I believe there is a specialized chip for HDCD decoding (Pacific Microsonics), usually located in the DAC or CD player unit.
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I can confirm that HDCD takes place in the DAC, enabling you to use your choice of transport. In fact, in addition to using a dedicated transport (Rotel RDD980), a CD/SACD player (Marantz 8260) and a network player (Airport Express), all three stream their signal to an old Assemblage DAC-2, and in all cases the HDCD indicator lights up with an HDCD encoded track is playing.
If the transport decodes HDCD and the DAC does not and you feed the digital signal to the DAC, you won't get HDCD decoding. If the transport does not and the DAC does and you feed the digital signal to the DAC it will decode HDCD.
In my instance my older Rotel transport does decode HDCD but my DAC does not. So, if I want HDCD decoding, I can use my analog outputs to my preamp and listen that way. But I find the DAC sounds better even without the decoding.
The older generation DACs offer HDCD, but I think most newer ones do not.
Both HDCD and Redbook will be sent via SPDIF (or AES/EBU depending on the transport) digital format; both are 16-bit 44.1KHz resolution. The decoding of HDCD happens in the digital domain by a digital filter. As Dracule1 said, originally the filters were sold as separate chips (PMD100 and then PMD200). It's possible that the decoding could be built into a DAC chip or could be implemented in software.
I'm not aware of any external DACs that decode HDCD. Not many CD players decode it these days either.
A DAC won't have balanced analog inputs; it could have these types of connectors for its digital input(s): XLR (for AES/EBU), BNC (SPDIF) or RCA (SPDIF).
I'm a fan of balanced analog connections, but whether it yields better sound depends on the environment. If your preamp has balanced inputs, then I'd look for a DAC with balanced analog outpus.
Possibilities include: Benchmark DAC1, Lavry DA-10, Cambridge Audio DacMagic.
Yes, HDCD capability is (or isn't) in the DAC. All transports supply the information off the disc, Redbook or HDCD. DAC's themselves almost universally employ a D to A chip of some kind. Some are better than others, but if they DON'T do HDCD, then the extra digital information for HDCD processing (of an HDCD disc) is disregarded (basically dumped.) Otherwise, on HDCD implemented DAC or CDP, a Pacific Microphonics chip is used which WILL recover the HDCD info. The problem is that the Pacific Microsonic chips aren't the highest quality, which is why most hi-end DAC's/players don't do HDCD. That is, except for Mark Levinson, which got permission to make THEIR OWN high quality HDCD decoding chips under additional license from Pacific Microsonics.
One other (high end) exception is Wadia. Unlike Mark Levinson, they do not use a custom HDCD chip. In fact Wadia DAC's don't use ANY D/A "chip" in the usual sense. Wadia uses their (claim to fame) patented "Digimaster" decoding software. Basically, Wadia DAC's are really high speed computers using the proprietary software to decode digital audio data. For that reason, the HDCD information is not dumped, but processed by the software. So although you won't get an "HDCD" indicator light on a Wadia, you WILL get the best HDCD perfomance (I've heard.) Is it better than the Levinson's custom HDCD chip. I haven't heard the Levinson, but the Wadia HDCD reproduction is truly amazing.
The PMD100 and PMD200 digital filters were always highly regarded. They were a selling point for better Redbook play back.
The PMD filters are no longer in production. Some companies are implementing the decoding in software.
The reason high-end players/DACs tend not to decode HDCD today is strictly based on cost -- licensing fees.
Plenty of DACs that decode HDCD, unfortunately they are all a few years old. Besides those mentioned above, Adcom, PS Audio, and Proceed come to mind.
A well mastered HDCD disc played through a quality HDCD player or DAC is superb. One of my favorites is Beck's "Sea Change." Joni Mitchell "Blue" and "Court And Spark" are a couple other great ones.
Bob - did you compare HDCD to exactly same Redbook. I'm asking since I noticed that only great sounding mixes ended up as HDCD creating impression of great sound in general. Do you know of any poor recordings on HDCD?
