Very practical information from Telarc:BEWARE of Home Theater Receivers with DSP
For the best performance, use a preamplifier or receiver with an "analog pass-through" circuit. Many multi-channel receiver/preamplifiers provide multi-channel analog inputs that are routed to analog-to-digital PCM converters for Digital Signal Processing control, often at 44.1 kHz. The signals are then passed on to digital-to analog converters for the final output to speakers. This "feature" will cause ALL signals, regardless of source, to be no better quality than that of CD playback. Since you are playing a SACD with a sampling rate 64 times that of CD, we recommend using a receiver or preamplifier that passes the multi-channel analog signals through entirely in the analog domain. Keeping the signal in analog, without any further digital inter-steps, will insure you will be enjoying the full quality of SACD. We also further recommend that all "effects" programs be disabled, such as "concert hall", "stadium", "nightclub", etc. These ambience programs, which are more suitable for home video use, will destroy the carefully mixed surround presentation you will find on Telarc Surround SACDs.
Editor's Note: This sage advise applies not only to Telarc SACDs but all SACDs from high resolution masters. Keep your signal path pure analog after conversion from DSD. Also if your equipment from preamp to speakers does not pass ultrasonic frequencies consider an upgrade with a goal of frequency response of at least 40kHz, and if possible the full 100kHz. There are plenty of preamps and power amps that are flat to 100kHz, Only a few speakers so far, and even fewer microphones that are flat to 100kHz, however this is growing as well.
I think it's a bit more complicated than you suggest here. If, for instance, one listens in an acoustically problematic room (and who doesn't?), then the benefits of running room-correcting EQ may very well outweigh the costs of either converting the analog signal to digital PCM or converting the DSD directly to PCM (if, say, your processor accepts DSD over HDMI).
ReplyDeletePersonally I think it is better to look for acoustic treatment solutions instead of resorting to electronic EQ and converting DSD to PCM. But this is a decision each listener will have to make for themselves.
ReplyDeleteAll other things being equal, I agree. However, since I have to share my listening room (i.e., the living room) with the rest of my family, there are serious limits as to what I can (or even want to) do. In other words, all other things are hardly ever equal. I suspect that almost all listeners would benefit from electronic room EQ more than they benefit from preserving the DSD signal.
ReplyDeleteIt really depends. Some stereo recordings sound great straight with no EQ effects, but some really benefit from a little sweetening or a bass boost. This is one of the benefits of surround, in my view, which takes care of all that by miking the back of the house. Direct analog connects, at least on my system, do not allow for any bass boost or EQ adjust, so some DSD recordings are a little lacking in the nether regions :^]
ReplyDeleteI listen in 2 channel stereo and select "Audio Direct" on my SACD player which bypasses the video circuitry and turns off all the displays. On my tubed preamp I select "Direct" which bypasses everything except the volume control and input selector.
ReplyDeleteI firmly believe in signal purity, especially keeping DSD in pure DSD form. If an SACD is bass light I would never resort to EQ, instead I sell the SACD. Over time I have discovered which recording companies make natural sounding recordings with full deep bass response. As everyone one knows Telarc DSD recorded SACDs are my absolute favorites and these are just some of the many reasons why I love them so.
The difficulty here is that few (if any) SACD players can perform bass management or apply delay times in the DSD domain, and a similar situation exists with receivers. Any small degradation in the relatively benign conversion to PCM (preferably at 24-bit/88.2kHz, in the player or in the receiver) will be massively outweighed by the ability to bass manage properly, apply delays and, yes, maybe even apply gentle room correction. The acoustically treated, freshly built room in the right proportions with the proper ITU speaker layout may be the most desirable in theory - but for those in the real world in real homes and who are not mega-wealthy, more pragmatic solutions are best. Telarc are quite right though to caution people against the use of poor DSP performed at standard resolution: but I'd be quite happy to put my SACDs through, say, a Meridian surround processor and go digital-all-the-way.
ReplyDeleteIt seems to me that what's needed to allow people to add supertweeters without spending an arm and a leg is a monoblock supertweeter amp that takes its input from a wide-bandwidth line output. This way, the connections to the tweeters would be short. Another useful feature would be selectable crossover point. A potential candidate for this sort of amp is the Circlotron, which has an approximately 1 MHz bandwidth, looks like it can be built for a reasonable sum, and can be found at http://www.passdiy.com/pdf/Build%20The%20Amazing%20FET%20Circlotron.pdf. I'd make one power supply for each pair.
ReplyDeleteAfter recommending the FET Circlotron, I discovered that its output stage has a quiescent current of approximately 1.2 A. Because of the absurdity of wasting so much power to drive a supertweeter, I reconsidered another DIY amplifier which I had rejected because of its relative complexity: the B22 by AMB Laboratories (www.amb.org/audio/beta22/).
ReplyDeleteThe quiescent current of its output stage is one-tenth that of the Circlotron, but it has twice the bandwidth.