#13309 - poslundc - Wed Dec 10, 2003 11:21 pm
Well, I've written my stereo mixer and it seems to work just fine, but I've noticed that the hardware doesn't quite live up to my expectations.
Particularly, I can hear a somewhat quieter version of the left channel in the right headphone, and vice-versa.
This seems to be entirely a hardware artifact to me. If I only write out the left or right channel then the instruments in those channels disappear (confirmed by looking at the FIFO contents in memory in VBA), but the "bleed" still occurs on the instruments that are playing.
It occurred to me that it might be my crappy headphones, so I tried my brother's. The problem wasn't quite as bad, but it was still there.
Have others encountered this problem? Is there something I could do in software to remedy it? I kind of feel cheated out of the full-panning 8-channel implementation I've done just to find that the stereo doesn't really work.
Dan.
#13537 - Burton Radons - Tue Dec 16, 2003 7:10 am
Stereo bleeding is a useful part of sound perception; I can't remember where I saw it but I've seen it recommended that a channel be placed 25% away from the edge, so 100% in one ear, 25% in the other. When I do that in my mixer I get very noticeably more full-bodied sound, at the expense of doubling the mixer cost. So if it can be achieved for free, I'd consider that a bonus.
#13547 - poslundc - Tue Dec 16, 2003 4:20 pm
OK, well I guess more to the point, am I the only one who has encountered this problem? Is it just my crappy GBA with my crappy headphones, or do others also find that if they play a sound in one side they also get a bit of it in the other side?
Dan.
#13612 - sgeos - Thu Dec 18, 2003 9:17 am
| poslundc wrote: |
OK, well I guess more to the point, am I the only one who has encountered this problem? Is it just my crappy GBA with my crappy headphones, or do others also find that if they play a sound in one side they also get a bit of it in the other side?
Dan. |
I have no way of testing. Do you have a demo of sorts that I can listen to?
-Brendan
#13617 - poslundc - Thu Dec 18, 2003 3:30 pm
OK, I've thrown together a quick ROM that plays a MOD file, but disables the right output entirely.
ie. REG_SNDCNT_L = 0x0A0F
http://www.danposluns.com/sound.zip
Dan.
#14050 - Maddox - Sun Dec 28, 2003 11:20 am
postduck,
I can explain what is happening. The wires in your head phone are close together, right? Well, it is a well-documented fact that an AC signal in a wire induces a current in a near-by wire. Since these wires are too close together and since the GBA audio voltage in somewhere in the neighbor hood of 500-600 volts at 3 amps, it is easy to see how the sounds from the two channels can induce part of their signals onto each other. (BTW, it usually will be the right channel messing up the left, just like right-handed people are stronger and smarter than left-handed redneck-types.)
All you have to do is separate the conductors (w-i-r-e-s) from each other. Many headphones have wires that are side-by-side and can easily be pried apart. Please be careful, though, as this will require a sharp instrument, something you may want your mom to help with, and also, there will be more wire for you to accidently hang yourself by (you seem to be the type).
Merry Christmas,
Maddox
_________________
You probably suck. I hope you're is not a game programmer.
#14054 - poslundc - Sun Dec 28, 2003 4:49 pm
Maddox,
I am aware of what causes the problem. I was just looking to find out if it was something unique to my GBA (if it was due to the plug's connection, which I think it is, as the wires in my headphones are already separated) or if others experienced it as well. I might be willing to do a full-panning mixer if I thought the problem was something only I was experiencing, wheras I just don't think it's worthwhile if it's a problem everyone's GBA suffers from.
| Maddox wrote: |
| All you have to do is separate the conductors (w-i-r-e-s) from each other. Many headphones have wires that are side-by-side and can easily be pried apart. Please be careful, though, as this will require a sharp instrument, something you may want your mom to help with, and also, there will be more wire for you to accidently hang yourself by (you seem to be the type). |
Thanks, you've managed to thwart my suicide attempts until the next time I need to work with electronics. Do me a favour, though, and the next time you feel the need to spell something condescending out to me, don't put all of those hyphens between each letter as I'm not so good with word puzzles.
And here I thought the holidays made me bitter... O_o
Dan.
#14081 - sgeos - Mon Dec 29, 2003 8:23 am
| Maddox wrote: |
| ...it is a well-documented fact that an AC signal in a wire induces a current in a near-by wire. Since these wires are too close together and... |
Come to think of it, I hooked my PC speakers up to my GBA a while back. Why not hook your speakers up to your GBA and see if you still experience the same problem.
-Brendan
#14082 - sgeos - Mon Dec 29, 2003 8:34 am
Here are my results from your test ROM.
GBA Speaker: Low Volume
Headphones A, Right Side: Low Volume
Headphones A, Left Side: Good Volume
Headphones B, Right Side: Good Volume
Headphones B, Left Side: High Volume
PC Speaker, Right Side: Lower Volume
PC Speaker, Left Side: Higher Volume
In other words, both speakers always produced music. The left side was just louder.
-Brendan
#14089 - poslundc - Mon Dec 29, 2003 4:15 pm
OK, so it's not just me, then.
Which is just as well, since I've already recoded my mixer for half-panning and am not planning on changing it back any time soon. :)
Dan.
#14095 - sgeos - Mon Dec 29, 2003 8:04 pm
| poslundc wrote: |
OK, so it's not just me, then.
Which is just as well, since I've already recoded my mixer for half-panning and am not planning on changing it back any time soon. :) |
I was using an original GBA. I'd like to point out that the SP, the GC GBP and any future units may not behave in the same way.
-Brendan