Audiophile Journeys with a PC

Adding in the Subwoofer

The next step is to add in the subwoofer. As I'm feeding the I2S output from the PCM2707 to the TDA1543 and both Opus PCBs simultaneously, it's possible to use the TDA1543 output solely to drive the subwoofer. The Opus DACs will be used with the 300Bs and Transparence speakers maintaining a crossover-less setup for the midrange and highs.

The Linnn Isobarik 5150 is configurable to crossover between 41-81Hz in variable steps. I started off at 41Hz initially, but found that the sub gave away its corner of the room location frequently when rendering sub bass. I'm out of space in my main living room and with the Linn being quite the behemoth, there really is nowhere else for me to put it. Crossing over at 48Hz seemed better to my ears, so we'll proceed to look at the room response with the sub in place.

Opus plus Sub

That's better; we now have a decent response to around 25Hz. The nature of the Linn sub in my room is quite "boomy" and the bass lacks definition, even with a minimal amount of gain (possibly due to placement). Crossing the unit in a little higher does help with this, but then things get lumpy around 60Hz where there's already a peak from the main speakers. It'll be interesting to see how applying DRC will level things out.

Opus plus Sub with DRC The wonders of DRC - a predicted near flat in room response between 25 Hz and 15 KHz.

Now we're talking! A predicted response most of us dream of at the listening position. The correction file was hastily loaded into Convolver and a few tracks played to see how things sounded. At the risk of sounding like a salesman, I can tell you I was pretty knocked out by the results. The integration of the subwoofer is almost seamless, only hinting at its location on the very lowest notes. All the perceived boom factor from the bass is gone. What remains is the tightest, most articulate bass I've heard outside using my Sennheiser headphones. I already knew the Supravox drivers in open baffles had real promise, but armed with DRC and a subwoofer, they simply move up to another league.

Switching DRC on and off is pretty much a day and night change. Listening without the filters is almost torturous when you've been subjected to what is possible. It's not that things get fatiguing; it's just that everything sounds chaotic and bloated without DRC to correct the abnormalities. The sonic quality of both DAC kits combined with a PC as the feed has surpassed my expectations, far in excess of what I can recall from the HDA Xplosion card I dismissed as lackluster in my previous attempts of using a PC based front end.