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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Adding volume control between equalizer and power amp
I want to built an Equalizer preamp for my power amplifier(stk4141 II).The equalizer is "Rod Elliott (ESP)-Eight Band Sub-Woofer Graphic Equaliser".This circuit has input and output buffer ...
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How to avoid overloading pre-amp with a low output load?
When I connect a typical voltage pre-amp's output to an oscilloscope with 1 MΩ internal impedance, I can see the output clearly.
When I switch the oscilloscope impedance to 50 Ω, I cannot see the ...
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Connection Abbreviations on my plate amplifier control board and amplifier board
I've been looking everywhere for a common list of abbreviations found on my plate amplifier boards. They're located on the board connections that tell me what wires do what between the tone control/...
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Replacement transistor for a radiation detector
I am trying to reproduce this circuit from "Elektor" issue 06/2011, page 22, by Burkhard Kainka:
I replaced the two transistors with SS9014C. Is that a good choice?
From testing, it seems ...
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Changed TL072 to OPA2134 - high shelf cut on highs
So I've changed TL072 op-amp to OPA2134 on ART Tube MP V3 preamp. Everything is working except it appears that high-shelf cut is being created (~9 dB at 10 kHz) (measured with pro audio interface ...
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Identifying transistor topology in discrete phono preamp
I try to understand how preamp of Bozak CMA-10-2DL works. Can someone please help me identify what kind of topologies transistors Q1, Q2 and Q3 are forming? Is it active or passive phono preamp? Seems ...
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What is the maximum dBu I can send into a microphone input in this schematic?
The schematic below is from the Icom 9700 radio service manual (page 80). I would like to feed this input from a mixer board's ALT-3/4 outputs, and I want to avoid blowing the TS462 microphone preamp ...
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Can an audio isolation transformer between a preamplifier and an amplifier cause the amplifier's fuse to blow? [closed]
I'm building a microphone preamplifier. I was having problems with hum (intermittent ground hum when touching the case) and decided to try adding an audio isolation transformer (600 ohm : 600 ohm) ...
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How can the microphone senstivity be improved? It works for only a few centimeters
I am using an electret microphone with the preamplifier circuit attached below. The problem is that the microphone works only when I speak very closely to the microphone. If I speak from a distance, ...
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Excessive DC offset in high-speed opamp amplifier circuit
Background
A while ago I got my dad's old Musical Fidelity A1 MKI integrated amplifier from the early 80s (I believe). I found a blog that featured a lot of interesting information about this ...
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Trying to record from DIY op-amp results in seldom pops and clicks
I have a 741-based audio amplifier PCB here from the 70s:
When I tried to test it, I powered it with a 24V battery (I tried 12V as well with no difference,) then I shorted pins 15-19, connected the ...
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Voltage Buffer Vs Impedance matching
I am designing an Amplifier circuit for the microphone. For this, I am using a buffer in between two stages for isolation and I am confused between 2 circuits. I know, in voltage buffer circuits, the ...
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Output-Z (electret) higher than Input-Z (preamp)
What happens if an electret microphone capsule (JFET in catridge) is connected to a preamp with considerably lower input impedance than the capsule's output impedance itself?
ECM output Z: 2.2K
Preamp ...
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Understanding this MM/MC discrete phono stage
I am challenging myself at understanding my integrated amp's MM/MC phono stage; The amp is a Rega Elicit mk. I. It is a somewhat complex design and as a hobbyist I'm out of my league. The circuit ...
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Something about the impedances of charge amplifiers
it is my understanding that due to the effect of virtual grounding, the input impedance of a charge amplifier is basically zero. If that's the case, then is there any reason to even worry about the ...
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Extremely Noisy Preamp Circuit on Breadboard (EDIT: Oscillation?)
I built a simple circuit (included below) on a breadboard and have been having some trouble with noise. Generally speaking, I get what seems like random noise averaging at about 1.5Vpp. Otherwise, I'm ...
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Why am I getting this distortion in this circuit?
Can someone explain to me why I am getting this distortion for the following circuit? Input is a pure square wave. It happens at any input frequency or voltage. I was thinking the output would be a ...
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No Output for Preamp circuit in TINA
Is this a spice problem or a design(me) problem? The rails are producing the expected 9 and -9 volts, but nothing is coming through on the output. I haven't ever done op amps without a bias voltage ...
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Suggestions for Improving this Pre-amp Circuit
I made this preamp circuit for a dynamic mic and am mostly happy with it, but I'd love to get suggestions on how to make it a little better. I'd like it to have as little coloration as possible, and ...
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Why Am I Not Getting my Expected Output in this basic Op-Amp Circuit?
I thought that A = 1 + Rf/Ri for an op-amp non-inverting amplifier? With a 1mV input, I'm getting output voltages in the uVs...
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Microphone pre-amplifier op-Amp outputs larger voltage when Mic RL is larger
I am following TI's pdf Non-inverting microphone pre-amplifier circuit with AOM-4544P-2-R microphone. I probe the circuit on the Vout after the op-amp, (not on the mic directly). I am playing around ...
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Old Zener diode codes
I am trying to identify another Zener diode from a wem pa 100 pre amp, there is no spec on any of the various schematics I have seen, or to think of it there is never any on any WEM schematic for any ...
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Bats ultrasounds detector with LM324
I have some questions about this small project, a device to detect bat ultrasounds and reproduce in a speaker. It's based in a post of the Element14 community, Episode 578. I have adapted it and I'm ...
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Suggestion about drag and amplify pulse
Following picture is Photodiode I/V pre-amp of my circuit
My target pulse from OPA356 output, which range is 15mVpp /130ns-width to ...
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How can a resonance circuit work as a current amplifier?
I have been working on current amplifiers for my RF circuit. I was thinking about pre-amplifying the current by a tank circuit. The input of the circuit is just a mp3 player, which has not much ...
user321220
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Is there a risk of a DIY pre amp damaging a microphone?
I'm looking for a preamplifier to use with an aquarian A1S hydrophone. This is an application where signal integrity is not very important and we're going to filter and do a fourier transform on the ...
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How does this microphone preamplifier work?
This preamplifier circuit is designed by Andy Collinson for dynamic microphones. I can't understand how it works.
Why is the microphone input connected to the emitter of Q1 instead of the base?
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Standards for measuring analog audio signal devices
I'm making a Analog Channel Strip for a project. I'm searching for standards that let me or give me an advice of how to measure Dynamic Range, THD and THD+N, SNR, Frequency Response and input/output ...
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Combining a mono signal with a stereo signal
I'm creating a stage sound system
I have already created a preamp for the microphone and led the connector through which I will feed the music. Now I need to mix music with a preamp. The problem is ...
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Non-inverting NE5532 with 1.56 gain not working
I made 4 preamp's for laptops and cellphones using 2 NE5532 IC's. The expected gain is 1.56 so, I used a 5.6K resistor as the feedback one and a 10K from the inverting input to a 47uF bipolar ...
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Noise problem in preamp to digital processor
I'm building a guitar audio processor. I inherited this circuit from someone else's project. I am seeing a significant amount of noise on the input. I digitize the input using a 16b ADC and clip to ...
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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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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 ...
user132893
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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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