Can this audio DAC directly drive a speaker?

Can the **broken link removed** directly drive an 8ohm speaker? how do I know from the datasheet if this is possible or not possible?

Since the output of this DAC has full range of 3.5 Vpp (typical) shown in page 7, and I use it with LM386 audio amplifier that has a gain of 20 with no extra parts used to set the gain, wouldn't that cause the LM386 to be in saturation as soon as the DAC output connected to the LM386 reaches 175mV? That really is a very small signal actually. Since the input of the DAC is 24 bits, that means that the binary value 0000 0000 0000 1100 1100 1100 corresponding to 175mV (assuming linear relationship) shall be enough to cause the LM386 to saturate.

Am I missing something here? Does the output of the DAC need a voltage divider to reduce the voltage by atleast than 1:40 maximum 24 bit binary input to the DAC shall give no more than 87.5mV (half of 175mV) as its after conversion output?

Hi,

it is rather clear:
* it is no amplifier and it includes no (power) amplifier
* it says "line level outputs", this means just a signal as power_amplifier input
* it says "Test-load = 10kOhms" which is far away from your desired 8 Ohms
* A bit confusing is the specificaton: "Max AC-Load Resistance". (In my eyes it should be "MINIMUM load resistance")... specified with 3kOhms

Added:
LM386
You should use a volume control pot between DAC and AMP.

Your bit value calculation is wrong:
for a 3.5V pp signal (full scale) ..= -1.75V ... +1.75V (referenced to zero audio signal = mid scale)
175mV is just 10% of full scale peak.
so the binary value is 0b 0000 1100 1100 1100 1100 1100


Klaus

matrixofdynamism said:

Can the **broken link removed** directly drive an 8ohm speaker? how do I know from the datasheet if this is possible or not possible?


Am I missing something here? Does the output of the DAC need a voltage divider to reduce the voltage by atleast than 1:40 maximum 24 bit binary input to the DAC shall give no more than 87.5mV (half of 175mV) as its after conversion output?

Click to expand...

Yes,
you are forgetting that audio power amplifiers also provide current gain. Lots of it.

KlausST said:

Hi,
Your bit value calculation is wrong:
for a 3.5V pp signal (full scale) ..= -1.75V ... +1.75V (referenced to zero audio signal = mid scale)
175mV is just 10% of full scale peak.
so the binary value is 0b 0000 1100 1100 1100 1100 1100

Click to expand...

Slightly confused here; for PCM signal from a .wav file (e.g with 8 bit PCM), quite signal would have value of 00h and a full signal would be FFh, that is what I thought, but you have said that the mid scale is the quite value i.e no signal which would be FFh divided by 2 giving 7Fh.
The DAC does not take -ve supply, so the output can go down to 0V only, also the same with the LM386, there is no -ve supply.

The DAC does not take -ve supply, so the output can go down to 0V only, also the same with the LM386, there is no -ve supply.

Click to expand...

The relevant keyword is AC coupling. Similarly many audio amplifiers in the lower power range (e.g. 10 or 20 W) work with single supply and a large output capacitor removing the superimposed DC voltage. Or alternatively use a bridge amplifier which can output bipolar AC voltage to the speaker without a negative supply.

The input of an LM386 is 0V (ground) and the input signal swings it positive and negative a little. Fed from a DAC it should have an input coupling capacitor feeding its grounded volume control. The positive output voltage of the LM386 has an output coupling capacitor to feed the grounded speaker.