Hi Theo: Fluxbusters can be divided into two types. The first type involve shorting the cartridge output into itself while playing, and therefore the amount of current pushed through the cartridge coils is limited to whatever the cartridge can produce by itself. This means that the fluxbusting process is completely safe for the cartridge, but the effectiveness of the fluxbusting process is limited.
The second type uses an active (powered) fluxbusting device (combining a sine wave signal source and power output stage) to forcibly inject current through the cartridge coils. Since the active fluxbusting device can force far more current through the cartridge coils than the cartridge can produce on its own, the effectiveness of the fluxbusting procedure is enhanced. However, since more current is forced through the cartridge coils than normal, there are those who fear that the current may reach dangerous levels for the coils, or may weaken the magnets that create the field that the coils operate in.
As long as the active fluxbuster designer did his job properly, the fluxbuster should be current-limited to not exceed a level that remains safe for most MC cartridges made (the finest wire used in cartridge production is 12 micrometers - smaller than that and the production failure rate becomes too high).
If any problems occur with an external fluxbuster, it will be when it is used in an application that falls outside of what the fluxbuster designer envisioned.
One such possibility would be when using MC cartridges that were built with early types of Alnico magnets (during the 1950s, 1960s, and possibly the early 1970s), that did not retain their magnetic strength very well. With these cartridges it may be safer to use passive fluxbusting (unless you have access to a magnet recharging service).
A second possibility would be when using MC cartridges with IC or printed-circuit (photo-etched) coils, as the resulting coils will have far smaller conducting cross-sections than any normal wire. Examples of such cartridges would include Yamaha's MC-1s and MC-1X, JVC's MC-1, MC-2E, MC-L10, and MC-1000. With these cartridges, again it may be safer to use passive fluxbusting.
A third possibility would be when the active fluxbuster has failing internal components. If you purchase an active fluxbuster second-hand or NOS, I strongly suggest that you test it out on a broken cartridge first before your prized reference MC!
Everyone should keep around at least one borked Denon DL-103 (which uses 14-micrometer wire in the coils).
>Any suggestions as to a brand or model with which you have had favorable results?
I don't think that too many models are available today, and I don't have any experience with any of them. I'd suggest going with a reputable brand - for example, Aesthetix's Benz ABCD-1 MC Cartridge Demagnetizer.
I hope that the above answered your questions and cleared up any opaque areas. If you have any more questions, please feel free to ask.
kind regards, jonathan carr
