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(6/5/2014) (edits-additions 6/12/2014)

Retro: Looking back at the Infinity Black Widow tone arm...when it is partnered with a classic match-up; an ADC-XLM mkII induced magnet phono cartridge.

So here I am writing about this 35 year old tone arm and cartridge. The tone arm, which I detail further below, is the Infinity Black Widow.  This tone arm is the lowest mass tone arm of them all.  3 grams effective mass!  To match this extremely low effective mass arm, I've mounted a cartridge, of a type, known to have a stylus tip mass lower than almost any other cartridge made.  Only a handful of cartridges have ever had such low mass stylus/cantilevers.  The cartridge (so far) of this type that I've managed to get my grubby paws on is an ADC XLM-II.  There are a couple of others I'll likely try. The XLM series were highly highly innovative and created by the legendary designer, Peter Pritchard.  (More about the XLM design features and its "induced magnet" architecture further below.)

hint; click on thumbnail to view image full size

It could be said that this arm and this cartridge were meant for one-another.   The ADC XLM-II cartridge came first.  Then some time later came the Black Widow tone arm.  It was designed to work with such cartridges as the ADC XLM series, the Sonic Research Sonus Blue and Gold Blue, and a handful of other cartridges that were in need of an extremely low mass tone arm.

Above photo.  The Black Widow tonearm, again with the ADC XLM-II cartridge, this time, is mounted on a Thorens TD124 idler driven turntable. 

I chose to evaluate the arm and cartridge on two very different types of turntables.  Both are made by Thorens.  The TD150 and the TD124. The TD124 has greater power delivery at the rim of its platter.  A product of this higher power is a more energetic and forceful delivery than has the little TD150.  In this way the listening comparisons made will include the variance between turntable drive types that I have on hand.  Idler drive -TD124.  Belt drive - TD150. And yes, the moving coil cartridges I've owned have been listened to on both turntables. (as well as some others)

 But first some of my history:  The past twenty years for me have been a kind  of hunt......or maybe it has been a journey.  One in which I've sampled progressively better and different turntables. And I've sampled better and different tone arms,..... and then cartridges designed to match the arms.  The purpose of the hunt has been to find something approaching a kind of audio nirvana within my listening room.  If not 'nirvana' then to find the most enjoyable sounds attainable within budgetary constraints.   

On this 'hunt' the cartridges I've tried have been recently manufactured and almost exclusively of the moving coil variety.  Moving Coil cartridges had became de-riguer back in the 1980s.  Even as the Lp was being phased out and replaced by those smaller shiny silver Compact Discs, A small stubborn group of die-hard Lp devotees continued to collect and play records.  Many of these moved away from moving magnet cartridges in favor of the Moving Coil variety.  When my renewed interest in things Lp took hold in the mid 1990s, it seemed logical to spend some quality time, and discretionary spending, on  this variety of pick-up.... the moving coil.

Fast forward to this moment and it seems it might be a good time to stop, get off the escalator, and sample some source components from the past that maybe I didn't take enough time to check out.  If I remember correctly, I had been busy doing other stuff.  But that is another story.

While I'm taking this pause I want to ask internally some questions: 

Have I missed something important?  

Moving coil cartridges, the type so many discretionary spenders lust for today.  Are these the ultimate answer for Lp playback?  

Should I try some samples of interesting moving magnet designs from the past?  

Does spending more deliver more?  

Should I reconsider my 'consumerism' in this upward spiral of ever increasing prices?   

My one answer to any of those self-imposed questions is a definite 'maybe'.  And, while I'm at it, I should reconsider everything that I do in this hobby as a standard procedure and at periodic intervals.  That's definite.

Now, after listening to the above pictured obsolete tone arm / cartridge for quite some time..... enough hours to account for a new cartridge break-in* period,  I can state that there is something of value in the above combination.

*it is a new cartridge (but nos)

Subjective listening to recorded music isn't a career for me, it is just an obsession.  Obsessed as I normally am, I'm just playing through the records I typically do.  Spinning Lps out of my library from the three main groups I keep;  Rock, Jazz and Classical.  Before I get into my listening analysis I should make note that I did find that the ADC XLM-II, with its Diasa-Elliptical stylus, does require some attention paid to dialing in the VTA/SRA.  There is a sweet spot.  Set it to 92 SRA.  Hit this adjustment close to  -spot on-   and the sonic delivery comes together in the most life-like, most atmospheric,  most coherent top-to-bottom, and generally most pleasant manner.  

