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Thai-Scandinavian Engineering

The Bird of Prey

The Bird of Prey Tonearm
By: Michael Fremer

September 4th, 2025

Category:

Tonearms

The Bird of Prey Tonearm Takes Flight!

Top of the tonearm food chain?

One thing you learn from doing this for decades is that orthodoxy can be a straitjacket. You must give odd birds a test flight before you dismiss them. Then you dismiss them! Ah, but I’m kidding my friend Robin Wyatt who, yes let’s immediately dispense with that part: the importer is a friend and a one-time business partner in the enterprise of releasing Rufus Reid Presents Caelan Cardello.

That worked out well for everyone! And his wife Carol and mine show dogs and are friends as well. They are part of "the dog world" and participate in "dog shows", which when people ask what those are like I say, "they are like hi-fi shows, only with less pooping in the elevators".

As a few other friends who have offered equipment for review have found out, I don’t let friendship get in the way of honest reviewing. Unforgiving readers are looking over my shoulder as I write. Friends are more forgiving and if a review breaks a friendship, it wasn't much of one to begin with.

The Bird of Prey

This unipivot tonearm defies convention in more than a few ways. First, it doesn’t have an anti-skating feature. That’s almost grounds for dismissal in certain quarters—J.R. Boisclair’s for instance, who thinks skating compensation is near the top of the most important set-up parameters. He's probably reading this rolling his eyes. I figured Robin knows I share J.R.’s skating position, so The Bird of Prey must somehow solve skating without special compensation, or why else would he want me to listen to and review this arm?

 The underhung 8 inch arm supplied with the Yukiseimitsu AP-01 Turntable was a totally unexpected and very pleasant listening surprise: underhung, and also with no anti-skating compensation because there’s a belief among some in Japan that skating is among the worst vinyl playback sins (in that they agree with Boisclair) and that since, they believe, skating is caused by overhang and tonearm offset angle, eliminating those eliminates skating!

They are more than happy to exchange skating for a relatively large increase in harmonic distortion produced by the increased LTE (lateral tracking error), which is what underhanging the arm and doing away with the offset angle creates (for those here unfamiliar, "overhang" is literally the distance the stylus "overhangs" the spindle (the pivot to spindle distance [arm length] plus the overhang equals an arm's effective length).

However, while the underhang and lack of offset angle diminishes skating it does not eliminate it. Instead, on a blank disc the arm skates in to the center of the record and stops. Place it near the end of the side and it skates out to the center and stops (I'm no suggesting using a blank record to set anti-skating).

Point is, despite these problems, the AP-01 sounded great, probably in part because even order harmonic distortion can sound pleasing! I enjoyed the listen, but I'd have been happier had they then a use your own arm option that they now do. To be clear: the B.O.P.". is neither underhung nor does it lack an offset angle.

Other B.O.P. Features

Lack of anti-skating out of the way, consider the rest of the design front to back: the headshell is best described as "vestigial". It's a relatively light, elongated "U" shaped empty-in-the-center piece of machined aluminum (or as one observer sarcastically put it, "it's like a tuning fork") with a platform-like inner surround. The cartridge first bolts to a thin metal disc with finger lift that hangs from the center of the "U" shaped section secured by a small screw riding in the inner-surround that adjusts both overhang and offset angle. The headshell's rear is a thick, integral aluminum block with a center opening into which the arm tube is clamped. The picture is worth 1000 words, but the more you consider it the more you have to respect it as some pretty neat precision machining.

The headshell is available in various weights and it's even available with an SME style collet for SPU cartridges. In fact, the options for this arm are too great to cover in a review and could lead to some confusion, so let's just say, if you're interested ask about your desired options.

B.O.P. comes with two arm tubes, one straight and one "J" shaped. The standard "J" shaped arm is made of Brazilian Pernambuco wood, obviously hollowed out for the wiring to pass through. The review sample's extra cost straight pipe is fabricated partly from Pernambuco wood that's used for making violin bows among other things and partly from aluminum. It's apparently an endangered species and subject to smuggling (the wood, not aluminum). I am hoping Thai-Scandinavian Engineering doesn't use smuggled wood.

At one point Mr. Wyatt told me that the manufacturer can "tune" the tubes to better compliment the buyer's musical tastes. This for me is a red flag. It tells me to expect a purposely "colored" listening experience. I'd rather the cartridge added the color, but your opinion/needs may differ, so onward!

You can order the wand in various lengths depending upon your turntable's needs (mine needs a 12" arm). The arm wand includes the internal wiring—a pure silver formulation exclusive to TSE) that exits out the side of the arm in a stiffened enclosure and terminates in XLR plugs.

Thai-Scandinavian Engineering can provide XLR jacks-to-XLR plug wiring that goes from the termination point to your phono preamp, or you can have XLR jacks to single-ended RCA or you can have it wired for field coil cartridges, or however you wish. You have to provide a means to secure the relatively heavy XLR junction.

Thai-Scandinavian Engineering provides this rig for permanent installations:

Here's how I did it for review purposes:

The draped wiring exiting the side of the arm is unavoidable and will not be to everyone's esthetic liking. Had this been a permanent installation I could have neatened it up somewhat and of course I would have used the permanent aluminum block shown above.

Now let's get to the main attraction, the magnetically stabilized, viscous damped, high mass bearing housing of nickel plated brass, and assorted unusual and unique parts. Again, a picture is worth 1000 words:

With the bearing assembly flipped upside down you are looking down on the unipivot point locked into a brass block that also contains a pair of bearing stabilizing disc magnets, one on either side of the unipivot point. The two sets of 8 teeth, each grooved, sit in a viscous fluid filled damping trough. Unlike single "paddle" damping systems, this one produces a great deal of "drag". The more the fluid, the greater the drag effect. The greater the fluid viscosity the greater the drag effect.

Here's another view that better shows the pivot point and "teeth" length and behind it the bearing cup and damping trough. You can see the arm wand's end on one side. The aluminum counterweight stub has wood damping inside.

Here's the bearing cup and trough viewed from directly on top. The cup can be raised, lowered and locked in place via a pair of grub screws to set VTA/SRA.

