Upgrade Review

High Fidelity "Hi-Fi & elektronik"'s review of Pedersens Gyro


Danish machineworker conjures supersound out of british enthusiast-turntable: Pedersens sense for sound

With a price of "only" 10.000* DKK (approx. £ 850, $ 1200, € 1350) the beautiful english Michell GyroDec turntable are already one of the best purchase of the high-end class. But the sound gets to superclass when machineworker Gert Pedersen from Ølstykke, Denmark modifies it.

The story about Pedersens Gyro starts as many other fairytales in newer danish hi-fi culture about 10 years ago, at the enthusiast Niels Nørby's place on Frederiksberg (=Niels Nørby, famous danish loudspeaker-designer/builder).

Nørby was so so happy with his new Michell GyroDec. Happy with its beautiful design and with its modular build, with all the mechanics visible and easy to reach, in case something needs to be adjusted or servicised.

The GyroDec's mainly a really good construction. It is solid as the few and made to last a man's life. The soundquality deserves a solid 11 already as standard (00-13 -danish school marking system, with 13 as the best).

So far, so good. But Niels Nørby wasn't completely satisfied back then in the 80's. For example, he didn't like the way the soft suspensioned subchassis sometimes pitched in the springs. Every time the pickup was lowered into the groove, and at each powerful musical groove in the LP, the sound was shaking of audible wow and flutter - temporary changes in the plate's rotational speed, heard like vibrato or blurred stereoperspective.

The reason for the wow was that the GyroDec's heavy subchassis, hanging in three spiralsprings, could rotate at exactly the same axis as the plate. Since both tonearm and pickup are attached to the subchassis, they were moving with irregular speed proportional to the records surface, even though the LP was rotating at a steady speed.

That's why Niels Nørby invented an ingenious string-system, that would let the turntable's triple-suspensioned subchassis spring freely up and down, but also kept it from moving sideways! The system worked real fine and gave a remarkably steadier soundrendering.

As another nice effect of this the GyroDec's bass-quality improved. Therefore, very soon the turntable was rebuild completely: new suspensions with rubberbands replaced the original springs. And extra damping of the founded metalchassis plus vibrationsdetaching of the motor gave even better sound.

Unfortunately, Nørby's GyroDec started to look very odd with all these funny Storm P-solutions.

GyroDec clones was a scourge in the 80's.

Just rewinding a bit. In middle- and late 80's it was very modern among analog-freaks to modify GyroDecs. Mostly because the turntable had shown to be very durable and easy to work with. But also because it (because of it's low price) was very widespread.

Many members of Hi-Fi & Elektronik's testteam was experiencing as well. Among these the undersigned, who used the GyroDec as a reference for years. True "freaks" like Peter Holstein even suspended the GyroDec-chassis on a halfswollen bike innertube. And we even know people, who planned to let it float in a big vessel filled with quicksilver. Luckily, it was never realized!

The constructor John Michell himself improved the GyroDec a couple of times. Among other things, he introduced spikes, and replaced the original plate made of almuinium with a special resonance-dead type made of polyvinylacrylate. Later, he turned the centerbearing around, so that the plate now is held by a centerspindle at almost same height as the plate's mat, reducing eventual play in the bearing's influence on the stability.

As late as 1993 Gert Pedersen from Ølstykke bought a new GyroDec for himself. With practical experiments he also found out that the suspended subchassis itself wasn't any garantee for good sound - though you've assumed this for years.

Only by lowering the subchassis so much in the springs, that there is firm contact to the chassis and down through the spikes of the GyroDec to the underlay, improves the bass and dynamics appreciable.

Destiny was, that Gert Pedersen and Niels Nørby exchanged experiences about their GyroDec-modifications. And soon was Gert Pedersen ready to try Niels Nørbys ideas out. As an experienced and perfectionistic machineworker he worked hard on making the proper suspensions look good, so that the basic design of the GyroDec wasn't ruined. Gert Pedersens systematic work made Nørby want Gert to modify his own Michell for him, with the new "pretty" suspensions - and that's where it started...

During the last years, Gert Pedersen has been trimming Niels Nørbys original ideas and improved several private owned GyroDec's for unbelievable low prices.

The GyroDec's are playing better and better as the modifications gradually are perfected. So it was with special interest and curiosity we examined the machine, when we recently got the chance to burrow the elegant smoke-coloured GyroDec on these pictures. It has been through the whole upgrade, with even four modification-steps.

Four steps to the heavenly vinyl-sound.

