Crackle from 1 voice card and sd card reading problems

Hi,

I have two problems with my lovely ambika:

  1. I get a crackle from one of my voice cards. I have 5 SMR4 and 1 SVF card. The SVF causes the crackles. If I play it alone, I don’t hear the crackles, but if I play it with the other 5 cards together, I hear the clearly the noise. Even if I turn down the volume on the ambika and the gain of my mixer, the crackle is still there. There isn’t any crackle (or just very little), If I play the 5 SMR4 cards alone.
    Here are two examples:
    https://www.dropbox.com/s/w0fthj2jadngdpz/All%206%20voice%20cards.aif
    https://www.dropbox.com/s/rdndp896xywcllk/Without%20SFV%20-%20very%20little%20crackle.aif

2. I ALWAYS need to reinsert the sd card several times after each power-up of the ambika, until the ambika detects the card. What could be the problem? I get the “SD Card I/O error”. I tried serveral sd cards (sdhc and normal) and the problem persists.

Hi

1: I woud check that there is no contact between the offending SVF card and the one below/on top. I had a similar issue and found some components touching solder points of the card on top.

2: Check the soldering quality of the sd card reader. Check for cold soldering on any of the thin contacts of the card reader. Also check that the reader´s interior is clean.

Hope this helps!

Thanks!

  1. The voice card is on the bottom (position 6), so it isn’t any contact with another voice card.

2. I will do it. But strangely even if the sd card gets detected, as soon as I turn the Ambika off and on again, I need to reinsert the card again.

I had the same problem with a sd card, in fact it was apparently not fully compatible, I bought a new one and since then it works perfectly

1. On the mobo, try changing the 10k resistor above the resistor network (and near the TL072) with a 4.7k instead.

2. I have also observed this problem with some SDHC cards, but never with old-school SD cards.

@flocked: It can always be in contact! Either with the one below or the on on top!

Just check that it clears each and every component and/or solder point.

Another thing to do to try and isolate the issue is swap the voicecard around to a different location to see if the crackling disappears or changes in tone or volume. That way you can see if it follows the voicecard or is an issue with location 6

Touch up the solder on the stacking headers for the SVF. I had a similar problem during my build with a voicecard dropping out, and turned out the stacking headers can misbehave if not soldered quite securely.