metal cases of the potentiometers and switches, and lastly the bridge and strings. It would be possible to add a tip-ring-sleeve jacks in place of the standard tip-sleeve jack on the guitar, and connect the pickup wires (through the tone and volume pots) to the tip and ring, and ground all the metal parts and shield foil in the guitar to the sleeve. That would turn the guitar pickups into a floating differential source - but I don't think that would have any advantage over just running single ended.
@@jimmurphy5355 This absolutely makes sense, sir. As well as a low output impedance (may be some classical wahs will stop working because they rely on a high output impedance).
You're very welcome. Glad that this video is useful. Thanks also for sharing your thoughts. I agree that it should be beneficial convert the first operational amplifier stage to a bandpass filter to limit frequencies to above ~100Hz and below say ~10 kHz or lower depending on target application.
@@majortom5838 Thanks for the comment. In addition to the single input justification as your neatly explained, this single to differential amplifier has a variable gain that can amplify Guitar's Audio signal 2x to approximately 100x via adjusting the potentiometer. Alternatively we can use an Amplifier stage with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html
or We can also use an RDAC or digital potentiometer if more accurate gain setting is desired.
@@jimmurphy5355 Thanks for watching and for the insightful summary. If you'd like to use differential signal directly from Guitar, then we can use the first differential stage in the Instrumentation Differential Amplifier design ua-cam.com/video/2xJpqfexsPg/v-deo.html or using both output branches in the Darlington Differential Amplifier discussed in ua-cam.com/video/z8f7iZei5cY/v-deo.html.
It looks like this could easily be done with a dual opamp IC like a NE5532 or LM358 for a single chip solution. Very handy for a simple signal boost to a mixing board or AD convertor. It would not be a bad idea to put a simple RC bandpass filter on the output to clean up any harmonics or out of band noise generated by the opamps.
Thanks for sharing your thoughts and dual op amp Texas Instruments chip suggestions. Agreed that depending on application, it should be helpful to include at least a lowpass (if not bandpass) filter at the output of the first op amp so that limits the output frequencies to say 10 kHz or so (depending on specific application). For more Audio amplifier/attenuator videos see Bridge Audio Amplifier Explained ua-cam.com/video/EDpu6urAtHA/v-deo.html
VCA Electronic Gain Control (Part 1): Voltage-Controlled Attenuator Overview ua-cam.com/video/cFzYZsPEtP0/v-deo.html
It's basically a transformerless active DI box.
Well said. It represents a barebone transformerless active direct box to provide an amplified audio signal and higher input impedance.
Hi Sir. I like your videos and they are quite clear. But for this video, why not consider the function of capacitor of 10pf, at the time of 6:22 while using KCL for A1? Thks
Thanks, Glad that you like my videos. Good question, the 10pf capacitor is just a stabilizer cap that is practically open circuit given that its impedance (1/jcw) is very large for the frequency range (bandwidth) of operation of this circuit. Hence it is just considered open for gain calculation. More amplifier circuits videos are posted in ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html video playlist.
Nice I will try this out for my Bass and Guitar!!!
You are welcome! Glad that you liked this video.
An Electric Guitar Amplifier to XLR Audio output is explained in this video. For more Circuit videos:
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And the Analog Circuits Video playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html I hope these Circuit design and analysis videos are interesting.