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-   -   Non-magnetic latching? (http://www.diyaudio.com/forums/parts/218036-non-magnetic-latching.html)

muckrake 16th August 2012 05:04 PM

Non-magnetic latching?
 
I've opened a couple models of small sealed latching relays and the latching mechanism in both had small permanent magnets for retention. Can this possibly affect sound, being quite close to the contacts? Also, does anyone know of latching relays that use spring-based retention? From what I see in datasheets, the type of mechanism isn't normally listed.

Osvaldo de Banfield 16th August 2012 05:07 PM

May be. As some people here believes that the name of brand of a capacitor also affects sound:D

Oh, put them about 1Km far from output transistors to prevent hall effect in them.:D

jcx 16th August 2012 05:19 PM

possible source of microphonics if conductors move relative to the magnet, or actuated coil for that matter - doesn't have to be latching relay to have a B field

some audiophiles are sure ferromagnetic component leads are audible problems

but others (likely even some of the same audiophiles) rate transformer attenuators, switched by reed relays as the "the ultimate" volume control

there are precision scientific, industrial measurement instruments - including AP audio analyzers that use relays all over

understand your parts, cirucit, design, layout to evaluate, control any issues

muckrake 16th August 2012 05:36 PM

Maybe I should rephrase the first part of my question: while the comments indicate than any effect would be miniscule, can someone give an order-of-magnitude estimate of such an effect in dB relative to the signal? For example, if it's < -120 dB then it cannot possibly be audible; if it could be larger than this, then audibility is at least arguable.
Also, I'm still curious if they make spring-latched types.

Osvaldo de Banfield 16th August 2012 05:57 PM

Forget it. The spike voltage at the coil turn off may be coupled if not properly damped (Diode and cap across the coil). Mechanical noise would be negligible.

gmphadte 17th August 2012 05:00 AM

Even if there is a magnet, its magnetic flux path will be through the rotor and will leak negligible flux.

Gajanan Phadte

disco 21st August 2012 08:27 PM

To quote Eva:

"Mechanical contacts have been used for ages and over time they are well known to become dirty, oxidized, noisy, coated by a layer of every substance volatilized in the ambient, etc... In the end they produce great amounts of distortion when small signals are involved. For example, relays have a minimum current rating and special ones are required in order to switch small signals. After some aging, the contacts in standard relays and switches have trouble to start conducting when current/voltage is too low. This becomes worse when some DC component is involved due to electrolysis."

muckrake 21st August 2012 09:19 PM

Quote:

dirty, oxidized, noisy, coated by a layer of every substance volatilized in the ambient
And none of this applies to hermetically sealed relays.

mickeymoose 22nd August 2012 01:10 AM

Only to those that were sealed in a vacuum.
Low-level signal relays or switches use bifurcated gold-plated (or other noble materials) contacts. You never use "toggle" or preassure type switches or contacts for low-level signals, allways use self-cleaning (like slide) switches. E

muckrake 22nd August 2012 01:38 AM

Quote:

Originally Posted by mickeymoose (Post 3135258)
Only to those that were sealed in a vacuum.

Sealing in vacuum makes no sense due to the pressure difference. It's much easier to use a non-reactive gas such as argon or helium at slightly below atmospheric pressure (i.e. at max altitude the relays are likely to be used at). This decreases structural requirements of the relay body and seal. Since we're talking about low-level signals, arcing is not an issue.


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