dsj@alice.UUCP (David S. Johnson) (02/06/85)
I've owned Carver's outboard "sonic holography" unit for about two years now. I've found it to have both plus's and minus's, with the net effect varying from record to record and also depending on my mood. Here are the major effects it produces in my listening room (although these too vary from record to record): (1) GENERAL SPATIAL: Soundstage widens well beyond my speakers, rises up above them, and also seems to be a few feet behind them. The speakers are much less the obvious source of the music (which I like). This is very nice for reviving old rock and jazz records that were "dual mono" stereo (each instrument isolated in a single speaker) and enlivening more recent rock records that are almost mono in their lack of obvious stereo separation. The instruments all separate out nicely so that you can hear each one individually. However, the impression of depth is more on the order of "everything is two feet behind the speakers" than "everything is happening at various distances behind the speakers," the latter being what I expect from a well-recorded LP or CD. (2) WEIRD SPATIAL: Occasionally sounds will seem to come from in front of the speakers. These usually sound unnatural, as if I were listening to them through giant headphones. (3) CENTER SPEAKER: If the record I am playing is recorded so that a lead instrument or voice appears to be coming from center stage, the relative volume of that voice may decrease so that it blends more in with the rest of the mix. Correspondingly, instruments to right and left become more prominent. This saves some records and destroys others. It seems to occur mainly when the center voice is created by "pan potting" (sending the same mono signal to both speakers). (4) REVERBERANCE: The recording becomes more reverberant (more echo). This is fine on dry recordings, but awful on records with already high levels of natural or artificial reverb. (5) FREQUENCY RESPONSE: There sound seems to become slightly warmer, corresponding perhaps to a slight boost of the frequencies in the 150-600 Hz range. Lower bass may also be strengthend, but is perhaps a bit less sharply defined. Occasionally the overall volume seems to increase. General Conclusion: It's a great toy, but I'm glad I can switch it in and out of the system when I want to (I wouldn't recommend the Polk speakers that do the same trick acoustically, because then you're stuck with the effect all the time). David Johnson - AT&T Bell Laboratories, Murray Hill, NJ