I'm building prototypes for cheap conference interpreter consoles using off the shelf modules including ne5532 op-amp based pre-amplifers for both headphone preamps and mic preamps. I've got two working prototypes and am now working on cutting noise and looking to see how I can refind the design to reduce component cost and improve ease of assembly.
There is no need for stereo in the design and the conference floor input would usually be mono, as would the output for transmission to the audience. However,, in my prototypes all of the audio signal switching components, and most of the pre-amp modules I used, are stereo.
In the case of the headphone pre-amp, I have successfully used two individual mono audio signals at the input, and split the output to two independent sets of headphones (the design spec requires two headphones with their own volume control and input channel selection). Doing this means one less pre-amp is required but adds a lot of faffing about making custom cables to join and split the audio signals.
On the microphone I've just shorted together the 'left' and "right' channels on the import from the mic. This means the output is two identical audio channels but not true mono as such. Since the audio signal switching elements of the design currently carry 2 channel audio signals using three wires, the two identical signals are retained internally to the output bus connectors which are RCA pairs. Since both channels contain the same mono signal, I can take mono from any one RCA but I guess at half the potential amplitude.
I'm wondering if I can safely 'bridge' the output of the NE5532 amplifier for full power by simply joining the Left and Right channel, or will they cancel each other out or cause damage or distortion?
If I can bridge the outputs safely then I could look to use single channel switching components to potentially reduce component cost. I could also bridge the headphone preamps, using two pre-amps instead of one but with a lot less additional complication with custom cables.
The two amp modules I'm currently using (sources from AliExpress) are the XH-A902 (for the mix preamp) and the single power supply dual ne5532 pre-amplifer board (for the headphones).
I'm also keen to learn how to deal with capacitive coupling as I get a nasty hum when I touch the metal microphone case, and it is greatly attenuated when I also touch some parts of the console itself. The power supply is unearthed and always will be so earthing is a problem (is this called floating earth?).
Anyhow, that's it for now.
There is no need for stereo in the design and the conference floor input would usually be mono, as would the output for transmission to the audience. However,, in my prototypes all of the audio signal switching components, and most of the pre-amp modules I used, are stereo.
In the case of the headphone pre-amp, I have successfully used two individual mono audio signals at the input, and split the output to two independent sets of headphones (the design spec requires two headphones with their own volume control and input channel selection). Doing this means one less pre-amp is required but adds a lot of faffing about making custom cables to join and split the audio signals.
On the microphone I've just shorted together the 'left' and "right' channels on the import from the mic. This means the output is two identical audio channels but not true mono as such. Since the audio signal switching elements of the design currently carry 2 channel audio signals using three wires, the two identical signals are retained internally to the output bus connectors which are RCA pairs. Since both channels contain the same mono signal, I can take mono from any one RCA but I guess at half the potential amplitude.
I'm wondering if I can safely 'bridge' the output of the NE5532 amplifier for full power by simply joining the Left and Right channel, or will they cancel each other out or cause damage or distortion?
If I can bridge the outputs safely then I could look to use single channel switching components to potentially reduce component cost. I could also bridge the headphone preamps, using two pre-amps instead of one but with a lot less additional complication with custom cables.
The two amp modules I'm currently using (sources from AliExpress) are the XH-A902 (for the mix preamp) and the single power supply dual ne5532 pre-amplifer board (for the headphones).
I'm also keen to learn how to deal with capacitive coupling as I get a nasty hum when I touch the metal microphone case, and it is greatly attenuated when I also touch some parts of the console itself. The power supply is unearthed and always will be so earthing is a problem (is this called floating earth?).
Anyhow, that's it for now.