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[alfredokiwi]

This topic is a response about a user complain on its Radias due low output levels on his recordings. Here I want to share my point of view, because is important to detect this issue on recordings & mixing.

"Signals leveling and matching between audio stages is the main problem on studio setup. Dynamic ranges refers to the variation between quiet and loud sound or volume. A good design should follow a normalization of outputs levels and impedance matching.

On my blog at www.alfredoblogspage.blogspot.com.ar is explained the findings on R3 and Pa500 keyboards, both with low levels on its outputs.

The reference voltage for the decibel volt (0 dBV) is 1 VRMS, which is the voltage required to produce 1 milliwatt [mW] of power across a 1 kilohm [kΩ] load. The most common nominal level for consumer audio equipment is −10 dBV, and the most common nominal level for professional equipment is +4 dBu. But for mixing consoles +6dBu is the normal value.

Here a table from wikipedia about the different levels

ARD, Germany +6 dBu -> 4.384 Volts peak to peak
Professional audio +4 dBu -> 3.474 Volts peak to peak
Consumer audio -10 dBV -> 0.894 Volts peak to peak

And this situation is what confuses manufacturers when deciding to set output levels on its products. For me the best is to set the line outs at maximal +6dBu or 4.38 volts and use an external attenuator in the case of an consumer audio amplifier (home theater, VCR, TV sets) to reduce the excess of signal. The problem is the lack of levels when a product is set for a consumer audio appliance (0.894 volts) versus the nominal value for a mixing console (4.34 volts) a big difference !!!, an this mismatch affects professional studio products.

In the case of Korg keyboards Pa500 and R3 they come with very low levels, maybe to connect it to a home theater, affecting dynamic range and final quality on recordings using a mixer that requires more output.

One example and its solution, at home I have an Behringer MX1602 mixer and Emu 0404 PCI card for recordings. On the setup it was impossible to reach maximal dynamic range.

The problem was an mismatch of impedance's + levels between the Behringer console and Emu PCI card, despite that they follow a standard. Because the Behinger console delivers more output levels as required I put an external passive attenuator resolving the issue. Using the main mixer faders to reduce output levels don´t resolved the issue, because I connected the EMU card on the "main inserts" and the only solution was to correct is passively via resistors.

Reaching a good dynamic range is not easy and more when impedance mismatch + leveling differences are present between devices/audio stages, it not depends only to have maximal volume.

The key is to have maximal sound variation or "dynamic range".

Allan Parsons Project was one of the followers of "dynamic range" quality on his music, he says that this aspect is very important in any professional track/recordings."

An example about R3 before and after circuit corrections


After correcting levels + improving the DAC output stages

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