Soft Start and Speaker Protection

[Tripmaster]

Hi

I am considering adding the following two circuits to my 2x300VA LM3886 Chipamp


Soft Start

http://diyclub.biz/catalog/product_info.php?products_id=402


Speaker Protection

http://diyclub.biz/catalog/product_info.php?products_id=349

I am building the same amp for my father and would feel happier if I were able to lower the mains inlet fuse value.

Has any one had experience with either of these?

Thanks

Richard

 

[AndrewT]

the upc is often recommended in this Forum.
try a search for comments.
The soft start time period of 5 to 8seconds is going to seriously heat the Power Resistors.
You can either shorten the time delay to 200ms to 300ms
or
swap the Power Resistors to a Power Thermistor

 

[Professor]

Maybe this? I have made this scheme for my amplifier. Power button without fixing.

 

[Ted205]

http://www.esr.co.uk/velleman/k4700.htm

 

[Tripmaster]

http://www.esr.co.uk/velleman/k4700.htm

Hi

Thanks for this link, not a bad price either. Its a shame they don't sell a soft start power module.

Richard

 

[Tripmaster]

the upc is often recommended in this Forum.
try a search for comments.
The soft start time period of 5 to 8seconds is going to seriously heat the Power Resistors.
You can either shorten the time delay to 200ms to 300ms
or
swap the Power Resistors to a Power Thermistor

Hi Andrew

I've asked this company to provide a schematic. Why do you think they set the range between 5-8 seconds?

I'm not sure if you remember, but I purchased a couple of thermistors a while ago (see Power Supply Beginners Guide) I haven't tried these yet.

I've almost completed a pair of Bob Brines FT-1600 wide range speakers and I'd like to try and protect the new addition to the family, cant wait to fire them up!

http://www.diyaudio.com/forums/showthread.php?postid=1891230#post1891230

Thanks

Richard

 

[AndrewT]

5-8s in the mistaken belief that this is an acceptable way to slow charge the smoothing capacitors.

 

[Tripmaster]

5-8s in the mistaken belief that this is an acceptable way to slow charge the smoothing capacitors.

 

[Ted205]

have you thought about making your own softstart ?

maybe a 555timer that switches a relay ?

 

[PJPro]

Take a look at these....

Loudspeaker Protection - P33.

Soft Start - P39.

I haven't actually used these myself but did order both over the weekend.

 

[PJPro]

And akis is looking for guinea pig for his soft start circuit. See here.

 

[Tripmaster]

Hi guys!

I could follow a schematic but my dads been waiting patiently whilst I've been building my speakers, and I'd like to source these items without having to put together a BOM. I also think my could wife needs a bit of TLC after the speaker project!

I have an eye on a PASS amp and would like to make sure the Soft Start is compatible with a wide range of amps.

Thanks

Richard

 

[Puffin]

You could always use these. Vely Rice and lurk relly grood.

An externally hosted image should be here but it was not working when we last tested it.

Converter says £6.20.

Whoops you got there already. Has worked for about a year no probs

 

[Tripmaster]

You could always use these. Vely Rice and lurk relly grood.

Converter says £6.20.

Whoops you got there already. Has worked for about a year no probs

I didn't realise you had bought one of these. Did you get it along with the remote pot?

 

[Puffin]

I bought two. Yes with the remote pre.

 

[richie00boy]

That DIYclub speaker protection doesn't seem to detect faults on the lower half of the output stage. Could be wrong as it's late and I only had a quick look...

 

[Qbert25]

Here is an interesting project for both features in one board.

Soft start Speaker protect - ARESAUDIO electronics & audio engineering

 

[mrWagner]

I'm also thinking of aspeaker protection for my chipamp, because the speakrs pop when I turn off the amp.
So I thought of something like this.
I only need it for the turn off pop, nothing else. I was thinking of a simple switch, but I would forget it sometimes. I would use the main trafo with a 24V relay that can hadle up to 40V and the trafo gives out 30V.
Is this schematic good?
Any suggestions for relays for a simple chip amp (2x20w)? There will be no under load switching.