snoopdan 5,000+ posts
Banned
Ive had numerous emails and questions over the years about this amplifier series on how to mod it. Ive also seen a couple of threads that had misinformation concerning the mods available so I hope that posting this will help people who actually use the search feature on here and find this.
History / Background -
The HK series board is made by the Anaba group, who primarily makes MA Audio and Visonik brand lines. The amplifier models were named the MA Audio HK4000 and the Visonik 4000xd. The HK 4000 series is the biggest amplifiers that they offer.
Mods :
Two main mods can be done to get the amplifier to perform "more" than what it was designed to do.
1. You can remove the protection circuit by removing resistors R256, R37, R41, and R262. Just make sure you clip them cleanly from the board. This allows the amplifier to run below 2 ohms. This DOES NOT MEAN THIS AMPLIFIER IS ONE OHM STABLE....it just allows you to give it that load without a protection circuit shutting the amplifier off. This amplifier should never be run daily modified and wired to below 2 ohms. This protection removal was originally employed by people who were doing burps for just a few seconds and even then the amps dont last forever in this manner. My advice : dont do the ****.
2. Replace the 1/4 watt resistors on all the FET's with 1/2 watt resistors. This will significanly lessen the possibility of you smoking them while running below 2 ohms. This still does not get around the fact that you shouldnt be doing #1 mod anyways, but this does increase the lifespan of your HK board. Below is me pointing to the area's of the board where the resistors are located right next to the FET's.
Visonik 4000xd
Good luck!