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Old 7th April 2003, 07:16 PM   #1
Yonnat is offline Yonnat  France
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Default Relay or not relay ?

Hi all,

the question today is: do you use relays on the output of your Aleph to protect the speakers ?
Is it usefull ?, what is the react of the amp when you put it on or off ?
Thanks for yours replies.

Yonnat.
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Old 8th April 2003, 06:27 AM   #2
PsykoK is offline PsykoK  France
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To protect your speakers, you can use a kit from Velleman ref:4700.
Selectronic sells this kit for 24.5

@+
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Old 8th April 2003, 07:11 AM   #3
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Default Re: Relay or not relay ?

Quote:
Originally posted by Yonnat

relays on the output

As far as I understand, no owner of Aleph has claimed his speaker damage. Nevetheless, If you want the relays, apply them and you will have the additional contact points in the signal paths (a potential source of bad sound).

JH
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Old 8th April 2003, 11:16 AM   #4
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I had a considered using the relay to short the output to ground. NP says somewhere that driving a short with an Aleph is not recomended, but should not damage anything. I would feel safer listening to my amps with friends systems if there was some dc protection, but I don't want series contacts in the signal path.

Brian
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Old 8th April 2003, 11:21 AM   #5
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Alephs are pretty much rock solid. If you must have some kind of DC protection, and the amp is driving an inductive load like a woofer, i'd probably use a circuit based around a crowbar ... otherwise you could use a relay to short the +ve input of the speaker to ground and leave the +ve output of the amp out of circuit (not all types of amps can live with this). This will work so long as you're not using a bridged amp such as the Aleph-X etc. But I'd tend to consider these are last resort options as they will undoubtedly hurt the sound.
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Old 8th April 2003, 08:13 PM   #6
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I don't recall any instance where an Aleph (after the 0) took
out a speaker from failure, and it is now 12 years later.
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Old 8th April 2003, 08:50 PM   #7
Yonnat is offline Yonnat  France
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Hi,

thanks all for your replies and special to Mr Pass for his contribution, I think like JH that relay may not be a good solution but we are a few guys who are building this project and someone are thinking we have to protect our speakers but no me and that why my question.

Thaks a lot.
Best regards.

Yonnat.
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Old 10th April 2003, 02:38 AM   #8
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I wasn't talking about adding the relay in series with the speaker. I was thinking of a large spst relay that would short the output when a fault was detected and somehow power the amp down until the protection circuit was reset by hand.
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Old 10th April 2003, 04:37 PM   #9
Yonnat is offline Yonnat  France
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Hi Brian,

that can be a idea but to do it we have to make measure on the audio signal and I try to avoid this, so I will make like the original.

Thank you for your post.

Yonnat.
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Old 10th April 2003, 06:01 PM   #10
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What are the drawbacks to a series relay to the speaker?
Some people fear this like the black plague ?

Can you use over-engineer the design and use a high
current (contact) relay ?

or for redundency,

parallel two relays for extra current.

or for the extreme paranoid person,

parallel three relays for uber current capability.


I see two paths;

1. Disconnect speaker if a fault is detected, protecting
the speaker.

2. Don't disconnect the speaker and force your
amplifiers to short itself out hopefully blowing
fuses...

I researched the archives and some people that
did not have series relays had only one rail fuse
blow, but not the other... then the DC offset blew
the speakers.

I'm going to use two 20A - 30A rated PCB relays (parallel) for
my protection circuit, maybe even three depending on
PCB space. That should eliminate the fear of contact resistance/contact failure..

Reminds me of the USA government..........
joke -> department of redundency department.
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