Van Den Hul Colibri Stradivarius Signature

Article Link - https://positive-feedback.com/interviews/a-j-van-den-hul-interview/

MBA: Speaking of building new cartridges, you brought your newest effort the Colibri Signature Stradivarius to Axpona 2017.

AJ: The first Colibri cartridges were produced in 1995-96; over 1000 Colibri's were made in the mean time. The last modification to the Colibri was a change to the magnetic circuit where I brought the sonic quality to tape level when the original recording cut was made well.

Colibri Signature body has a special coating, also sanded outside. The external structure is different than on inside. Looking at the harmonics of scratches, it produces a reducing body coloration. More natural sound with more space for the acoustics during the listening.

The application of The Extender helped here a lot. Without The Extender, there was no change to have The Colibri Signature Stradivarius.

The drying schedule looks like this:

• 4 weeks for first layer
• 4 weeks for second layer
• 4 weeks for third layer
• This is followed by an additional three months of air curing and hardening process

Most MC cartridges can produce a standard output with actual magnetic. Their output can be equal to twice the value of the standard Colibri. The [new] Colibri Signature Stradivarius has now the double of the output of a standard MC cartridge: 0.70 mV /5.6 cm/s. This steeper modulation-output curve improves the dynamics.

MBA: I thought it was interesting that you used Gold, not Copper wire, to wind the Colibri's coils. What led you to that?

AJ: A "slowly" drawn gold-wire sounds better compared to the regularly "fast" drawn copper-wire. I use a 20 to 25 micron soft gold-wire for winding and find it better for very low level conducting. This Gold wire is drawn at extremely slow speed (this isn't actually new as A.J. and I talked about drawing speed and its effect on the sound back in the '90s—MBA.) This maintains much better the integrity of the conductor; around 5 cm/second, there's no mechanical drawing variations modulations and dramatically improved analog sound. Higher drawing speed adds extra crystal boundaries. Lower speed decreases number of crystal boundaries and layers and gives therefore a purer sound. The quality of the wire makes or breaks the final result after all other work on components and construction is done well.

Soft metals have a high number of free electrons. This combined with a very high purity, produces the best sound specific on very low signal level like concert hall acoustics. Actually, I am working on a graphene conductor to increase number of free electrons. It must be treated with care. Both parameters must be maintained: Increase the mechanical strength and at the same time decrease the impedance.

MBA: Another unique feature of your Colibri Stradivarius and Stradivarius Signature cartridges is the cantilever length and the absence of a front pole piece. What are the advantages of this design?

AJ: The Colibri is an Unipole Modulator: Standard is rearly positioned in the magnetic center or moves symmetrically in the magnetic field. The final electrical result is the sum of both magnetic modulators. This, however, causes a difference in modulation. That's reason enough to work only one magnetic pole. By shortening the cantilever, the sonic result is better pulse response and an extended frequency range.

The applied cross-coil comes, thanks to the shorter cantilever, closer to record. This was an issue in the beginning. To solve this problem required playing the with tracking force, compliance and suspension. Initially, I used a 2.5 mm long cantilever but the cartridge had a problem tracking the record. After some experiments, I settled on 3.5 mm cantilever length for the whole Colibri series.

It is common to set the antiskating when tracking at minimal 70 micron or higher. The standard record cutting is between 20 to 40 microns. The incorrect antiskating setting causes standard a worn right side of the stylus what causes too soon record damage. The left side of the stylus is still very well shaped without a worn diamond "plane." 

MBA: A.J., one last message for our readers about their cartridges!

A.J. "Cartridge and arm like men and women: minimize the mismatch!"