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RME User Forum → ADI-2 & 2/4 Pro series, ADI-2 DAC series → ADI- 2 DAC FS voltage
Hey All- I'm sure this is very simple, but I'm not nearly as smart as you guys. What level would I set the volume at if I wanted to have 2 volts output? Thanks!
Install the upcoming firmware, then you can switch Volume Display to dBu scaling, use +2 dBu for XLR, +8 dBu for RCA.
(Remark: XLR is always 6 dB hotter than RCA).
Meanwhile:
• Switch off Auto Reference Level.
• Use Reference Level +7 dBu and Volume -5 dB for the XLR out.
• Use Reference Level +13 dBu and Volume -5 dB for the RCA out.
Less conservative, if you don‘t need any headroom for DSP functions you could:
• Use Reference Level +1 dBu and Volume +1 dB for the XLR out.
• Use Reference Level +7 dBu and Volume +1 dB for the RCA out.
You end up with 1.95 V, the closest to 2 V that can be set.
It’s not too complicated if you’re familiar with gain staging and digital audio formats.
Think of the ADI-2 as blocks:
• Digital Input (no headroom)
• Optional Sample Rate Converter (3-6 dB adjustable headroom)
• Digital Processing and Volume Control (24 dB headroom)
• DA-Conversion, digital part (no headroom)
• DAC chip’s analog stage (ca. 3 dB headroom)
• ADI-2’s analog output amplifier (DAC 18 dB, Pro 20 dB mechanical relay stepped gain staging)Practically the “Auto Reference Level” function does all necessary calculations and adjustments (digital volume and analog reference level) for you, so you just don’t need to care.
I found the above post of KaiS, which is a very clear and good explanation, perfect for understanding the DAC and Auto Ref level.
Still the 2 V question is clearly answered directly in the manual! Chapter 31.12.
Still the 2 V question is clearly answered directly in the manual! Chapter 31.12.
It is, but this chapter could mention the 6 dB hotter XLR level too.
That’s why I put this information into my reply with a clear cookbook advice, instead of heading to the manual.
The less technical minded user might take some time to work himself through the manual, if at all.
People want to do it right, sometimes are quite picky with their levels.
At least the level question comes up here very often, one way or the other.
Thank You!!
MC wrote:Still the 2 V question is clearly answered directly in the manual! Chapter 31.12.
It is, but this chapter could mention the 6 dB hotter XLR level too.
Well, the whole page there is based on RCA and mentions that XLR is +6 dB. But I get it - I will rewrite it to make that more clear and add the XLR voltages to the example list.
I did the rewrite in both Pro and DAC manuals, with text and a better table. Check it out...
2 Volts ar not 2 Volts
-RMS
-Peak-Peak
In chapter 31.12 its 2V RMS.
See here for conversion of Volts to dBu which I found several times very useful:
??? The 2 Volts in that chapter are RMS, because analog audio ref levels are always RMS. So 2 Volts are 2 Volts, and nobody needs a discussion there about how to measure on a physical/theoretical level.
Or I didn't get your point.
I am in electronics, so I like to mention what is is, RMS, Peak-Peak or zero to Peak.
May be I am to picky 
Probably the question “Peak to Peak” or RMS voltage arises, because some manufacturers like FIIO started to specify their levels in p-p, “Peak to Peak”.
You get nice high figure out of an average capable output, using this unconventional method:
E.g. a standard measurement of 2 V RMS turns into 5.7 V p-p, with the same device, a difference of 9 dB, looking nice in the specsheet.
The power difference is even more dramatic:
Real existing 125 mW RMS turn into fictional full 1000 mW p-p, an increase of 800% for free, isn’t that great!
Fictional, because this power isn’t delivered at any time in reality, not even during short peaks in the music.
Calculating the same way for ADI-2 Pro balanced headphones output you’d get 55 V p-p and 23.2 W p-p, per channel, equals 46.4 W, out of a 20 W PSU!
The real figures, BTW, are 19.5 V and 2.9 W RMS.
Here you can see what is measured, and a detailed explanation.
RMS voltage is good for calculating power.
Peak-to-Peak to be observed to avoid clipping.
Okay we know now, voltage refers to RMS in general audio specs.
RME User Forum → ADI-2 & 2/4 Pro series, ADI-2 DAC series → ADI- 2 DAC FS voltage
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