Topic: Simple question about HP line level

I have a simple question, the original ADI-2 (rack mountable, blue and silver) headphones out is quite powerful. I'm currently using it for headphones as well as sometimes for line-in to a consumer integrated amplifier..

The question is, at what point do I get a line-level signal out of the headphones output? Ie how much gain needs to be applied to the headphones gain knob for it to push out a line-level equivalent signal ?

2

Re: Simple question about HP line level

Define your personal line level first. -10 dBV? +4 dBu?+19 dBu? And you can easily measure this yourself by a loopback cabling into the input where the ref level gives a defined value.

Regards
Matthias Carstens
RME

3 (edited by torbenscharling 2021-05-25 15:39:53)

Re: Simple question about HP line level

MC wrote:

Define your personal line level first. -10 dBV? +4 dBu?+19 dBu? And you can easily measure this yourself by a loopback cabling into the input where the ref level gives a defined value.

Excuse me? Consumer gear uses -10 dBV

If anyone has the info I need, please provide. Should be in the manual, since it's not, I would assume an RME engineer would know, and thus be able to provide the customer with the correct information. Forget about measuring anything.

4 (edited by KSTR 2021-05-25 18:21:21)

Re: Simple question about HP line level

It is in the manual, though a bit hidden.
Full clockwise, PH out is +19dBu @0dBFS, as is line out in "Hi Gain" mode. In "-10dBV" mode line out goes down to +2dBV @0dBFS, so a headroom of 12dB.
Hence dial in the volume knob to result in 14.8dB (+19dBu=+16.8dBV, so correction needed is +16.8dB - +2dB = 14.8dB) less signal than fully clockwise. How do you do that? Measure (-14.8dB=18.2%), in some way or another ;-)

5 (edited by torbenscharling 2021-05-26 10:41:02)

Re: Simple question about HP line level

KSTR wrote:

It is in the manual, though a bit hidden.
Full clockwise, PH out is +19dBu @0dBFS, as is line out in "Hi Gain" mode. In "-10dBV" mode line out goes down to +2dBV @0dBFS, so a headroom of 12dB.
Hence dial in the volume knob to result in 14.8dB (+19dBu=+16.8dBV, so correction needed is +16.8dB - +2dB = 14.8dB) less signal than fully clockwise. How do you do that? Measure (-14.8dB=18.2%), in some way or another ;-)


Thanks for that explanation. So it's not in the manual, as stated.

Kinda funny (and a little bit sad for human kind) that no one can answer this simple question other than "measure" smile

6 (edited by KaiS 2021-05-27 09:03:22)

Re: Simple question about HP line level

torbenscharling wrote:
KSTR wrote:

It is in the manual, though a bit hidden.
Full clockwise, PH out is +19dBu @0dBFS, as is line out in "Hi Gain" mode. In "-10dBV" mode line out goes down to +2dBV @0dBFS, so a headroom of 12dB.
Hence dial in the volume knob to result in 14.8dB (+19dBu=+16.8dBV, so correction needed is +16.8dB - +2dB = 14.8dB) less signal than fully clockwise. How do you do that? Measure (-14.8dB=18.2%), in some way or another ;-)


Thanks for that explanation. So it's not in the manual, as stated.

Kinda funny (and a little bit sad for human kind) that no one can answer this simple question other than "measure" smile

Because there is no reproducible way to set the volume knob other than full, the only way to set an exact level is measuring.

MC already suggested, the use of the loopback to ADI-2’s inputs makes for a quite precise measurement.


On the other hand:
A common standard consumer line level does not exist.

If you go for the Tascam level -10 dBV you have to keep in mind that this level is meant to be used with analog tape machines which have a headroom of about 12 dB for peaks above reference level.
Therefore: -10 dBV + 12dB = +2 dBV =~ +4 dBu.

There is a preset on ADI-2 for +4 dBu reference level for the line out.
Now compare, and set the same loudness for headphones out, done.


BTW: a typical CD player puts out +8.2 dBu (2 V).


Annotation:
dBV is referenced to 1 V
dBu is referenced to 0.775 V (or 1 mW into 600 Ohms)

Re: Simple question about HP line level

And if you want to do some calculations, use the Sengpiel tools:
http://www.sengpielaudio.com/Rechner-db-volt.htm

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13

Re: Simple question about HP line level

The approximate position of the volume knob can be set, assuming a standard log pot in a standard circuit here. I've mentioned 18% of full scale level, and that is at ~60% of rotational electrical travel. So, at about 1 o'clock position.