Here's how the bearing looks in place:

Now you see the bird's "wings". Obviously one on either side. These can be raised and lowered to provide extra stability and note the weight at the rear (one on each side). Those can be slid forward ahead of the unipivot bearing to change the arm's effective mass. They can also be used to provide lateral balance-like how SME balanced its knife edged bearing. That's the arm's unique game plan. You can adjust azimuth either by rotating the arm tube within the bearing block, or preferably by rotating the headshell.

Though there's not yet an instruction manual the importer sent a note from the arm's designer regarding the arm's "Universally Adjustable Effective Mass, which he says means "...not only compatability with practically any cartridge, but also the ablilty to revise system resonance from the ubiquitously accepted 10Hz down to 5Hz or less; a natural requirement of half-speed transcription whereby once brought back up to speed, a 10Hz system resonance would otherwise create an unwanted 20Hz spike in the resulting media (I'm not sure I can agree with this claim unless I'm not fully understanding it. The resonance is in playback and I don't see how the 1/2 speed mastering produces a 10Hz resonance in the lacquer that doubles upon vinyl playback_ed.) Adjustment of effective mass is simplicity itself. Start by removing the end stub. Affix cartridge in situe in accordance to your prescribed alignment, then weigh on a balance. The author uses a cheap digital balance that cost <$1, but you can buy dedicated balances if you choose. Adjust outrigger weights forwards or backwards until the desired effective mass is achieved. Now reinsert endstub and attach weights until the desired VTF is achieved. In order to establish your required effective mass a number of online resources are available, simply search for “cartridge resonance calculator” – here is a useful example from Resonant Frequency.

Bird of Prey Arm Behavior

If you are paying close attention you've noted where the arm's very high bearing mass is located: well above the pivot point. Like Franc Kuzma's 4 Point, the Bird of Prey is a negatively balanced arm. That is, the mass of the arm, unlike most unipivots, is located above the pivot point. Most unipivot arm designers try to locate the mass below the pivot point, to add stability (VPI, original Graham 2.0, etc.). Like the 4 Point, so much mass is above the pivot point, when you raise the arm from its resting position it wants to continue its upward path. The Kuzma Safir is so negatively balanced, if you raise it up enough, it parks itself with the arm tube pointing up at about a 45 degree angle.

This is not a design defect in either the Kuzma or the Bird of Prey, but you must be careful setting tracking force and obviously having vertical damping is critical playing back warped records because the arm will tend to want to continue its upward movement reacting to a warp.

With a negatively balanced arm, the higher up above the record surface you measure VTF, the more it will be "off" into negative territory and so the actual VTF at the record surface will be too high. Positively balanced arms like SAT's produce the opposite result. That is, the higher off the record surface you measure VTF, the heavier it will read there but will be lighter at the record surface, so you have to add tracking force to compensate. It's less of an issue with 12 inch arms. SAT provides a detailed formula for this. The practical solution is to use a stylus force gauge that measures at record surface.

If you lift the Bird of Prey too high up the arm tends to "go up". You have to lower it adjacent to the platter to below record level to get it to behave normally. Again, not a problem once you understand why it's behaving as it is, and what to do about it.

Which forces me to repeat another issue: the lack of an owner's manual. Everything I did was run past Robin Wyatt. A $15,950 arm deserves an owner's manual as do buyers spending $15,950.

The first cartridge installed was (appropriately) a Miyajima Labs INFINITY mono cartridge. Robyatt Audio imports the brand, plus at almost 15 grams it's heavy and I figured the vestigial headshell would benefit from some mass (honestly, I don't understand the design rationale of low mass headshells). Plus it tracks at 3.5 grams.

The arm's lateral movement, for obvious reasons is somewhat sluggish and its behavior unlike that of most other arms (perhaps a Well Tempered arm, which sits in a silicone pool would behave similarly). I didn't bother trying a WallyTractor on it to check the nonexistent anti-skating because even if had anti-skating it clearly wouldn't move laterally or move much if it moved at all.

I'll get to how the arm behaved with a more typical stereo cartridge and how it did on the Ortofon test record's trackability bands but for the mono cartridge installed I was more interested in how it sounded and tracked playing mono records.

Mounted on the B.O.P. the Infinity's familiar, notably rich, full, startlingly "the music's there" minus any mechanical aftertaste was fully there only with greater clarity and intensity than I've ever before heard it: rich, vivid but perfectly balanced and not at all cloying or leaning particularly on the midband to add heft and "richness". Between note silence was immediately noticeable as was "stop and start" precision.

Masterpieces by Ellington (Analogue Productions 45rpm edition) produced overwhelmingly rich and full three-dimensional images, each distinctly presented in three-dimensional front-to-back space. The cartridge/arm combo delivered the opening lower register clarinet line that sings the "Mood Indigo" melody deeply, richly, and as mellifluous as I've ever heard it yet the horns lost none of their brassy tone and reeds vibrated correctly. When "Yvonne Lanauze" (real name Eve Duke) enters singing, she's in your room. Well, that effect is true with most high quality tonearm/cartridges, but with this one, let's say she's in you room!!!! The humorous trumpet "wah wahs" that follow should sound wet and they did.

A mono record binge followed and I won't list any so we can keep moving here, but for mono records, the B.O.P./Miyajima Labs Infinity combo was spectacular. If you're looking for a second arm position option for mono playback, this combo is easy to recommend.

An Unknown and Known Stereo Cartridge

After spending a lot of time with the INFINITY mono, it was time to install a stereo cartridge. First Mr. Wyatt brought over a Tzar DST with a Corian body specially made for him (cost approximately $10,000). It tracks at 6 grams. The one I reviewed in Stereophile had a recommended 2.4 gram VTF. 6 was scary high for me so I started with a mono record (lateral cut grooves, less likely to be damaged, if at all by high tracking force) and I listened to and recorded a track from an excellent Craft reissue of Kenny Burrell's eponymous 1957 Prestige release (CR00861). I'd already recorded it using the $1199 Ortofon MC X40 MC cartridge mounted on the $19,000 Supatrac Nighthawk and you can hear that combo in that review.