And, while I'm getting the preliminaries noted, I should add that this tone arm and cartridge is one of those that requires a chassis ground between the body of the arm and the body/chassis of the turntable.  And then the turntable needs to ground to planet earth.  Otherwise there is a soft buzz from the speakers.  Naturally I took care of this.

The phono cable, which plugs into the 5-pin DIN type socket at the bottom of the tone arm base, is custom made.  I used a Cardas female din plug, Canair microphone cable and Bullet RCA plugs to terminate.  I do have the original equipment cable that came with the arm, but cables from this era are not up to today's standards and should be replaced.

The signal chain is the same between moving magnet and moving coil cartridges,  -except-  that any of my low output moving coil cartridges require a voltage step-up.  To achieve this I use step up transformers ( Beyer Dynamic 1:15 / 1:30) in the signal path betwixt cartridge and phono stage.  The phono stage is a Hagerman Labs Trumpet. Recent vintage from 2013.


On either player, (the TD150 and the TD124), the sound is fast and tuneful.  There is nothing 'laid back' about it. The sound is detailed.  It is cleanly articulated. It has excellent stereo separation.  The soundstage appears to have fore/aft depth.  Width of the soundstage seems to exist within the space between the speakers. (as is common with the associated components I've got)  Spatial placement of the instruments and voices is clear and seems almost pinpoint.  There is clean, taut and deep bass.  Solid.   I've got airy articulate treble.   A midrange that is entirely coherent with the top and bottom of the spectrum.  No frequency range has any overt  or outstanding character.  Dynamics are sudden and delivered with a sense of power.  I get a sense of rhythm that can have one tapping toes and bobbing heads.  On the TD124 there is a greater sense of the force of delivery.... an up front presence that the TD150 doesn't manage.  Hence greater toe-tapping compulsions on that player.  One might expect the TD150 to offer a more detailed and airy presentation in direct comparison to the TD124.  But that isn't really the case.  This TD124 is well maintained and has some upgrades that significantly improve its signal-to-noise ratio.    (Figure an SNR of this particular player (sn 13943) at -50db.)  So really, the TD124 is the obvious choice over the TD150.  Yet, that little TD150, all by itself, tells an attractive version of the same truth.

Moving coil cartridges I've listened to at length: 

the Ortofon MC Jubilee, 

a pair of wood-bodied and re-tipped Denon DL-103R low output moving coil types,

A Shelter 501 type II

The moving coil types listed above tend to have some sonic traits in common.  A sense of 'more meat' more matter (of a palpable presence) in the mid-range frequencies.  The Jubilee tended to see a bit deeper into the groove and retrieve more musical detail than the other mc cartridges on my short list.  It had a nude Shibata diamond.  The diamond was bonded to a solid boron cantilever. A fairly long cantilever.  Perhaps its low frequency reproduction, while authoritative, did not have as much control in the bass region as does the Shelter. I hear just a touch of flab there.  The Shelter describes textures and timbres in those same low regions with a sense of accuracy and 'truth' that is more to my satisfaction.  The Denon I would rate between the two at low frequency realism.   

Now let me consider the ADC XLM-II when mounted to the BW arm.  There is less meat in the midrange, that is certain.  And it seems a touch less forward sounding than the Shelter and Denon mc types.*   But....the ADC XLM-II, as configured, seemed to retrieve just as much musical detail as the best of my moving coil types!  And, by the way, its bass reproduction goes deeper than any of my MC types I've had, while managing to keep textures and timbres accurate sounding. Impressive.  On the whole the ADC  brings forth its music in a natural and entirely pleasant manner.  Clean.  Articulate, beautiful and accurate.  I think it manages to sound fast and dynamic while at the same time maintaining a sense of natural flow.  A rare talent.

Harry Peterson wrote in the Absolute Sound Magazine (1975) that the ADC XLM-II is "...the most accurate of all cartridges..."  With this in mind as I was listening I think I see what he meant.  I can sense that this sound may be very close to the truth of the master tape from which the records were created.  But I think HP's comments should be considered within the scope of that period in audio history and with regard to what other cartridges were available then.

*I should note that the Jubilee wasn't very forward sounding and I'd also say that it has less of a 'jump factor' and seems far more relaxed than any of the other cartridges I've heard, except perhaps in comparison to a Shure V15VxMR, which also displays a relaxed, perhaps even laid back demeanor.  

Comparing Apples to Oranges.

