dB volume level for 1.5v RMS output on Bartok

This is probably a question for one of the dCS engineers.

On the Bartok one of the line level output settings is 2v RMS, when the volume control on the Bartok is set to 0dB.

If you would like 1.5v RMS at output what level in dB do you need to set the Bartok volume knob after setting the line level setting to 2v RMS?

As the volume is on a logarithmic scale it is difficult to set this or work it out without measuring the output with a test signal and a oscilloscope.

dCS can you help?


Hi Qrio and welcome to the forum.

I am not a dCS engineer , only one of the members here.

In a way there isn’t a straightforward answer to your question and I wonder what you are trying to achieve. The output voltage depends not only on the line level voltage chosen and the setting of the volume control but also on the modulation level of the program being played. Normally this may vary from one file to another and also throughout a piece of music. You will only get 2V output ( if that is selected) when processing a signal modulated at the maximum level of 0.0dBfs. However this is normally going to be an unknown to you. That level may also rarely be reached with well engineered practical music files . However it can be reached with some rock/pop material which has fallen victim to the “loudness wars” but even then it may be briefly ( albeit repeatedly) .

So if you have set line level voltage to 2v and set the volume control to -2.5dB ( the approximate difference between 2v and 1.5V) Bartok won’t necessarily output 1.5V. It depends upon the program. You could only guarantee that output voltage with a test file where all samples are at 0.0dBfs.

Thanks Pete.

I understand what you are saying.

The reason why I’m looking for the RMS value of 1.5v at the output is due to the equipment connected at the analogue outputs of the Bartok is critical to having this max value. If the value is higher then it will clip (if the signal is large enough), causing distortion further down the chain.

This can probably be programmed in a future software release, currently a value in dB will suffice as this can be set with the volume knob.

Then if it clips at voltages in excess of 1.5V the answer is to select the line level output of 0.6V with Bartok.

I wonder exactly what you mean by clipping at 1.5V as most correctly engineered inputs rated at that input sensitivity will have an overload capability well able to encompass a 2 V maximum input (which is the redbook specified output of a standard CD player). As I have mentioned the difference between 1.5 V and 2.0 V is only 2.5dB which would be a very low overload capability. So I assume that the input sensitivity specified by the manufacturer is well below 1.5V. Is that correct?

It can reach peaks of 1.5v RMS, anything above will clip. 0.6v will be too low.

“So I assume that the input sensitivity specified by the manufacturer is well below 1.5V. Is that correct?”

It will have some tolerance, but the exact value isn’t specified.

“As I have mentioned the difference between 1.5 V and 2.0 V is only 2.5dB which would be a very low overload capability.”

How did you calculate 2.5dB attenuation will give 1.5v RMS at output?

It is the ratio expressed in dB between the two voltage values and is calculated using an equation. For ease you can find calculators online.

I remain unsure about your concerns from a practical level. You are saying in absolute terms that an output of 0.6v is too low to be of use and that any output above 1.5V such as 2V is too high to be of use. If correct that effectively gives you a dynamic range of only approx 8dB ( the ratio in dB between the two voltages). That is impractical.

As I mentioned earlier I wonder what you mean by “clip”. When an input sensitivity is stated as e.g 1.5 V it does not mean that a voltage below that will not be sufficient nor that a voltage above that will clip. It means that the stated voltage will produce a total of distortion and noise at a predetermined level ( e.g. 0.01%). Clipping is not usually considered as being reached until that figure reaches 1%. So are you saying that your analogue equipment will be satisfactory at 1.5V ( e.g. THD+N = 0.01%) but with half a volt more input that THD+N figure leaps to 1%?

I wonder if you are simply reading the figures and thinking that they all have to match exactly as if the output voltage figure of Bartok is a sort of key that will only fit the lock of an input that has the same figure?

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I managed to get a response from dCS, so the theoretical matches practical- 2.5dB reduction is measured with a full scale signal for 1.5v output. That is quite something as they are usually a bit off.

Pete, I thank you.

I think you are getting into too much detail for what I was asking. I don’t want to get into deep dive mathematics which involves Laplace transform / Fourier analyses to the equipment that the Bartok is connected. Plus I don’t have the lab equipment to test.