I found this combo's playback produced soft indistinct transients on everything. Yes, the midrange was rich and creamy and female vocals were lush and you could say sonically sensuous, but overall to my ears the performance was mushy and lacked rhythmic authority and transient "snap". I've got the Tzar/Bird of Prey Burrell recording but unless there's strong demand from readers I'm not going to post it.

The few stereo records I was willing to put under 6g VTF were also distinctly and similarly soft. Not my thing. I recall being more enthusiastic about the earlier Tzar I reviewed in Stereophile that tracked at 2.4 grams. Mr. Wyatt sent a bottle of less viscous silicone and that did reduce the sonic thickness as well to some degree but it didn't change the overall presentation or my reaction to it.

But this is not a Tzar review. nor is it a review of Mutech's RM-Hayate MC cartridge (price sensitive to tariff and currency conversion, but around $8000), and a review is forthcoming but with the demise of Transfiguration, this ring magnet based, boron cantilevered, semi-line contact stylus cartridge is in that same rarified category and its sonic presentation is way more to my sonic liking. It spent weeks on the Supatrac before I moved it to the Bird of Prey so I had a very good handle on its performance, both musically and mechanically.

Moved to the Bird of Prey, I first chose to check the horizontal and vertical resonant frequencies using the Hi-Fi News test record. The silicone diminished somewhat the intensity of the resonances but both vertical and horizontal were around 8Hz so I felt no need to adjust the effective mass.

The RM-Hayate MC tracked cleanly the 50µm and 60µm tracks of Ortofon's accuracy in sound test record and tracked with but a slight bit of right channel buzzing the 70µm and 80µm tracks both of which are more highly modulated than any music track its going to encounter and that is very good performance, despite there being no anti-skating mechanism.

Just to be clear, that doesn't mean the cartridge damper isn't being unevenly pressured across the record surface, just that it doesn't show in the test track or as I found out enjoying dozens of records, in playing music through the combo.

But one record in particular was sufficient for me to tell you about this arm's sonic character and why it has a following and that record is Anthony Wilson's new one, House of The Singing Blossoms on Sam First Records (not related to the French Sam Records label).

I was sent a test pressing with no information and I chose to not look at the email containing it (or to my friend Bob Levy's Positive Feedback review) because I just wanted to listen. Thus I first encountered the double LP live set through the Mutech cartridge/Bird of Prey combination, with the arm mounted on the Wilson-Benesch Prime Meridian turntable please do not forget.

The live set begins as a piano trio—bass, drums, piano and then the horns enter—all obviously arranged by Anthony Wilson. It's in his blood after all. And the sound is spectacularly three-dimensional and harmonically rich and full—almost as if my system had turned "tubular". The background is drop dead quiet. The instruments appear in three-dimensions against a black backdrop. The horns effectively growl, the saxophones have reedy essence, images are stable and then the crowd applauds and the room opens to the applause, though there's little "room sound essence" so that it's not clear until the applause that it's a live recording. A baritone sax wails in the right channel, deep and chesty. Dynamics are outstanding. The acoustic bass has weight and natural transient detail.

Finally Wilson takes a solo in the left channel and he's right there in three dimensional, tactile space. The outstanding sonics encourage you to crank it up, which I did. When the track ends, the applause is there against the black backdrop and how can it get better than this? Without credits I don't know who's playing (other than Wilson).

Following the applause Wilson starts playing a very familiar tune. It's Joe Zawinul's "In a Silent Way" and you can feel Wilson's fingers touch the strings. There's a bit of piano, bass and drums and then the horns explode delicately across the stage. The recording is insanely great I don't care analog, digital, whatever. There's a bass solo center left and the drummer taps time off to the right, and back on the stage and so it goes. Following the familiar track comes another: Zawinul's

What is there to criticize about this recording and how the cartridge and arm present it? There's nothing to criticize. I don't care what are your particular sonic tastes, I think you'd like this presentation!

Then it was time to play it on 1)The Wilson-Benesch Graviton tonearm fitted with W-B Tessellate Ti-s cartridge 2) The Acoustical Systems AXIOM tonearm fitted with Lyra Atlas Lambda SL mounted on the A*STELLAR turntable (nothing at the time was mounted on the Supatrac Nighthawk). Playing this record was not a chore!

While the two other arm/cartridges (and the belt drive turntable) are different and don't sound identical, the two arms mounted on different turntables sounded closer to one another than they did to the Mutech/Bird of Prey, which produced a warmer, more harmonically saturated and you could even say more inviting presentation.

Were you sitting here comparing you might conclude that the latter two set-ups were kind of drab sounding and lacking in inviting harmonic richness. Or you might conclude that the Mutech/B.O.P. presentation though exceedingly pleasant—more than pleasant and actually more like "real live music" —was built upon an incredibly pleasing, even handed set of colorations so well delivered and balanced that they were difficult to impossible to hear until you made the comparison and why bother doing so when you're having such a great time playing tunes?

Remember that I had the Mutech on the Nighthawk for quite some time and played many records on that combination. The Mutech does have a textural rich, physical presentation with accomplished, generous harmonics and is not at all "cool" or analytical sounding— the sonic direction to which the Tessellate mildly gravitates towards, but what was a pleasing direction on the Nighthawk was full blown on the Bird of Prey.

Conclusion

The Bird of Prey is an odd but unusually visually attractive, intriguingly designed magnetically stabilized unipivot bird. I don't understand the reason(s) for light weight at the headshell, though I do understand high mass in the rear. Affixing the cartridge holder with the single screw leaves an indentation that over time can make setting overhang difficult as the screw seeks to settle in the indentation rather than where you wish to affix it, though many other arms have a similar issue and it can be argued that the single point connection is an effective energy drain point.

The lack of anti-skating is still a concern even if it appears to not be an issue. Chances are good there's uneven force applied to the cantilever damper, though the silicone diminishes it to some degree. Having a way to easily change effective mass to better match cartridges is a fully useful feature. The arm's versatility and available head shell, wiring and arm tube options are real pluses, especially for vinyl enthusiasts who like to regularly explore "options".

Many unnamed records later in all of these comparisons, and being fully aware that the Bird of Prey manufacturer offers sonic "flavors" to your liking, it's difficult to perfectly pin down the arm's mutable, "moving target" sound, but based upon what I heard I think the design's full rich sonic character heard through all three cartridges used, is "built into" the design.

