More thoughts on our Dual 505-2 with Denon DL-160

A few months ago I think I wrote here that I was struggling with vinyl sibilance and inner-groove distortion with our Dual 505-2, then fitted with its original MM Ortofon cartridge and DN-165E stylus. A partial solution was found with the upgrade to the significantly better Denon DL-160 MC cartridge.

We’ve moved house and played a lot of the black stuff since then, and some of it has been found to sound rather tired after a heavy life with previous owners. The result was that for some of our older discs, the inner-groove distortion and vocal sibilance caused by previous wear was getting me down.

Last night and this morning before work I spent some time with the deck in its new home, with the aim to get things set up as well as is possible.

Step 1: Align the cartridge

The first step in this journey was to find a suitable downloadable protractor to check that the cartridge was properly aligned – it’s so easy to get this wrong and somewhere in the move I’d lost my previous unit. So, off I went to Google and found this printable example, which printed exactly to the right scale on our printer the very first time.

I followed the instructions on the template, only after cutting the bottom strip (with the alignment markings) off so as to prevent the paper scuffing the arm and stylus.

The result was immediately obvious – much more detail, a little less distortion in the inner groove of older records like our copy of Marillion’s “Misplaced Childhood”. The soundstage is a little wider and set further around the speakers, both in front and behind. Centred vocals and instruments are really marked as dead-centre now.

Step 2: Check tracking weight and antiskate

Rather dangerously, this was done by ear, on the basis that I’m listening for increases or decreases in distortion in known tricky passages.  Queen’s “You Take My Breath Away” from their “Day At the Races” album was chosen for this – our first-run copy has significant problems on the left channel with sibilants blatantly distorting.

It turned out that I had to track much heavier than the Denon’s recommended 1.5g – actually I had to double that to 3g in order to take some control of the distortion. With other discs this rewards me with more detail and deeper soundstage, with better perceived stability.  My best guess at this point is that the cartridge is either a little stiff for this rig, or that the weight calibration of the tonearm has crept out of tolerance.

As for the anti-skate, the best overall sound (least background noise and lowest distortion on tricky discs) was found to be with 2.5g set in the Spherical range according to the dial on the deck – this gives a much more consistent sound across all discs tried so far.

Step 3 – Experiment with running with or without the sub-chassis suspension

Our new abode has victorian wooden floorboards on flexible joists, which happen to excite a resonance in the spring-suspended sub-chassis of this deck, particularly noticeable when someone walks across the room, or puts the washing machine on.

It turns out that turning the transport screws fully-anticlockwise to bolt the sub-chassis down cures this problem, and I’ve yet to hear any adverse affects of doing so except perhaps a very slight increase in the perception of motor rumble when listening at high volume levels on headphones. I don’t listen like that very often, so I think we can live with that.

Results

I’ve listened this evening to Jean-Michel Jarre’s “Oxygene” and Enya’s “Watermark” LP’s and am enjoying new levels of soundstaging and detail retrieval. Maybe once I’ve done some study this evening I’ll let loose with some more challenging material to see what happens. The signs are good, with hopefully little further damaging to our aging collection.

 

Dual 505-2: Taming vinyl sibilance

I’ve been really happy with our record deck since we inherited it a few months ago, but one common problem has been playing back 70’s and 80’s pop/rock LP’s that have been, shall we say, well loved.  I had an idea while last re-aligning the cartridge/stylus that part of the treble reproduction issue I’ve been experiencing with these discs was that the cartridge was slightly vertically offset in comparison to the vertical alignment of the groove – almost as if the cartridge mounting is somehow twisted slightly on the arm.

The Dual 505-2 has no azimuth adjustment to speak of, but the cartridge is held in with a pair of bolts, and so the azimuth could easily be corrected by inserting a washer or some other small object to act as a shim.   I didn’t have any washers to hand that were less than 1mm thick (way too thick for this project), so for the sake of experimentation I’ve experimented with a piece of copper tape retrieved from a no-longer-working hard drive enclosure.  It’s less than 0.25mm thick, and easy to cut and fold to the right height.

To get a rough measurement of what was required, I chose an older duplicate disc and set it playing, and observed the end of the cartridge right above the needle riding the groove.  I estimated that the left side of the cartridge (as it faced me) was about 0.5mm too high compared with the level of the LP spinning underneath it, so I cut a small piece of the copper, folded it to get the approximate thickness required and cut a bolt-hole through it, before inserting it between the cartridge and its mount.

After doing up the bolts and re-checking the overall alignment, I started the same disc playing and listened.  Much of the treble harshness had gone, and vocal sibilant distortion was down around 50% – much more listenable for some of the older discs in our collection.  What’s more, newer/cleaner discs are sounding much more dynamic, and their overall soundstage much more focussed – much more digital, one might say.  Bryan Ferry’s “Boys and Girls” was a particularly problematic recording, but was much improved in this evening’s round of listening tests. The same improvement was noted on playing a slightly ratty copy of Michael Jackson’s “Thriller” LP.  We’re closer to hearing the music, and further away from hearing the equipment playing it.  That’s a good thing in my book.

Next on my list is to trim the copper shim to make the installation invisible, but it certainly proved my little theory and proves a nice illustration for anyone else wanting to try the same thing.