I don't have any experience with HDCD but whole scheme is a little bit weird. It has 15 bits of music and 1 bit (LSB) switching dynamic range. Techniques like that are called "in-band signaling" but I'm not quite sure about the purpose. In redbook CD one more bit (MSB) serves similar purpose (unless range in HDCD is greater than 2:1). In addition HDCD disk played on regular CD player will perform as 15 bit of weird dynamics + 1 bit of constant noise.
As I said - I don't have any experience with HDCD but judging by lack of any effords to improve quality of the recording/mixing, schemes like HDCD or SACD are attempts to force strong copy protection. I don't know why HDCD is more expensive - manufacturing is identical and royalties are the same. What about SACD - what costs another 100%? Greed killed many good standards before.
Add the Esoteric P-70 and I believe the D-05 to the list of DACs that support HDCD. The Classe SACD-1, SACD-2, and several Cary players also support it.
Kijanski - there's much more going on with HDCD than dynamic range switching. The recording is made at 88.2 khz/18 bits. It is then analyzed by the HDCD encoder which decimates the signal to 44.1 khz and applies on a moment by moment basis the selection from a suite of encode processes (compression, filtering,etc) that best preserves the characteristics of the original signal. The encoder also modulates the low order bit to tell the decoder which inverse process to apply at any moment. The result is a 44.1 khz/16 bit data stream that can be played by any CD playback system.
On playback the HDCD decoder reads the low order bit modulation pattern and applies the appropriate inverse process on a moment by moment basis to create 44.1 khz/18 bit data stream from the 16 bit data stream off the disk.
One other important feature - the filter in the decoder is a perfect conjugate of the filter used in the encoder, which by itself improves fidelity.
The intent was to do most of the number crunching on the encode side while the decoder remained simple.
The only responsibility the transport has is to provide an exact copy of the bitstream encoded on the CD (another argument against those who whine about CD data errors - none of this would work without perfect recovery)
Look up other threads on this.
As to the original poster's question about small footprint dacs that decode HDCD, the only brand I'm aware of are the Assemblage 2 series. They were in a half width chassis like PS Audio uses for their current small component series. I've got one of their last ones manufactured, a 2.7 Platinum and it still sounds very fine. With an HDCD disc (and some redbooks,) I still prefer it's sound to the sound of the internal dac in my Marantz Sa11S1. As to Kijanki's question about non-hdcd vs redbook cds of less than stellar quality, the Doors are available in some HDCD issues. You could compare Rhino's redbook remasters to the English HDCD remasters to make a comparison, although not an exact one.
Ghostrider45 - All CDs are made from higher number of bits from master tapes thru decimation to 16bit/44.1kHz. Bit nr 16 (LSB) switches dynamic range of the other bits but it cannot play well on redbook CD player since it has no way of knowing what is playing and will play with weird dynamics.
Whole scheme assumes that in loud passages you can't hear resolution of quiet instruments. Theoretically it supposed to work but I read opinion of recording engineer that it sounds a little strange.
Photon46 - I don't have HDCD player and asked if anybody listen on the same unit to exactly same issue of, for instance, Doors that you mentioned, in CD and HDCD.
When it says that older disk was remastered for HDCD sound in general could be improved. It's like comparing regular and remastered Doors album.
Kijanki, I recall reading that HDCD is 3dB louder than Redbook so this makes it difficult to make direct comparisons.
I run the analog outs of my Denon 3910 (decodes HDCD) into a balanced input of my BP26 preamp and the digital out of my Denon 3910 via a DAC1 to another balanced input of my BP26 preamp. When playing an HDCD enocded disc I can switch between the two inputs to compare, but it's very hard to get past the level difference.
Ghostrider45 - sorry, it does work. It was just system error.
What they describe is just simple stretching of dynamics:
"In addition to dynamic decimation filtering, HDCD uses the control data to fit a 20-bit dynamic range into a 16-bit signal. Two types of complementary amplitude encoding/decoding are available; the use of either is optional. At the high end of the dynamic range, "peak extend" allows the user to boost gain by up to 6 dB. For quiet signals, "low level range extend" may be used to add up to 7 dB of gain. With both dynamic processes, the control data allows the decoder to restore the dynamics of the original signal."
Stretching 15 bits into 20 bits has to produce hole somewhere - I suspect its medium loudness. I'm not criticizing HDCD since I don't have any experience with it but wonder why new schemes they coming out with have extremely strong copy protection (SACD cannot be copied at all). Any time I see HDCD in store it is recording that sounded great on CD and often remastered.
