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Decca London cartridge - rebuild by The Cartridge Man

21st century high-end

[Italian version]

Product: Decca London cartridge
Rebuild by: The Cartridge Man - UK
Approx.cost: 250 € + donor cart
Reviewer: Mark Wheeler - TNT UK
Reviewed: April, 2004

The Decca pick-up cartridge is a unique BEAST and demands a much longer descriptive review than a typical cartridge; there is so much audio folklore surrounding these monsters that stories have to be told. The stereo versions evolved from their mono predecessors. Mono recordings are purely lateral wiggles in the vinyl groove and mono pickups would therefore have very little horizontal compliance and laterally oriented generators. The mono Deccas had a “T” shaped mounting block supporting the top of a vertical tempered steel armature passing through the magnet & coils assembly. The armature movements would induce changes in the magnetic field that in turn generates a voltage in the coil, much like the vibration of a guitar string generates a signal in the coils of an electric guitar pickup.

The stereo Decca London pickups simply added a vertical generator system and derived the stereo signal by sum-&-difference to a 3-pin output block: positive left; positive right & common negative ground. There were numerous compliance & stylus combinations variously named Blue, Maroon, Gold & body coloured so. Most Blues were 2-3gm trackers (or mistrackers) with spherical styli (18mm), Maroons were diverse with various elliptical profiles, and Golds were 1.5-2gm elliptical (8x16mm). HiFi choice issue 13(1978) found the lateral compliance of the Blue to be 12cu(x10^6cm/dyne) and the Gold to be 20cu(x10^6cm/dyne) both implying a medium to high mass arm above 10gm. Unlike most cartridges there is no internal suspension damping suggesting benefits of arm damping.

Deccas engender strong opinions among listeners: they're either the Holy Grail or the spawn of Satan. They either give a unique glimpse at the contents of your vinyl collection or remove the contents of your vinyl collection in a swathe of vinyl swarf, depending who you are talking with at the time.

HiFi Choice (ibid) obtained a frequency response & squarewave from their spherical tip London Blue, which were pretty good for a £40GBP induced magnet, with a high tip-vinyl resonance of 28kHz, The majority of competitors in the same test being around 20kHz with some as low as 15kHz! The graph also shows the effects of different lateral & vertical compliance in the two traces of low-frequency arm-cartridge resonance. Compared to many competitors this is a very flat response through most of the audio band with just one obvious resonance glitch at 350-400Hz but still within +or- 1dB.

Back in the 70s & 80s controversial HiFi-News & Record Review journo Ken Kessler swore by them (especially the aussie Garrott Brothers retipped models). Doug Dunlop, legendary designer of Concordant pre-amps & rebuilder of Quad II's, used only a Decca London Gold on his Source turntable with Odyssey arm. Mike Moore who designed the Source/Odyssey recommended this arrangement. The latter pair of audio mavericks are both now dead, but lots of people who use Deccas live to a ripe old age so I doubt any epidemiological pattern.

I spent many hours in Dougie's listening room, in the late 80s & early 90s, evaluating boxes full of the NOS valves (tubes) that he favoured in his products. The only source he ever used was The Source, and its designer Mike Moore was an occasional visitor too, which guaranteed the set-up. A glorious big subchassis turntable with 5-point suspension supporting the sculptural Odyssey arm, which supported his Decca Super Gold cartridge, although he had other Decca Londons too.

We'd listen through Doug's Excelsior pre-amp (my personal favourite of his range) swapping between renowned valves from Mullard, Teonex, Telefunken, Siemans and other legends of the triode fraternity. His hot-rodded Quad II were numerous in versions featuring triode input & phase-splitter in place of the EF86 pentodes, and a variety of output valves. Surprisingly there was a tetrode in place of the rectifier, which dictated the character of any configuration, substitute a KT88 for a 6550 and the whole amp sounded like the output stage had been swapped. We also compared the competition from Audio Research & Quicksilver as well as occasional solid-state encounters. Mostly this lot voiced through Dalquist DQ10s or my own Underground Audio active Decca Ribbons, which being half the size of coffins were a nightmare to transport a pair in my old MG & Alfa Romeo. Quad ESL57 occasionally made an appearance or some Underground Audio prototype I was developing.