Some of the consistent harmonic richness is an exaggeration, some of the notable silence—unusual in character— is a suppression of sustain and/or highest frequencies (you can more easily hear the room sound behind the instruments before the applause on the Wilson nonet album through the other arms) and I believe had I the time or inclination to try additional familiar cartridges I'd hear these same characteristics filtered through those cartridges' sonic characters.

At the same time every record I played using the Mutech/B.O.P. combination sounded vital, "musical", enjoyable and uncolored (even when I was convinced I was hearing a consistent character) because it was evenly applied across the full frequency bandwidth and this arm does deliver the full top to bottom bandwidth free of audible lumps or bumps.

I certainly would avoid using it with a warm sounding cartridge unless you can't get enough of that sound, and I'd definitely try to pair it with a lean, detailed, "fast" cartridge, which I bet would produce an idea balance or detail, speed and saturated colors. But that's my taste.

And finally if you're looking for an arm to put in a secondary position for use with a mono cartridge, to give you that "old school" mono sound, you could start and stop with the Bird of Prey and you definitely won't regret it. I fully enjoyed my time with The Bird of Prey.

Specifications

The Bird of Prey tonearm is available in multiple lengths, including a 12-inch version reviewed here. Price of arm as reviewed: $15,950

. Specifications (for the 12-inch version)

  • Effective Length: 304.8 mm (12 inches)

  • Mounting Distance: 291.6 mm

  • Offset Angle: 18 degrees

  • Overhang: 13.2 mm

  • Pitch of Headshell Mounting Grooves: 12.7 mm

  • Effective Tonearm Mass: 14g-52g

  • Cartridge Weight Range: 7-20g

  • Tracking Force Range: 1.5-10g

  • Minimal Null Point: 125mm

  • Maximal Null Point: 251.7mm

  • Tonearm Weight: 520g 

Features:

a magnetically stabilized, viscous-damped unipivot design. The tonearm allows for azimuth and VTA adjustment and can use different armwands. According to the importer, it can accommodate a wide range of cartridge weights. 

Manufacturer Information

Manufactured in Thailand by Thai-Scandinavian Engineering and distributed worldwide by Robyatt Audio

Comments

  • 2025-09-04 08:21:10 PM

    Come on wrote:

    Transparency about the relationship and a honest review without sugarcoating, I think anyone can make his conclusions, I did so.

    Regarding “light weight at the headshell”…I assume it has to do with the effective tonearm mass (or the optional variations) to reach by design. To my knowledge, the further away some additional weight is from the bearing, the more exponentially it goes into the effective mass. So 2g more mass at the headshell don’t mean 2g more effective mass of the arm, but maybe 10g, while 2g more mass near the bearing mean not much more than 2g more effective mass of the arm.

  • 2025-09-05 12:40:12 AM

    bwb wrote:

    Unlike single "paddle" damping systems, this one produces a great deal of "drag".

    I believe an object moving very slowly through a fluid experiences very little drag. Think about walking slowly through a swimming pool versus how difficult it is to run.

    This is the situation with the arm moving across the record. The frequency of vibrations from the stylus transmitted down the arm are much higher and are damped, but the frequency of the arm across the record is a fraction of a Hz.

    I have measured the horizontal friction using a Wally Skater and it is close to zero which seems to confirm my hypothesis. The viscous fluid does not produce any "drag" against this motion. . For that reason I don't think the design of the arm affects the skating force as you speculated.

    I do agree about the lack of a manual. Hard to explain without pictures, but there are an infinite number possible combinations of the height the outriggers along with the amount and position of the weights which also affects effective mass. You can also adjust how long the pivot is which will actually keep it from floating up if you keep it relatively short. Too short and not enough vertical travel. Too long and it floats up when lifted. How all of this affects the performance of the arm should be explained.

    • 2025-09-05 01:52:40 AM

      bwb wrote:

      I'm not an engineer so my take on the viscous drag could be wrong , would love to hear from someone knowledgeable in hydrodynamics.

    • 2025-09-05 10:48:22 AM

      Michael Fremer wrote:

      I’m obviously also not an engineer but by feel this arm is more difficult to move laterally than say a 4 Point with trough in use.

      • 2025-09-05 11:38:11 AM

        bwb wrote:

        but the question is.....is it more difficult when moving at the same speed as the arm does when in use? It takes maybe 15 minutes to travel across the record. We can't really mimic that to feel what it is like.

        All I know for sure is when using the Wally Skater it displays no more horizontal friction than my Kuzma Airline or several other arms I have, which is basically none.

    • 2025-09-09 02:14:28 PM

      Michael Fremer wrote:

      I did put the WallySkater on the arm before packing it up and i found that the plumb bob lined up with the finger lift indicating no anti-skating applied, as expected, and that when I moved the hanging piece containing both strings, the arm's movement lagged in time as expected but that's not really a problem. I did discuss this with a few people and all said the speed with which an arm moves across the record is as you describe above—very little drag and not a problem. However, based on experiences with other arms using horizontal damping troughs, the BOP did move more slowly, perhaps because of the multiple "prongs" in the fluid. So an accurate observation but a less than accurate conclusion drawn from it and the Ortofon test record performance backed that up.

  • 2025-09-05 08:06:54 AM

    Robin Wyatt wrote:

    The rationale behind the vestigial headshell is that a tone arm benefits from quick energy transfer from the stylus and cantilever into the arm the super light headshell allow that to occur. The mass needs to centered around the bearing to allow total control of the LP modulations. Given the Bird Of Prey can accommodate effective mass from 14g-52g no other arm can come close to that. The one thing I would like to reiterate is the noise floor on this arm is so much lower than any other arm available that some owners actually have to check to see if the stylus is in the lead in groove. The result of that black noise floor is more detail more dynamics and more music from you LP’s, by definition.

    • 2025-09-05 11:56:41 AM

      Come on wrote:

      Robin, fastest possible enery transfer away from the cartridge into arm and base also in my understanding is one of the basic goals of tonearms, which is why I'm sceptic in case of other material used for arms than (damped) titan or slower metal, but no wood or other material, slowing down the direct energy transfer. This to me seems like always a compromise between sound cosmetics and optimal energy transfer.

