exxos's Atari, Amiga & retro forum

T'PAU wrote: 23 Dec 2022 12:17 Not quite sure though, if I can put 570 pF (+/- 5% tolerance each) instead of 560 pF in there. Any thoughts? :?:

10K 560pF LPF = 28KHz cut off.
10K 800pF LPF = 20Khz cut off.
10K 1nF LPF = 16KHz cut off.

If I remember rightly a lot of car audio gear and maybe other audio equipment cut off at about 14KHz anyway. I think it was because only children and cats and dogs could hear much above that frequency anyway :lol:

The counterargument is for a higher cut off frequency because the upper harmonics are needed to modulate the lower frequencies correctly.

I can only assume that is what C-lab did. 14KHz being the upper "normal" human hearing frequency and 28KHz is double that for the harmonics. Because the high cut of frequency is allowing more noise into the system as well.

In terms of microphone inputs, I would not really think anyone would care about harmonics anyway. So arguably 1nF may be a better choice in that circuit.

"Designers choice" really on this stuff.

Finished it now and... it works! :yay:

The missing caps on R124 and R131, well, actually I did a triple-sandwich now! Worked quite good and overall height is not bigger than the tantalum caps.

No significant (if any?) changes on output. Couldn't even say, if bassboost is there or not. Maybe I have to try it with some more music or so.
But nevertheless it works. ;)

Input I tried with the line-out of my BD-player. Works pretty good! Recording level can now easily be adjusted by the sampling software, see this quick video.

No fuzzy sounds, no noticeable noise... great success I would say! :dualthumbup:

Who can spot the difference to the picture in my previous post? :D

Good to know that.

:bravo: will have to try the clab mods on my falcon one day :)

T'PAU wrote: 26 Dec 2022 22:53 Finished it now and... it works! :yay:

The missing caps on R124 and R131, well, actually I did a triple-sandwich now! Worked quite good and overall height is not bigger than the tantalum caps.

No significant (if any?) changes on output. Couldn't even say, if bassboost is there or not. Maybe I have to try it with some more music or so.
But nevertheless it works. ;)

Input I tried with the line-out of my BD-player. Works pretty good! Recording level can now easily be adjusted by the sampling software, see this quick video.

No fuzzy sounds, no noticeable noise... great success I would say! :dualthumbup:

Who can spot the difference to the picture in my previous post? :D


Falcon_Audio-Mod_Tantal.jpg

Nice that everything worked! :dualthumbup:

I made a PDF out of these instructions, to make everything a bit more neatly arranged.
I added the missing parts C26, C79, C613, C614. So the actual modification dealing with the SMD parts should be complete now, as shown in Rev. L schematics.
The eleven ceramical caps dealing with filtering and stuff, can also be found in this Rev. L schematic and the "Action required" part of the same "Atari Falcon 030 User Guide" PDF.

My PDF is german but you'll get the important information anyhow. ;)

Nice recap for those who plan to do that mod.

8-)