Volumio goes to x86…

…and I’m rather excited.

I’ve been a fan of the Volumio Project for rather a while now, since discovering it as a good platform for my Raspberry Pi audio player a year or more ago.  Several self-built MPD-based setups have come and gone since the Raspberry Pi arrived, but Volumio has been the mainstay for reliable playback with control from numerous devices.  The main draw for me has been the combination of its web interface, the fact the hard work has been done for me in terms of getting all the software components working together, and the fact that the whole package does seem to sound good.

On reflection I’m not sure that the various “audio optimizations” at the kernel or any other level really make an audible difference, but I do know that the whole package does seem to work more reliably on the limited resources of Raspberry Pi hardware than anything I’ve been able to cook up myself, at least without significant effort expended.

So why does an x86 port excite me so much?  Two reasons:

  1. More processing power availability opens the platform up to interesting things like DSP and dual-use such as streaming to remote machines and the like without falling over.  Presently I’d have multiple Raspberry Pi’s set up with dedicated tasks.  That’s been educational, but arguably a lot of hassle to set up and maintain. A single machine would make some of this stuff easier.
  2. Opening up the platform to more common (and more powerful) hardware fvastly extends the range of audio and storage hardware that can usefully be used with it, and perhaps extends Volumio’s exposure on the wider marketplace.

The Raspberry Pi is an amazing platform for what it is – and audio systems based upon its limited bus bandwidth are capable of sounding incredible. But not everyone has a NAS to throw their music onto, which makes the Pi’s USB2 storage a pain to deal with when using it for networking, local storage AND the audio device all at the same time.  And even those two do use it with a NAS are hampered by the 100MB Ethernet connection.  Sure, streaming even “HD” audio files  won’t tax it, but storing, backing up and indexing large audio collections will.  And THIS is where even an old Netbook could best it.

At some point where time allows, I’m looking forward to putting my elderly ASUS Netbook through its paces with a 192KHz-capable USB2 audio device and either a USB drive or “Gigabit” Ethernet adaptor (its own onboard Ethernet, like the Pi’s, is limited to 100MB), to see how it stacks up against the Pi running on the same hardware.  I know from running the RC download today that the distro works and plays audio even on the onboard audio, and the default setup to use the onboard display, keyboard and mouse to show the Web interface by default is a lovely touch.


Getting an EMU 0202USB working with a Raspberry Pi

In the last couple of weeks, out of curiosity, I’ve bought a Raspberry Pi to play with at home.  It’s really very impressive to see what can be done these days with a $35 computer – an “educational” model at that!

Our Pi is currently in place as our digital audio player, courtesy of the Volumio linux “audiophile” distribution, and an EMU 0202 USB audio interface.

Once the Pi was booting Volumio off the SD card, I found two things that needed doing:

  1. Set up the Pi to pull files off our NAS device.  In theory this can be done from the Volumio web interface, but I had to go hacking around editing config files to make this work seamlessly.
  2. Set up the EMU for optimal digital playback.  I take a somewhat different path on this to most “audiophiles”.  I’m specifically aiming to implement a software volume control, provided I can run the digital audio chain at 88.2KHz/24bit, or higher.  This means CD/MP3 content gets upsampled, while some recordings made natively at 88.2KHz/24bit get to be played that way.

The Volumio forums helped me out with point 1, but I’ve lost a lot of brainpower and free time to getting the EMU to work properly.  I could get it to play out at 44.1KHz/24-bit, but any attempt to play native files at higher rates, or to have MPD upsample, resulted in obviously robotic-sounding distorted playback.  It turns out the key was simple:

It seems the clock rate on the EMU 0202 and 0404 USB devices is assigned to a fader in ALSA, which in this case I accessed using alsamixer.  There were two faders for my 0202:  PCM and Clock rate Selector.

The latter has a range of stepped values, equating to the following sample rates:

  •   0% 44.1KHz
  •  20% 48.0KHz
  •  40% 88.2KHz
  •  60% 96.0KHz
  •  80% 176.4KHz
  • 100% 192.0KHz

What I’ve learned then is that to get the setup working, I needed to not only set Volumio (or the underlying MPD player) to resample to the target output rate of 88.2KHz/24-bit but ALSO to set the Clock rate Selector to 40% in alsamixer.

All works happily and I’m loving the more “analogue” sound of the EMU in that mode!

UPDATE, 23RD FEB 2014:

I’ve managed to get MPD to reliably resample to 176400Hz/24-bit (32-bit internal, 24-bit at the card.) by forcing the Pi’s turbo to “always on” and a slight overclock. It’s not *quite* perfect yet, so i might see if I can push it a little harder before documenting our full setup.