      As you mentioned this goal of fastest energy transfer but also offer sound tuning by different material, I assume you are aware of compromises...or do you see it differently?

      • 2025-09-06 10:10:47 AM

        Robin Wyatt wrote:

        The way I understand it is the energy from the cartridge moves into the arm quickly at the front end of the arm as we would expect. As this energy meets a different medium in its travel, its resonate frequency and speed diminishes. Now as that energy dissipates it is fading away into the different density of the wood usually as heat. If the arm is one material the energy continues its motion unhindered and reflections move unhindered within that material- “ringing”. I assume that is the design theory behind Carbon fiber in the SAT and Supratrac as the composite nature of the material dissipates the energy too! One piece aluminum titanium etc will not have those properties.

        • 2025-09-06 04:23:08 PM

          Come on wrote:

          Thanks for your feedback Robin and the interpretation seems to make logical sense, but there are some topics where I see a different logic from a material and engineering point of view.

          Main aspects of basic tonearm material are usually low weight, maximum stiffness, low self resonances, fastest energy transfer rate. The optimum is all at the same time. The goal of the material usually should be, not to stop the energy transfer (rate) before cartridge resonances run dead on the way to the record player base. In my opinion the goal of damping characteristics of tonearm material itself is not to kill all cartridge resonances within the arm tube (those resonances should be dissipated from the arm through the bearings to the base as quickly as possible), but to avoid that an arm tube builds up own resonances while dissipating cartridge resonances as fast as possible.

        • 2025-09-06 04:23:35 PM

          Come on wrote:

          When we look at the materials Wood, Aluminium, Carbon and Titan, Wood is the material with the lowest speed, lowest stiffness and lowest energy transfer rate and it has many different and hard to calculate own resonance patterns…but the suboptimal basic material behavior, its isolating nature and those own resonances seem to make a kind of organic sound. Carbon is extremely good for most of those demands and good in transfer speed, but it also has complex resonance patterns, which can be optimized in a construction at a high price and effort. Aluminium is the cheapest metal solution with good results across the board but high self resonances which must be damped. Titan with extremely good weight/stiffness/transfer speed values has - other than aluminium - even high inner damping, but tonearms using it usually have additional measures to reduce remaining resonances anyway (like liquid damping between a titan and carbon tube, reaching highest transfer speed and damping at the same time). As your arm ranks at the price level of some of such sophisticated carbon or titan constructions, it’s always interesting to understand construction principles.

          Several of Michaels descriptions of the sound from the Bird of Prey somehow match my previous assessments of the behavior of wood as part of the core material of an arm construction in producing a designed or random harmonic sound while probably not focusing on maximum information retrieval.

          At the end the result counts and although 15-20k$ seems to get a kind of standard price level for tonearms, competition is hard among new adventurers and seasoned perfectionists. I wish you the best for your business!

          • 2025-09-07 07:02:42 AM

            Robin Wyatt wrote:

            I think that this was the core of the review, to quote-—more than pleasant and actually more like "real live music. So your hypothesis as to the sonic characteristics of different materials maybe accurate but have no indication of the sonic whole. The designer seems to have got it right when Mr Fremer makes the statement above! Especially when compared against mega expensive Wilson Benesch and SAT tonearms costing five times more.

            • 2025-09-07 08:00:23 AM

              Come on wrote:

              I'll leave your statement as it is, which is also why I said “at the end, the result counts.”

              Regarding reviews in general: I simply read a lot between the lines, and from my point of view, this is necessary in order to learn more than trivialities from reviews.

              I think Michael currently is the best reviewer and nearly the only one who still makes more or less meaningful comparisons.

              But reading between the lines is also about recognizing methods that enable a “live and let live” approach between honest reviews and manufacturers' interests.

              One option is to only write individual tests with generally almost exclusively positive statements and without comparability to competing products (which is what almost all reviews on the market do).

              Another is (without or after going into sometimes critical detail) to make general, emotionally felt statements about quality that leave room for interpretation in any direction, but basically sound positive.

              Yet another is to provide comparisons with exorbitantly more expensive competing products, which on the one hand always sound positive for the cheaper product (simply because of the disproportionate comparison), but which do not provide any information about the competition among products in a similar price range.

              As readers, we have to live with all of this, and I also understand some of the reasons why this happens. Most of us readers have surely found a way to draw concrete conclusions from reviews and to interpret the statements made by reviewers anyway.

    • 2025-09-21 03:10:03 PM

      SUPATRAC wrote:

      "Given the Bird Of Prey can accommodate effective mass from 14g-52g no other arm can come close to that."

      The SUPATRAC Blackbird and Nighthawk can go far beyond 52g of effective mass, out of the box. Both come with a 20g mass adaptor which can be attached very near the headshell - do the maths. A second and third mass adaptor can be added to take the arm to an effective mass of hundreds of grammes. Hifiaf.com tested the Blackbird with half a kilogramme attached and reported superb results. Since the sideways pivot does not bear the weight of the arm, pivot performance and wear are not significantly affected by the addition of very high mass in the way that vertical uni-pivot or gimbal bearings are.

    • 2025-09-21 03:20:31 PM

      SUPATRAC wrote:

      I forgot to mention the low mass end - the Blackbird is around 11g with the mass adaptor removed. It was developed to work well with the very high compliance Shure cartridges when the brush stabiliser is not engaged. Out of the box it can be configured between 11g and several hundred grammes with no compromise in performance.

  • 2025-09-07 09:35:53 PM

    CCW wrote:

    Michael,

    I'm generally a fan of your helpful information and professional tone ; however the above is a controlled execution veiled as civility. While professional in tone, I would try to be more self aware of tone in the future. This was not your finest hour.

    KDC

    • 2025-09-08 02:12:20 AM

      Come on wrote:

      Not to defend Michael, but just for a different opinion:

      For someone writing real reviews (considering and mentioning underlying, at least questionable technical theories) and not just doing marketing work veiled as review (as so many others), this was written as positively as possible (especially in tone) for what I expected. We’re on a 16k price level, not 1 or 2k.

      At the end Michael writes honest and non-superficial reviews for readers like myself, that’s why I support it.

