I'm calling this the "new Hotseat" because it's now a lowback chair (which makes for better imaging and measurements) and moved slightly farther back than before (because the speakers are now angled slightly more outwards than before, for better imaging in the back of the room).
The panel EQ for the hotseat position is currently identical to the one now used in the back of the room (I haven't yet wired up separate EQ's for panel frequencies...which could be done but I haven't yet seen the need). The EQ differs only for the "subs" where it is extremely important. Flattening the bass at the center makes it way too strong in the back of the room, and flattening the bass at the back of the room makes it far too weak for the center of the room, generally speaking, so there need to be different bass EQ's--no question about it--if both positions are taken al all seriously. The back of the room EQ also works pretty good in the sides of the room, where people watch movies so I call it the "Movie EQ"
The measurements don't look quite as good as when I did them two years ago. (Note: these are just ad hoc measurements without a stand so far. When I need to get really precise, to show the effects of small changes, I will start using a stand again, which takes considerably more effort.)
 |
| Left Channel New Hotseat |
 |
| Right Channel New Hotseat |
The left channel has a weird triangular shaped peak around 90 Hz where the right channel only has a modest "rise" (which in context looks more like depressions on both sides). But (unlike the back) the lowest frequency bin (22.4 Hz) is not depressed compared to the midrange, only slightly depressed from the region around 40 Hz (where a huge modal peak is being suppressed by EQ). Somewhat troubling is the rolloff above 1k which shows the -3dB engineered "Peterson Dip" (inspired by the Gundry/Linkwitz Dip) but only on top of much deeper lowpass shelf. I think the lowpass shelf is largely resulting from being off axis from the speakers, which is hard to fix without messing up the imaging in the back of the room. It doesn't sound as rolled off as it looks, there is a wonderful 3D image but only behind the speakers, sounding just slightly "distant" and never forward or aggressive as the Acoustats can sound on axis without EQ.
The original and still used Hotseat EQ has greatly increased bass compared with the Movie EQ, achieved through both higher "Gain Compensation" level and a few actual boosts (up to 6dB). I don't clearly remember doing so, but I must have allowed for up to 6dB boosting by having a 6dB cut in the MiniDSP's which do the phase linear 8th order Linkwitz / Riley crossover. It was absolutely necessary to do that in the high pass panel DSP because I could get +6dB ASRC* inter-sample-over peaks and clipping otherwise, but it not in principle necessary to do that in the lowpass bass DSP because low passed bass doesn't stimulate ASRC clipping.
(*Digital is not as simple as you think especially when there is Asynchronous Rate Conversion (ASRC). I would have greatly preferred fully synchronous digital transmission in which the data is unchanged, but the miniDSPs don't have that option like my older Tact preamp. But I've turned the defect into a feature by reducing the miniDSP digital input levels by 6dB which then permits up to 6dB boosts in the downstream DEQ's without risk of clipping. Inter-sample-overs can occur when new datapoints are interpolated in between existing near-clipping high frequency datapoints....this almost never occurs in audio signals except with test signals designed to elicit the effect like those used in jitter tests--where there are often maximum level waves at the half the sampling rate.)
 |
| Hotseat EQ gain levels |
 |
| Movie EQ gain levels |
 |
| Hotseat Right EQ |
 |
| Hotseat Left EQ |
Not only am I using boosts in the Hotseat sub EQ's, I'm running the EQ at 0dB whereas I'm running the Movie EQ sub EQ at -9dB. This is because generally speaking the back of the room needs a lot less bass. However, that also means that I could boost the bass where needed up to 9dB or more in the movie EQ, which might be useful at the very lowest frequencies. I'm already boosting the bass by up to 6dB in the Hotseat EQ, which makes it effectively up to 15dB higher. Not knowing this, I had been shying away from using boosting in the Movie EQ even when I thought it might be helpful.
No comments:
Post a Comment