Review: Rega Carbon MM cartridge


(Rega Carbon MM conical cartridge; Image from Rega website)

In recent months I’d found our vinyl playback becoming increasingly distorted, especially on sibilants.  It seemed to me that our beloved Denon DL-160 MC cartridge tip has seen better days, and likely needs repair or replacement.  The problem was, with what should we replace it, even only for a short time while it’s away?

I had already kept a backup in our Ortofon DN165 with an OM-5 “generic” stylus which never really seemed to fully “sing” up against the Denon, but a quick swap showed that it was indeed more able to track inner grooves far better and with far less sibilance than the Denon was showing, especially on the recent Pulp “Different Class” 180G reissue which seems to be very densely packed towards the end of side 1.

But – the Ortofon really is no match in terms of tonality on our Dual 505-II compared with what the Denon could do with a new tip.  So, while we started to work out what do with the Denon, I hit up some online forums to see what people think of the cheapest available cartridges.  This narrowed the choice mostly to Audio-Technicas, either the AT-91 or the AT-95E.  Then I came across the Rega Carbon, which was well regarded in these two reviews:



So – for about £27 including delivery, I ordered on Amazon and was surprised to have one delivered to me by Sevenoaks Audio.  I mounted it within minutes of arrival and spun a few discs before leaving for a holiday.

First impressions…

…surprisingly good.  The overall balance was very similar to how I remembered the Denon DL-160 sounded when it was new to us.  Tracking ability of the deck was much improved – and it cleaned up many of the distorted sibilants in our rather well-loved first-run copies of Michael Jackson’s “Thriller”, and Al Stewart’s “Year of the Cat”.

Since our return, I’ve spun another varied and very enjoyable 10-15 discs with it, and am now sat enjoying a lovely rendition of an 80’s repressing of Pink Floyd’s DSOM.   So now I’m collecting some brief thoughts on how it now sounds after some 15-20 hours of playing time.

Longer term impressions…

It’s settled down – a lot.  The initial slightly brash treble presentation has become much more smooth, and surprisingly detailed considering how I’d have expected a conical stylus to sound, based on my limited understanding of the physics involved.  It rarely sounds as if it’s missing any significant high-frequency detail, though it’s fair to say its useful upper-limit in its frequency response is perhaps 1-2KHz lower than the Denon.

Surface noise is much-reduced compared to the tired Denon or mid-life Ortofon.  I’m therefore feeling much more able to just plunk a clean-looking disc down and get the needle stuck-in without spending significant cleaning time.

The overall sound is now much more balanced across the whole playing surface of any disc.  The balance change from “The Great Gig in the Sky” (end of Side 1 DSOM) to “Money” (beginning of Side 2 DSOM) is much less noticeable.  The latter sounds absolutely stunning in its detail, overall balance and sound-staging.  The tightness of the room reverb in the recording studio is now absolutely evident, with the background sounding “darker” than ever before.  The cymbals are absolutely crisp, as are the vocal sibilants.

Again sticking with DSOM as the example, while the apparent width of the soundstage feels narrower with the Carbon than with the Denon DL-160, the apparent depth of the soundstage feels much more accurate. Centre-panned voices seem to stand forward of the rest of the band. Individual instruments take on a definite space and are much more able to be followed than with the Ortofon.  Arguably in this more subjective respect, the cartridge does as good a job as the Denon ever did in our rig.  In some ways, it’s better – fine details seem much more apparent, and solid, than I’ve ever heard on this rig before.

“Us and Them” – the Rega pulls sparkle and space out of a dense mix in an increasingly tricky part of the disc.  It actually makes our rather tired copy sound brand-new. The huge chorus section has always sounded screechy with either of our previous cartridges – but with the Rega it just sounds big, and heavy and much cleaner.  Fine details of Sax placement, piano, organ and guitar riffs, complete with their acoustic space, are still audible even in the really heavy sections.  The synths, guitars and organ in the closing section perhaps have less sparkle than I remember, but their placement in the soundfield is much more assured, and much less distorted.

The overall impression is that this cartridge is a stunner – and it simply delivers *music* at whatever pace was intended. It delivers space and detail enough to communicate the message, if not always to convince you that the band is playing live right in front of you. And it does all of this without any apparent resonant tradeoff, nor any significant omission in any other area.

