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.
193
questions
0
votes
0
answers
63
views
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, ...
- 133
0
votes
1
answer
110
views
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 ...
- 201
2
votes
1
answer
90
views
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 ...
- 3,463
0
votes
1
answer
112
views
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 ...
- 101
1
vote
1
answer
511
views
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 ...
- 171
0
votes
1
answer
283
views
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 ...
- 29
2
votes
1
answer
142
views
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....
- 29
1
vote
3
answers
665
views
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 ...
- 21
0
votes
0
answers
352
views
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.
...
- 708
-2
votes
1
answer
105
views
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 ...
user268029
0
votes
2
answers
165
views
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 ...
- 93
0
votes
1
answer
231
views
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 ...
- 489
0
votes
3
answers
111
views
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 ...
- 231
2
votes
3
answers
4k
views
How to build a low noise MIC preamp
I want to be able to talk on the microphone of my Headset A and send that signal out to the earphones of my Headset B. Something similar to what I show you on the image below.
For that purpose, I ...
- 123
0
votes
0
answers
166
views
AV Receiver playing music using RCA Analog input (AUX) from Mobile 3.5 mm stereo source
I have a pioneer AV Receiver VSX-832-K with RCA AUX INPUT "input (Sensitive/Impendency ) 200mv/47K ohm"
issue :
when i am trying to play music from mobile using 3.5 mm headphone jack using ...
2
votes
1
answer
287
views
Does the type of preamplifier used for a piezoelectric sensor change its physical resonant frequency?
Two common amplifier circuits used for piezoelectric sensors are voltage amplifiers and charge amplifiers (pictured respectively).
With the charge amplifier, the sensor is shorted but this is not the ...
- 121
0
votes
1
answer
64
views
Signal distortion in simulation of a current to voltage converter
I'm trying to simulate a current-to-voltage preamplifier as part of a circuit I'm building. The current signals I'm working with range from pico-amps to nano-amps. With a gain of \$10^8\$ ohms, a 50 ...
0
votes
0
answers
192
views
How To Make A Two-Channel Audio Mixer?
I'd like to make a 2-channel audio mixer. I'll connect one of the entrances to my phone with an aux cord. I'm going to put my headphone mic on the other one. I'll also connect a potentiometer to both ...
- 1
1
vote
3
answers
729
views
Panning between two active audio signals
I want to have a circuit that pans between both my active pickups.
I have designed a simple summing opamp with a 50k center click potentiometer acting as a panner but even though it worked, when at ...
- 21
2
votes
2
answers
996
views
Electret microphone preamp is buzzing , weird noise and cannot find a solution
I'm building an electret microphone pre-amp following this application note, the output of the preamp is connected to an LM386 and then to some headphones.
So my pre-amp circuit looks like this, where ...
- 31
-1
votes
3
answers
230
views
How do I design preamplifier and amplifier (for a speaker) circuits from scratch? [closed]
I am 3rd year electronics student.
I want to design a speaker from the circuit level.
As this is my first time, I have no clear idea how to start and where to start.
Can anyone please suggest to me ...
1
vote
1
answer
153
views
Troubles with mic preamp for headphones with integrated microphone
I am designing a preamp intended to interface with a microphone in common headphones (e.g. apple earpods, or sony headphones with a microphone) which will then connect to my ADC's inputs.
I've ...
- 11
0
votes
2
answers
147
views
Pre-amp connection problem
I am trying to complete the circuit shown above. I am having trouble as the ground connection is not clear to me. Please help me to complete that circuit.
And also tell me how to connect C5 ground ...
14
votes
1
answer
347
views
Why is there a winding on a capacitor?
I just came across this tube RIAA preamp on which there is a coil on the input capacitor, can someone please explain what's the reason of such thing? The schematic and the actual circuit bellow.
The ...
- 427
4
votes
2
answers
536
views
Ultra low noise charge sensitive preamplifier
I developing charge sensitive preamplifier for radiation detector. This is a very sensitive device, the smallest amount of noise can completely ruin the signal.
The schematic and the PCB you can see ...
- 91
1
vote
1
answer
378
views
Cartridge loading in Rodec phono stage
I saw a very strange design of phono stage in Rodec MX180 consoles. 3 generations of those mixers (mk1, mk2 and mk3) have this phono preamp on board!
They have an input filter with 1nF cap then 220 ...
- 231
0
votes
3
answers
214
views
Sound through the earphone is also sent to the amplifier when using a jack splitter after a audio mixer
I implemented the following audio mixer circuit with just 2 input audio sources:
http://www.theorycircuit.com/audio-mixer-circuit/
Both sounds got mixed properly.
Then, at the end of that audio ...
- 123
0
votes
0
answers
789
views
Ultra low noise power supply for pre-amp
I have designed the following power supply smoothing circuit for my turn table preamp. This will be powered by a 24V 'wall-wart' type adapter.
I tried to combine a transistor/zenner diode voltage ...
- 167
0
votes
0
answers
50
views
How to make a preamp that is ON when input is a MIC but OFF when a LINE level?
My question is very simple:
Is there a way to create a "preamp" circuit that is automatically ON when there is a MIC connected (for example, a desktop PC microphone) but OFF when there is a LINE ...
- 123
0
votes
2
answers
1k
views
TL082 electret preamp and LM386 power amp
I have spent the last few days trying to prototype a TL082 electret mic preamp (based on this schematic). I swapped the TL071 in ...