The first step consist in replacing each of the original three screwspirals with advanced rubberband suspensions, just like the ones you see on SME's valuable Model 30 turntable. Accurate machined and beautifully polished units of stainless steel attaches the rubberbands, who are special rubber types, that's not decomposed by the ozone in the air.

The rubberband suspension easily carries a much heavier chassis than the original springs and has even an effective damping of resonances, so that the unappropriate movements of the turntable are calmed down faster. Professionals speak of a lower "mechanical Q-value".

Second modification-step consist in rotation-stabilization of the chassis just like Niels Nørbys original ideas. For this job, Gert Pedersen uses a strong kevlar fishing line, characterized by a minimum of elasticity. The wire is attached with small poles and are vibration-disconnected with small rubber-linings, so that resonances in the wires are not spread to the chassis.

Third step consists a total vibrations-insulation of the motor. Just like the chassis, it's hung up in rubberbands. Four bands are radical attached with specialdesigned mountings, so that the motor, for the sake of the belt-drive, are height-adjustable.

The fourth and - temporary - final modification includes effective resonancedamping and mechanical reinforcement of the chassis around the main (center) bearing: here, Gert Pedersen totally disassembles the turntable and pours a metal-mass into the chassis's hollows. After that, sand is filled into the big hollow, and gets sealed with a "lid" of acrylic, glued with silicon-glue.

A 3 mm (0.12 inches) thick steelplate are attached from the downside, and a big plastic container are glued from the upside. Altogether they form a big chamber, which gets filled with sand. The extra weight and stiffness in the steelplate and the sand's sluggishness, makes altogether the most effective resonancedamping of the GyroDec, that you can realize at a reasonable price.

The chassis on Pedersens Gyro are hung up in rubberbands, attached to beautifully machined adjustable-spindles in stainless steel. The kevlar-wire underneath, prevent the chassis, and therefore also the tonearm from waving sideways or rotating around the turntable's centeraxis, which normally results in wow and flutter.

Sound is in beautiful resolution and extremely powerful

The quality of Gert Pedersens modificationwork is absolutely first class. The same is to say about the manufaction. But of course, you can see that the GyroDec no longer is original.

On the other hand are Gert Pedersens modifcations so well carried out that they almost underline the GyroDec's functional construction. You immedially understand how the technics work and that is probably the most interesting thing about such a topclass analog-turntable. Unlike a CD-player where all the technics are packed together almost impossible to understand for ordinary people, Pedersens Gyro absolutely show it's technic.

But how does it sound with all these modifications?

The price of Gert Pedersens work must be considered a token payment. But the price seems completely idiotic when you hear how much better sound that's coming out of the modified GyroDec. In proportional to the original (which is worth all the 10.000 DKK it costs) we're here experiencing a MEGA-improvement.

The bass seems to reach an octave lower than usually, and here's extremely good bass-dynamics without the bass seems to be emphasized. On the contrary, we have never heard the single bass-tones this clear before!

Listen to Mark Johnsons or NHØP's pizzicated double-bass and Pedersens Gyro reaches deeper than anything else we've heard: every time the master-bassplayers strike their strings, the bass seems to pump a low-frequency, bassdrum-like chockwave out of your loudspeakers. This well defined tone striking is heard much clearer on Pedersens Gyro than on most other turntables.

The rhythm is underlined in a very different reliable matter than when certain (especially Scottish!) turntables play bass with a very exaggerated level between 50 and 200 Hz!

Up through the middletone an incredible dynamic sound is preserved, which absolutely increases the sound realism. And the treble, which on the old GyroDec's was more damped and thick than actually musical, is now so clear and precise that it makes fun with even extremely expensive CD-players!

Of course, Pedersens Gyro doesn't make any LP better than it is recorded. And there's many bad records in any collection. But if you rediscover your good LP's - the ones with low noise-level and minimal level of wow and flutter - Pedersens Gyro will play with such a great precision, that you'll get addicted.

The stereo-perspective and the pianostrikes on Keith Jarretts analog-records (on ECM) are rarely heard better than here. And we haven't heard a such precise sound at Stravinskys chamber-music-arrangements since we tested the big and valuable SME Model 30, years ago.

So, at this test-team we are several who now consider how to sell our valuable american turntables to justify a purchase of a new GyroDec. 


Test-Result: (a danish school-mark system: from 00 to 13, 13 is the highest)
Quality-impression/design: 11
Start assembly-difficulty: 6
Daily use: 8
Technical construktion: 11
Soundquality: 13
Price: 10


*10.000 DKK was the price of a Michell GyroDec in 1993. For present prices, see Michell's homepage

Please continue to the description of the Pedersens Gyro/Orbe upgrades