Everything else they describe is mix and disk preparation. They claim superior A/D conversion but I wonder what are they converting. Most of recordings are already stored in converted (digital)form. Other techniques like dithering on lower bits can be and I suspect are used in mastering for regular CD.
K: you need to add the "www."
RE: Bob's comment about MS killing the technology. I don't know if that is so or not. but what I do know is that Keith Johnson's (co-inventor of HDCD) ReferenceRecordings site seems to be doing very well and of course all the issues are in HDCD:
and there's a new format on his website you can read about (I haven't yet) called HRx.
I just wish he'd bring back RR LP's ;-)
Nsgarch - thanks for the info. HRx is much cheaper than SACD and contains physical disk - which I like. It is one more argument to connect computer to my Benchmark DAC1. I wouldn't mind buying few record even if the format won't become popular. My DAC will be always able to play it. I suspect that physical disk is supplied to be inserted as a proof of ownership - otherwise how could they stop pirating.
It might be a little inconvenient but I need some form of exercising anyway.
Rameau in HRx looks interesting. I have "Une Symphonie Imaginaire" by Minkowski and his guys (excellent sound and recording).
I want to thank each of your for your generous response here. As you can see I am not very familiar with this technology. However, I have been doing some research and of course I have learned much from reading your comments here.
I do understand that there are other than HDCD or Redbook CD's available. I have also read something about DVD-A disks. I guess my question should have been ... Can my newly acquired Parasound 2000 transport and basic DAC be expected to decode other than Redbook CD's?
It could very well be that there are some Redbook CD's that are just as sound worthy as HDCD's. As stated earlier I have many Redbook CD's but have never heard them played on a really good system that includes a good CD transport and DAC. Here are the primary specs for the DAC: AD1853 for digital/analog conversion and can support up to 192KHz/24 bit sampling. Digital input signal sampling: 32K to 96K PCM format.
At any rate what I will look for is a list of "Redbook CD's To Live For" (smile). I am sure there are some really great sounding Redbook CD's tht I have not been exposed to yet. I just want to experience the best sound I can get from the many CD's I have as well as add other formats that can be decoded on my transport and DAC. Thanks again everyone.
Kijanki: Sigh..., of course dynamic processing is part of the picture, but you left out much of the article and only picked out the paragraph that seemed to support your statements.
For the rest of the story:
"Dynamic-decimation filtering is HDCD's response to the well-known problems inherent in filter design for digital conversion systems where the Nyquist frequency is only slightly above the range of human hearing. "A filter designer who has to make a 'brick wall' filter at 22 kHz is confronted with conflicting requirements," Ritter explains. "You want to have flat frequency response out to at least 20 kHz, but you can't have any energy above 22 kHz or you will get alias distortion. This requires a very sharp multipole filter with a very steep transition between the passband and the stopband, which has a number of distortive effects on the signal. It smears transients and causes significant ripples in the passband. If you try to simplify the filter, then to avoid totally unacceptable aliasing you have to start rolling off at 13 to 15 kHz, and even then the signal will not be completely cut off by 22 kHz."
Ritter describes the HDCD approach to this problem: "We slightly delay the 88.2kHz signal, not enough to cause any sync problems but enough that we can do a continuous Fast Fourier Transform. The resultant information is digitally analyzed in real time by an algorithm that determines, based upon a model of the mechanics of hearing and psychoacoustics, what is perceptually dominant in the signal from instant to instant. And that information is used to optimize the decimation filter. One moment you might have a sudden sharp transient, so it uses a filter with minimum time dispersion to pass the transient cleanly. The next instant, there might be a cymbal crash, so it uses a filter that minimizes alias distortion. All the filters are the same length, so you are not getting a phase shift as this is going on."