So – maybe I had a duff DL-160, and maybe our Ortofon had seen better days.  Maybe the DL-160 was perhaps a less-than-ideal match for our deck. But whatever the reasons for the differences I’m hearing, this cartridge absolutely *sings*, and it does so with a poise and fun-factor that I’d always heard vinyl was supposed to offer.   The Denon got us there for a good year or more, and I when I add up its total known playing-time in our care it’s really about time it was repaired or replaced.

Then I consider the price-tag, and I can only conclude that regardless of its peers, the Rega Carbon is an absolute gem and works incredibly well with our Dual 505-II, with its ultra-light original tonearm and (admittedly) customised heavy non-suspension base.

I’d tell any vinyl lover to just buy one to try for novelty-value, regardless of whatever other “prestige” cartridges you might also have. You might be surprised at how well it actually compares.  It’s always good to have a more-than-passable backup to a much better cartridge – but in our case, I’m suddenly in much less of a hurry to re-tip or replace our beloved Denon. I now have the time to get it right.

Oh, and if you need more evidence to commend this little gem – I can tell you one more thing:

Any good hifi component, or system, should make you want to listen to your music more.  Judging by the pile of played discs building up on my desk that need putting back onto the shelves, I can tell you that this has certainly got us listening to a *lot* more music, in a phase of live when I can tell you we’ve had the least actual *time* to listen to it.

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.


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.


NAD 3020 where it should be: In our rack!

NAD 3020B: Keeper or Clunker?

Been a while since I last posted on anything audio-related – I’m taking that as a good sign because I know I’ve been enjoying a *lot* of music lately.

NAD 3020 where it should be: In our rack!
Our NAD 3020B in use. (Please forgive the poor photo!)

Many an audiophile posting online has an extremely polarised attitude towards the humble NAD 3020 series of integrated amplifiers, which seem to be very much a “love ’em or hate ’em” box. I always thought I was in the “love ’em” camp, but until I inherited a 3020B from my father at the end of last year I never quite knew why. It’s not been the easiest of journeys, so please bear with me as I try to explain what I’ve found and what was going on at the time I found it.

If there’s any one lesson to glean from this experience, it’s that getting hifi sounding good is as much about the interaction of components working together as it is about finding of well-engineered components and slinging them together according to a spec-sheet.  These are also differences that I feel can make or break a system over the long term, but may not be immediately identifiable in typical demonstration arrangements that most stores can offer.

When inheriting our current system, my intention had been to replace my existing components one-by-one so I could check how the sound was changing at each stage on the way. I first swapped the speakers, as mentioned in another post. I then started repairing and using the record deck – plenty of other posts on that particular subject. With that now mostly bedded-in, i’ve come to the final part – using the 3020B.

Build quality

As a whole the unit feels well manufactured. Years of dust needed cleaning out of the phono contacts before connecting anything, but the speaker output binding posts are firm and accept 4mm banana plugs without modification – this amplifier was made in the generation(s) before the EU got their teeth into manufacturing regulations in the mid-90’s.

The source-select buttons are known on this series to be of slightly cheap construction, resulting in the plastic caps flying across the room when a new source is selected. Also, the source input sockets are somewhat loose.  This might be a result of their PCB flexing slightly when connections are made, or it might just be that the dimensions tolerance of the sockets themselves isn’t quite right. Again, this is a common flaw with amplifiers of this series, perhaps even of this generation.

The switches operate silently so far as the audio path is concerned, and the Bass, Treble, Balance and Volume pots/knobs also operate silently – rather impressive for such an old unit, especially if it’s ever been exposed to cigarette smoke, pets, small children and life’s little accidents as I know this one has.

Overall this unit is in better physical condition than I could have asked for – some surface grime aside, it’s basically unmarked except for the small hole drilled into it side where an intruder-alarm used to have a line threaded through it as a crime-prevention method. It’ll be an extremely rare find on Ebay that turns out in such good condition.

Sound quality – Take 1

Used with the Tannoy Mercury M20 loudspeakers it had been paired with in its previous home, the first impressions were that it is far warmer in tone than the 302 I was comparing it to, even with all tone controls at neutral and the loudness control off. Bass has more depth, stereo imaging is wider and deeper, but treble felt like a veil had been placed over the speakers.

Some experimentation with the Soft Clipping circuit showed no audible difference whether it was switched “in” or “out”.  I prefer to be safe rather than sorry, so I’ve left it “in” for now.

Another interesting experiment was to assess any audible differences between using the “Normal” (Low and High-pass-filtered) and “Lab” (Unfiltered) power amplifier inputs.  Theoretically the “Normal” input should be used, to filter out frequencies below 20Hz and above 20KHz, enabling the amplifier to use all its power in the audible frequency range and to run without interference.  The “Lab” input sounds better to my ear – soundstaging feels more solid, and the tonal balance a little more accurate throughout the entire frequency range. (See the first comment on this post for more about the correct selection of “Normal” vs “Lab” input).

