Speaker Turn On Delay and DC Protector Board Set (V2)

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#101
coolnose said:
Just wondering, are we really breaking DC as we are breaking the amp's output ? If so, the DC voltage should be around 1V max when the relais cuts off - or am I missing something ?
Click to expand...

Suppose your amp is working on +/-24V DC & one of the power rail fails sending 24V DC to the spk. The resulting arc due to DC current might even melt/fuse the relay contacts permanently. This situation is far more dangerous from the normal turn ON/OFF transients of 1V or so. Special relays are manufactured for this sole purpose by Amplimo.

Loudspeaker Protection and Muting

Under extreme test conditions even Amplimo relays (rated 100A DC) have failed! The same author here describes the operation of MOSFET SSR in detail

ESP - MOSFET Solid State Relays
 
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#102
I have a Pass F5 power amp with the current limiting portion of the circuit removed, and so I absolutely must prevent the short circuiting of the output terminals, as even a momentary connection would frazzle the amp boards. I am using Neutrik Speakon connectors to prevent this happening, with success.

Would this delay/dc protect circuit short the outputs in any of it's modes - ie. during delay, when DC tripped etc, or does it simply disconnect the circuit?

Many thanks
Lucas
 
#104
LucasAdamson said:
I have a Pass F5 power amp with the current limiting portion of the circuit removed, and so I absolutely must prevent the short circuiting of the output terminals, as even a momentary connection would frazzle the amp boards. I am using Neutrik Speakon connectors to prevent this happening, with success.
Click to expand...

as long as you know the possible consequences
of forgoing the output protection circuit,
then you can do that with your amp...

NP gave a sound advice, even the late M Leach
mentioned the same in his amplifier construction articles
about SOA protection circuits...


Would this delay/dc protect circuit short the outputs in any of it's modes - ie. during delay, when DC tripped etc, or does it simply disconnect the circuit?

Many thanks
Lucas
Click to expand...

no it does not, it simply disconnects the speakers to prevent it from frying,
voltages as high 1.5v can not burn your speakers but a full rail can..

so at least an output offset speaker protection circuit is minimum requirement for me...😉
it will not affect the operation of the amp except to disconnect the speakers,
some audiophiles dislike the SOA protection circuits because according to them
it interferes with the music....
 
#105
Problems obtaining transistors for PCB

I can't find the transistors for the diyAudio Speaker Protection PCB's:

(1) DigiKey tells me to call them for the BC182A-ND Transitors. They don't
list the 2SC945 transistors.
(2) Mouser does list the BC182A but says it's not available. 2SC945 is not
listed.
(3) I have found a BC183B transistor but it has a different pin out.

ON Semiconductor stopped making the BC-182 on 30 June 2006. Where did
you purchase the 2SC945 transistors? Any ideas?
 
#107
I'm building a true dual mono Honey Badger using two Antek AS-4445 transfos. Is it OK to wire this board from one of the trafos? From a "pure" dual mono point of view I'd say no, but I can't imagine this would have too much of an effect sonically. If so, would I use a 6v or 12 v relay? The build guide doesn't give a suggestion for a 15v secondary.
 
#109
Transistors for Speaker Protect board

mrsavage,
These are the parts I came up with from Newark/Element14:
For T1-thru-T5:
NTE ELECTRONICS - NTE123AP - BIPOLAR TRANSISTOR, NPN, 40V, TO-92
Newark Part Number: 06M7367 - Manufacturer Part No: NTE123AP


For T6:
NTE ELECTRONICS - NTE287 - BIPOLAR TRANSISTOR, NPN, 300V TO-92
Newark Part Number: 06M7407 Manufacturer Part No: NTE287
 
#113
Using 5v relay for 12v secondary

Hi,

Just got the board yesterday and have been busy shopping around digikey and mouser. But I'm having some problem with choosing the right relay for the board.

I have a 20VA 6.3v-0-6.3v which i intend to use for the board by using them as a single 12.6v secondary. Will 2 of Invalid Request as suggested in the BOM work or should i be looking at (2 x 6v) or (2 x 9v) instead. Don't quite understand the equation behind the choosing of the right relay. And hope someone could kindly explain it to me. Please pardon my ignorance. Thank you.
 
#115
I'm going to use an Antek AN0124 transformer to power the speaker protection board. Is this the correct wiring? I used 12v relays on the board.

Primaries
Red, Black 115v
Red, Black 115v

Secondaries
Blue, Green 24v
Blue, Green 24v

Both reds to the IEC 115v input, both blacks to the IEC 0v input.
Both blues to one side of the Euroblock input connector, both greens to the other. It doesn't matter which side, right?
 
#118
Thermal switch

Hi,

Can I add in the thermal switch at this location as shown on the attached schematic?

Thanks.
 

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