And all the time we were listening to the Decca London Gold or the Decca Super Gold (a later improved reissue Gold). So I know what they sounded like on my record collection. Years earlier I had acquired an old Blue/Maroon with a turntable purchase (Connoisseur & Hadcock GH Unipoise) and given this spherical tipped antique a few spins on the vinyl before moving the Hadcock to my Transcriptor Saturn (one of the ancestors of the Michell Gyrodec). My only memory of that experience was that it confirmed all my prejudices, based on legends & reviews, of terrible tracking, & distorted top-end. It was the first time I had ever seen a cartridge jump-out-of-the-groove. It was chucked in a drawer in my spares rack and duly forgotten until I stumbled across it recently while looking for something else and remembered the magic of Doug's system.

Enter Len Gregory stage-left. The Cartridge Man, as he is more famously known, was asked to rebuild it. The Australian Garrot Brothers (now also dead in a suicide pact, there really does seem to be a fatal Decca connection) made legendary line-conact retipped Deccas, and A J Van den Hul has fitted his esteemed tips to them too. Len is garnering a reputation for his complex-profile line-contact retips so it seemed right to try his skills on my Decca. He has also developed some extra Decca tweaks that are audibly obvious beyond the stylus change.

My Decca body colour is blue but it behaved more like maroon compliance & had several red parts too! In my Hadcock, LF resonance was 14Hz suggesting the new suspension compliance to be similar to the Gold.

I fixed this risen Lazarus of a pickup in my Hadcock GH242SE (arm base rewired with Kimber Silver Streak balanced) mounted on Michell Gyro SE (DC motor powered by early QC cased big-toroid VC supply). This was not easy because the Decca is not as tall as most and clearance for the cueing lift was right on its lower limit. I set up the alignment & balance at 1.9gm (Len Gregory recommended 1.8-2gm). The line contact stylus needs more bias than a basic elliptical shape. The first thing I noticed was the high level of handling noise; leave the volume up and any contact with the subchassis produces a clatter even with the arm securely on its rest. So how does it sound now?

Like William Blake's "Doors of perception opened wide" it can provide a vision of "Heaven & Hell". Before it had run in the traditional Decca vices & virtues were there to hear. Tonal balance different from most moving magnet or moving iron types, more like moving coil below the upper mid-range (above that just the raw sound of a brand new diamond). Narrow image width and little depth, but what is there remains very stable.

If you consider the vectors of each side of a stereo groove: the horizontal component is the musical information where the Decca is medium compliance; the vertical vector component is the spatial information. A lateral mono groove is 2 identical signals 180° out-of-phase therefore central mono through a typical stereo cartridge, which phase inverts one coil at 90° to the other, both being at 45° to the disc surface. The Decca differs by having a vertical generator system, but hampered by the low vertical compliance. So the stylus has a harder job to push in response to the vertical information component compared with the lateral.

The soundstage has a quality that is hard to describe without descending into pretentious reviewspeak (a curious language previously only used by wine writers). Unlike many transducers, different frequency bands do not position differently regardless of instrument position. I mean that high frequencies do not retreat towards the tweeters & low frequencies do not wander amorphously around the room. Because the image placement never wanders with frequency, singers' sibilants stay where their mouths seem to be, chest voice is standing in the same plane as consonant detail. Reviewers in the comics use terms like tangible or tactile for this quality, and on singers this is the most I've heard from a cartridge. I prefer the terms realistic & convincing.

Tonally it seems to work very well with BBC balance speakers (Rogers, Spendor, Chartwell, etc) the antithesis of flat-earth low-Q lean balance speakers (Isobariks, Saras, SBLs), but the flat earthers would love the timing and start-stop SNAP of this beast. The transient snap of snare drums (Andy's Chest on Lou Reed's Transformer for example) or reggae rim-shots is unsurpassed.

So after a couple of days I clamped side D (on the reverse of side A from the old days of autochanger stacks) of Lou Reed's Metal Machine Music onto the Michell. This bizarre piece has a modulated locked run-out groove well away from the label, to stop the aforementioned autochanger lifting the arm automatically before the dazed listener realised they were still listening to the same 2 second loop. It's a real record with a wide range of frequencies rather than a test disc so I like to burn-in overnight with it.

Next morning before work (that's how keen TNT-audio writers are) I ran the tracking test on Image Hifi's “Vinyl Essentials – The Ultimate Pickup Test Record” (Image LP003) and it managed the highest100mm modulation. This came as a real surprise! It had begun to sound edgy at 60mm, which usually anticipates that 70mm will clearly mistrack, but it managed each band just sounding like it was going to break into audible distortion without actually committing itself. This edge-of-the-seat excitement is what Decca listening is all about.

