hellblau

If the combination of loudspeakers and room allows, by only physical room treatment, a satisfactory frequency response, that's a lucky strike. Usually the owners of the typical European apartments' (small) rooms are not that lucky, so the DRC is a life-saver especially in the bass range, which cannot be tamed with surface room treatment. :-) The BBC dip was introduced - as far as I know - to counterbalance the excess of upper high frequencies (2000-5000 Hz) due to close miking of - tipically - acoustic instruments (violin, piano, etc.), in comparison to the "natural" sound of the same instrument in an auditorium. The spectral distribution of close miking often made the recording sound "too brilliant" compared to the real world listening esperience. Anyway, we're talking about the recording technique of the '60s.

I've been using Digital Room Correction for more than ten years now (in the beginning with the TacT digital preamplifiers), so I could try different loudspeakers, different rooms and, yes, different target curves. I said "generally speaking" and "usually" because your experience, the music you listen to, your sensibility end personal taste may vary, thus leading to different target curves and different ambient responses (including an "almost flat" frequency response). What I can confirm is that targets with "mountains and valleys" cloning the ambient response are, in the best case, useless, especially in the bass range (20-300 Hz). The rest of the range can be "tailored", with slopes, valleys (the old fashioned "BBC dip" at 2000 Hz being perhaps the most famous example) or gentle peaks copying the ones of the natural response of the system (loudspeakers+room). The less the target is above the measured response, the better.

Generally speaking, the target curve should be close to a straight line (like in your first image), usually with about a 1dB/octave slope from bottom to top range. Trying to copy the bass ambient response with the detail shown in all the other images you posted is totally pointless: human hearing sensitivity is low in this area, while it is much higher in upper midrange (2000-5000 Hz), therefore fine adjustment of the frequency response in this area does make sense. (fine adjustment = + - 2-3 dB, always using "gentle" slopes). Here are my Martin Logan Electromotion ESLs in my room: the red line is the reference target curve.

I've be enjoying the Mini I-Pro for almost one year now. I got it in Germany via web. I took a short peek online at the new model. It looks basically the same harware (Sabre 9016), plus the Bluetooth and some aesthetic improvements. They claim some other upgrade in the circuitry: we'll see when the first reviews will be released. If I had to buy it now, I'd probably try to get the new model.

+1 for the Matrix Audio Mini-I Pro. Amazing unit for the price, easily found on the internet. It comes with rock solid drivers - never underestimate their importance when choosing a USB DAC - probably because the XMOS chip owns a well written standard driver.

Windows 10 Pro x64, no updates since the monster - update of mid November 2015. Service is still set "Disabled".

Updates are often part of the problem, not part of the solution. To PERMANENTLY disable the Windows 10 updates go to Control Panel, Administrative Tools, Services. Locate the Windows Update Service, right click, select Properties and then set it to Disabled (default is Automatic). End of the story! Easy uh? :-)

I had the Wadia 121, which broke 10 months after purchase (Line out mute, like I had plugged the headphones). Good sound, but poor support (Wadia customer support never replayed to me; the USB driver was never updated) and a bad designed unit software, that didn't save the settings after a switch off, and forced me to set again the unit (gain, etc.) every time (I consider the option "Always on" a total nonsense in general). Now going with Teac UD-501. Good sound - a little different but overall the same category, at half the price - much better software (it saves the unit settings), rock-solid USB driver (that, by the way, was updated), much higher output voltage. Unfortunately, no line out volume control, and no remote. I use Dirac Live, and in my opinion the difference between DACs are a fraction, sometimes a very little one, of the difference that the DRC can make. Beware of the shining hip ultra-bargain-price Chinese DACs, particularly if you use the USB: without a good USB driver, a DAC can be a nightmare!

You're welcome LBob. My speakers are B&W 804 Nautilus (1st series, year 2000), and yes, they seem to have a kinda "factory BBC dip", though a little too deep, resulting in loss of detail in the high-midrange (crossover cuts at 4 kHz), at least in my room. The top-end models, like the 801, had the "Nautilus shaped head" including the midrange (same loudspeaker as mine) in a spherical structure, thus probably improving the dispersion and then the linearity of the room response around the crossover frequency. Another important parameter is the "Global DSP gain" (misleading term in this case, since "gain" can only be negative. See "ab" in the picture below). The default value is -8 dB, but you should try to set the highest value you can before clipping occours in "close to 0 dB recording", like pop-rock records. I set -5 dB, and probably I could go even higher. Anyway, everything is explained in the user guide.

You may want to experience target curves similar to the ones below, wich are applied on my equipment/room. 1) A slight slope - let's say 1dB/octave from 100 - 200 Hz. This will look similar to the Dirac default curve. 2) Same as point 1., with a 2 - 4 dB dip in the 3 kHz region (sometimes called "BBC dip"). Quoting Electro-acoustic models : "Around 3 kHz our hearing is less sensitive to diffuse fields. Recording microphones, though, are usually flat in frequency response even under diffuse field conditions. When such recordings are played back over loudspeakers, there is more energy in the 3 kHz region than we would have perceived if present at the recording venue and a degree of unnaturalness is introduced. This applies primarily to recordings of large orchestral pieces in concert halls where the microphones are much closer to the instruments than any listener. At most listening positions in the hall the sound field has strong diffuse components."

Not exactly "lower": I listen mainly to classical, which means high dynamic range. My target is basically a Moeller Curve, the one is known to have the best listening results.