I am removing two compasses from either side of the cabin bulkhead and would replacing them with two six inch marine speakers. The speakers would be mounted in the same holes that the compasses were mounted. The compasses are redundant with the binnacle, KVH Sailcomp, and Raymarine autohelm. Currently we have Signet instruments and are contemplating changing instruments as well. The speakers would be approx 12 inches away from the nearest instrument. Would installing the speakers interfere with the performance of the sailing instruments, Signet, Navmam, Raymarine, or TackTick and Autohelm 4000?
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Rick, that's a tough one to know without trying.
But why not just score shielded speakers? Then you don't have to worry.
But why not just score shielded speakers? Then you don't have to worry.
Magnetic speakers???
On another forum the question of where to put the speakers and the best answer was Omaha. I presume that you will still have a magnetic compass in the binnacle. Watch the compass and have someone move the speakers around on the bulkhead and elsewhere and see how much effect it seems to have. Also move the boat around so that you can check the effects facing east-west and north-south. All four points should be checked. I have a friend that placed her bird cage in the cabin near the compass with the result beinga ten degree error.
On another forum the question of where to put the speakers and the best answer was Omaha. I presume that you will still have a magnetic compass in the binnacle. Watch the compass and have someone move the speakers around on the bulkhead and elsewhere and see how much effect it seems to have. Also move the boat around so that you can check the effects facing east-west and north-south. All four points should be checked. I have a friend that placed her bird cage in the cabin near the compass with the result beinga ten degree error.
Speaker power will matter
Rick, unfortunately the speakers are driven by magnets at the base of each cone and the more powerful the speaker, the more powerful the magnet. You'll encounter the least problems with 2 low-powered speakers in symmetrical positions on either side of the companionway, but should do Ross's experiment with moving things around to see how that affects your binnacle compass. It's supposed to be a standard procedure with binnacle compasses to determine the variation throughtout the full 360 degrees (yes, the results will be uneven from more than one direction depending on other deck hardware placements) and keep a crib sheet with that information at the nav station or someplace handy.
Rick, unfortunately the speakers are driven by magnets at the base of each cone and the more powerful the speaker, the more powerful the magnet. You'll encounter the least problems with 2 low-powered speakers in symmetrical positions on either side of the companionway, but should do Ross's experiment with moving things around to see how that affects your binnacle compass. It's supposed to be a standard procedure with binnacle compasses to determine the variation throughtout the full 360 degrees (yes, the results will be uneven from more than one direction depending on other deck hardware placements) and keep a crib sheet with that information at the nav station or someplace handy.
binnacle compass
The binnacle compass is approx six feet away from from the bulk head which the speakers would be mounted. The KVH Sailcomp Fluxgate sensor would be approx 4-5 feet from the nearest speaker.
The binnacle compass is approx six feet away from from the bulk head which the speakers would be mounted. The KVH Sailcomp Fluxgate sensor would be approx 4-5 feet from the nearest speaker.
Speakers' magneting field
Previously on a list, it was recommended to walk the speakers you are contemplating buying (if at a marine store)over to the compass display and note how far (or close) the magnetic field begins to affect the compass cards. Some "shielded" speakers aren't so well shielded (sorry, Fred! <G>).
Previously on a list, it was recommended to walk the speakers you are contemplating buying (if at a marine store)over to the compass display and note how far (or close) the magnetic field begins to affect the compass cards. Some "shielded" speakers aren't so well shielded (sorry, Fred! <G>).
Shielding
There is nothing that will shield the permanent magnets in the speakers so they don't affect the compass. You can only move them away from the compass or use speakers that don't have magnets in them.
There is nothing that will shield the permanent magnets in the speakers so they don't affect the compass. You can only move them away from the compass or use speakers that don't have magnets in them.
Well Bill, ever compared computer speakers to
off-the-shelf open-magnet speakers? I mean, have you tested them against the front of a CRT monitor to see which distorts? Shielding works. Sorry, but what you said is not true. And because I've been around a while I was hesitant to address your suggestion about speakers without magnets. I've never heard of such a thing. A magnet has to be there or they're not speakers. But, you never know, so I called the experts a Crutchfields. They've never heard of such a thing either. So that part of your post is not true either. Sorry for going to such lengths but when you say such things, it gets some of us moving.
off-the-shelf open-magnet speakers? I mean, have you tested them against the front of a CRT monitor to see which distorts? Shielding works. Sorry, but what you said is not true. And because I've been around a while I was hesitant to address your suggestion about speakers without magnets. I've never heard of such a thing. A magnet has to be there or they're not speakers. But, you never know, so I called the experts a Crutchfields. They've never heard of such a thing either. So that part of your post is not true either. Sorry for going to such lengths but when you say such things, it gets some of us moving.