      • 2025-09-08 04:03:35 AM

        CCW wrote:

        I appreciate the perspective, and professionally stated. Of course it is possible to draw different conclusions based on what parts one emphasizes. This would probably be most hashed out over a nice cup of coffee and a friendly conversation about jazz. :)

        • 2025-09-08 09:54:02 AM

          Come on wrote:

          Thanks, got the hint…thanks to AI my disc was shortly stuck but then continued :)

    • 2025-09-09 09:32:01 AM

      Michael Fremer wrote:

      I don’t see it as an execution at all. It was a skeptical review of an unusual product but a very positive one based upon how it sounded. What part was an execution? It measured well, it performed well and it sounded great. When compared to three other high performance arms it had a more distinctive sound that I described. Were they wrong and BOP correct? I leave that to readers to decide.

    • 2025-09-09 02:04:13 PM

      Michael Fremer wrote:

      What part of the "controlled execution" was deadliest: "...the Infinity's familiar, notably rich, full, startlingly "the music's there" minus any mechanical aftertaste was fully there only with greater clarity and intensity than I've ever before heard it: rich, vivid but perfectly balanced and not at all cloying or leaning particularly on the midband to add heft and "richness". Between note silence was immediately noticeable as was "stop and start" precision.”

      Or was it this back stabber: "The cartridge/arm combo delivered the opening lower register clarinet line that sings the "Mood Indigo" melody deeply, richly, and as mellifluous as I've ever heard it yet the horns lost none of their brassy tone and reeds vibrated correctly. When "Yvonne Lanauze" (real name Eve Duke) enters singing, she's in your room. Well, that effect is true with most high quality tonearm/cartridges, but with this one, let's say she's in you room!!!! The humorous trumpet "wah wahs" that follow should sound wet and they did."

  • 2025-09-09 11:13:50 AM

    Kenneth Millette wrote:

    In late '23 I purchased a Bird of Prey tonearm new from Robin to replace a seriously underperforming gimbaled 12" Fatboy on my VPI HW-40 TT. Both Robin, and the manufacturer provided all of the guidance and parts that I needed to accomplish the installation. A manual would be great, but BOP installation is so turntable dependent, that easy access to help is needed, appreciated, and available. Bottom line, I have never heard better vinyl reproduction than what I have with the BOP. It is deeply revealing of the myriad complex sonic attributes that real voices and instruments produce. A few points: The need for anti-skating is not "settled science" in all cases, and it's application ignores the existence of null zones. A/S may make sense with axial bearings, i.e.: gimbals and even 4-point bearings, but less so with unipivots with very low friction, especially when stabilized, and with perfectly adaptable effective mass, as in the BOP. Next, MF's comment that the arm "tends to 'go up'." is a "red flag" for me. My arm will only go up about 10 degrees before it reaches a stop, provided by the teeth, which are in the trough, and damped with a silicon lubricant. I have to lift it to that point, and it comes back down naturally. It does not just go up. If this happened to MF, and I take him at his word, then the arm was not set up properly, which brings everything else into question. Lastly, I do use a different iteration of the Tzar cartridge than MF mentions, and I am able to set the effective mass accurately for it, and the sound is absolutely natural, not just in audiophile terms, but in absolute natural instrument a voice terms. I'm a genuine fan of Mr. Fremer, and I typically find his reviews very insightful. With this particular one, I am bewildered.

    • 2025-09-09 11:55:22 AM

      Come on wrote:

      What do you mean with "its application (Antiskating) ignores the existence of null zones"?

      To my knowledge there indeed are areas where skating force is highest (outside of the record), where it tends to zero (middle of the record) and where it gets a little stronger again (end of the record), but these zones have nothing to do with the null zones, but are defined by the relation of friction force (defined by groove speed by radius) and tracking error angle, which both change across the record. (I accept correction of someone who knows better any time!)

      Most antiskating mechanisms go for an average setting to address that but there are also mechanisms with magnets of varying strenghts used, which more exactly address the actual skating forces throughout the record surface.

      You're correct, although antiskating deniers are probably in a minority, the need for antiskating is no settled science among manufacturers (while the existence of skating force is, among physicists). However, I have not yet come across a manufacturer of tonearms with offset, who advocates doing away with anti-skating. The argument for "no antiskating necessity" of "no offset" tonearm manufacturers is, less lateral forces through the "no offset" design. Increased tracking error for them is a different topic. But for an arm with offset like the BOP I have no clue why skating force shouldn’t play a major role (but then, I’m no tonearm designer).

      • 2025-09-09 11:59:02 AM

        Come on wrote:

        Sorry, the BOP has no offset, my fault. So the above argument probably is the one of the BOP.

        • 2025-09-09 12:09:21 PM

          Come on wrote:

          By the way, the full background for building tonearms without offset would be very interesting and I don't get it yet. Less (not zero!) lateral force to the cart (which could be compensated with more antiskating) is the one thing. Much higher tracking error (reflected by clean tracking of just 50-60µm as for the BOP instead of 80+µm usually at this price point) is the other side. Is there any other reason to build "no offset" arms other than saving money for an antiskating mechanism? I guess there must be more behind the aproach.

        • 2025-09-09 01:38:51 PM

          Michael Fremer wrote:

          The BOP does have an offset angle spec'd at 18 degrees

          • 2025-09-09 03:30:28 PM

            Come on wrote:

            Oh sorry, I also forgot that you even wrote about it in the second abstract of the review…then my first post counts and the design dispenses with anti-skating without including the usual main argument to justify this and to lessen the negative effect.

            Meanwhile I have an idea what Kenneth could mean with the null zone topic. I guess Kenneth thought, there the arm behaves like a linear tracker and at least a non-variable anti-skate setting would worsen the assumed lack of lateral force exactly there.

            To my knowledge the one thing is, the arm doesn’t behave like a linear tracker there for a few reasons and while lateral forces might indeed be relatively low there and quite good without antiskating, these are just 2 narrow zones within other major less optimal zones.

            Anyways, if the sound of the arm matches the taste, all fine.

