#### mononoaware

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Hi everyone, (Sorry mistakes edited)

After reading many forum threads online and with the help of calculators etc, calculations made but think I have some errors.

I apologise for the long post, I will do my best to keep it concise.

With the limited specifications available, I would like to know how much each 'click' of the DAC volume (level 1-37) will come out of the 1x Monoblock Power Amplifier into the 1x speaker as "watts RMS into 8ohms".

Here is the setup I would like to try:

DAC (SMSL SU-8) RCA Output > RCA cable > Monoblock Power Amplifier RCA Input > Speaker wire > Low Power-handling Speaker (Fostex FE103NV driver in enclosure)

I am aware of the risks involved connecting DAC direct to Power Amp (unintended DAC volume level risk), and the risk of connecting High-Power Amplifier to Low Power-handling speaker (unintended gain level cooking speaker voice coils).

I would like to confirm calculations before I connect everything together.

(1x Digital-to-Analog Converter)

- RCA Output at Max volume: (Unbalanced) 2.1Vrms

- Volume Control Steps: 37

(1x Monoblock Power Amplifier)

- Rated output power: 20Hz-20kHz, THD+N<0.1%, 4Ω 300W

- Voltage gain: 1 kHz 31 dB

- Input Impedance: 10 kΩ

(1x Speaker in enclosure)

- Impedance: 8Ω

- Rated Input: 5W

- Max Input: 15W

Converting 1x Monoblock rated power into 8Ω should be around 150watts RMS (half).

= Converted Rated output power: 20Hz-20kHz, THD+N<0.1%,

After reading online that Voltage is more important factor of power.

Using this calculator (Convert Decibels to Voltage Gain / Loss): http://www.sengpielaudio.com/calculator-gainloss.htm

31dB gain = 35.48 volts.

Then using calculator: https://www.rapidtables.com/calc/electric/watt-volt-amp-calculator.html

I entered 2 values: "8" ohms and "35.48" volts, clicked calculate which gives "4.435" amps and "157.35" watts.

Confirmed this by 35.48^2 / 8 = 157.35.

Vin (v) = Vmax/linear gain

To find "Maximum output voltage (Vmax)" of 157.35W @ 8Ω.

Vmax = sqrt (157.35x8) = 35.479v

Then this equation to find "Linear Gain (Y)":

"XdB: 10^(X/20) = Y" so "31dB: 10^(31/20) = 35.48x".)

So Linear Gain is

https://www.audiosciencereview.com/...rstanding-gain-on-power-amp.11309/post-322681

Then using the reverse to confirm 20 * log(35.5) = 31.004dB (31dB Specification).

Vin (v) = 35.479 / 35.5 = 0.999v

Input Sensitivity = 0.999v

So 1x Monoblock Vmax (157.35W / 8Ω / 35.48v) is achieved at just 0.999v RCA input.

0.999 / 2.11 x 100 = 47% volume level = 100% output from 1x Monoblock.

Which means only (slightly less than) half of the DAC's 2.1Vrms Max output can be used (37 x 0.47 = 17.52), which means only 17.52 steps of volume from volume level 1.

0.999 / 17.52 = 0.057v per step of DAC volume.

Then going back to the linked Calculator (Voltage and Gain): http://www.sengpielaudio.com/calculator-gainloss.htm

And entering 2 values: "31" dB, "0.057" volts. Gives 2.022 volts increase from Monoblock per step of DAC volume.

Then going back to this Calculator: https://www.rapidtables.com/calc/electric/watt-volt-amp-calculator.html

And entering 2 values: "8" ohms, "2.022" volts. Gives 0.511 watts RMS @ 8 ohms per step of DAC volume.

So each volume "click" from "level 1" of the SMSL SU-8 DAC should theoretically increase the RMS output from the 1x Monoblock amplifier to 1x speaker by:

Which means using the DAC volume, 10 clicks DAC volume =

Does this all seem sound?

Are there are any errors, or do you notice I am doing something wrong?

Thanks again if you made it this far.

After reading many forum threads online and with the help of calculators etc, calculations made but think I have some errors.

I apologise for the long post, I will do my best to keep it concise.

**Objective:**With the limited specifications available, I would like to know how much each 'click' of the DAC volume (level 1-37) will come out of the 1x Monoblock Power Amplifier into the 1x speaker as "watts RMS into 8ohms".