All the above having been said, I've got the Shelter 501-II mounted to a Graham 2.2 tonearm and up on the Technics SP10mkII standing next to where either the TD124 or TD 150 is positioned.  This setup has more presence.  Its rhythmic delivery can be quite forceful and forward.  Like I want it.  That sense of presence and meatiness in the midrange prevails in this configuration.    (By the way, this is as much to do with the tone arm and cartridge as with the different turntable motor units.  I've had the combo on the TD124 and experienced similar observations.)


In this apples to oranges comparison It doesn't take but a few seconds of play to recognize that the Shelter/SP10 has a huge amount of presence.  It is just so plainly obvious. I think most people hearing the two setups would tend to state that it simply "blows-away" the BW/ADC on either turntable I've had it.  It should also be noted that I have yet to try the BW/ADC on the SP10.  Perhaps I will some rainy day.  I'd have to cut another arm board.

In favor of the Black Widow / ADC, I have determined that it can be listened to at length with no perceivable listener fatigue.  The Shelter/SP10 may have me looking for something else to do after a couple hours of steady listening.  

There's more to the story so here's the rest....

It was a couple of years ago when during the course of a conversation with one of my audio buddies that the purchase of this tone arm became possible.  And I jumped at the opportunity.  I'd always been fascinated with the arm.  The Infinity Black Widow.  A classic legendary piece.  Of course it was well known that the Black Widow was extremely limited to a very narrow choice of just a few cartridges that can best utilize the arm's very low mass to maximum advantage.  Those cartridges that have a history of matching up well to this arm are still known.  I knew at the time where I could find such a thing.  So I bought the arm and then surfed over to ebay and bought a (New Old Stock) ADC XLM mkII induced magnet cartridge. 

The cartridge I bought  was offered as NOS and still sealed within its factory packaging.  Designation is ST XLM II. Near as I can determine, it is an XLM mkII,  It has the Diasa elliptical stylus. I can't tell if the diamond is mounted within a sapphire socket, as the 'improved' versions are purported to be, but It has the omni-pivot suspension design.  The all important compliance rating is not offered in the owners manual.  I'll test and report for arm/cart resonance to help determine the actual compliance of this particular sample.  I expect it to compare closely to the previous ADC XLM improved mkII. The same.  I expect.

This was one of the later ADC XLM series that came attached to a carbon fiber head shell as part of a package.  The whole assembly is designed to slip onto the end of an ADC tone arm, and then you're ready to go.  The cartridge itself, which mounts normally on 1/2 inch spaced holes, is easily detached and appears just like the other ADC cartridges that don't come attached to a head shell.  But this one has a matte black colored magnet body, where previous versions came in a gold colored body.  

Wait a minute! Is this a moving magnet cartridge?  One might well ask.  ADC calls their design "induced magnet".  In a more common moving magnet design a magnet, cylindrical in shape, fits over and locks onto the cantilever. Then it moves with the cantilever as the cantilever traces the terrain of the record groove.  The magnet, moving in one direction and another, while in close proximity to right and left hand coils just above, and through electro-magnetic induction, generates the electrical current that is the source signal of the music one hears.  

But the designer and owner of ADC, Peter Pritchard, had another idea.  His was to retain the overall moving magnet layout but reduce the mass of the cantilever/stylus assembly by removing the magnet entirely.  With reduced mass, the stylus/cantilever assembly can trace the record groove with much greater control than would a heavier assembly.  But there still needs to be a magnet that moves within the field of the coils.  Otherwise you don't generate any current.  Therein is the genius of the induced magnet design.   In place of the cylindrical magnet, a much lighter tube of magnetically permeable metal fits over the cantilever just as the magnet would.  This 'tube' is 'energized' into a state of magnetism by a remotely located magnetic circuit held within the casework of the cartridge body.  Otherwise, the cartridge operates like the  moving magnet cartridge we have all come to know.

The arm. Infinity Black Widow circa early ~1980s

The Infinity Black Widow tone arm did not have an easy birth.  Its earliest version was a very low mass two-section aluminum arm-tube version. It had the unfortunate tendency  to break when mishandled. The later versions featured a graphite arm tube.  There was a two section graphite tube, then finally a 1 piece tapered graphite tube.  Later, a damping trough was available to accommodate  lower compliance cartridges becoming more and more popular in the 1980s.  I have this last version and with the damping trough.  With the high compliance cartridge I've currently mounted, there is no need for it.  The trough is empty for now.

