Krell Cipher SACD/CD player Measurements

Sidebar 3: Measurements

To measure the Krell Cipher, I used Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see www.ap.com and the January 2008 "As We See It"); for some tests, I also used my vintage Audio Precision System One Dual Domain. It wasn't possible to measure the player's performance from its current-mode CAST output, but I did do so from its balanced and unbalanced outputs.

To test the Cipher's performance as an SACD player, I used the "provisional" Sony Test SACD. Although Krell doesn't mention DVD playback on their website in their lists of features and specifications for the Cipher, I found that it would play DVD-A discs. So as well as 16-bit test signals burned to a CD-R, I used 24-bit files burned as a DVD-A on a DVD-RW. While the Cipher would play commercial SACDs and DVD-As without problem, it would sometimes not recognize the DVD-RW, presumably because of that medium's low reflectivity compared with pressed discs.

Navigating the Pierre Verany Test CD, the Cipher demonstrated excellent error correction, coping with gaps in the data spiral without glitches in the analog output until those gaps reached 2mm in length. The player muted its output when the gaps were 2.4mm long. The maximum output level at 1kHz with CDs and DVDs was 3.835V from the balanced jacks and 1.918V from the unbalanced RCAs, sourced from impedances of 350 and 175 ohms, respectively. With SACDs, the maximum output level depended on the filter selected: Filter 1 gave the lowest levels, at 1.8V/900mV, balanced/unbalanced outputs; Filter 3 gave the highest levels, at 3.237V/1.62V. Both the balanced and unbalanced outputs preserved absolute polarity (ie, were non-inverting), the XLRs being wired with pin 2 hot.

With CD and DVD playback, the Cipher's frequency response depended on which of the two filter options was in use. At all sample rates, Filter 2 gave an earlier high-frequency rolloff than Filter 1 (fig.1). As with earlier Krell SACD/CD players, both the ultrasonic response rolloff and the absolute level varied considerably with which of the four filters was being used (fig.2; see also fig.1 here). All filters had responses that were flat within the audioband, but Filter 3 was 5.1dB higher in level than Filter 1, Filter 2 was 0.55dB higher, and Filter 4 was 3.3dB higher. These level differences are sufficiently large to invalidate any listening tests comparing the filters unless compensated for with the preamplifier's volume control. Channel separation (not shown) was superb at >125dB in both directions below 5kHz, and still 110dB at 20kHz.

Fig.1 Krell Cipher, PCM frequency response at –12dBFS into 100k ohms with data sampled at 44.1 and 96kHz with: Filter 1 (left channel blue, right red), Filter 2 (left green, right gray) (0.5dB/vertical div.).

Fig.2 Krell Cipher, SACD frequency response at –3dBFS into 100k ohms with: Filter 1 (left channel blue, right red), Filter 2 (left cyan, right magenta), Filter 3 (left green, right gray), Filter 4 (left blue, right red) (2dB/vertical div.).

Testing the Cipher's resolution by sweeping a 1/3-octave bandpass filter from 20kHz down to 20Hz while it played a dithered 1kHz tone at –90dBFS from CD (fig.3, top pair of traces below 5kHz), all that can be seen is the dither noise used to encode the signal. The bottom pair of traces in fig.3 were taken with 24-bit DVD data representing this signal; the noise floor drops by around 16dB at high frequencies, which suggests that the Krell has almost 19-bit resolution in this region, less at low frequencies. The middle pair of traces in fig.3 were taken with SACD data. As with the Krell Evolution, which Fred Kaplan reviewed in September 2008, the Cipher's conventional outputs are a little noisier than the best players I've tested with SACD, resulting in only a modest increase in resolution compared with CD. However, I performed this test with the Cipher set to Filter 1, which, on Krell's recommendation, was how FK had listened to SACDs; the low output level of this Filter slightly compromises absolute resolution.

Fig.3 Krell Cipher, 1/3-octave spectrum with noise and spuriae of dithered 1kHz tone at –90dBFS, with: 16-bit data (top), 24-bit data (middle), DSD data (bottom) (right channel dashed).

Fig.4 repeats the spectral analysis for 16- and 24-bit data with an FFT technique; again, it reveals that the increase in bit depth drops the noise floor by around 16dB above 1kHz, though a few very-low-level idle tones are unmasked by the reduction in noise. Figs.3 and 4 also show that some power-supply spuriae are present, though these all lie at or below –120dB and will therefore be inconsequential. Commendably, with DSD data there was no change in the noise floor as the signal level changed (fig.5).

Fig.4 Krell Cipher, FFT-derived spectrum with noise and spuriae of dithered 1kHz tone at –90dBFS with: 16-bit data (left channel cyan, right magenta), 24-bit data (left blue, right red) (linear frequency scale).

Fig.5 Krell Cipher, spectrum of 1kHz sinewave with DSD data, DC–1kHz, at 0dBFS into: 100k ohms (left channel blue, right red), –40dBFS (left cyan, right magenta), –60dBFS (left green, right gray) (linear frequency scale).

Linearity error with 16-bit data (fig.6) was less than ±1dB above –110dBFS, and was dominated by the recorded dither noise. With an undithered CD signal at exactly –90.31dBFS, the Cipher's excellent linearity and low noise readily allowed the waveform to be reproduced with good symmetry (fig.7). This graph was taken with Filter 1; Filter 2 gave an identical result. DSD data at the same level gave a well-formed sinewave (fig.8).