Here's your proof!
Fred, you'll want to be calm and seated when you click the link below and read the specs for non-magnetic speakers (but I'm not sure the technology is being used for bigger speakers):
Fred, you'll want to be calm and seated when you click the link below and read the specs for non-magnetic speakers (but I'm not sure the technology is being used for bigger speakers):
non-magnetic speakers
When the speakers are powered, the speaker wires themselves could cause interference if close enough to the flux gate. As far as non-magnetic speakers, here's a definition from the following link. -snip- There are also non-magnetic speaker element types. The most well known types of those are piezo speaker elements and electrostatic speakers. Piezo speakers can generally used for high frequency playback. Piezo elements are generally used to make all kinds of simple beepers / alarms and sometimes used to make some high frequency speaker elements. Piezo elements consist of special crystals that change their shape when voltage is applied to them. -snip- Don't know how they sound though. Sail On... Terry
When the speakers are powered, the speaker wires themselves could cause interference if close enough to the flux gate. As far as non-magnetic speakers, here's a definition from the following link. -snip- There are also non-magnetic speaker element types. The most well known types of those are piezo speaker elements and electrostatic speakers. Piezo speakers can generally used for high frequency playback. Piezo elements are generally used to make all kinds of simple beepers / alarms and sometimes used to make some high frequency speaker elements. Piezo elements consist of special crystals that change their shape when voltage is applied to them. -snip- Don't know how they sound though. Sail On... Terry
Piezo's are buzzers. As far as those communist
speakers, 10% THD!!!*yks and they seem to be some kind of an electrical motor too. Power is 220 volts, *yks and 50hz. They need euro power. And they don't explain how they work. Anybody have a stereo with those output specs? *o Wonder what they do?
speakers, 10% THD!!!*yks and they seem to be some kind of an electrical motor too. Power is 220 volts, *yks and 50hz. They need euro power. And they don't explain how they work. Anybody have a stereo with those output specs? *o Wonder what they do?
Electrostatic speaker don't have magnet.
and should have less current(it use high voltage) going through speaker wire thus produce less magnetic field, cause less magnetic interference. Drawback? They are big and expensive
and should have less current(it use high voltage) going through speaker wire thus produce less magnetic field, cause less magnetic interference. Drawback? They are big and expensive
Lots of interference, I guess
You can place a speaker in a soft steel box or cover most of it with steel or mu-metal. That will stop it from interfering with the crt display on your radar Fred :>) But all that extra metal will bend the Earth's magnetic field lines and change the deviation of your magnetic compass or flux-gate compass autopilot. You magnets can't be shielded from each other. Interesting discussion.
You can place a speaker in a soft steel box or cover most of it with steel or mu-metal. That will stop it from interfering with the crt display on your radar Fred :>) But all that extra metal will bend the Earth's magnetic field lines and change the deviation of your magnetic compass or flux-gate compass autopilot. You magnets can't be shielded from each other. Interesting discussion.
Living in paradise
Fred, From what you decribed, you are living in paradise aready. Why would you care about speakers? If I were you, I'll turn off the darn blaster and go sailing. I put speakers on my boat because of my kids whom I like to send away to far away places.
Have fun..
Fred, From what you decribed, you are living in paradise aready. Why would you care about speakers? If I were you, I'll turn off the darn blaster and go sailing. I put speakers on my boat because of my kids whom I like to send away to far away places.
Have fun..
Ahhhh.... nothing like a little Heat!
