Gain calculation


#1

Hey guys,
I am educating myself in this world of Wi-Fi audio and amplification.

My system has a DSJ + a preamp + bhk300s (these ones eargely anticipated).

Reading the technical specs, I understand that Dsj’s output voltage in low mode is 0.340v for balanced output. My preamp has a 12db gain for balanced input-output. Therefore, the maximum output after the preamp should be 1.2v (roughly 4 times the input voltage). This 1.2v would be enough to drive we BHKs past 200w@8ohms.

Am I correct?

Regards


#2

Yes, your math is correct. The BHK has a gain of 30.5dB which would yield 40V over 8 ohms.

I recommend that you set the DSjr in high output mode with the DACs volume maxed when using an active preamp. This will give you the best S/N and headroom. Remember, the spec’d output voltage is in reference to 0dBfs. Most information on a recording that has a high dynamic range will be much lower than this.


#3

Darren,
Thank you very much. I was keeping the DSJ at low output so that I could med out the preamp’s pot. My point is that using the DAC to attenuate the signal is potentially less harmful than using the preamp’s pot. Also, this avoids the DSJ noise floor.

I will experiment with the setting you suggested.

Regards.


#4

The high/low gain settings are done in the analog domain so the noise floor will move with these settings. The overall S/N ratio should roughly be the same, however.

When lowering the gain using the volume control, so that you are no longer maxed out at 100, the DSjr noise floor will not move relative to the signal. So not maxing the DSjr out and then adding analog gain afterwords to make up for it will effectively lower the S/N ratio of the system.


#5

Let me see if I got this right. With the DSJ volume at 100, S/N is the same whether the attenuator be on or off.

This way, I should be better off applying less gain down the chain, so to keep that optimum S/N, than turning down DSJ volume and applying more gain on the preamp.

Is that it?


#6

Yes, that’s correct. But I still recommend people try things both ways, if you can’t hear a difference do whatever’s logical to you, and if you do hear a difference you have your answer.


#7

Will do. Thanks for the advice.