            For me personally the red flags would be your red flag plus on a theoretical and assumed implication basis the missing antiskating alone and even more the combination with an offset design, the wood used and the long thin headshell (assumed prone to vibration) while on the other hand I wouldn’t have the need for the massive mechanism to match effective mass (which can for sure be a feature for some). For me personally all of this is the background of what you stated as “This unipivot tonearm defies convention in more than a few ways”. It’s certainly a too technically advanced construction to be what one might otherwise call a salesman’s design, but it leaves me puzzled. Finally it seems all of this (assumed intentionally) contributes to the sound, which seems to be great. Just a personal opinion of a reader, if inappropriate, remove.

    • 2025-09-09 02:09:21 PM

      Michael Fremer wrote:

      The Fatboy using a 3D printed resin prototype material is a seriously underperforming arm for sure. I didn't give that exactly a rave review. But I think skating is a settles science. And why low friction would negate skating or the need for anti-skating compensation is not clear to me. That the arm is negatively balanced was not the "red flag" comment! And I was careful to mention it is NOT a design defect in either the BOP or the Safir. Both the Safir and BOP behaved similarly in that regard so I wasn't surprised. I'm more surprised that yours does not. Again, that's not a problem. Just an observation and an explanation I made in both reviews. The "red flag" is the "tuning" to a particular sound....

      • 2025-09-09 10:02:25 PM

        Kenneth Millette wrote:

        For Come on, in the arc that the cartridge describes playing an LP, assuming that overhang is set correctly, there are 2 points of zero skating. In the general vicinity of these points, skating force is low. (I referred to these areas as "null zones". I apologize for the confusion.) This is especially true with a 12" arm, which makes a more gradual arc than a shorter arm. However, anti-skating is applied across the entirety of the arc. So applied anti-skating is helpful and unhelpful, depending on location. In addition, setting anti-skating force can be overdone as easily as underdone. For Michael, my contention is that having the ideal effective mass set for any given cartridge, which only the BOP can do, in concert with proper tracking force, and near zero bearing friction combined with effective damping magnetically and with fluid dynamics... these allow the stylus to remain stable, centered, and deep in the groove. In addition, as mentioned, the need for anti-skate is variable across the surface of an LP. Assuming that A/S is properly set, which is often not the case, it will be still be excessive in two regions per side. There must be a named theorem stating that anything that can be done, can be done badly. Murphy's Law, perhaps. If we could have the correct amount of A/S applied for every location of the stylus across an LP, then that would be an advancement. The probabilities I'm looking at tell me, on balance, the 12" BOP does not profit from anti-skating. VPI, as you know, only began installing a provision for applying A/S because customers demand it. They still believe that you're better off not using it. It's a little like pharmaceuticals, you never know who is going to get those nasty side effects. Getting back to the two arms I have mentioned, I don't believe that A/S could help the Fatboy, but I do think it could hurt the BOP. If you insist that A/S is settled science, please accept that it's also a mixed bag. And I've totally left out LP excentricities, which further seek to unsettle the stylus. The BOP is more capable in this arena, for the same reasons mentioned above.

        • 2025-09-10 12:51:35 AM

          WallyTools -J.R. wrote:

          The mechanics of skating force are so widely misunderstood in our industry for some reason. No, there is no point across the record surface where skating force comes even close to zero assuming you are using one of the typical alignments (Baerwald, Loefgren, Stevenson). Skating force does vary SLIGHTLY depending upon which of those three assumptions you are using AND by what cutting standard for innermost/outermost modulated groove (IEC, DIN, JIS) you have aligned for - but the variation amongst all six combinations is less than 10%.

          If you watch my Sound Bite series on skating force (https://youtu.be/Bsbwolr2AZM) you see in video #1 of the 6 the role of the effective moment arm which (on Baerwald/IEC) how independent of frictional force variation skating force is highest at the outermost area of the record, is 11% less at 90mm playing radius and is only 4% less at the innermost (60.325mm [IEC]) playing radius. When you see that video, it should become very clear how skating force is generated and how its force potential changes across the record surface.

          You can't get away from skating force with ANY type of arm unless it is a linear bearing. NOT even a pivoted tangential tracker can get away without skating force BUT such force in those arms is typically VERY slight.

          By the way, I thought it was a nice review on an interesting arm design. Pretty clever to have the center of gravity above the pivot point on a unipivot arm and still remain relatively stable.

          • 2025-09-10 02:59:27 AM

            Come on wrote:

            Oh my, seems I also mixed up the various theories (of which I count yours as valid for the moment). At least they all go roughly in the same direction in relation to the discussions here.

            As you say, it's really strange that an assumed crystal clear mathematical/physical problem is so controversial. It seems it's mainly because the influence of the different contributions to skating force is controversial. I’m sure some time you will develop a cartridge, able to constantly measure the skating force applied to it, so we have the only final final word on the topic. ;-)

            • 2025-09-10 08:21:07 AM

              Robin Wyatt wrote:

              As you stated yourself you mixed up various theories. But your claim about anti skate being clear proven math is also wrong. Just like contradictions in geometry like Euclidean or Beltrami-Klein geometry there are opposing mathematical arguments. So if you have proof of the validity of any skate please share- I don’t want Bosclair’s commercial claims I want yours or an independent dynamics scientist.

              • 2025-09-10 08:37:07 AM

                Kenneth Millette wrote:

                Hello J.R., I have not watched all your videos, and will not have the time to do so until tonight. But when I read your post, that claims that with properly set overhang, there are no null points, which would occur in locations during playback where the cartridge is perfectly tangential to the groove. If what you claim to be true is true, then the obvious question is, Why do we use so much overhang in the first place? Since this is a complex mathematical problem, and since you post your take online, which, of course ultimately encourages the purchase of tools, which you sell, still, I make no claim of conflict of interests here. I decided to turn to AI for a quick take on this question. I recommend that everyone with an interest in this question - make this google search: what is the purpose for setting up a tonearm with overhang? I will insert here the first few paragraphs of the reply. Make the search and you can read all of it. "Setting up a tonearm with overhang is a key part of proper cartridge alignment on a turntable. Its purpose is to reduce tracking error and the resulting distortion by adjusting the cartridge's position so the stylus traces the record groove as accurately as possible throughout the record's surface. How overhang minimizes tracking error A pivoted tonearm, unlike a linear-tracking arm, moves in an arc across a record. This means the stylus is perfectly tangent to the record groove at only two points, known as the "null points". At all other points, there is a minor angular tracking error. Overhang is the distance the stylus tip extends beyond the center spindle when the tonearm is positioned over the spindle. A precisely set overhang, used in conjunction with a specific offset angle for the headshell, helps distribute this tracking error to minimize overall distortion."

