[Puffin]

Can somebody just confirm that you do not need to remove the op-amps to complete the passive mod ? I removed caps 35 & 36 and substituted with new caps and resistors as per the photo supplied by Tilt in post #5.

 

[Puffin]

This is the picture.

 

[Puffin]

Sorry, here it is.

 

[d-cee]

Quote:

Originally Posted by Puffin /img/forum/go_quote.gif Can somebody just confirm that you do not need to remove the op-amps to complete the passive mod ? I removed caps 35 & 36 and substituted with new caps and resistors as per the photo supplied by Tilt in post #5.

my opamps are still in there (cos i couldn't freaking remove them!) and it's working fine

 

[Puffin]

I carried out the mods as in my previous post above. Because I cannot leave things alone I decided to remove the op-amps. After removing them, switched on - - No Sound !

Looked at the start of this thread and connected the caps up where "Tilt" connected his (the holes by C12 & C13) Music again.

Well that says to me that if you leave the op-amps in, they must still be in the signal path ?

 

[thegeek]

Well yes, the last picture posted above is not a passive output, it's merely a replacement of the coupling caps. It would improve the sound, but imho the passive out is without doubt the best.

 

[VncentValntine]

Hey guys, is there a uF range which I should keep the caps? Would a high quality 1uF cap be a good start? And would it really matter what brand or type of resistor I use that connect to ground? Am I good as long as it's 100 ohm?

 

[Negatron]

Quote:

Originally Posted by VncentValntine /img/forum/go_quote.gif Hey guys, is there a uF range which I should keep the caps? Would a high quality 1uF cap be a good start? And would it really matter what brand or type of resistor I use that connect to ground? Am I good as long as it's 100 ohm?

The value of the output cap determines the low frequency cuttoff. If your DAC is looking into a 10K input, the -3db point will be 15.9Hz. Scale that up to a 20K input and you get an 8Hz f3. Much better. It's personal opinion, but I find smaller caps sound better/more detailed, so if possible change the input Z of the amp it looks into. Always a good excuse for a high quality pot upgrade.

 

[VncentValntine]

Okay I've completed the passive output mod, but now I have a question... When playing music, if there is absolute silence or very little music is played i hear this slight crackling in my right ear that is neither constant or consistent. Bad solder? Unbroken-in cap? Anyone have an idea? Thanks in advance

 

[d-cee]

Quote:

Originally Posted by VncentValntine /img/forum/go_quote.gif Okay I've completed the passive output mod, but now I have a question... When playing music, if there is absolute silence or very little music is played i hear this slight crackling in my right ear that is neither constant or consistent. Bad solder? Unbroken-in cap? Anyone have an idea? Thanks in advance

hmm, yeah check the soldering for cold joint or maybe a short somewhere

 

[VncentValntine]

Okay I re soldered everything I soldered originally, still no dice, I should also add that it noticeably lessens through time

 

[d-cee]

Quote:

Originally Posted by VncentValntine /img/forum/go_quote.gif Okay I re soldered everything I soldered originally, still no dice, I should also add that it noticeably lessens through time

it could be bad caps

try reversing the caps and see if it happens in the left channel

 

[VncentValntine]

well damn! I switched the caps and it's still on the right side! What could I do to narrow this down? What numbers should I be looking for? Is it possible the 100k resistor might have something to do with it?

EDIT: Well I fixed it, the cold solder joint was from the 100k resistor to ground... thanks d-cee

 

[VncentValntine]

BZZZ! wrong, just happened to be coincidental. I realized bad grounding should cause a hum, not this. And this crackling came back after like 30 min of use...