I started fooling around with Surround Sound in 2005, and that's about all it was, fooling around. I had purchased 5 speakers from my brother-in-law, and I experimented with placing them on the back counter of my kitchen, where they quickly got in the way and had to be removed.
The current system really got going around 2018 or so, but it's still based on my 2005 Yamana HTR-5790 receiver, which has always worked very well for stereo and everything. It's got very good amplifiers (for 7 channels!) and good performance everywhere. It can decode common surround signals from coax and optical connections. What it doesn't have is HDMI inputs and the ability to receive surround sound via HDMI.
That hasn't been an impediment, since I can either take the coax low res digital straight from my Oppo BDP-95 for movies, or the seven channel analog output from the Oppo for high resolution audio multichannel discs. Normally I just use the analog for everything, so all my digital decoding is done by the Oppo. The only way this is a "problem" is that I'm not getting high resolution (from high resolution audio discs, not movies) from the few high resolution discs I have in pure digital form for the fancy processing in the receiver. But that doesn't matter much, since the Yamaha receiver doesn't do fancy processing on the seven channel analog inputs. Instead, I do all the basic digital processing required in the Oppo, which has menus for setting the delays and levels for each channel. So the only way that this is a "problem" is that I'm not getting all the fancy digital processing applications like Audessy, that may correct for EQ and phase. And I wouldn't even want Audessy much, except the later versions which allow you to do the fine tuning on your phone. And that set of Home Theater Processors are still very expensive even used, because they have that feature.
Anyway, I'm getting the seven channels and routing them to amplifiers in the Yamaha and thence to speakers. With levels and delays set in the Oppo. That's pretty much all there is to it.
Except, what about when there is 5.1 channel content? I could play it back just as that, which is theoretically fine. But because my side speakers are not optimally placed, I often find it better to play 5.1 channels on my 7.1 speakers by duplicating the side content in the back. When I do that, I lower the level by 2dB so it still balances OK. I use a rotary switchbox (made by dB systems no less) to switch from pure discrete 7.1 to 5.1 expanded to 7.1. And then I have a preamp for the sides having a level control with two marked positions. I use the higher position for discrete 7.1 and the lower one for fake 7.1.
My project to add optimally placed side speakers has gone nowhere in 5 years since I bought the required wall hangable small speakers, currently still in my bedroom to remind me to install them.
(I have tried many other solutions for the 5.1 to 7.1 conversion. For some time I used a well known box from the 1980's. After using it a year I found it distorted the sound intolerably. Then I tried using various delays and EQ's. Finally I decided that simply duplicating the sides in the backs, and lowering the level by 2dB, worked better than anything else. I also tried a historic Integra processor, but found it did nothing useful, and was basically a pain in the neck because it only produced distortion if input or output levels exceeded 1 volt. The Yamaha is good at least to 3 volts on inputs and outputs.)
I could solve this 5.1 to 7.1 conversion problem problem "better" with a fancy Home Theater Processor that might cost $5000 (do they still make those???) or more, but it's not been worth it to me when I could have afforded it (and now it's simply unaffordable).
Anyway, my simple idea is implemented with the units on top of my kitchen rack. The bottom DEQ box is for the rear speakers and it only does level adjustment for the backs, plus level and spectrum displays (so you can see at a glance if the backs are doing anything). The level adjustment feature that this box actually does could just as well be done by a preamp (like the upper two boxes) but I happened to have the DEQ and not another preamp. (It inherently adds about 10mS of additional latency, which I have compensated for in the Oppo adjustments. When used for the fake 7.1 the additional delay is a bonus that makes it sound a bit better--like an even larger room--but isn't that important either way)
The upper DEQ box is for the subs and currently does nothing more than level and spectrum display. (I thought it was also doing some eq but it appears not. At some point in the last couple years I bypassed it. I'm not sure that was out of design or necessity--such as it might have been adding hum). Currently the upper DEQ box is non-functional, it appears to have the usual power supply issue. But since I'm not doing any processing there anyway, it doesn't affect the sound. But it was very useful to have the spectrum display on the bass because I could measure ground loops exactly and work to eliminate them. The spectrum display on the subwoofer signal enabled me to solve and fix about a dozen ground loops over the years. The complicated kitchen electronics (my central computer, video, and audio for the whole house, plus TV and radio) are prone to those. Now the box that did the helpful bass spectrum displays needs fixing.
The upper two preamp boxes are for the sub and sides. It allows convenient setting of the levels, which I need to do for the sides when changing from discrete 7.1 to fake 7.1. Also historically I used to mess with the sub level a lot depending on recording. But I've had it dialed in pretty well for everything recently and hardly mess with it at all anymore. Still I like have "controls" that I can just reach up and control as opposed to complex apps which may not do anything until you take another measurement.
The stereo frequency response (including subs) is quite flat, though I think some of my low frequency optimizations that used to live in the subwoofer DEQ would have made it flatter there. Still it sounds pretty good.
No comments:
Post a Comment