I was asked by the folks at NativeDSD.com to see if readers at ComputerAudiophile.com would be the right audience for testing the results of two different DSD AD converters, a unique experiment in recording music. My answer was a resounding yes; the DSD (and overall DA and AD converter) technology is nothing new to us here, and this would be a great and fun way to find out what our DSD-capable equipment (and our ears) are telling us about things like sweet spots within DACs, the importance of DSD bit rates, etc.
In the brave new world of High Resolution Music Downloads many music fans have asked a big question. Is there a difference in sound quality that comes from recordings made at different resolution levels and different Analog to Digital Converters (ADCs)?
A Unique Opportunity
The experts at Native DSD.com are giving you a unique opportunity to compare session files from a brand new performance of “A Midsummer Night’s Dream” by the Budapest Festival Orchestra under the direction of Ivan Fischer. The session was recorded at two different Direct Stream Digital (DSD) bit rates – Single Rate DSD (DSD 64fs) and Quad Rate DSD (DSD 256fs) with two of the industry’s best Analog to Digital Converters – the Grimm Audio AD1 (at DSD 64fs) and the Merging Technologies Horus (at DSD 256fs) Live in Budapest.
You can’t really do a comparison like this justice without top flight equipment and recording talent. On this recording, we have both.
For this unique project, Jared Sacks, Founder of Native DSD and Producer and Recording Engineer of Channel Classics teamed up with Tom Caulfield, Mastering Engineer for Native DSD and a Veteran Recording Engineer and DSD Expert. The record producer was veteran Hein Dekker.
Jared Sacks produced an analog mix of the performance with the Budapest Festival Orchestra. From that analog mix, Jared used his Grimm AD1 DSD 64fs converter and created a Stereo and Multichannel edition of the performance from the Grimm AD1 that was stored on the Merging Pyramix DAW system in Single Rate DSD (DSD 64fs).
Tom Caulfield took the exact same signal and used the Merging Technologies Horus DSD 256fs converter to create a Stereo and Multichannel edition of the performance on the Horus that was stored on the Merging Pyramix DAW system in Quad Rate DSD (DSD 256fs).
There was absolutely no post production involved in these files.
Comments from the Engineers:
“Setting up with the usual amount of equipment in the hollows of the MUPA Concert hall was more crowded than usual with Tom taking a side table to set up his computer to parallel record the Budapest Festival Orchestra. Since we always make an analogue mix during the sessions it was a simple task to split the feed close to the two converters without any loss of signal. Channel Classics has been using a custom made analogue mixer from the Dutch electronics master Rens Heijnis who also developed custom made battery powered microphone preamplifiers that we use in Channel Classics DSD recording sessions. All of this equipment is connected with 3T carbon cables from Van der Hul. For this DSD comparison, we selected a simple 4 minute Scherzo from the sessions.”
“Over time, Jared and I have discussed the merits of higher than 64fs DSD bit rate recording. He records all his projects with arguably the finest DSD A/D converter available today, the Grimm AD1. One of its characteristics however is it only operates at 2.82MHz, 64fs DSD – Single Rate DSD.
All DSD encoding has as an artifact a modulation noise far exceeding the level of the incoming analog signal. DSD can shift this noise energy to above the useful audio frequency band, where it can be filtered. Using higher DSD bit rates (DSD 128fs, DSD 256fs) simply raise the noise envelope an octave for every doubling of the bit rate. The shifted noise envelope shape, and amount of noise energy remain the same. Just the frequency where the noise starts to become a measurable percentage of the lowest audio signal level doubles for every doubling of the bit rate. Also, at any DSD bit rate, the noise is uncorrelated to the signal, like tape hiss. That's very different than a correlated linear distortion or modulation.”
So the discussion went; the actual encoding of the audio band should not be affected by the DSD bit rate, since regardless of the bit rate chosen, the audio band is well outside its frequency spectrum and influence…theoretically. The in-audio band conversion quality should be the sound quality determining factor, not the DSD sampling rate.
Well, Let's Test That!
Of course, there is only one way to really find out whether the theory and the expectation of DSD recording meet the reality. And that is to create a new recording on two of the top DSD converters and listen to the results. So they did!
What resulted was a pair of exactly level matched Stereo and Multichannel files – at 64fs DSD from the Grimm AD1, and at 256fs DSD from the Horus. Both were recorded with identical Pyramix Digital Audio Workstations.
Recognizing that there would be interest in comparisons at Double Rate DSD (DSD 128fs), they also converted the Quad Rate DSD recording from the Horus from Quad Rate DSD (DSD 256fs) to Double Rate DSD (DSD 128fs). That gives you, the listener, yet a third set of Stereo and Multichannel files to listen to and compare.
The Story in Pictures
Budapest Palace of Arts Hall: downstage microphone detail, including a stereo pair flanked by the three main ITU placed primary mics, and the two surround mics poking out of row 4.
Upstage spot mic detail with producer Hein Dekker conversing with (not-pictured) stage personnel.
It's ultimately all about the music! Follow along if you can.
Ivan Fischer conducting, while vocalists Anna Lucia Richter soprano, Barbara Kozelj mezzo-soprano prepare to join in.
Listening to a take: L to R, Jared Sacks recording engineer, Ivan Fischer conductor, Anna Lucia Richter soprano, Barbara Kozelj mezzo-soprano, with Hein Dekker producer looking on.
Cables anyone? What it takes to mix in analog, record in DSD
Merging Horus at lower left paralleling the Grimm A/D Converter at top. The red Cat-6 data cable contains the 256fs 5.0 channel DSD bit-stream being recorded.
Now It’s Your Turn
And now, it’s your turn to listen to the results of this historic recording session where you can test the quality and performance of different DSD bit rates and two top notch DSD converters.
Below you will find links to the performance at multiple DSD rates. I invite you to download these files, free of charge from Native DSD. Once you have downloaded the files and compared the results, we’d like to invite you to report your results and comments as responses to this article below.
I look forward to reading your comments and results. Make sure you tell us about your DAC, and the bit rates you listened to. And most of all, I hope you enjoy this fun exercise, and enjoy helping the folks at Native and Channel Classics make some DSD recording history!
Note: Jared and I will be doing a seminar at Axpona Chicago on the 25th of this month. I hope to see some CA folks there, where more questions can be asked directly.
* DSD 256 from the original Merging Horus AD converter
* DSD 128 downsampled from Horus 256
* DSD 64 downsampled from Horus 256
* DSD 64 from the original Grimm AD converter
Click below*for the free DSD track downloads of the session files from Mendelssohn's A Midsummer Night's Dream recording sessions.