Another element in the process of downconverting for CD is word-length reduction to 16 bits. "We never simply truncate," Ritter says. "And with the introduction of Version 2.0 of the Model One at the end of 1998, available as a flash-ROM upgrade to existing units, we now have a palette of four 16-bit dither options." The dither and the dynamic decimation together, Ritter believes, add up to a big improvement over typical CD sound. "The reduced distortion-sharper transient response and reduced aliasing-becomes part of the digital recording and will be heard on any player, whether it has HDCD decoding or not," he says. Nonetheless, the optimal playback setting is one in which the playback filters are matched to those used in recording. To achieve this, the Model One hides control information in the signal that tells the HDCD decoder which filter to use. This data is encoded as a pattern in the dither used for word-length reduction. It occurs only 1% to 2% of the time, and the company says that extensive testing has shown that it is inaudible."
Note that all this processing takes place on the encode side.
Ghostrider - I read this before but have hard time to understand importance of it and also why wouldn't this be applied to regular redbook CD in downmixing. This is more of preprocessing technique and has nothing to do with HDCD. If I learn that, for instance, TELARC is using similar technique to downmix their redbook CDs I wouldn't called TELARC CD a different standard. TELARC currently uses DSD recording format/technique - does it change CD standard?.
I'm also not certain how much it affects the sound. There is probably very little energy above 20kHz and it is already filtered out in downmix processing. Whatever left above 20.5kHz is folded into passband starting from 0Hz but people who own NOS players don't complain. They even claim better sound.
So - now they claim that what differentiate them from just simple downmixing process is that they hide somehow information about status of adaptive filter at given moment in the music itself. Hiding it in the lowest bits while it's used only 2% of the time maximum (as they claim) is strange. Maybe I'm slow to understand it, but if they used adaptive filter in downmixing why do they need to match it in playback? They stated before that when high frequency info was present (like cymbals) they applied sharp antialias filter and when it wasn't present they bypassed filter. All this was done to avoid using sharp antialias filter in the player. Fine, but now there is no high frequency above 20.5kHz in the mix and even phase is the same for all signals - I don't understand what they are matching (and how)? Oversampling and Bessel filtering in my DAC sounds simpler to me.
Error correction code (Reed-Solomon) is pretty weak and the player bypasses the data with the wrong checksum. That would mean that adaptive filter info hidden in the lowest bits (as a pattern or a sequence) can be lost (fingerprints or scratches). It cannot be that important.
Again - I don't question that it sounds great. I'm just trying to understand. Perhaps the fact that it is not very popular has nothing to do with technical merits (SACD was killed by greed in my opinion).
While we're letting it ALL hang out ;-) I thought I'd mention the JVC XRCD. USA operations now being handled by Elusive Disc:
I have purchased a number of these (at CES's) and found the reproduction to be really amazing - especially the remasters of some great older recordings, like the Reiner/Bartok 'Concerto for Orchestra'. They can be played on any Redbook playback system.
I'm not as versed in digital audio technology as you folks, but I am able to understand the process in concept, and it does seem unique.
Thanks for you gracious comments and advice. I am most appreciative. As you can see, most of this is new to me. I had no idea what a DAC was until I was forced to start doing research after the purchase of the Parasound 2000 transport.
My basic knowledge told me that a belt drive transport should provide sound similar to a turntable with this same feature. Of course I was then forced to look at how to get the sound from the transport to the pre-amp, power amp and then speakers. It was then that the term DAC came up.
Since my last post I've purchased the "Lite Audio DAC-AM Modified" by Pacific Valve Company. This looks like it will work OK for me, however, I undertand there are better on the market but I am just getting my feet wet. Also, I understand this DAC can be further upgraded. Initially I was thinking about the purchase of a used DAC but I thought I would have to have that modded in order to bring it up to todays tech standards.
Is anyone here familiar with the Lite Audio DAC-AM? And can you give me some info on it? Will it reproduce 2 channel (stereo) music OK? I am not interested in TV, movies, etc. My primary listening will be to vocal and instrumental jazz, small and large scale classical works with a focus on choral music. Thanks for all assistance and your response.
1. "...The DAC do all the work".
2. "balanced in/outputs produce a better sound than does regular RCA in/outputs" all else being equal.
3. "compact DAC "the smaller the better" that offers good to excellent sound for not a lot of money": some of the Audio Alchemy DACS are small and though old and no longer come with customer service, offer good Red Book/HDCD sound, and can be found used here on Audiogon for not a lot of money.
4. "what should I be looking for...." Gee, I wouldn't know where to begin, but this is a good place to start.