I've seen pictures of the internals of name brand audiophile
amplifiers using speaker relays. :hehe:
After talking to a relay expert from a well known relay manufacturer, he recommended the mercury wet contact type
of relay. They form a clean contact on every swipe. The problem
with 'dry' relays is breaking that oxide layer that forms on
the relay contacts.
If you are paranoid about blowing up expensive speakers, use
fuses to protect the individual drivers. One fuse for the tweeter,
another for the midrange, another for the woofer, each will
have their own unique fuse rating. I fuse my tweeters all the
time and it works fine.
Speakers usually can take some DC voltage abuse, the
duration depends on power handling of the driver. The other
issue is the mechanical damage of the driver, higher DC
offset can probably do more harm than a lower voltage
from a mechanical point of view. :hehe:
If you don't want relays, capacitors, or crowbars shorting
the rails forcing a blown fuse situation as speaker
protection, then your choices narrow.
Why not just use a simple dc offset detector and have it
drive a relay connected to the main input power of the
amplifier to remove power when there is fault ? The detector
needs to run off it's own dedicated power supply because
it's the 'watch dog'.
Even if you remove AC input, the rails will take time to
drop in voltage and your speaker will still be subject to
DC for a short time. Your watch dog can drive another relay
that disconnects both rail voltages from the amplfiier section.
If you are clever, you can design a circuit to engage the
relay, force a high current situation to break the relay contact
oxide, then remove the high current and let the relay operate
as normal.
..... OR you can turn on your stereo system full blast for
a second during initial turn on -- to force high current <-- hehe
amplifiers using speaker relays. :hehe:
After talking to a relay expert from a well known relay manufacturer, he recommended the mercury wet contact type
of relay. They form a clean contact on every swipe. The problem
with 'dry' relays is breaking that oxide layer that forms on
the relay contacts.
If you are paranoid about blowing up expensive speakers, use
fuses to protect the individual drivers. One fuse for the tweeter,
another for the midrange, another for the woofer, each will
have their own unique fuse rating. I fuse my tweeters all the
time and it works fine.
Speakers usually can take some DC voltage abuse, the
duration depends on power handling of the driver. The other
issue is the mechanical damage of the driver, higher DC
offset can probably do more harm than a lower voltage
from a mechanical point of view. :hehe:
If you don't want relays, capacitors, or crowbars shorting
the rails forcing a blown fuse situation as speaker
protection, then your choices narrow.
Why not just use a simple dc offset detector and have it
drive a relay connected to the main input power of the
amplifier to remove power when there is fault ? The detector
needs to run off it's own dedicated power supply because
it's the 'watch dog'.
Even if you remove AC input, the rails will take time to
drop in voltage and your speaker will still be subject to
DC for a short time. Your watch dog can drive another relay
that disconnects both rail voltages from the amplfiier section.
If you are clever, you can design a circuit to engage the
relay, force a high current situation to break the relay contact
oxide, then remove the high current and let the relay operate
as normal.
..... OR you can turn on your stereo system full blast for
a second during initial turn on -- to force high current <-- hehe
thylantyr said:
Thanks. I think somebody has once posted the name of a
european (dutch, I think) company that also sells that type
of relays.
thylantyr said:
Yes, and they have no minimum hold current either, I think.
Unfortunately, they are nowadays forbidden on this side of
the Atlantic.
Even the hardcore objectivist engineer Randy Slone advises
against speaker fuses. He claims they have thermal distorsion.
Even the hardcore objectivist engineer Randy Slone advises
against speaker fuses. He claims they have thermal distorsion.
Another hardcore objectivist Rod Elliot says;
http://sound.westhost.com/project33.htm
Naturally, one can simply rely on fuses. Although these also have finite resistance it is small, and use of fast blow fuses can be quite effective.
We all know that audio system design is a game of compromise.
Sort your list of gremlins from top down. Fuses 'sonics' are
at the bottom of my list and protecting tweeters is on top.
I have revealing tweeters and I abuse my systems pretty
hard into high spl and I can't hear any 'extra' distortion
with an inline fuse. Maybe I use 'magic' fuses and don't even
realize it
against speaker fuses. He claims they have thermal distorsion.
Another hardcore objectivist Rod Elliot says;
http://sound.westhost.com/project33.htm
Naturally, one can simply rely on fuses. Although these also have finite resistance it is small, and use of fast blow fuses can be quite effective.
We all know that audio system design is a game of compromise.
Sort your list of gremlins from top down. Fuses 'sonics' are
at the bottom of my list and protecting tweeters is on top.
I have revealing tweeters and I abuse my systems pretty
hard into high spl and I can't hear any 'extra' distortion
with an inline fuse. Maybe I use 'magic' fuses and don't even
realize it
Christer said:
http://www.amplimo.nl/en-us/dept_56.html
See bottom of page. Actually it is the same as Plitron shows, I think. Cost is reasonable at Euro 6.21.
This is only for your information, I never used it myself.
Steven
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