K4700 protection board and class d

[Banne]

Hi! I have a problem with the 4700 protection and a ta2022 tripath based amp regarding the speaker ground.
I have tested the protection board and it seems all fine but when i connect the 4700 ground to the amp speaker ground only one channel works,
if i skip the protection board the amp works fine. Anyone knows why it behaves like that?

 

[jamesfeline]

Hi

I don't think the K4700 is suitable for class D amps .. only normal analogue amplifiers.

Look at the silicon chip magazine class d amp (classic d) their protection system works in a different way (using opto isolators) I think its to do with the high frequency dc off set that causes the k4700 to trip


all the best

Nick

 

[Banne]

Well the problem isn't that the k4700 is tripping, its not.
It just doesn't let the other channel trough to the speakers/speaker (left speaker) when i connect the ground from k4700 together with speaker ground.
What if i just connect the k4700 ground to chassis gnd instead of amp spk gnd?

 

[theAnonymous1]

Are you using one K4700 per channel? The TA2020 is a full-bridge amplifier. The negative speaker outputs are not referenced to ground and they can not be tied together.

Have a look here...

http://www.velleman.eu/downloads/0/infosheets/infosheet_k4700_mono.pdf

 

[Xerxes75]

I started a thread a while back concerning the Velleman K4700 and my TA2020. To be short the answer was that I needed two K4700 unit because the amp is bridged. I did not had the time to try it but I think the solution is a good one.

theAnonymous1 posted the PDF which led me to this solution...

 

[theAnonymous1]

To be honest, unless you're driving a tweeter without a blocking cap or some other similar situation, a speaker protection circuit for the TA2020 is a bit overkill.

 

[Banne]

Ok
Thank you for all the info guys.
The thing is that the amp is actually driving the tweeters in a couple of diy speakers with a n active crossover so that's why i tried to use this protection board in case of dc failure or some other nasty fault that would destroy my precious tweeters.

 

[Xerxes75]

The protection is indeed overkill, the reason I want to use it is because I have a nasty thump at on/off.