All Questions
60
questions
0
votes
2
answers
86
views
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 ...
- 2,088
1
vote
0
answers
79
views
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) ...
- 111
1
vote
2
answers
209
views
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 ...
2
votes
2
answers
106
views
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 ...
0
votes
1
answer
135
views
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 ...
- 91
0
votes
1
answer
103
views
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 ...
- 5
0
votes
1
answer
103
views
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 ...
2
votes
1
answer
117
views
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 ...
0
votes
2
answers
219
views
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 ...
- 447
0
votes
1
answer
67
views
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 ...
- 131
3
votes
1
answer
2k
views
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 ...
- 41
1
vote
1
answer
56
views
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 ...
- 13
4
votes
4
answers
239
views
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 ...
- 63
2
votes
1
answer
490
views
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. ...
- 215
0
votes
0
answers
197
views
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,...
