Any mention of Dual turntables usually brings one of the many incarnations of the company's CS 505 to mind. The original '505 was a typical Dual design, taking its cue from the basic turntables that had been around since the 1950s by being built on a sprung-steel plate. It was a budget deck, which sold mainly to those looking to take their first step on the audiophile ladder. But Dual made more ambitious models too.

The mainstay of its early '70s range was the 1229, a suspended-chassis, three-speed idler-drive deck that was similar in many ways to the models BSR and Garrard were making at the time, only far better engineered and much better finished. A synchronous motor and a full size (12in) platter set the 1229 apart form the herd and it sold well, despite its relatively high price of around £115 with plinth, cover and Shure DM103 cartridge.

Little Belter
Dual went further up-market in 1975 with the 701, a direct-drive, semi-automatic turntable which, it was claimed, delivered performance of a 'professional standard'. The same year it unveiled the CS 601 seen here, the first belt-drive model in its range. Supplied with a plinth, lid and factory-fitted Shure V15/III-LM cartridge [HFN Aug '73] and finished in a choice or either white or simulated walnut, the CS 601 (as the complete package was known) was not a cheap option at around £135. But 'professional' levels of performance were claimed once again.

Ad highlights the CS 601's single-play operation with full automation – a compelling proposition for a deck in this class, combining ease of use with top quality sound

Even though the new turntables from Japan, such as the Sony PS-X4 [HFN Sep '17], were beginning to make German company Dual's offerings look a little old fashioned, they still enjoyed a loyal following. The CS 601 featured a powerful eight-pole synchronous motor which operated almost silently and had its speed locked to the mains frequency. The arm could be operated either manually or automatically, which saw the various sequences completed in a brisk, efficient manner. The arm itself was made from an aluminium tube that was both straight and rigid and this was suspended on a self-adjusting gimbal bearing and balanced by a carefully decoupled counterweight.

As for the supplied V15/III-LM cartridge, this was the top model in the Shure range at the time and was well known for its fine tracking ability. The cost of this pick-up accounted for around £40 of the CS 601's price, showing that the turntable itself represented good value for money given the quality of what was on offer.

Home On The Range
The CS 601 remained in Dual's often bafflingly diverse and constantly changing range until around 1978, when it was replaced by models such as the CS 510 and CS 502. Both of these decks dispensed with some of the automatic functions as well as the expensive Shure cartridge and so were cheaper as a result. If one still wanted a Dual deck with a factory-fitted V15/III-LM then your choice lay between the CS 704 and 721, both of which were direct-drive.

Close-up of the CS 601's arm bearing and counterweight. Note provision for coarse (slide) and fine (screw) adjustment of the arm balance

Circular Logic
It is difficult not to be impressed by the way this deck's mechanical logic operates. It's all the more impressive when you consider that there are no electronic systems to control things, as would be the case if a similar piece of equipment were to be designed today. For example, to play a record manually all one has to do is unlock the arm from its rest and place it on the record – the motor starts automatically with no further intervention. Returning the arm to the rest switches the motor off again in the same way.

Fully automatic operation is instigated by moving the lever on the right of the plinth to 'start'. This sets the motor in motion and the arm cues in to either the 12in or 7in start point, depending on the setting of the speed control. Moving the lever to 'stop' parks the arm and stops the motor, or the manual stopping sequence can be used instead. Meanwhile, a small knob next to the control lever is used to select between single play and continuous repeat, the latter being cancelled as part of an automatic stop sequence should this be requested.

Further refinements lie beneath the surface, such as the speed change mechanism being blocked unless the platter is rotating. This prevents damage to the belt if the speed change lever is accidentally moved while the power is turned off. The controls all have a light, positive and accurate feel too, like the dashboard switches of a quality German car of the period.

Dual's unusual 'Vario Pulley' is used to give some fine speed adjustment. This clever arrangement sees the motor pulley split into eight segments whose overall diameter can be changed using a tapered pin which is pushed down into the top. With some Dual turntables this has to be done with a screwdriver, once the platter has been removed. In the case of the CS 601, however, a mechanism is provided that brings fine control of the speed out to a discrete knob, which can be found mounted in the pivot of the speed lever.

