Sometimes there is need to convert the line level signals to a signal level that can be connected to your microphone input. Because the line level signals are typically in the range of 0.5 to 2 VAC and the microphone signals are in the.00245 VAC or millivolt range. You will need to attenuate the line level signal to match the microphone level. Hi folks, I want to run the audio (Line Output) from my mixer (Behringer USB1204FX) to the MIC input of my HF R400 video camera. Even after some research I still do not know which attenuator specifactions or products are compatible with my HF R400.
Are you confused by line level versus mic level? Well, you're not alone. We're often asked to explain the difference. Simply stated, these both refer to the voltage level of an audio signal.Wired and wireless microphones are typically connected to mic-level inputs, whereas most other audio devices use line level. (We'll get to instrument- and speaker-level signals in a minute.) The voltage of each signal type varies significantly, however, making it important to know how they differ.What is mic level?A mic-level or microphone-level signal describes the voltage generated by a microphone when it picks up sound, typically just a few thousandths of a volt. This voltage varies in response to changes in sound level and distance.
Of the four main types of audio signals, mic level is the weakest and requires a pre-amplifier to bring it up to line level. Microphone levelis usually specified between -60 and -40 dBu. (dBu and dBV are decibel measurements relative to voltage.)Several different types of devices are used to boost microphone levels to line- level signals. Mixers are probably the most popular piece of equipment, since they can also combine multiple signals together into a single output. But preamplifiers and mic-to-line amplifiers do the job just as well and are available as single-channel or multi-channel devices.What is line level?A line-level signal is approximately one volt, or about 1,000 times as strong as a mic-level signal, so the two do not ordinarily use the same input. This signal travels from your pre-amp to the amplifier that powers your speakers.There are two standard line levels:.10 dBV for consumer equipment (like MP3 and DVD players). +4 dBu for professional equipment (mixing desks and signal processing gear)The other two types of audio signals you'll run into are instrument and speaker levels.
Like mic-level signals, instrument-level signals (such as an electric guitar or bass) require preamplification to bring them up to line level. Post-amplification speaker-level signals are even higher in voltage than line level and require speaker cables for safe signal transfer.Matching LevelsIt's crucial to match a device to the correct input, since there's no real technical tolerance for mistakes. For example:. Connecting a microphone to a line-level input will result in almost no sound at all, because the mic-level signal is too weak to drive the line-level input. Connecting a line-level source to a mic-level input will cause the sound to be loud and distorted because the line-level signal is much stronger than what the mic input will accept.
(Note: Inputs and outputs on some higher-end mixers are mic and line level switchable.)Helpful Hints. A mic- level input is typically a female XLR connector. A line- level input is typically an RCA jack, 1/4' phone jack, or 3.5 mm phone jack. Don't assume that the levels match just because one connector fits properly with another.
Inputs are generally very clearly marked. If there is only a mic input on a device (for example, a digital recorder or a computer) and you need to connect a line level device to it, you can reduce the voltage by using an attenuator or a DI (Direct Injection) box, available at most music stores. There are even cable versions with built-in resistors that accomplish the same task.
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Different wireless receivers have different output levels. This is true for the Shure line of products and with most competitor brands. Consult the user guide of each wireless receiver to determine its output signal level. Miclevel can vary as much as 20 dB between different receivers. Justin BollerJustin Boller is an Applications Engineer at Shure Incorporated by day, assisting customers with product selection, system design, and troubleshooting.
By night he is a professional musician, performing on tuba, electric and acoustic bass, guitar, trombone, and other instruments in various musical ensembles. He holds a B.S. In Music and an M.S. In Arts Technology from Illinois State University. When there's any spare time, he also enjoys tinkering with electronics, cycling, and cooking on the grill. Further Reading.
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A place to discuss DIY audio, share plans and schematics, and link to interesting projects. Just keep in mind impedance matching, I’m not sure what the impedance of your input and outputs are but sometimes you have to keep this in mind.
A basic attenuator will probably work with modern equipment, but you never know. An impedance mismatch can lead to poor power transmission, distortion, and noise. But if you’re saying you already made a cable like this before and it sounded fine, ignore all that.Check out this link if you want some more info about what you’re working on:But yeah, your idea of just swapping out one of the resistors might not work. The resistance values all need to change in relation to each other, and it’s usually not linear. The link I posted above also talks a bit about this. You’d probably want to just buy something already made, doing a non-linear adjustment of three resistors can get a bit tricky.
Its kind of a long story, but I'm building this for a friend, he found some 90s broadcast 1U microphone mixers, wants to use them as gritty summing mixers in his studio. Therefore he needs 8 of these attenuators (looking around they go for about 30$ each, he bought the mixers for $50). They also need to be relatively matched in pairs of two (for stereo) which is one of the reasons I was thinking of a pots/trimmers.He's coming out of his Apogee Rosetta 800 into the mixers but running into line vs mic issues.The Rosetta should have an output impedence between 50-75ohms and the mixers (i'm assuming are designed for dynamic mics since its broadcast and no phantom power) should have an input impedance around 200-300 ohms.
A good input:output impedance ratio is around 10:1, so you’re already pretty close. Plus if what you’re looking for is that “gritty” sound, you might not hear the distortions. I’d say you probably don’t have to worry about it too much.I’m not saying there isn’t a cheap and simple solution, I just personally don’t know any. My background is more on the theoretical side of things, so I usually just follow best practices.
The line - mic level adjustment for mixing is a bit wonky, and sometimes to perfect wonkiness it takes a bit of cash. I’ll keep digging around though, and let you know if I find anything.
What you're calling the bridging resistor is called the shunt resistor. It sets the output impedance of the signal and should probably be in the range of 100-200 ohms.100 ohms gives you -53 dB of attinuation150 ohms gives you -50 dB of attinuation200 ohms gives you -47 dB of attinuation.1500 ohms gives you -30 dBTo get -30 dB to -50 dB you'd need a pot between 1500 and 150. However, this is high impedance for a microphone signal.
I'm reading that you are supposed to stay under 200 ohms.Let's do this experiment again using a fixed shunt resistor and floating values for the series resistors. Let's assume 150 ohms for the shunt resistor. Then for -50 dB you'd need a pair of 47k series resistors. For -30 dB you'd need a pair of 4.7k series resistors.To build this you could use a ganged 50k log taper potentiometer like. I would wire a 150 ohm resistor in series with each leg of potentiometer unless it has stops that prevent it from trimming all the way to a short.
This would give you an attinuator between 0-50 dB. If you wired a 4.7k resistor in series instead you could get the 30-50 that you were originally requesting.
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