Those who have read my little review of the Tannoy Mercury M20 Golds might be aware I’ve inherited some other items that they were originally purchased with sometime in 1985, we think. In this little article I’ll be explaining a little about our (immediately) beloved turntable – the Dual 505-2. By modern standards, if purchased new I would guess this record deck would compare with the likes of the Project Debut Essential package or similar. Our example appears to still be fitted with its original Dual ULM165E cartridge and DN165E stylus. We have no idea what playing time the stylus has seen, nor whether it is indeed the original stylus or an after-market replacement.
Fault-finding and repair
Upon arrival the platter would not spin, and I had been warned of the need for replacement drive and pitch-adjustment belts. After some Google abuse in an attempt to find a service or owners’ manual for this unit, I found my way to the Vinyl Engine which had an English owner’s manual available.
Dual 505-2 disassembly/reassembly
After downloading and reading the owners’ manual, I then attempted to take the inner plinth out of the wooden frame. This isn’t as easy as it looks; so having armed yourself with a Leatherman, Dutch courage and a glance at the owner’s manual, it goes something like:
- Lock the tonearm in place.
- Remove the stylus and put it somewhere safe to save it getting damaged.
- Remove the rubber turntable mat, and the platter.
- Remove the plastic lid.
- Ensure the transit screws are in the “playing” position, to give the suspension mounts full movement.
- Turn the whole deck on its back (so it rests with the hinges against your work surface).
- Slide the suspension spring bases out of their homes in the plastic base plate. The whole plinth assembly can then separate from the base. Note that the captive mains, signal and ground cables prevent the plinth separating completely from the base, without further work to release the cable entry glands.
- Breathe. Carefully.
- Reassembly is essentially a reversal of steps 1>8.
Checking the tonearm, motor and microswitch interaction
Another thing I learned during my Google session to find the manual was that one of the most common faults with these decks is that the microswitch seizes up if the deck has not been used for a while.This is the switch that starts the motor spinning when the tonearm is moved into the playing position. The cure recommended on most online forum posts I found on the issue was to simply use a screwdriver to operate the switch enough times until it starts working again. If I recall correctly, the switch is on the underside of the plinth next to the motor, and has either a yellow or blue plastic cap that connects to the tonearm assembly, via a system of levers that I could not easily work out. Within about 10 pushes the switch mechanism freed itself and the motor started spinning. With hindsight it was risky leaving the mains plugged in while I took everything apart, but it paid off and as it turns out there were no exposed terminals that a stray finger or screwdriver could have found. Phew.
As mentioned earlier, I had been warned of the need for a new drivebelt. It turned out that the belt itself was fine, but it needed a little gentle persuasion to realign it so it ran inside the speed selection mechanism. I tested the speed selector a couple of times to check that the belt stayed in the correct position, which it did. While I had the deck apart I also discovered that the toothed pitch adjustment belt had somehow snapped, so without any spare parts to hand I simply removed it and hoped for the best.
Function test, and adjust pitch
Having reassembled the deck I plunked down Suzanne Vega’s debut LP, and found both platter and cue mechanisms to work as designed. The result was quite stunning – the aged stylus and cartridge combination was working well enough with the photo stage of my NAD 302 amplifier to extract a remarkably pleasant sound from the disc, albeit at a slightly higher pitch than normal.
So, off came the platter and out came the Leatherman to attempt a quick-and-dirty adjustment of the pitch control pulley. Having worked out that the belt links the surface-mounted pitch control knob to the control pulley on the motor assembly, I could reason as to which way to turn the pulley to make the required adjustment. Using the narrow flat-blade screwdriver on the Leatherman, I turned the pulley through 90 degrees anti-clockwise by locking the blade in the teeth of the pulley and pushing gently in the right direction.
Trying the test LP again showed I’d adjusted too much – the song was now playing slightly slower than normal, so I went back and halved the difference. The LP now played what I considered to be ‘normal speed’ (turns out I do have an intuitive sense of ‘perfect pitch’, though it helped to have a CD of the same album to compare, which did indeed synchronise perfectly both in terms of track length and perceived pitch/tempo.
First impressions of sound quality
This is a subject for another post of its own, I’m sure. What immediately strikes is that the sound quality on offer is surprisingly good, but there are no good words or phrases I can think of to describe how it differs to the same material played from CD or other known digital sources in my system. When the disc is clean and in good playing condition, and has itself been mastered and manufactured well, the soundstage is noticeably wider and deeper than my digital sources, and the overall presentation is simply more musical. It’s not that the vinyl source is ‘warmer’ or more detailed as has become the stereotypical wording used by audiophiles writing in print or online when selling the plus-points of vinyl – just that the overall result is simply more pleasing to me. My wife confirmed this, noting that the vinyl feels more ‘real’, more as if the musicians are being presented in a space around and in front of us, compared with the digital sources forcing the soundstage to be artificially contained within our room.
Stay tuned for more on what work we carry put on this deck, and for some more in-depth reviews of what it enables us to enjoy!Update @23:42
Put picture back into the post as originally designed, correct spelling/typo’s, add the following list:
Things still to do:
- Install a replacement stylus in case I broke anything in transport or handling. Turns out the current one (and its cartridge) are replacements with only 50hours playing time on them, but I’ve already ordered a Dual DN-165E replacement stylus from Stylus Plus, so at least I’ll have a spare.
- Replace the pitch control belt – not because it’s needed in normal operation, but I feel it’s only fitting to bring this one back “to spec”.
- Check alignment of the cartridge. When I first started using the deck, I noticed a significant amount of sibilant distortion when nearing the end of a side. This isn’t uncommon, but a quick alignment according to the “Stevenson Method” has made things noticeably better at the expense of slightly increased sibilant distortion at the beginning of each side.
- Clean all our LP’s and replace inner sleeves.
- Try the phono stage of our inherited NAD 3020B in place of the current NAD 302.