Traditionally Dual made idler-drive decks but the wording on the platter mat's central disc highlights that this is a belt-drive design

As for the platter, this rests on a larger die-cast pulley which has been accurately and carefully machined. This runs on a centre spindle with a gently radiused tip that's supported on a plastic pad at the bottom of a deep phosphor bronze bush in a substantial die-cast housing. Upon this the 12in platter rests, which is another large casting that has been dynamically balanced with lead weights fitted at selected positions around its perimeter.

Rare Treat
For optimal damping the platter features a bonded mat and has strobe rings cast into its underside to aid in fine tuning the speed, which is 33rpm only. An orange neon lamp illuminates the strobe, and the position of this can be changed for 50Hz and 60Hz markets. The strobe is viewed via an intricate set of lenses and mirrors, the window being just to the left of the stylus tip when the tonearm is at rest.

The arm too shows many examples of considered design. The downforce is applied dynamically using a spring-loaded roller on the pivot, the static setting being made by a counterweight which is decoupled by a soft plastic insert. The counterweight screws in and out for fine adjustments, or it can be telescoped in and out for larger changes, such as those that may be needed if fitting a heavier cartridge.

The cartridge itself is mounted on a removable carrier within the headshell, this being released by folding back the finger-lift. Standard pick-ups can be fitted using nuts and screws, but the Shure V15/III-LM clips into place on a special mounting. This ensures correct geometry without the need to resort to alignment protractors and the like. All these details point to the first-rate design and engineering of the CS 601. Indeed, there are many exotic and seemingly more specialised turntables to be found out there which are nowhere near as well thought out or constructed. It is a rare treat to use something which has clearly been created with such care.

When it comes to its operation, this is a very pleasant turntable to use, the only fly in the ointment being the difficulty of playing 12in 45rpm singles, which the mechanisms do not allow for. Manual operation is the best way to deal with this issue, of course. The alternative, if using the deck in automatic mode, is to flick the speed lever from 33rpm to 45rpm once the stylus has landed on the record. Needless to say, automatic repeat isn't available for 12in singles.

Tim Listens
Spinning up our original example of the turntable with a factory-fitted V15/III-LM cartridge in place showed the Shure pick-up to be a good match for the Dual arm. The two combined give the distinctive 'V15 sound', one that is slightly soft but still full of detail. Others may have more bite, but the V15's famous tracking ability ensures a smooth, relaxing listen from all but the most well-used and worn of records.

The CS 601 package included an attractive tinted dust cover, large enough to be closed while a record was being played

The title track of Steely Dan's album Aja [ABC AA-1006] was a good example of just what this turntable is capable of. There was a fine sense of poise in a laid-back, easygoing sort of way, with percussion that shimmered rather than crashed and well placed, well integrated vocals. A pleasing bass tubbiness was also noted, for with some arm and pick-up combinations this recording can sound a bit too dry.

The piano revealed very little belt-drive waver, and what I did hear was only really apparent when comparing the same track via a good direct-drive turntable (or from CD). The CS 601 is not unique in this respect, of course, although its slightly restricted soundstage is arguably a more defining characteristic. I felt there was little in the way of extension beyond the centreline of each loudspeaker, and I've heard other decks project a more solid centre presence too, but these are minor complaints against what is a remarkably refined sound overall.

Strauss's Horn Concerto No 2 in E flat [Philips 412 237-1] sounded creamy smooth on the CS 601, the instruments set against a pleasingly quiet background (except for a small amount of buzz from the motor coils, heard directly and not through the loudspeakers) during the opening passages.

Exploded view of the CS 601 turntable in the service sheet shows that it is far from a simple deck in its construction. A complete overhaul is a complex task should it be needed

Maybe a little more sharpness from the strings on this recording would have added some extra excitement, but the balance offered did allow the piece to be enjoyed at a decent volume level without unrealistic amounts of glare being generated. Again the width of the soundstage appeared limited, but placement of the individual sections of the orchestra within it was notably well defined.

Touch Of Class
As with some of B&O's designs, I don't think this turntable would appeal to those who like the intrinsic sound of the LP format itself. Instead, the CS 601 plays records without making them sound too much like records. The downside is that you never feel like you are in the front row at a performance; others capture a better sense of immediacy but the price can be harshness and fussiness elsewhere.

