Questions tagged [preamp]
A preamp takes in very weak DC voltages or audio or RF signals and amplifies them enough to be used by a more conventional amplifier. Input may be in microvolts and output maybe 1 volt RMS or peak. They are often specific to amplify DC, LF/audio, RF or microwave bands. No preamp can cover DC to microwave bands and have good parameters at both DC and RF without software offset and gain correction.
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What is the purpose of these passives in a microphone pre-amplifier circuit?
This is the typical application circuit of the MAX4466 "microphone preamplifier" op-amp.
Are these resistors/capacitors purely for generating a bias voltage? If so, aren't there much simpler ...
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Building a MEMS Microphone Monitor System
While I've never used a breakout board when building an electret mic, I have used the small Spark Fun 09068 and Cinimark admp401 boards for MEMS mics. They seem to work with a 9v battery box I built ...
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Pre-amplifier for digital oscilloscope
I have an ATTEN ADS1062CML 60 MHz 2-channel digital oscilloscope and it has quite poor input sensitivity. My idea is to build a 2-channel low-noise pre-amplifier. I mostly need the oscilloscope for ...
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What is the difference between using transistors and op-amps in pre-amplifiers? [closed]
What is the difference between using transistors and op-amps in the design of audio preamps? What are the advantages and disadvantages of using each?
Based on my research, using op-amps is better as ...
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Tube preamp overdrive question
Is it possible to add an overdrive gain pot (instead of just simply a bypass switch) to a preamp tube circuit?
I am designing a new amplifier, and I want to include an overdrive/distortion option to ...
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Controlling audio preamplifier with a digital potentiometer
I have created an audio preamplifier with THAT1512. As I am not an expert in electronics, I used the circuit designed by DIY Perks. It is supplied with +15V and -15V, similar to the circuit in the ...
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LNA and DC amplification
In a THz detector, it produces a DC output voltage proportional to the input signal intensity. I need high SNR.
My doubts are:
Can I use LNA as a preamplifier?
Is DC amplification possible with LNA?
...
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Name and cause for phenomenon in microphone preamp output as seen on scope screen
What might cause 1 kHz sinusoidal signal to change such as seen on the screen? How is this phenomenon possibly called?
I have quite a lot of hand microphones with built-in opamp preamp and electret ...
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Why won't my pre-amp circuit enable my condenser microphone to work with my boombox?
I recently bought a boombox for my mother to play and record cassette tapes. I didn't realize at the time that the boom box did not have a built in microphone. I then bought a condenser microphone for ...
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Building a dynamic microphone preamp
I'm looking to build a preamp for a dynamic microphone (SM57, rated at 150 Ω with -56 dBV/Pa). I've just finished a course in circuits and I'm having a bit of trouble approaching this design problem. ...
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Audio line-out to amplifier line-in matching impedance and voltage
I am an electronics hobbyist. After reading online my understanding is that an op-amp buffer or JFET pre-amp can be used to match a medium (lower) input impedance with a high output impedance. In my ...
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LM386 as pre-amplifier for electret capsule
Although I know the LM386 is intended as a power audio amplifier, I wish to know if it can be used as a pre-amplifier for an electret microphone capsule, as I intend to use it for that purpose. If yes,...
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Input voltage noise (RTI) calculation for preamplifier
I would like to obtain the RMS Input Voltage Noise (RTI) of the AD8428 preamplifier for the following setup
range of 0.1 Hz to 150 Hz with 1st order lowpass filter, koeff = 1.57 ---> BW(bandwidth) ...
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Reasons for subharmonic mains noise in preamplifier
I have a preamplifier based on an OPA1611 that I wanted to characterize. The amplifier is in a fully enclosed and earthed metal chassis, which has an AC-DC converter in it. The mains cabling goes ...
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How does the transient protection in this AC-coupled preamplifier work?
I'd like to build a preamplifier for measuring the noise of very quiet linear regulators using a baseband spectrum analyzer. I found this page, which presents a few designs for this and looks ...