Those mono lateral modulations are what the Decca excels at. Next up was the Cardas Frequency Sweep Record mastered by Stan Ricker. This opens with a 30Hz-30kHz sweep laterally modulated (in phase) track and as it sweeps beyond hearing limits and approaches the tip-vinyl resonance audible intermodulation products become audible. Typically these are very different between stylus qualities and generator types. Wideband low-output moving coils with good tips twitter sweetly with even harmonics while cheap moving magnets make a broad cacophony. The Decca sounded more like a MC and is a tribute to the quality of stone fitted by Len Gregory.

This is followed by a pair of vertically modulated 1kHz-30kHz (out of phase) sweep. This began to sound rough at a lower frequency (from a signal still beyond audibility) & produced noises unlike any other cartridge. The character of these colourations was remarkably similar to that of the handling noise described earlier implying that the lower vertical compliance allows the tip-resonance to excite mechanical resonances in the structure of the whole cartridge. The Decca London International arm designed with this cartridge in mind was a damped unipivot, so damping may ameliorate these problems. I didn't have any fluid handy for my Hadcock so that will have to be tried later. But the real surprise is that it tracked the vertical modulated groove at all implying that Len's modifications have increased that troublesome vertical compliance nearer to the lateral.

I hate faffing with test records so it was on with the music. Little Feat's The Last Record Album is a personal favourite and also a brutal test of vinyl replay. It is recorded with very heavy bass modulation to capture Ken Gradney's bass playing that can render the vocals weak and devoid of clarity and emotion with many turntables, arms & cartridges. Valerie Carter's vocal duets with Lowell George on Long Distance Love and One Love Stand were clearly delineated and every nuance of their delivery intact, better even than my old all Linn front-end that used to be the benchmark with this album.

Once run-in the soundstage did open up. The width increased without extending far beyond the speakers, but as good as many top-flight cartridges. This does suggest that vertical compliance is much improved by the rebuild.

Surface noise is horrible. I used to believe that it was a function of tip quality but this proves otherwise. It is very susceptible to vinyl roar, but the snap of its transients is joined by the crackle & pop of that well-known breakfast cereal. It may be that the vertical intermodulation noted gets excited by every bit of debris lurking in the groove & the extended stylus profile finds every particle right down to the valley bottom.

The retipped Blue suits the blues. Vocals are a peach, and vocal orientated valve systems need this on the front-end. More complex material needs a better tracker like the Music Maker 2 or a medium compliance MC with a good tip. The Decca sound just blends incoherently when the going gets tough in busy complex passages of orchestral material.

As if to demonstrate the strong areas of performance I bought 2 lps this week from Selactadisc in Nottingham (England) where they have a great vinyl department & racks of used lps too. A new release “Whip Them King Tubby” by Linval Thompson & Friends (Auralux LUXXLP001) is remastered from the 70's master tapes with no reprocessing or additional noise-reduction “as this would have resulted in a serious reduction in warmth and audio dynamics” (says on the insert). Much respect to the producers, their choice of “valve stages and analogue tape, without the use of computers or other digital technology” really works. I last heard some of this stuff on sound systems in the 70s & this lp sounded great with the Decca; all the flat-earth virtues of PACE-RHYTHM-AND-TIMING (PRAT) were there as well as any traditional flat-earth MC transducer (Linn Troika, Supex 901, AT OC9 etc).

The same shop supplied (at only £1.50GBP) a used copy of “The Real Deal” by the 29th Street Saxophone Quartet (1987 New Note NN1006) for my alto playing son. Again techy details are on the cover: One AKG C422 stereo microphone; Mitsubishi X-80 digital tape recorder; Teldec Direct Metal Mastering”. Many readers will be familiar with unsuccessful simple-miked recordings; appalling mid-80s digital masters & edgy DMM transfers but this one is superb. It demonstrates that all tools need skilled hands. We're used to a live alto in this room and this record came as close as any we've heard, the Decca producing realistic scale and dynamics together with accurate portrayal of tone & body.

The Cartridge Man retipped Decca would love a system based around big fast horn speakers. The very high output would suit valve phono-stages implying an obvious synergy with certain system philosophies.

Every audio-head should hear a Decca London pickup at least once, like every motorcyclist should own a Ducati at least once. The Cartridge Man rebuild makes this a 21st century high-end pickup for as little as 250 € (plus donor cartridge). I will keep my MusicMaker mkII for most listening, but I'm going to buy an extra arm assembly for my Hadcock GH242SE just so I can swap quickly to the Decca for those LPs that demand its unique virtues.

© Copyright 2003 Mark Wheeler - www.tnt-audio.com

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