                • 2025-09-10 10:44:05 AM

                  WallyTools -J.R. wrote:

                  I was not responding to anything related to cartridge alignment. There is nothing wrong with your quote above. I was responding to “in the arc that the cartridge describes playing an LP, assuming that overhang is set correctly, there are 2 points of zero skating. In the general vicinity of these points, skating force is low. (I referred to these areas as "null zones". I apologize for the confusion.) This is especially true with a 12" arm”

                  I was also one of those thinking longer arms had lower skating force (I make that admission in the video series) but this is not true either.

                  The determination of the cause, and the calculation of, skating force is defined in multiple papers within the public domain. Check out Kogen, Bauer, Oakley, Gilson, Wright and others who have written on it so don’t take my word for it. My contribution may be in offering an explanation that doesn’t require an understanding of vector forces and mathematics. I’ve added nothing new to the understanding of skating force.

                  It isn’t a matter of opinion any more than Euclidian versus Beltrami Klein geometries are in conflict with each other. In the latter case, one deals in flat planes and the other deals with hyperbolic planes on a flat disc. Different “playing fields”, but not in conflict with each other.

              • 2025-09-10 11:11:09 AM

                Come on wrote:

                I think you know I didn’t write anything like “anti skate is clear proven math”, but if you mean this of what I wrote: “You're correct…the need for antiskating is no settled science among manufacturers (while the existence of skating force is, among physicists)”

                …then prior to researching things, let me just get clear, what I mean (maybe then we agree already):

                To my knowledge, the dispute between all existing opinions is not, that skating force does or does not exist for any kind of arm concept (that’s common agreement and physics imo). At dispute is its relevance, magnitude and exact or combined cause together with the need or not to compensate it. Do we agree here? That was my point.

                Some arguments against applying anti-skating come from the time when suggestions for compensation were or still are magnitudes too high. Then indeed possibly better no anti-skating than strong overcompensation. But those times when we vastly overcompensated are over, also but not only due to JR‘s and other’s researches. Other arguments against anti-skating have been guesswork: “anti-skating is always slightly imprecise and may cause harm”. Both arguments usually came from folks who have never personally dealt with the topic intensively. Again others, who dealt with the topic made a compromise…lower the lateral force by a straight no overhang tonearm, pass on anti-skating mechanism and live with the higher distortion and still a certain but lower amount of skating force to the cart. As I said before, a tonearm with overhang but without anti-skating is something I don’t understand, because then you have high enough skating force to the cart to damage it long term, higher tracking distortion values (measurable and audible with tracking tests). That also under those conditions, a tonearm/cart combination can still sound very good, is another topic. One could say “you don’t know how it could sound”, but that’s guesswork. For me personally the risk to damage suspension and stylus alone would be reason enough to compensate meaningfully.

                • 2025-09-10 11:13:49 AM

                  Come on wrote:

                  Sorry this time the damn website delay caught me, please delete the double post.

              • 2025-09-10 11:53:12 AM

                Come on wrote:

                Regarding “J.R.’s commercial claims” I must make a statement:

                JR has to make some business, so there’s a commercial side, but I’m serious, for me, he is one of the few in this industry who makes me wonder why he offers so much for free, which means a lot of work. He’s always there for a call, chat or mail, even when questions are mainly not around his products. He clearly has more interest in spreading knowledge than just the points at which he can offer products (which is extremely rare in this business). His products imo are really affordable, considering not only what we are willing to pay for the rest of our hobby, but also considering the effect. The Wally Skater for example is so useful even if you don’t want to apply anti-skating, but just to see if your tonearm does what it should. Even though no one is free from mistakes, I have to say to all snake oil screamers and anti-capitalists…you concentrate on the wrong one!

                What I do understand however, is that the one or other manufacturer who hasn't spent half as much time working on the fundamentals of his products as JR has, isn’t happy about his findings in case they don’t match with their choices and they have no good arguments for them. But from a consumer side I must say, good to have more transparency and background, so it’s harder for those without proper basics to sell shiny products at the price of properly backed up technology. Those who say “the manufacturers know their stuff” I must say, I not rarely made the opposite experience.

            • 2025-09-10 10:06:57 AM

              bwb wrote:

              develop a cartridge, able to constantly measure the skating force applied to it

              that seems like a great idea to me

              • 2025-09-10 10:45:43 AM

                WallyTools -J.R. wrote:

                It’s been done and I have two such devices made by Orsonic. It’s not a playback cartridge but it does show horizontal forces during playback.

                • 2025-09-10 11:10:40 AM

                  Come on wrote:

                  Wow, so you're not depending on the math of others but know from measuring that skating force is roughly 12% of VTF?

                  • 2025-09-10 11:29:24 AM

                    WallyTools -J.R. wrote:

                    Oh no! The Orsonic is a fun COARSE tool. It is not a trusted measurement instrument.

                    • 2025-09-29 12:20:59 PM

                      SUPATRAC wrote:

                      Just to clarify something for readers, it seems to me that JR is correct that the skating force arises not because of whatever angle the cartridge is at, but because the drag vector of the record does not pass through the pivot. This always produces a skating torque whether you're at a null point or not.

                      The direction of the drag force is determined by the velocity (i.e. direction) that the record is moving at the point of frictional contact. With an offset/overhang arm the idea is that this drag vector always misses the pivot by about the same margin as the arm progresses.

                      You can argue that failing to set an appropriate anti-skate compensation does not have a huge effect on performance until mistracking occurs, but it's not really arguable that diamond wear will happen faster on the spindle side, and some cantilevers will start to hang crooked, if that matters.

                      Like a stopped clock, anti-skate is only precisely right twice a day, so argue about the optimal strength of it, but surely there is no doubt that it's better to have an anti-skating force hovering around the correct value than to apply none at all.