New Speakers - Old Compass - Different Readings


Mark Erdos
 

Okay, this is stupid of me so, please hold off on the "what were you thinking" comments. We are all entitled to a little bit of stupid once and a while...

The outside speakers in the cockpit were shot. I purchased a replacement pair based on size and square shape. I think the original speakers were custom built for Amel made by Audax and housed in the plastic casing (does not act as magnetic shield) . I purchased a set of DC Gold N4C speakers. The magnets on the new speakers are much more powerful than the old speakers. I did not realize the DC Gold speakers would have much higher power magnets. I had sent an email to the manufacturer and they assured me they would not interfere with the compass if they had 3 feet of space. This turned out to be total load of codswallop. I can move the compass with the speakers when they are 6 feet away. When the speakers were briefly in the cut-outs my compass was off by about 90 degrees. I now think the new DC Gold N4C speakers are going to be a lesson hard learned.

I would still like to replace the speakers. I am now looking at PolyPlaner MA-4054 4” cone size two-way coaxial speakers. PolyPlaner claims "ultra-low magnetic field speakers eliminates the problem of speakers magnets affecting navigation equipment such as compasses and autopilots". I guess we'll see.

The instructions for the Plastimo Offshore Compass simply reads:
Deviation correction :
If deviation is no more than 7° : simply draw a deviation table assessing the error, and keep it for future reference.

If deviation is between 7 and 20° : we recommend that you have your compass compensated as a start, and then draw a deviation table. The compensation procedure is a delicate operation and should ideally be carried out by a professional compass adjuster.
I have a Raythenon fluxgate compass connected to the auto-pilot. I also have secondary electronic compass connected to my navigation software. I know the normal variance between my magnetic compass and the fluxgate. My question is: Once I install the new speakers, how do I adjust the helm magnetic compass to compensate for the change in the magnetic field surrounding the compass?

Thanks!

Mark

Cream Puff
SM2K #275


Steven Bode - SV Intention 1994-SM#117
 

Hi, Mark.

So, I don't get it. What was stupid about this post that I don't understand? I need to replace my cockpit speakers as well and was just about to pull the trigger on the DC Gold 4" speakers. They're no good? What did you end up doing? Can they be wrapped in shield or something? 

Kind Regards,
- Capt Bode
SV Intention
Amel SM #117 1994


Mark Erdos
 

Steve,

 

I learned a lesson here with the speakers. I found some great sounding 4” DC Gold speakers with good bass but the speaker magnets were so powerful they threw off the compass and I sold them on eBay. I shopped for a long time and finally found a really great replacement pair with magnetic shielding that did not impact the compass. The best part is they sound awesome with a good range and are not too expensive. They will almost fit in the existing cutout from the original speakers. You will need to file the hole just a little bit bigger and drill more screw holes. You will need to fill the old holes with something like MagicEzy. MagicEzy - Cream is a really good color match. Other than that, the fit is pretty close even though they are round.

 

Here is a link:https://www.fusionentertainment.com/marine/products/speakers/ms-fr4021

 

I have had these for about 4 years and highly recommend them.

 

 

With best regards,

 

Mark

 

Skipper

Sailing Vessel - Cream Puff - SM2K - #275

Currently cruising - Santa Marta, Colombia

www.creampuff.us


Steven Bode - SV Intention 1994-SM#117
 

Hi, Mark!
Once again, thanks for your awesome help with this. I was looking at the Fusion speakers as well, but thought that the DC-Gold's were the cream of the crop. Guess those Beryllium magnets they use makes great sound, but have another drawback.
-Bode