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Troubleshooting simple JFET preamplifier design
The circuit shown below (with actual measured values) simulates correctly in as much that it provides some gain.
When I have built the circuit connected it to a signal generator using a 1mVp-p zero dc ...
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Single wire electrodynamic pickup preamplifier (transformerless ribbon mic)
I'm currently working on an experimental string musical instrument. It isn't my invention though. The source of inspiration called Dvina has an unusual pickup system. It senses the current induced in ...
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Noise of low-frequency RC high pass filter preamplifier circuit with LT1028
I want to build a low-noise and low-frequency preamplifier with the first-stage opamp of type LT1028 offering an input-referred voltage noise density of about \$2~\mathrm{nV}/\sqrt{\mathrm{Hz}}\$ at \$...
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Transistored pre-amplifier
We have a transistorized preamplifier, which has a sinusoidal signal source as input.
vi = VI sin(ωt). Being VCC >> VBE, VBE = 0,8V and the capacitors have infinite capacitancy.
How can I ...
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What makes an op-amp good for electret microphone preamp vs other op-amps?
What makes an op-amp good for use in an electret microphone preamp vs other op-amps? Being JFET, current bias, voltage bias, etc?
Does an op-amp that requires a negative voltage supply work better or ...
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What is the input impedance of this circuit?
Here is the relevant part of the schematic of the Befaco InAmp, a Eurorack preamp for line level and instrument level signals:
I am trying to determine whether I can safely connect the AKG c1000S ...
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Input selectivity for a RF receiver pre-amp
In his answer to my question about common emitter amplifiers, @glen_geek commented that the RF receiver pre-amp I used as an example (shown in Figure 1) was "too simple" and that "any ...
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Preamp stage for audio amplifier using LM741CN clipping too early [duplicate]
I'm trying to build the preamp stage for an audio amplifier circuit using the LM741CN. I'm using a variable resistor for Rf so that I can vary the gain.
What I'm finding is that when I have Rf set to ...
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Single-ended 3.3V guitar preamp circuit is clipping and offset
I'm designing an audio signal frontend to take an electric guitar analog output and deliver it to an ADC channel on a microcontroller. The µC/ADC are 3.3V devices (...
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Why does this op amp stop working after some time?
I have an audio streaming device I bought that has analog audio output that is way too low (it’s supposedly line level, and I’m not the only one who’s complained about this).
I’ve been using this as ...
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simple NE5532 preamplifier circuit troubleshooting - sound disappears at upper end of gain potentiometer
I'm a bit lost trying to solve an issue I'm having with the attached microphone preamp circuit. If anyone recognizes what this problem is, I'd be very grateful for any help - thanks so much in any ...
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Is signal from electret microphone capsule (with FET) inverted?
Can I assume that the signal from an electret microphone capsule is inverted due to common source configuration of jfet?
I would like to have non-inverted signal on my sound's card line input. Then I ...
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Expected voltage on external gain resistor pre-amp
I want to build an amplifier with digitally controlled gain, using the THAT1510 pre-amp IC.
The IC provides two pins to set the gain, using resistors.
I want to switch between resistors with analog ...
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lowering output level of a phono preamp
I built a RIAA phono preamp that works great from these schematics:
But the output level seems a bit too high. What would be the best way to lower it?
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FM receiver With LM386 - Need a Preamplifier
I am building a hoppy FM Receiver and I created the Preamplifier stage 1 and linked it with the LM386 Stage and it goes OK but The output sound from the Speaker is weak so I tried to do some ...
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Active low pass filter built around an LM386
I have some theoretical electronics knowledge from uni, but when it comes to applying it in practice, things can get a little bit complicated.
I've built simple stomp box, basically a piezo transducer ...
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Op amp introduces phase shift at high audio frequencies
Context:
I am trying to design a solid-state microphone preamp using dedicated audio op amps (ex: API 2520).
Goals:
flat ≈60-66dB of gain from 20Hz to 20Khz
Limit changes in phase shift as much as ...
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LM358 Electret microphone preamp
I am trying to make an electret mic preamp with lm358.
here are the pspice simulation results.