Fig.6 Krell Cipher, linearity error, 16-bit data (2dB/vertical div.).

Fig.7 Krell Cipher, Filter 1, waveform of undithered 1kHz sinewave at –90.31dBFS, 16-bit data (left channel blue, right red).

Fig.8 Krell Cipher, Filter 1, waveform of dithered 1kHz sinewave at –90dBFS, DSD data (left channel blue, right red).

As expected from a Krell player, the Cipher offered very low amounts of harmonic distortion, with the second and third harmonics highest in level (fig.9). In fact, the distortion is around 10dB lower than with Krell's older Evolution 505 player. This graph was taken into the benign 100k ohm load; dropping the load to 600 ohms actually reduced the level of the third harmonic, leaving the second harmonic unchanged at –110dBFS (0.0003%, fig.10). Tested with an equal, full-scale mix of 19 and 20kHz tones, the Cipher offered very low levels of intermodulation distortion (fig.11), though the fact that I had only a 16-bit version of this test signal on disc means that the noise floor in this graph looks rather hashy.

Fig.9 Krell Cipher, spectrum of 1kHz sinewave, DC–10kHz, at 0dBFS into 100k ohms (left channel blue, right red) (linear frequency scale).

Fig.10 Krell Cipher, spectrum of 1kHz sinewave, DC–10kHz, at 0dBFS into 600 ohms (left channel blue, right red) (linear frequency scale).

Fig.11 Krell Cipher, HF intermodulation spectrum, DC–30kHz, 19+20kHz at 0dBFS into 100k ohms, 16-bit CD data (left channel blue, right red) (linear frequency scale).

The Evolution 505 offered a rather idiosyncratic performance when tested for jitter rejection with CD playback. By contrast, the Cipher's jitter rejection was superb, with no accentuation in its analog output of the odd harmonics of the low-frequency squarewave component of the J-Test signal (fig.12).

Fig.12 Krell Cipher, high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz: 16-bit data from CD (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz.

The Krell Cipher's measured performance can be summed up in one word: superb.—John Atkinson

COMPANY INFO
Krell Industries
45 Connair Road
Orange, CT 06477-3650
(203) 298-4000
ARTICLE CONTENTS
Share | |
COMMENTS
commsysman's picture

Nothing Ayre makes sounds as good for CD or SACD playback as the $1000 OPPO BDP-95; I have both the OPPO and the Ayre C5xe/MP.

From now on, the BDP-95 should be used as a direct comparison to any player you test that costs over $800. It should be your standard for comparison.

If you don't, you are just wasting your time...and everyone else's.

IMO all of the players for over $1000 have been made pretty much obsolete and irrelevant by the BDP-95. What an amazing unit for the money.

 

soulful.terrain's picture

 

Krell has always made some of the most gorgeous gear ever and when it comes to performance, Krell has always performed flawlessly.

I do agree with the prior poster about the Oppo. Oppo has made it tough on the audacious audio. They have a great product that is by no means a slouch.

John Atkinson's picture

Quote:
Oppo has made it tough on the audacious audio. They have a great product that is by no means a slouch.

We have received another sample of the Oppo BDP-95 that I am taking round to Fred on Tuesday for him to compare with the Krell and write a follow-up.

John Atkinson

Editor, Stereophile

soulful.terrain's picture

Thanks John. I appreciate it and look forward to it.

Mark

Axiom05's picture

I was auditioning some amps yesterday, using the Cipher to play CD's. I was appalled and frustrated at the time it took for the Krell to read the discs. What is so difficult about reading a CD that it should take more than a couple of seconds? There is no excuse for this sort of performance from a product as this price point.

Muzik-Luvr's picture

I can't get around the seemingly arrogant actions by Krell to suggest nothing was amiss with the unit and only sending a different one at the reviewer's request/insistence. Imagine how this may have played out for a paying customer that experienced the same issue(s). I'll continue enjoying my current source (bel canto PL-1) until something much more compelling (to me) comes along!!

Oenophile's picture

The reviewers issues with the CDP would sum up modern Krell. And how do you think us 'regular folk' get along with unreliable equipment warranty/claims when even review samples fail to work properly.

I have a dead 505, and recently have had my KPS-28c repaired (for the second time). Built like a tank and reliablility may apply to Krell amps, but their CDPs appear to be trouble. And how are the SACD Standard owners faring? 

wongpk's picture

Just bought the Krell s350 CD player. Thought it was good value coming from Krell.. Alas, how wrong I was. Some CDs cannot load, or plays a few second then stopped. Contacted Krell and yet to receive reply and doubt they will do so. Pity I didn't read the Cipher review with the same problem. Now I just live with it..... sad.  Was told there are bound to have some discs cannot be read. But these play well on my cheaper Marantz 6004 on Stax headphones. Anyone has some solution?

wongpk's picture

To be more objective, the sound from the s350a coupled with the S300i amp is surprisingly good. Sound staging is excellent with a lot of ambience from my Apogees Centaur Major and plays effortlessly. Only disappointed cannot play some UltraHD CDs or some silver discs. Where it could, the sound quality was truly mind boggling ! Listen o Autumn in Seattle 32 bit CD and you can see the transients and wide staging of the piano. Wished I could get some support from Krell though.

 

X
Enter your Stereophile.com username.
Enter the password that accompanies your username.
Loading