Understanding DSP and Surround Sound Modes
A lot of our articles have to do with choosing the right product or setting it up properly, but sometimes you need to know how to use what you have. Using surround sound modes properly is something I don’t see a lot of people doing most of the time. In fact, most of the time I see people using whatever surround mode happens to be engaged on the receiver. Occasionally, they wonder why everything sounds weird, or they click the button until they get a lot of program material in the surrounds. Let’s lay down some basic foundations.
Purity Sounds Better Than it Actually Is
There are two surround sound modes I think everyone should be very familiar with. There are variations, but in general, most AV receivers have these.
The first is Direct/Straight, or Pure Direct mode. Pure Direct mode is “garbage in, garbage out” and is meant primarily for listening without any alteration from the receiver. Pure Direct mode will feed your source directly to the amplifiers and bypass your bass management settings and room correction. Often, Pure Direct will also turn off your video circuitry. It is meant to use the amps in your receiver and not much else. There is an “audiophile” thought that any process going on in your receiver that isn’t directly contributing to the sound is somehow detrimental. That means that any video processing or passthrough will damage the sound quality. Of course, this makes no sense but don’t tell that to the audiophile. When Pure Direct is handy is when you’ve made some changes to your system and you’re not sure if you like what you hear. Engage Pure Direct and hear what it sounds like without the changes.
Direct or Straight (there are a ton of names for it) matches the input to the decoding. With many modern receivers, you can “force” a specific upmixing. So, no matter what signal comes in, it will use the Dolby Surround upmixer to utilize as many speakers as possible. Direct or Straight mode will take an incoming stereo signal and only use the Left and Right speakers. Since you may have a subwoofer in your system, Direct or Stereo still use the sub, provided your main speakers are set to Small (as you should regardless of the physical size of the speakers). Most of the time, Straight or Direct modes will default to the native audio formats when you give the receiver a Dolby (Digital, TrueHD, etc), DSD, MLP or DTS multichannel source. Receivers are pretty smart and so they figure you’re not going to be as interested in bypassing much when you have a nice multichannel signal. Most importantly, the Direct or Straight mode still utilizes the room correction system in your receiver. You paid extra for it, you should use it!
Fancier DSP Modes for the More Experimental Among Us
I’m not a DSP-hater. I think they can be pretty cool, particularly when you aren’t using really expensive speakers. Taking your stereo CDs and aging them back through Dolby Pro Logic II or IIx, for example, can give them new life. Some of those Sci-Fi or Movie modes can also bring alive some of the movies you’re watching on cable or satellite TV stations that aren’t encoded in surround sound. There’s nothing wrong with experimenting with the modes afforded you by the manufacturer of your AV receiver, I just don’t want you to be ignorant or unaware of what mode you’re using. Also, the Dolby Surround and DTX:X upmixers let you take your surround signals and mix some of them into the overhead speakers. Experiment with them. You may like what you hear!
Party On, Wayne!
One of the most practical and fun DSP modes that exists in nearly every AV receiver is the 7-channel Stereo or All-Channel Stereo mode that sends a stereo signal to every pair of amps in your receiver (and often a summed mono signal to your center channel as well). The result is a lot of sound in your theater. Some Party modes will also engage the additional Zones you may be using. On either case, this mode is a boon for creating tons of sound-particularly in a larger room. It’s also handy for when you simply can’t turn up a single pair of speakers loud enough-perhaps because of the available system power or due to the limitations of the point at which a single pair of speakers may distort.
German Bathroom May Be Neat, But do You Need It?
That leaves all the rest of the DSP surround modes. While Jazz Club and Cathedral might be novel for particular music pieces, they really don’t have any place in your regular home theater use. In 99.9% of cases (based on our own user-inquiries) these modes get listened to once (at most), never to be used again. Fortunately, most AV receiver manufacturers (with the notable exception of one or two holdouts) have opted to limit the amount of DSP modes available on newer products. I say fortunately, because the more you eliminate the oddball DSP modes, the less likely it is that you’ll stole into your friend’s house to watch a movie in the latest Spectacle or Stadium mode that he just loves due to the enhanced surround effects.
In summary, remember this: Friends don’t let friends use bad DSP.