KILL C64 SID BUZZ - NOW!

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Razmo
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Post by Razmo » 03/07/2007 - 8:46

Well... I've seen a HardSID noisefloor on a 8580 SID at about -80dB... so the chip can surely be rather quiet. the 6581 has the oscillator bug though, that let the osciallators keep "ringing" when the envelope has reached it's end point, and that's impossible to get rid of. ths bug is not present on the 8580.
Regards, Jess D. Skov-Nielsen (Razmo).
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Post by Analog-X64 » 03/07/2007 - 21:17

Tonka wrote: It certainly couldn't hurt, though it's not something I could do with my soldering 'skills'!

I think up to a point though, there will always be a degree of noise due to the fact that the chips are such old technology. I guess the best quality we could expect would be the same sort of noise level that the Hardsid gives out, but whether that's possible with a real C64 and all it's noisy old components (including the video output, which I'm sure is the next main culprit next to the audio in), I'm not sure...

Be interested to listen if you do it though...
I have spare Cables so I will make one or two up and see if there is any difference.


I love having people like Razmo around, just full of nice technical bits of information.
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Post by Kenz » 04/07/2007 - 16:47

Here's a couple of quick test mp3s. It's probably not the best choice of tune as the SID is left "open" at the end so there's still noise even in the clean track (but you can still hear the difference!)

Fist Jingle (Noisy)

Fist Jingly (Solder Blobbed)

Note that these were recorded from an old breadbin C64 which usually has a VERY noisy SID chip. I'm going to record some more tracks now (for a rather spiffing new Binary Zone CD project!) so I'll let ya know how I get on ... :D
Tonka wrote:LOL! I can't help wondering what was happening to you in the original picture to make you pull that face...

*Visualizes Natz in full bondage gear beating Kenz with a rubber chicken*

:lol:
Oh bugger, I thought I'd switched the BZ webcam OFF that night! ;)
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Post by Tonka » 04/07/2007 - 17:37

Kenz wrote:Here's a couple of quick test mp3s. It's probably not the best choice of tune as the SID is left "open" at the end so there's still noise even in the clean track (but you can still hear the difference!);)
ACTUALLY... *Dons geeky glasses and snorts heavily through flared nostrils* What you hear there is not SID noise - it's actually the 6581 ADSR bug that Razmo was talking about earlier in the thread.

The envelope on a 6581 doesn't close properly unless you give it a proper STOP command (layman's talk here)! Until then, it just goes on an infinite loop (in this case, it's the arpeggiated square wave from the first half of the jingle). Another good (bad?) example of this is the Palace Gardens loader intro.

[edit] Ahh, upon reading what you wrote PROPERLY (with both eyes), I see that you already knew that anyway... *Removes geeky glasses and shuts up* :wink:
Note that these were recorded from an old breadbin C64 which usually has a VERY noisy SID chip. I'm going to record some more tracks now (for a rather spiffing new Binary Zone CD project!) so I'll let ya know how I get on ... :D ;)
LOL! Imagine the headaches it would have saved us when doing the first 2 Sound Interface Device CD's if we'd done it this way... :frustration: Poor old John Wells making us blank screen versions of all those SID's AND all the post processing! :lol:
Oh bugger, I thought I'd switched the BZ webcam OFF that night! ;)
No - you left it on. I still have the RSI to prove it... :shock:

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Post by Lagerfeldt » 13/07/2007 - 21:21

And the tech Oscar goes to...

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Post by Razmo » 14/07/2007 - 12:56

And the tech Oscar goes to...
*DRUMROLL* ......... BOB YANNES!!! 8)
Regards, Jess D. Skov-Nielsen (Razmo).
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Post by Razmo » 14/07/2007 - 12:57

...and if you do not know who that is!? :argh: :whip:
Regards, Jess D. Skov-Nielsen (Razmo).
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Re: KILL C64 SID BUZZ - NOW!

Post by Feekzoid » 22/08/2007 - 15:44

On my original first C64, I found that by feeding the audio in as an OUT to my tape-deck/amp, I was getting the isolated "sample" channel - was really cool with Skate or Die, Turbo OutRun etc... sorta weird stereo, and being about 13-14 at the time, I thought it was awesome to hear just the sample-channel on its own (this was long before I started to write music/code on the C64 myself)

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Re: KILL C64 SID BUZZ - NOW!

Post by Tonka » 23/08/2007 - 8:42

Feekzoid wrote:On my original first C64, I found that by feeding the audio in as an OUT to my tape-deck/amp, I was getting the isolated "sample" channel - was really cool with Skate or Die, Turbo OutRun etc... sorta weird stereo, and being about 13-14 at the time, I thought it was awesome to hear just the sample-channel on its own (this was long before I started to write music/code on the C64 myself)
I seem to recall that you can get the same effect (digi's only) by sticking a 6581 chip into a 8580 motherboard (or is it the other way around? Can't remember now)...

Either way, it is SO not recommended as they are completely different voltages, etc and can seriously damage your SID/C64/LIFE! :lol:

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Re: KILL C64 SID BUZZ - NOW!

Post by Starglider » 20/03/2018 - 19:00

Thank you for the info contained in this thread. I signed up just to tell you that I made a video showing how to perform this mod, with some before and after tests.

"Everyone loves the Commodore 64 SID Chip, but it could be a little less noisy & buzzy couldn't it? There is a supposedly simple fix! But can I do it in 5 minutes?!?" https://www.youtube.com/watch?v=G6o-maxlvhE

My video contains no ads. Enjoy!

Starglider aka Perifractic

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Re: KILL C64 SID BUZZ - NOW!

Post by LMan » 21/03/2018 - 22:33

Thanks for the video!

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Re: KILL C64 SID BUZZ - NOW!

Post by Starglider » 21/03/2018 - 23:18

LMan wrote:
<span class="hotdate" style="color:#888;">21/03/2018 - 22:33</span>
Thanks for the video!
My pleasure!

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