Even having worked out which signal path to use, and to avoid the “Loudness” button, the amplifier was still not producing an overall sound I thought I could live with.  I therefore started to do some tweaking to work out where the “problem” was, if only to understand what was going on.

Experimenting with Pre/Power amp combinations

Both the 302 and 3020 have pre-out and power-in socket sets, allowing either to be used as the power amp for the other’s pre-amp section. First of all I wanted to see if the older 3020’s pre-amp section was the cause of the slightly muted treble. Some re-plugging later, I had both CD and LP feeding the 3020 pre-amp section, which in turn was wired to feed the power-amp of the 302. This combination had narrower imaging, slightly leaner bass, and still the soft treble that felt like it was hiding something.

Next I swapped the amp sections round, with the 302 pre-amp now feeding the much older power-amp section of the 3020, and everything seemed better. The soundstage was locked tight between the speakers for centred instruments and vocals, but there was much freer reign for anything panned between and even outside the speakers to be given space to do their thing. Either amplifier seemed equally capable of playing ‘depth’ information in recordings that have it, and so this was the way I left the units set up for some weeks while I got settled with the record deck and its cartridge.

Listening to the Tannoy’s through the 302 (using both its pre and power sections) I thought the sound was nicely tonally balanced, but always felt like I was listening through an imaginary window that the box placed on the musical world being painted in front of me. Conversely, the 302-pre and 3020-power combo gave slightly more extreme bass and treble presence, and effectively took away that windowed effect while fixing the veiled treble of the older amplifier used on its own.

System changes – a second chance?

Having settled on using the 302 pre-amp and the 3020B power-amplifier, a couple of things changed. First off, I found the new complexity of the system somewhat frustrating, but were willing to live with it if that’s what was going to give us the best overall sound. Then came the other major shift in our listening; I upgraded the phono cartridge to a Denon DL-160 MC (High output), seeking more accuracy of sibilants and better soundstaging. This much I got, but then many recordings were now too bright. Whether this was a result of longer-than-optimal running times on some discs, or perhaps due to an active mastering decision, I’ll likely never know.

Phono stages

With the new cartridge in place, switching between 302 and 3020 phono stages showed the differences between them were surprisingly subtle, but the older stage won out. It seems to reveal more midrange detail than the newer design, particularly with female vocals.  There’s also a lot more information being played from the background of mixes, better rendering things like room ambience and reverb tails. It also has better overall dynamics, and the soundstaging is a little deeper and wider.

This surprised me, since on paper the older design looks like it should perform worse than the new one. For one thing the signal-to-noise ratio quoted by the manufacturer is slightly higher in the older design, and I would expect its component tolerances to have drifted enough with age and use by now to have a significant negative effect, likely leading to loss of high-frequency detail and increased noise.

Just one side-note on the 3020 phono stage – it has two modes, one for MM (Moving Magnet) cartridges and the other for MC (Moving Coil) cartridges. MM carts typically have higher output levels than their MC siblings, but our MC is a “high output” model, compatible with conventional MM stages. Having tried the unit in both modes, neither sounds different than the other, even when the setting is “wrong” for the kind of cartridge in use. The phono stage shows ample headroom – I did experiment with using the MM cartridge with the extra amplification of MC mode and could hear absolutely no evidence of added distortion, even with discs mastered with very high recording levels. Further, using the MC mode with its extra gain ought to bring more measurable background noise into the mix, but I’ve yet to hear this in practise.

The 3020B on its own – Take 2

I decided to give the amplifier a second chance to fly solo, with vinyl as the primary source. Soundstaging now sounds wonderful with well-mastered discs in good condition – Pink Floyd’s “Dark Side of the Moon” and Eric Clapton’s “Slowhand” show a lot of their natural recording ambiences.  Newer, more synthetic recordings like Enya’s “Watermark” or Jean Michel Jarre’s “Revolutions” sound as modern as their source material and production values should present, with the end result sounding always convincing and really very human. Every instrument and voice has its own space in the mix, with no particular instrument or frequency range standing out above any other.

Poorer or duller discs can easily be improved with an adjustment via the tone controls. The effect of the tone controls is subtle but effective – I don’t feel like either circuit (Bass or Treble) impedes any other aspect of the sound passing through it other than whatever I’m telling it to do. Most bass-light recordings are usually too heavy in the treble, so a slight treble reduction usually brings things back into perspective. The inverse tends to be true if a recording is bass-heavy – usually a slight treble boost evens things out.

