Why do no $200 DAC's include a subwoofer out and HPF given that numerous DAC/AMP's from the same companies and prices include this feature? (Ex- SMSL)

[cavedriver]

Looking at recent DACs like SMSL's DO200 mk II (and many others) and comparing them to SMSL's DAC/AMP's like the A300 (and several others),

NONE of the DAC's have subwoofer outputs
MOST of the DAC/AMPs have subwoofer outputs

One might assume that the high pass filtering and signal splitting for the SW output is happening in the amp chip. Against this:
- SMSL amps use a variety of different amp chips.
- SMSL markets something called "SDB" or SMSL Dynamic Bass, that they claim to have patented

In favor:
- The literature for the Infineon MA12070 chip specifically mentions 2.1 capability

Has anyone done a teardown on these or know how SMSL is doing the HPF?

And yes, I know the MiniDSP 2x4HD at $200 can be used to get a subwoofer out, or if you're looking for balanced outs, then the Flex at $500 (like I need for my Hypex 502MP amp). I'm really just puzzled by why companies like SMSL seem to be leaving this market untapped when they seem to already easily be able to offer such a product.

 

[jasonRF]

SDB has nothing to do with the high-pass filtering; it is just an EQ setting that boosts bass and treble. My ao200 has SDB but no HPF, and I have verified that SDB is nothing more than +5dB bass and +4 dB treble built into the NJW1194 volume control chip.

If your DAC has a volume control, in principle you can use it as both a source and pre-amp with a 2.1 setup. Simply split the analog output; send one pair to the powered subwoofer and one pair to the power amplifier for the main speakers. Most powered subwoofers have built-in low-pass filters, but the main speakers will be running full-range unless you place some sort of high-pass filter between the DAC and the power amp. I don't know if these are any good, but in principle something like this could work:
rca inline high-pass filters

There are also low-pass versions if you need those for a subwoofer, and Amir did a review of one example:
inline low-pass filter

Jason

 

[newaudioguy]

I am in a similar boat, a device that includes subout and allows selectable (or even fixed <100hz) LPF would be great

 

[popej]

Has anyone done a teardown on these or know how SMSL is doing the HPF?

Does it really include HPF? It would be unreasonable to include permanent HPF, since then amplifier would require subwoofer, to cover whole audio band. Most probably sub out is a simple 3 resistors divider attached to amplifier outputs. You can connect active subwoofer to work in parallel with main speakers.

You can't make the same kind of simple subwoofer output in low signal device like DAC. You would have to add active devices, to make it work correctly. So it is most probably to complicated/expensive for manufacturer to bother.

Edit: I have looked at A300. It really seems to include switchable HPF. Maybe as a part of tone control?

 

[newaudioguy]

A300 has a low pass of <100hz for subout and a hpf I Believe if >100hz for mains