The Sonographe SD22 CD player by conrad johnson

Historical: 12 December 1991 review of an early CD player by Martin Colloms

​The US company conrad johnson are best known for their classic line of high quality valve/tube electronics which includes the long running, true high end  'Premiere' series.  However, this company is larger and more active than you might imagine and has other divisions which generate significant home sales such as Motif -  these high performance, non valve products, and  also Sonographe, a mid priced line.  Sonographe includes speakers and turntables in addition to amplifier electronics and of course, the SD22 CD player, latest  version from a series which has been in production for several years now.  

The Sonographe player submitted for review was one of the latest Bitstream types, low bit, high order  diigtal filter oversampling , as opposed to the earlier models which used multi-bit DACs.  Due to the constraints of low volume production these are not full in house designs; instead they are built on the foundation of an existing player sourced for c.j. as done for many other companies, from Philips. Additional casework helps to conceal the original indentity of the unit, with a c.j. fascia added to personalise their SD22.  Inside it is down to the skill of the individual designer to incorporate helpful modifications, often with the use of an additional audio circuit board to lift the performance of the basic player onto a higher plane. In other respects the SD22 is a standard 43cm  wide unit, drawer loading and complete with a simple, moderately featured remote  control.  The bolt-on fascia is made of anodised aluminium while the display, CD drawer and existing controls for track advance, stop and play all remain intact.  Aside from on/off,  the other buttons cover open/close, pause and programme.  More facilities are present on the control handset - for example, a number array for rapid track entry, plus search and repeat .  Rear panel facilities include the usual European miniature 2 pin mains terminal, and a pair of nickel plated phono sockets at a fixed output level.  No digital output is provided.  The output level is low by cd standards at 0.7v, although arguably this is a better match to the gain delivered by  c.j. and other line preamps  but it rules out absolutely the use of passive volume controls.  Thinking of a comparable deck available here in theUK at a similar price to the SD22  the Micromega Leader springs to mind, but of course on the US market, local  prices would favour the Sonographe.

Technical Details

Opening up this player reveals the expected multicell braced, moulded case  namely chassis of the current budget series of Philips CD players.  c.j's  added external steel casework lends further mass and stiffness. The transport is the established CDM-4 with brush type spindle motor and the  usual zero backlash, swing arm laser movement. The main feature is the c.j. audio board which is located in a spare compartment on the right.  Drawing power from the main Philips transformer, this board is conceived very like the much respected line stage of the PFl preamplifier.
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Here the power reservoirs are unusual, large polypropylene films - in fact, there are no electrolytics at all in this large add-on board.  Top quality audio components are used for this distortion cancelling, zero feedback circuit which has a very short signal path using matched complementary fets.  The IC audio output stages of the Philips chassis have been deleted and the c.j. board takes over this function. Small  5532 type op amps remain inside the '7321' series Bitstream D/A chip and cannot be by-passed.  A high quality polypropylene decoupling capacitor is added to the  D/A convertor power supply line to help lift its performance.

Sound Quality

For reference we used the Micromega Leader, a Meridian 203/200, a Micromega Duo BS and an Arcam Alpha CD. The system included a c.j. PFl preamp, Epos ESll and Quad 63/Gradient sub speakers, plus Krell KSA 150B and Meridian 605 amplification, also supplemented by  a more modest MF Tempest-Typhoon pairing.   In addition to taking careful account of the lower replay level,  the Sonographe SD22 was given several days to warm up from new before serious listening commenced.  First impressions were of a sweet sound, very low in digital 'glare' or harshness and this quality was maintained throughout the listening sessions. The mid and treble ranges showed this c.j. product at its best.  Setting a high standard for purity and clarity,  the mild but discernible effect of a touch of treble rolloff was not unwelcome on many recordings.  Through the mid range the sound has a valve like, analogue character - sweet,  relaxed and atmospheric - yet this was  not obtained at the expense of detail. As for the treble, the mid range focus and detail were both rated highly. Bass freaks might well be disappointed by the low frequency performance of the SD22.  The bass was a little odd, even 'phasey'.  Slam was lacking and the effect was one of softness with fairly good tune playing, the latter aided by  the fine mid range. The SD22 did not time particularly well  with bass lines a little behind the beat , and was rated just average for this factor,one which which is important to the appreciation of pace and rhythm in rock programme. As with many other products of similar single chip Bitstream design, the SD22 exhibited a mildly  compressive effect. Consequently transient peaks  on well known passages lacked their full explosive power and dynamic authority.
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A score of l6 marks was given, though those more appreciative of the sweeter, more musical aspects might well be tempted to score it higher;  to some degree, systems and / or personal taste will play their part here.At this level the  Sonographe SD22 represented  only a modest improvement  over the earlier l4 bit player series.

Conclusion

This Philips rebuild does not make a lot of sense at UK prices.  Sure, the sound is musical, sweet and superficially analogue-like, but to make the grade in the competitive arena, this class of player must today demonstrate firmer bass, better rhythm and superior dynamics. The Micromega Leader sets the pace here and the comparison is particularly relevant since both players use a very similar foundation to achieve their different results.   The low output level and phase inversion were only minor eccentricities in the broader context, as ultimately the new SD22 did not show a sufficient improvement  over its predecessor to warrant recommendation.

Lab report

Before diving into the nitty gritty of CD performance, it is worth noting that the kind of discrete fet analogue stage used for this player is unlikely to deliver exceptional distortion at high signal levels. In the event this proved to be the case – typically -60dB or 0.l% of distortion at full level was recorded, and the DAC was not itself responsible for these results. -90dB is routinely achieved. Channel separation was in the upper seventies range, falling to 62dB by 20kHz.  Channel balance was fine and no interchannel phase difference was present.  The output was linear phase but absolute phase inverted - not a problem for c.j. preamps which also commonly invert their line input signals.  Phase inversion was not felt to have unduly influenced the listening  test result.  Sourced from 6l0  ohms,  the output measured 0.7l5 volts which is  nearly l0dB below the 2v industry standard.