The pivot design is knife-edge vertical and  ball bearings lateral.  Anti-skate is magnetic and set by sliding the adjuster ring fore or aft.  Vertical tracking force is set by turning the counter weight, itself on a threaded barrel, one way or the other to adjust.  The counterweight is marked into .2gram graduations as a reference.  I used a digital vtf scale to set this important parameter.  No need to pay attention to the graduations on the counterweight.  But one could.  Vertical tracking Angle is set by releasing the set screw at the base pillar and then you either raise or lower the entire arm at its mount. 

The head shell does not offer slots, just round holes. In that way effective length between pivot and stylus tip is locked.  To set overhang one must adjust the mounting distance at the sliding base by releasing the large threaded lock and sliding the entire arm within its mount fore or aft.  There is enough room in the head shell mounting holes for adjusting offset angle (Zenith).  In practice alignment is easy when done in combination with a two-point protractor or an arc protractor.  The supplied specs of mounting distance, overhang and offset angle indicate an alignment design intent per Loefgren B with null points at 70.3 and 116.6mm.  I was able to achieve a Baerwald (Loefgren A) alignment using an arc protractor. The null points on the Baerwald are at 66 and 120.9mm. I think I prefer this alignment over the Loefgren B, but either should suffice provided the process is carried out with accuracy.


The specs: 

effective mass; 3 grams!
cartridge weights accommodated; 4 to 8.5 grams
pivot bearings; vertical...knife edge, lateral...miniature ball
arm tube; low mass graphite
effective length; 237mm
mounting distance; 222mm
offset angle; 21
mount type: sliding base. 

More on the cartridge.

It was some time in the mid 1970s that ADC brought out their XLM  mkII model.  An omni-pivot 'induced-magnet' stereo phono cartridge with an exceptionally high compliance rating. (And yet previous models did have even higher compliance ratings.) There is both positive and negative history about these ADC cartridges.  See quotes below.

Absolute Sound vol. 2 number 6, pge 140: ADC Cartridges; ADC-XLM  mkII & Super (1975)

  1. "The XLM is the most accurate of all cartridges in eliciting from the discs that which is on the master tape" (HP)
  2. " ....  reliability.  In our initial review of the XLM (volume 1, issue 1) we observed --and were the first publication to do so -- that earlier ADC pickups, notably the 10/E series, were troubled by stylus cantilever fatigue.  Troubled is hardly the word.  There simply was no arm, including ADC's own, with mass low enough to prevent the excessively compliant stylus assembly from being deformed.  Early XLMs were far more reliable, meaning, the stylus assembly, in transcription tone arms such as the SME, held up for about six months before giving out.  Even the later, and better sounding XLMs -- in a low mass arm -- managed to last for about the same length of time...."

Other ADC cartridges which would work on the Black Widow.:

ADC XLM compliance: 65 x 10-6cm/Dyne (1972), tip; Diasa elliptical
ADC Super XLM  compliance: 50 x 10-6cm/Dyne, tip; Shibata, (1972)
ADC XLM mkII compliance: 30 x 10-6cm/Dyne 1975, tip; Diasa elliptical
ADC Super XLM mkII compliance: 40 x 10-6cm/Dyne, tip;     (1975)
ADC XLM improved mkII compliance: 30 x 10-6cm/Dyne 1975, tip; Diasa elliptical
ADC ST XLM II compliance: 30 x 10-6cm/Dyne 1975, tip; Diasa elliptical (this is the one I have)

Other brand cartridges with compliance figures low enough to mate well with the Black Widow:

Sonus Blue compliance: 50 x 10-6cm/Dyne (1972), tip; ?
Sonus Blue-Gold compliance: 50 x 10-6cm/Dyne (1972), tip; modified line-contact
Sonus Super Blue compliance: 50 x 10-6cm/Dyne (1972), tip; Lambda (1982)
Stanton 881S compliance: 30 x 10-6cm/Dyne (1972), tip; stereohedron


omni_pivot.jpg (267632 bytes) omni-pivot

ST_XLM-II manual_1.jpg (581951 bytes) ST manual, pge 1

ST_XLM-II manual_2.jpg (831424 bytes) ST manual, pge 2

Associated Equipment:
Integrated Amp: Classe' CAP 151
Speakers: NHT 2.9
Phono stage: Hagerman Labs Trumpet
Step up transformers: Beyer Dynamic 1:15 / 1:30.  Sowter 1:10
Turntables: Thorens TD150 in R7-2 configuration, Thorens TD124 fully renewed. Technics SP10 mkII
tonearms: Infinity Black Widow, Graham 2.2, Zeta, SME 3009 S2, Rega RB250 with structural upgrades & rewire

for a complete overview of the associated components plus listening room see this link: user510