- 103
0
votes
2
answers
184
views
Need to identify this 3-pin Connector to a small amp. It's a Pre-Amp input
I could use the neighbouring 3.5mm stereo jack for sound input, but those connections are flimsy.
It's a 3-pin connector, 10mm long, 6mm wide and 7mm high with alignment slots on all sides but the ...
0
votes
1
answer
97
views
Safely connecting a preamp powered by a benchtop DC power supply to a power amp
I pulled the preamp out of a broken guitar combo amp. The preamp has positive, negative, and ground leads for powering it at +/-25V. I would like to power the preamp with a dual channel benchtop power ...
- 15
0
votes
1
answer
90
views
Alternative ways to step up voltage?
I want to drive an EOM crystal at 20 MHz for phase modulation. I recently bought a step up RF transformer (1:4 turns ratio), but it's not working fine above 2 MHz. I tried winding a transformer myself ...
- 1
1
vote
1
answer
226
views
Choosing an OpAmp for MEMS mic preamp stage
I am trying to create an updated version of a mems mic board, like this one from sparkfun. They use an INMP401 mems mic (which is not recommended for new designs) and an OPA344 for the preamp stage (...
- 426
0
votes
1
answer
2k
views
12AX7 Valve Overdrive/Distortion Effect Pedal
I'm following the schematic below using the recommendations plus a couple of extra LEDs. With the footswitch in the enabled position, I'm not getting any sound. In the bypass position, the input and ...
- 151
1
vote
1
answer
94
views
Help identifying a photodiode pre-amp PCB
Recently I found this PCB in a electronics junk bin. It's said that it's a photodiode preamp, but I was not able to find the datasheet or any information about the board.
Since the PCB looks neatly ...
0
votes
3
answers
434
views
Impedance match Fishman guitar pre-amp to IRIG2HD
I'm looking for some help in understanding impedance matching. I'm hoping one or more of you technically savvy electronics folks will jump in and give me a simple circuit recommendation.
...
- 3
0
votes
1
answer
124
views
Car microphone; very low signal
I would like to use a car microphone for bluetooth communication.
The mic is a BMW one: 84316938762.
The wiring diagram (TIS) marks the mic's two connectors for the pin 1 and 2: TIS (X18507).
...
- 947
2
votes
2
answers
320
views
Op-Amp output voltage exceeds the power rail voltage (in simulation)
I'm designing a RIAA pre-amplifier based on the 2 op-amps from an NE5532 package. It seems that something is wrong, because the output of the 2nd stage is giving a 400V output which is way above the ...
- 427
0
votes
1
answer
695
views
Simple 12V preamp circuit before speaker
In my apartment building, we have an intercom system with one central unit and multiple terminals, one per apartment. Unfortunately, after some unknown tweaks done a couple of years ago to the central ...
- 1
1
vote
0
answers
284
views
Guitar to iPhone JFET pre-amp circuit issue
I am following this tutorial to build a simple JFET pre-amp to connect a guitar to an iphone.
This is the schematic:
I have soldered the components as per the schematic directly onto the 1/4" mono ...
- 141
6
votes
1
answer
741
views
Designing 2-stage BJT CE class-A voltage pre-amplifier with specified goals and without global NFB
BJT CE Class-A Voltage Pre-Amplifier
Suppose a design requirement limits the selection choices to the following class-A BJT common emitter stage topologies. No global NFB is permitted. Only local NFB ...
- 77.2k
2
votes
1
answer
651
views
Op amp circuit with two capacitors
Based on an electronics lecture, we are dealing now with the preamplifier circuit for a detector. The figure is shown below.
Actual I am having the problem to understand the center operational ...
- 23
0
votes
1
answer
422
views
How to measure the output impedance of a valve preamp?
I was trying to measure the output impedance of a DIY preamp for the past couple of days without any luck. Each time, I got to the same result of around 3K3 ohm, which is unbelievably low.
This is ...
- 1
25
votes
7
answers
5k
views
What's the point in a preamp?
I'm talking in the context of guitar amps, but I assume that this question is relevant for any type of audio amplifier.
Very often in amplifier schematics I see two stages of amplification -- first, ...
- 714
2
votes
1
answer
1k
views
Attempting an audio pre-amplifier circuit with falstad.com
I'm new to electronics and discovered the falstad.com simulator. I wanted to model this audio pre-amplifier circuit:
So I went into falstad and drew this:
My pre-amplifier circuit on falstad
The ...
- 423
1
vote
2
answers
259
views
SparkFun Sound Detector Circuit Analysis
I would like to request some help in analyzing the op-amp circuit used by SparkFun here. I'm particularly interested in the pre-amplifier portion of this design.
The write-up included by SparkFun ...
- 175
1
vote
1
answer
2k
views
How to find feedback resistor value?
I want to implement typical guitar preamp scheme, like following:
I see, that it will have input impendance =2.2M...
- 405
0
votes
1
answer
127
views
Preamp Ground Loop Problem
I have built the blue circuit above for my microphone but the one of the problems I'm facing is that when I connect it to my laptop's audio input, it creates a humming sound. My assumption is there is ...
1
vote
2
answers
834
views
Troubleshooting TL071 to TA8207 100 Hertz hum
I worked out to build a pre-amplifier connected to a power driver in a single setups(a pcb). Problem arises when it's powered up. here are a few questions.
Setup has a TL071CP as preamp with a unity ...
- 205