The CS 601 first appeared in the 1975 edition of the Hi-Fi Yearbook [top] where its specification was likened to the 1229 [bottom]

A different cartridge may well reveal another side to the CS 601 but, as ever, turntables are all about a balance of compromises. In the case of the CS 601 and V15/III-LM combination, this yields a smooth but detailed and well-crafted sound and for those who appreciate properly constructed mechanical things it is a tactile joy. The sturdy, high quality build promises to give many years of trouble free use too.

Buying Secondhand
Always ensure the cartridge carrier is present before buying a secondhand CS 601 because these are hard to find on their own. The silver-plated contact strips onto which the carrier engages can tarnish with age, potentially causing a channel imbalance. Cleaning is straightforward, however, so long as one is careful not to disturb the wiring.

As with the CS 505, the tiny toothed rubber belt in the speed adjustment mechanism can become brittle with age and fall apart. Replacements are available, but are a fiddle to fit. The main drive belt wears too, the first symptom being the deck's reluctance to change from 33rpm to 45rpm.

Rear view shows the balanced lid hinge and the mains and signal cables. Most CS 601s were sold in this type of plinth, but it also came in 'chassis only' form

Normal manual operation but no arm movement during the automatic sequences is usually the fault of a small rubber tip which forms a friction drive under the arm base. These rot away over time and are no longer available, but a replacement can be made with a short length of flexible sleeving.

Hi-Fi News Verdict
This is a fine performer from Dual, which in more recent times was dogged by a budget NAD 3020/Wharfedale Diamond/student-squat image! Well put together, and with a sound that is both smooth and sufficiently revealing, a CS 601 should be a lasting source of musical pleasure provided, of course, it is maintained and looked after. Recommended, especially where automatic operation is required.

Dual CS 601 Turntable Lab Report

Dual provides a strobe pattern to assist in the manual fine-tuning of the CS 601's speed and, with the strobe 'stripes' stationary, its absolute accuracy was a mere –0.06% adrift. The belt-driven, flywheel-assisted mechanism – in practice a 1.3kg alloy platter with 0.8kg sub-platter and robust 8-pole synchronous motor – delivers good low-rate speed stability and a peak wow of just 0.03% [see Graph 1, below]. Higher-rate flutter components are a little more obvious with sidebands at ±10Hz, ±30Hz, ±43Hz and ±100Hz amounting to a peak-wtd figure of 0.08%. The latter is linked to the inbuilt PSU but the former three modes are also just visible on the unwtd rumble spectrum [not shown here]. The main bearing still met Dual's original >63dB weighted rumble specification at –64.5dB (DIN-B wtd, re. 1kHz/5cm/sec), a figure that improved to –65.7dB through-the-groove thanks, in all likelihood, to the rubber mat.

The 'torsion-resistant' 222mm effective length aluminium tonearm includes provision for a plastic 'cartridge holder' – headshell – with short fingerlift, and while this keeps the effective mass down to the sub-10g required for Shure's classic high compliance V15 III pick-up it also adds to the complexity of the arm's resonances [see Graph 2, below]. The main beam and headshell appear to bend at a low ~55Hz and ~85Hz [off the left hand X axis of Graph 2] with a series of other bending, twisting and harmonic modes associated with this, the 'self-adjusting' pivot bearing and other appendages at 185Hz, 260Hz, 290Hz, 400Hz and 560Hz. The spring-loaded downforce mechanism is effective but under-reads by up 20% at low settings (so a setting of 1g amounts to a 1.2g downforce and 2g is 2.15g). PM

Wow and flutter re. 3150Hz tone at 5cm/sec (plotted ±150Hz, 5Hz per minor division)

Cumulative tonearm resonant decay spectrum, illustrating various bearing, pillar and 'tube' vibration modes spanning 100Hz-10kHz over 40msec

• Turntable speed error at 33.33rpm 33.31rpm (–0.06%)
• Time to audible stabilisation 5sec
• Peak Wow/Flutter 0.03% / 0.08%
• Rumble (silent groove, DIN B wtd) –65.7dB
• Rumble (through bearing, DIN B wtd) –64.5dB
• Hum & Noise (unwtd, rel. to 5cm/sec) –50.0dB
• Power Consumption 2-7W
• Dimensions (WHD) / Weight 420x148x365mm / 7.6kg 

Review: Tim Jarman, Lab: Paul Miller

Source: www.hifinews.com