Input protection?

[Fizzy]

How vital is it to build a input protection (like this one http://www.41hz.com/forums/content.p...ier-Protection) on the amp11?

In the article it says something about 2uF MKT/MKP caps, all I have home is this bad boys ,https://www.elfa.se/elfa3~se_sv/elfa...8-33&toc=18856, 2,2uF 400 V (?!) MKP 4 caps, will this do, or will they just make things bad? What other caps should I get wich is better?

[krilli]

Those caps will be fine. (Very good in fact!)

Note that you can add the diodes after the input caps, as per this: http://www.41hz.com/forums/showthrea...diode-clamping ...

As to the importance of protection: After blowing up the Tripath chip in an Amp15 I will be adding input protection diodes to my amps

[Fizzy]

Thx for your answear! So you mean I can add them directly after the input caps on the amp11 where its left a lot holes for bigger cap? Will it be bad then to exchange the small cap on 3.3u for the one mentioned above if it fits?

[krilli]

Sorry, missed your reply!

Yeah, I think that's possible. Given that it works in the tiny Amp32, it should be possible on the Amp11 too somehow: http://www.41hz.com/forums/showthrea...diode-clamping

[Fizzy]

Yea their is extra holes for a bigger input cap so I could use them I guess. But then is it better to exchange the regular (small electrolytic 3.3u i think) cap against the bigger once I have and just add the diodes. Or should I keep the regular one and dont mind the other caps I have?

Or is it best to build all of board?

[krilli]

I actually don't know what's best. I'll speculate:

I think building on-board is probably more compact overall, and it's been indicated that it could be lower noise (less wire to pick it up).

The drawback would be that it may be harder to make it as mechanically stable and secure, compared to building on a board. Depends on how the amp board is laid out I guess ...

[krilli]

(And regarding the caps - I don't know if there's a difference ... I've tried both and I haven't been able to hear an obvious difference, but then again I've never compared side-by-side so I can't say

If you try, I'd be interested in the results.

[Fizzy]

Yea it should be space for the diodes atleast if i use the small input cap and then solder it to the agnd and 5 v pin.

How will I see If it works /not work if i try??

I will ofc replay when I test this (earliest next weekend)

[V-bro]

Note that you can add the diodes after the input caps

No, you MUST place them after the input caps because there needs to be the 2,5V biasing. If not there will only be positive signal and all negative signal will be clipped to zero!

And those caps are fine, but not perfect. Actually I like polyester caps best since they are much smaller and suffer less from high frequent feedback effects, which will result in lower noise level. Also they can be 1uF unless you want to use them for a subwoofer to go extremely low. 1uF will make on/off pops virtually zero...

[krilli]

No, you MUST place them after the input caps because there needs to be the 2,5V biasing. If not there will only be positive signal and all negative signal will be clipped to zero!

Oh! Yes, thanks for clarifying. I meant to say that you can add the diodes on-board after the stock input cap locations ... If you mount the diodes off-board, you must mount the input caps even further off-board

Thanks V-Bro!