I’ve figured out the trick to making a small room, such as my 18x25 basement studio, sound much larger.

It’s reverb.

But seriously, it’s reverb.... done correctly. The place to NOT do reverb is at the guitar amp. Then it just sounds like a typical guitar amp with reverb. Also, if you have ‘mains’ and/or monitors for singers, you don’t want the reverb in the mains and monitors.

The way to do reverb is to simulate the way it happens naturally. In a ‘live’ recording room of decent size, there is a natural reverb that comes across. And its main component is the sound bouncing off a far wall. Yes there is more to it, but if we can get a decent approximation of that first big** reflection we have gotten a large part of the way there.

Soooo.... what I’m doing is this. Two guitars and bass are playing in half the room. Each instrument amp has a feed, be it direct or mic, into a mixer. One aux channel is run into a reverb processor, and each instrument is fed into that channel. The speaker for that signal is a foot from the far wall, and pointing at that wall! So the ‘reverb’ sound is first bouncing off that far wall, and then returning to us. The highs for all those instrument channels are turned down about 30%, because highs are what a room absorbs... it is mids and lows that reflect back. The lows are also rolled off the bass channel, to prevent possible damage to the full range speaker being utilized for this.

The next step is that I’ve hung an omnidirectional mic in the middle of where we are playing. That signal is fed exclusively to the reverb aux channel, and mixed in very gingerly. You don’t want to create any feedback here. The highs on this are also rolled off a bit, but not as much as the instruments.

That whole reverb signal is leveled such that it is only slightly noticeable to us as we play. It is a ‘presence’, not a feature.
Doing that is audibly increasing the apparent size of the room, as we are all in the same virtual room space.

On my reverb processor, the ‘plate’ setting is working best for this. I originally tried the two ‘room’ settings, but even with tweaks those were not as good as the plate setting.

**not first of course, because reflections come from everywhere. And of course closer items reflect more quickly. But you get the idea.