Aleph X speaker protection

[kilowattski]

If this question has been asked already I could not find it in the search. I am knee deep in parts for the my Aleph X 100. As I am assembling the pcboards, I got to thinking, "would it be a good idea to add speaker protection for excessive DC offset"? I have absolutely no room for it in the chassis so I was contemplating building an external box (after the Aleph X is done of course). Am I being overly cautious? Is the circuit so stable I don't have to worry about it? Has amyone else thought of this? Or am I just a Luney looking to heep more work on himself?

[trigon]

Hope this help

VELLEMAN SPEAKER PROTECTION CIRCUIT KIT

2 Channel Loudspeaker Protection Kit

Trigon

[wensan]

Soft-start Speaker Protector

wensan

[jacco vermeulen]

Originally posted by trigon
VELLEMAN

Geat real, total garbage !

I have always used protection circuitry.
It not only protects your loudspeakers, it can salvage your amplifier in case of mishap.

Key factor, in my view, is the relay.
Use a closed gas filled relay with low resistance, fast response, and ample current/wattage rating.

If you want the best, use NAIS(former SDS).
The SDS S4 is not cheap, but is tiny, able to take 20 amps continuous, 80 amps max, responds in 0.005 Seconds, and has a constant flow resistance of 0.008 Ohms if all 4 contacts are used in parallel.

400 VA continuous, 4000 VA Peak, you've got no room for what ?

[EUVL]

Most circuits on the internet for speaker protection are for ground referenced output and hence no good for Aleph X. Have already posted a simple circuit (3 transistor) for differential amps in the Alpeh X Builders' thread some time in the summer.

http://www.diyaudio.com/forums/showt...ht=#post434018

If you want to be absolutely sure about the relay, find a mercury wetted one in electronics surplus stores in the US. Plenty of choices for very reasonable prices.

I have been using the circuit posted for over 6 months. Never activated though.


Patrick

[Nelson Pass]

I have seen so few failures of X circuits that I don't have
reasonable stats, but usually a failure that doesn't pop the fuses
first results in absolute offset, but not differential, so it is quite
rare to see a speaker damaged by a failed circuit (although we
see some where the volume was simply too high). So I simply
don't worry about speaker protection.

[Brian Donaldson]

Just put a big NP electrolytic cap in series with the speaker



Maybe for a little while until you gain some confidence in the amp, then chuck it.


Love the cup

[jacco vermeulen]

Originally posted by Brian Donaldson
Love the cup

It's Big !

[byteboy]

http://www.thel-audioworld.de/module/dc30/dc30.htm

For the AlephX you would have to use it as if connected for two separate amps, one connection/relay for each single speaker-output of one AlephX.

Would it be better/help to have the DC-servo (automatic correction of DC-offset) in case of such situations?

[jacco vermeulen]

Nice pic, Bro !

It even comes with a spare relay, nice touch.

However, the relays used are regular, of the shelf, types.
Nothing fancy, such as gas filled or mercury types as EUVL mentioned.
Problem with open style loudspeaker relays is that the contacts deteriorate in time, the relay resistance hightens.
A resistance between the amplifier's output and the loudspeaker raises the damping factor, with balanced amps as the Aleph X you have two resistors on the audio signal highway.

Thel's little gadget only has a couple of components that steer the relays.
An electrolytic cap, a diode and a transitor for delayed relay switch-on, a threesome of transistors for fast switch-off.

This kind of circuit has been published a thousand times in mags as Elektor, Electronic world, and the like.
Those guys came up with protection circuits much more sophisticated.
Electronic shops undoubtebly still offer protection circuit PCB's for those without HomeFab. Inc.

Air gap relays sell for 1 Dolares a piece.
(Destroyer has such lovely words, Um Homem Muito Sympatico)
I have zillions of them.