.... and a good discussion. What I see is there are a few discussion points that haven't been covered yet that really should have been. 1. Intended use of boat. That is, is this just a weekend condo or a boat one might do some relatively serious cruising in? By "relatively" serious cruising I don't necessarily mean ocean crossing but making a passage when there is a likelyhood of reduced visability (fog, thick haze, darkness, etc.) where a compass would be helpful or needed. If this is just a weekend condo then since there are already holes in the bulkhead it doesn't really matter - throw the speakers in and go with it. If one contemplates some passages where a compass is, or may be, needed then there are other concerns. There are sensitive compasses and there are not-so-sensitive compasses. The ones that are not so sensitive aren't going to notice the speakers near as much as one that is more sensitive so this is a factor. Then there is the condition of the gimbals - they don't last forever! When was the last time they were replaced? Old gimbals will reduce the sensitivity from factory original specs so, again, maybe the compass won't be affected much by the magnet. The typical OEM compass after a few years will likely be just so much eye candy - good for looks but not much else. Venus C. Plath: ·Accuracy of indication: less than or equal to 1 degree ·Lag error: less than or equal to 1 degree ·Oscillation period: greater than or equal to 5 seconds If one is into passagemaking under conditions that may be IFR then I'd recommned a good compass and have it serviced every so often. You can't rely on electronics - they can and do fail, and probably when they are needed the most. 2. Seaworthiness. Speaker cones tend not to be strong or water resistant. With water weighing 62.4 lbs/cu ft the pressure of a little bit of water on a speaker cone will blow right through it. As a minimum one should have some type of a structural case equal to the strength of the bulkhead around the back of the speaker to prevent a large stream of water from going to the inside of the boat. With all the disucssions in the past about capsize screens, etc. what good does it matter if one has 6-in holes in the bulkhead? Don't the Great Lakes get high winds from thunderstorms? 3. Someone questioned the need for speakers - good question. As someone who has a pair of JBL L-150's with a pair of Jensen 4-way (16" whoofers, 103db/watt @ one meter) as backup, on our boat there are no cckpit speakers. I/we like it quiet (personal opinion). Even the noise from a fixed-blade prop is too noisy. Shhhh.... q u i e t. Nice. Below decks is another story - with subwoofer, adjustable crossovers, etc. At least it was until we were ripped off at the HCH yard on Lake Union in Seattle and they wouldn't replace the stolen gear. Rick: Thanks for asking the question! As an aside, Infinity made speakers in the mid- 80s where the tweeters were flat. I can't say if they had permanent magnets or not though. The old radios of the '30s used wire-wound magnets to drive their voice coils. Permanent? - don't know.
.... and a good discussion. What I see is there are a few discussion points that haven't been covered yet that really should have been. 1. Intended use of boat. That is, is this just a weekend condo or a boat one might do some relatively serious cruising in? By "relatively" serious cruising I don't necessarily mean ocean crossing but making a passage when there is a likelyhood of reduced visability (fog, thick haze, darkness, etc.) where a compass would be helpful or needed. If this is just a weekend condo then since there are already holes in the bulkhead it doesn't really matter - throw the speakers in and go with it. If one contemplates some passages where a compass is, or may be, needed then there are other concerns. There are sensitive compasses and there are not-so-sensitive compasses. The ones that are not so sensitive aren't going to notice the speakers near as much as one that is more sensitive so this is a factor. Then there is the condition of the gimbals - they don't last forever! When was the last time they were replaced? Old gimbals will reduce the sensitivity from factory original specs so, again, maybe the compass won't be affected much by the magnet. The typical OEM compass after a few years will likely be just so much eye candy - good for looks but not much else. Venus C. Plath: ·Accuracy of indication: less than or equal to 1 degree ·Lag error: less than or equal to 1 degree ·Oscillation period: greater than or equal to 5 seconds If one is into passagemaking under conditions that may be IFR then I'd recommned a good compass and have it serviced every so often. You can't rely on electronics - they can and do fail, and probably when they are needed the most. 2. Seaworthiness. Speaker cones tend not to be strong or water resistant. With water weighing 62.4 lbs/cu ft the pressure of a little bit of water on a speaker cone will blow right through it. As a minimum one should have some type of a structural case equal to the strength of the bulkhead around the back of the speaker to prevent a large stream of water from going to the inside of the boat. With all the disucssions in the past about capsize screens, etc. what good does it matter if one has 6-in holes in the bulkhead? Don't the Great Lakes get high winds from thunderstorms? 3. Someone questioned the need for speakers - good question. As someone who has a pair of JBL L-150's with a pair of Jensen 4-way (16" whoofers, 103db/watt @ one meter) as backup, on our boat there are no cckpit speakers. I/we like it quiet (personal opinion). Even the noise from a fixed-blade prop is too noisy. Shhhh.... q u i e t. Nice. Below decks is another story - with subwoofer, adjustable crossovers, etc. At least it was until we were ripped off at the HCH yard on Lake Union in Seattle and they wouldn't replace the stolen gear. Rick: Thanks for asking the question! As an aside, Infinity made speakers in the mid- 80s where the tweeters were flat. I can't say if they had permanent magnets or not though. The old radios of the '30s used wire-wound magnets to drive their voice coils. Permanent? - don't know.
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