The Dual CS-506 is one of Dual’s belt drive models and was produced from 1979 through 1981. The CS stands for ‘Complete System’ but it is a fairly basic, semi-automatic model as far as turntables go. Most are familiar with Dual’s 12xx series turntables that are well known for their idler drives but their 500 series belt drive turntables are excellent as well.
The Dual CS-506 is a 2-speed (45, 33) belt drive that incorporates Dual’s ULM, or Ultra Low Mass, tonearm. As you can see the headshell is a little different. Standard 1/2″ cartridges will not fit this tonearm. Dual supplied an adapter and counterweight for those wanting to use a 1/2″ headshell, but if you’re looking at buying a vintage CS-506 today, be aware that without that adapter you won’t be able to utilize a 1/2″ headshell. However, there are usually a few to be found on eBay.
The styli for the original headshell was model TKS 45E and can still be found at some turntables parts dealers online.
The ULM is a straight-line 221mm tubular design and is made with aluminum tubing. As mentioned above, the cartridge is a proprietary design and originally manufactured by Ortofon. An interesting fact about the dynamically balanced Dual ULM tonearm is that, after balancing with the counterweight, tracking force is applied with a spring which means that, with a record clamp in place, you could turn the table sideways or upside down without it skipping a beat. Tracking force will also slightly increase with height, such as when the arm is riding over a warp, which results in more consistent tracking.
Other features of the CS-506 include:
- Drive: Dual 8-pole belt drive synchronous motor
- Starting time: roughly 2 seconds
- Platter: 304mm, 1.1kg, non-magnetic, removable
- Speeds: 33.33 and 45rpm
- Pitch control: 6%
- Wow and flutter: 0.04% WRMS
- Rumble: 70dB
- Tonearm: torsion resistant tubular aluminium
- Effective length: 221mm
- Stylus pressure: 0 to 3g
- 4 point gyroscopic gimbal suspension
- Tracking force applied at pivot via tempered flat wound spring
- Double damped cue control
- Illuminated strobe
- Removable spring loaded dust cover
- Multi-calibrated anti-skating
- 8 gram total effective mass with ULM cartridge
One common problem with the CS-506 is that the small plastic hooks that are used, along with the mounting screw, to mount the headshell tend to break. Always check before you buy one and make sure they are intact. And, be careful with them if they are intact because if they break it’s not an easy fix.
Dual had something called the Vario Pulley system for controlling pitch up to 6%.
There were apparently two variations of the CS-506, the 1st generation 506 and the 2nd generation 506-1. As best I can tell the 506 came with the ULM45E cartridge while the 506-1 used the TKS45E. The 2nd generation mount was lighter and more fragile than the first. Another difference between the two was the motor. The 506 used an 8-pole SM860, while the 506-1 was equipped with a 16-pole SM100.
The platter on the CS-506 is 304mm and weighs 0.9kg. It has built in stroboscopic marks on the side for the mounted strobe light.
Overall the Dual CS-506 is a good turntable. It has its idiosyncrasies but is a decent performer. Just be careful that the cartridge mount is not broken and remember that, if it doesn’t have an adapter, then you’ll probably need to buy one to use a 1/2″ headshell. The CS-506 isn’t the most popular Dual so prices aren’t that high. They can be found for $100 to $200.