I measured the voltage of the pins and the values were simulated exactly like the sample.
I tried with ...
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LTspice simulation of microphone preamp
Can someone help an idiot understand why this plot has dual traces?
The node is between C2 and R7. I have replaced an electret microphone with an AC source.
I don't know how accurate this is, so any ...
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Using diy lm386 preamp on standard commercial amp?
I have a small intercom-like device that has been siting around.
It looks something like this.
I suppose that inside is just a basic elect-mic and a button.
Also i have an power amp which i used to ...
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How can I remove noise in my preamplifier circuit? [closed]
I need a low noise microphone preamplifier for my Arduino. I used a battery and standard wire but I had noise in my circuit. I need gain 20-20kHz.
Can you help me with the schematic?
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Signal routing to power amp LM1876 based on TS5A22362 SPDT
Has anyone ever used the TI's TS5A22362 CI to route audio? I though of implementing the circuit below on which I intend to use the same supply voltage to switch between normally closed and normally ...
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Additional gain with in-amp for nanovolt-scale pre-amp
Currently I'm designing a pre-amp for detecting nanovolt-scale(~100nV, <1kHz) signal for experiment. I need a final gain to be around ~100000. Since the magnitude of the signal is extremely small, ...
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What can cause voltage irregularities across an IC chip?
This is the preamp section of a channel of a tape deck for which one channel is working and one is not. Swapping all the components between the channels does not affect which channel is working ...
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Tube amplifier preamplifier
I received this little two tube preamp
http://www.gikfun.com/electronic-diy-kits-c-7/6j1-tube-preamplifier-board-20-stereo-multiple-diy-kit-p-730.html
It comes with 9 470uF caps. The symbol on the ...
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Grounding adviseable on tube pre-amp powered by a 9VAC power brick?
I have an ART Tube MP pre-amp that is powered by a compact but rather heavy power "brick" that delivers 9V AC @ 1A. I use the pre-amp with a large-diaphragm microphone that gets its 48V ...
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TL072 opamp clipping problem
I'm trying to drive a TPA6120 headphone amplifier with TL072. I use single 24VDC supply with a TLE2426 virtual ground.
The TL072 works well and puts out around 21Vp-p sine wave. But as soon as I ...
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Small signal analysis of BJT dynamic microphone preamplifier
I am trying to do a small signal analysis for the following circuit
I did not have any experience with BJT so I am having a hard time to analyze the circuit. From research, I know Q1 is common base ...
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Small signal analysis of dynamic microphone preamplifier circuit
I am trying to do a small signal analysis for a dynamic microphone preamplifier circuit. The original circuit is using BJT but I did not have much experiences with BJT, so I switched all BJT to MOSFET....
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Grounding a chassis with two prong plug
So I kinda shot myself in the foot by purchasing a two prong wall wart to power an audio preamplifier that I designed. I forgot to consider the fact that I should ground my chassis to the earth ...
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High quality, low-noise, pre-amp circuit for condenser microphone (with phantom power)?
EDIT
Suggestions so far, and reference to another question indicate that a discrete FET based input stage, perhaps followed by a particular low-noise IC for a second stage, might be a good approach.
...
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Calibration of response of electronics : LTSpice [closed]
I would like to calibrate my electronics.
Row signal is something like pulse-A, width is 40nsec.
When I input this signal to preamplifier, output is something like pulse-B.
I would like to calibrate ...
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Pre-amplifier gain issues
I built a 2.1 subwoofer circuit. The schematic is below. The problem is the sound is low volume. It should be louder than this. I want to confirm the coupling capacitor values are ok in every ...
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Electret microphone and FET pre-amp
My question is about designing a microphone pre-amplifier that uses an electret microphone. I saw a video of Doug Ford on the EEVBlog, in which he shows some pre-amplifiers for microphones.
My ...
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phono preamp input stage - exotic design
I found a very exotic (at least for me) moving magnet input stage of a phono preamp. It's taken from an old cartridge measurement system from renown brand. I simply can't figure out the logic behind ...
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