Turning to digital sources, playback again felt like it was lacking some treble at first, and the soundstage was somewhat vague. For most TV and DVD content we watch this isn’t a bad thing, and easily fixed with a slight adjustment to the treble control.

With playback of CD or downloaded content from our EMU 0202USB, it seemed that while bass and mid-range were coming through with much more timbre than I’ve been used to, and a much more even tonal balance, the high-frequency content was being reduced slightly, and felt slightly hazy, if such a term can apply to audio.

Having noted a slight increase in treble response over the few weeks the system lived in this new state, I’d have been happy to leave it there, concluding that either the increased usage had brought some components and connections back within tolerance, or (more likely) my subconscious processing of what I’m hearing was adjusting to the new system.

But then I made a discovery:  I could change the settings to run the DAC at a much-increased sample rate of 176.4KHz and 24-bit, with internal volume processing being done in the computer at 32 bits. This had the overall effect of giving slightly more audible treble, but more importantly it gave a lot more definition and control to the treble content.

I’ll likely write separately about this transition, but it really does take the digital playback to a level that competes with the best of what our vinyl source can give us. Listening to Royksopp’s “Senior” album for example, bass frequencies go into (and possibly below) sub-bass territory and the system keeps up, resolving the basslines with good speed – at no time does any bass note feel like it’s stopping later than it should. Synthesised kick drums tend to have very short attack times, and these are resolved wonderfully, the tonality of each kick drum making even different synths identifiable.  This is something I’ve never experienced before.

Remastered recordings I’ve complained about before (Al Stewart’s “Year of the Cat” and Genesis’ “Trick of the Tail”) are still a little too treble-heavy for my tastes, but have huge amounts of spacial and vocal definition, and are finally on a par with the original vinyl releases of the same albums.


Based on some very practical testing, done by ear and confirmed with others who were unaware of the tweaking going on behind the scenes except for the cartridge upgrade, I have concluded that my 3020B is very much “a keeper”. Its warm tonal balance is generally flattering and does not interfere with the finer details of dynamics, soundstaging and definition. It is certainly able to show up any flaws of the recordings and source devices it’s amplifying. I think it fair to surmise that it does a good job with entry-level devices as they come out out of the box, but it does a truly great job when fed with higher-end devices, whatever form they would take.

On having two LP copies of Dark Side of the Moon

I’ve inherited two copies of DSOM, and am completely torn between them. On the one hand, I have what appears to be a first-run (or certainly close to it!) copy, which has clearly been played to death on older, heavier and less-than-perfectly set up decks than ours. It’s also picked up more than its fair share of scratches through the years. Our new cartridge has just done a wonderful job making this old disc sing, but it’s clear that the detail has now pretty much been scraped out of the grooves.

Despite the crackles and occasional scrapes, this older copy sounds somehow more direct and open than the CD copies I’ve encountered, revealing little details during instrumental sections that I’ve not heard before. Bass is crisp and taught – and there’s an impression of the mix being polished to perfection, of being finished somehow. All the sibilance and crackling distortion on vocals and guitars is gone. Keyboards are clearly well integrated with the mix – adding texture, rhythm and depth, but without taking space used by the guitars. Cymbals are crisp without being overdone. Toms, snare and kick are a little softer in timbre than I would perhaps like. Another evident fault is that the treble in the left side is somewhat reduced in level compared with the right.

And so onto the newer copy, about which all I know is that it’s a Dutch pressing that somehow found its way to a Bristol (UK) record store to be purchased as a replacement for the older and more tired copy. Using “Money” as the reference track, this disc sounds more detailed than the original, but the bass is somewhat lighter, and less detailed in timbre. The soundstage is certainly helped by the fact that treble levels are more balanced between left and right channels. Percussion is certainly tighter, and the mix holds together better in the instrumental section of the track.

The problem is that the extra detail and the subdued bass combine to form a presentation that really does not sound as polished as the earlier pressing. It’s actually quite fatiguing to listen to. More like the CD presentation actually, but not in a good way.

Moving on briefly to “Us and Them”, the newer copy is much tighter both in terms of soundstaging and pitch stability – but it lacks the low-frequency weight and timbre that make the song so intimate in its early stages.

So in conclusion the newer disc is certainly more “hifi”, so is worth keeping for that. But musically I feel that the older copy conveys more of the message – and so it’ll remain in our collection as a great example of how technical superiority doesn’t always help convey the musical message more effectively.

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.