Here is the setup I would like to try:

DAC (SMSL SU-8) RCA Output > RCA cable > Monoblock Power Amplifier RCA Input > Speaker wire > Low Power-handling Speaker (Fostex FE103NV driver in enclosure)

I am aware of the risks involved connecting DAC direct to Power Amp (unintended DAC volume level risk), and the risk of connecting High-Power Amplifier to Low Power-handling speaker (unintended gain level cooking speaker voice coils).

I would like to confirm calculations before I connect everything together.

**Specifications (incomplete):**(1x Digital-to-Analog Converter)

- RCA Output at Max volume: (Unbalanced) 2.1Vrms

- Volume Control Steps: 37

(1x Monoblock Power Amplifier)

- Rated output power: 20Hz-20kHz, THD+N<0.1%, 4Ω 300W

- Voltage gain: 1 kHz 31 dB

- Input Impedance: 10 kΩ

*I think this low-impedance input (for an Amplifier) will help in getting controllable gain from DAC for Low Power-handling Speakers.*(1x Speaker in enclosure)

- Impedance: 8Ω

- Rated Input: 5W

- Max Input: 15W

*According to Fostex the "5W" Power rating was achieved using a square wave signal, so apparently actual Rated Power is slightly higher (8-10W?).*

(Sorry currently misplaced the source of information)(Sorry currently misplaced the source of information)

**1. Amateur Calculations:**Converting 1x Monoblock rated power into 8Ω should be around 150watts RMS (half).

= Converted Rated output power: 20Hz-20kHz, THD+N<0.1%,

**8Ω @~150W**After reading online that Voltage is more important factor of power.

Using this calculator (Convert Decibels to Voltage Gain / Loss): http://www.sengpielaudio.com/calculator-gainloss.htm

31dB gain = 35.48 volts.

Then using calculator: https://www.rapidtables.com/calc/electric/watt-volt-amp-calculator.html

I entered 2 values: "8" ohms and "35.48" volts, clicked calculate which gives "4.435" amps and "157.35" watts.

Confirmed this by 35.48^2 / 8 = 157.35.

*This makes sense so far right? since the watts RMS output result is accurate.***2. Next,**my aim was to find out 1x Monoblock's input sensitivity in volts.Vin (v) = Vmax/linear gain

To find "Maximum output voltage (Vmax)" of 157.35W @ 8Ω.

Vmax = sqrt (157.35x8) = 35.479v

Then this equation to find "Linear Gain (Y)":

"XdB: 10^(X/20) = Y" so "31dB: 10^(31/20) = 35.48x".)

So Linear Gain is

**35.5x.**https://www.audiosciencereview.com/...rstanding-gain-on-power-amp.11309/post-322681

Then using the reverse to confirm 20 * log(35.5) = 31.004dB (31dB Specification).

Vin (v) = 35.479 / 35.5 = 0.999v

Input Sensitivity = 0.999v

**Is there something wrong here at this point? it seems like I am just finding the 1v reference voltage.**So 1x Monoblock Vmax (157.35W / 8Ω / 35.48v) is achieved at just 0.999v RCA input.

0.999 / 2.11 x 100 = 47% volume level = 100% output from 1x Monoblock.

Which means only (slightly less than) half of the DAC's 2.1Vrms Max output can be used (37 x 0.47 = 17.52), which means only 17.52 steps of volume from volume level 1.

0.999 / 17.52 = 0.057v per step of DAC volume.

Then going back to the linked Calculator (Voltage and Gain): http://www.sengpielaudio.com/calculator-gainloss.htm

And entering 2 values: "31" dB, "0.057" volts. Gives 2.022 volts increase from Monoblock per step of DAC volume.

Then going back to this Calculator: https://www.rapidtables.com/calc/electric/watt-volt-amp-calculator.html

And entering 2 values: "8" ohms, "2.022" volts. Gives 0.511 watts RMS @ 8 ohms per step of DAC volume.

**Conclusion:**So each volume "click" from "level 1" of the SMSL SU-8 DAC should theoretically increase the RMS output from the 1x Monoblock amplifier to 1x speaker by:

**0.51 watts RMS.**Which means using the DAC volume, 10 clicks DAC volume =

**5.1watts RMS**, 18 clicks DAC volume =**9.2 watts RMS.**Does this all seem sound?

Are there are any errors, or do you notice I am doing something wrong?

Thanks again if you made it this far.

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