Filter sound of SID6581. witch caps to use?

Parts Questions
1

Assembled a MBSID-module, everything is ok.

But…

I’m not really satisfied with the filters.

I tried different caps…  

* the 470pF (Styroflex) - quite no filter audible…

* replaced it by 1nF (Kerko) - very muffled sound, few and unstable resonance…

* with the original caps of the C64 box: little better, but not a *FILTER*!

Any suggestions witch capacitors are best?

MOS 6581 - [0483]

btw:

…I replaced the 1k resistors with 1k1 5%(couldnt find just 1k’s). got anything to do with my filter problem?

thanks.

./chrom

2

Assembled a MBSID-module, everything is ok.

But…

I’m not really satisfied with the filters.

I tried different caps…  

* the 470pF (Styroflex) - quite no filter audible…

* replaced it by 1nF (Kerko) - very muffled sound, few and unstable resonance…

* with the original caps of the C64 box: little better, but not a *FILTER*!

Any suggestions witch capacitors are best?

MOS 6581 - [0483]

btw:

…I replaced the 1k resistors with 1k1 5%(couldnt find just 1k’s). got anything to do with my filter problem?

thanks.

./chrom

3

I first used the cermamic caps, too. They are really no hit indeed.

Then I used Styroflex ones. I think they´re great. The center frequency is very stable all over the 8 caps!

The 1,1k shouldn´t be a big prob. Although I´m asking myself, why you didnt´find 1ks (they´re so f**** standard pieces, you know ) :slight_smile:

Anyhow: I think the Styroflex are the best ones to use (they´re relatively cheap for such a low tolerance). Perhaps you fried yours with soldering them - they´re *extremely* easy destroyed by heat.

Greetz!

4

I first used the cermamic caps, too. They are really no hit indeed.

Then I used Styroflex ones. I think they´re great. The center frequency is very stable all over the 8 caps!

The 1,1k shouldn´t be a big prob. Although I´m asking myself, why you didnt´find 1ks (they´re so f**** standard pieces, you know ) :slight_smile:

Anyhow: I think the Styroflex are the best ones to use (they´re relatively cheap for such a low tolerance). Perhaps you fried yours with soldering them - they´re *extremely* easy destroyed by heat.

Greetz!

5

thank you for the quick reply.

witch values did you use for the Styroflex caps?

the original 470pF ??

I don’t think I destroyed mine by heat… (but who knows) :-/

regards.

./chrom

6

thank you for the quick reply.

witch values did you use for the Styroflex caps?

the original 470pF ??

I don’t think I destroyed mine by heat… (but who knows) :-/

regards.

./chrom

7

Yes, PayC also uses 470pF so far I remember.

Just a reminder: in main.asm, you have to set “CBM8580_FILTER_FIX” to 0, otherwise your 6581 will be driven like a 8580, the result would be a wrong filter characteristic

And another note: from the three 6581 I own I’ve only one which sounds good. If your focus is on the filters, I would strongly recomment the 8580!

Best Regards, Thorsten.

8

Yes, PayC also uses 470pF so far I remember.

Just a reminder: in main.asm, you have to set “CBM8580_FILTER_FIX” to 0, otherwise your 6581 will be driven like a 8580, the result would be a wrong filter characteristic

And another note: from the three 6581 I own I’ve only one which sounds good. If your focus is on the filters, I would strongly recomment the 8580!

Best Regards, Thorsten.

9

is there any list with differences between the different MOS/SID production cycles over the years?

Or a shematic with the inner part of PIN 1-4 (filter)?

I got another 6581 and two 8580. will try these…

btw:

I came across “Captain Hastings” website http://compiler.kaustic.net/fm/ who built a AOUT-kind-of-module (digital pot) with the Analog Devices AD5204…

What about driving an analog filter module … moog style… :smiley:

… dont shoot, just an idea.

./chrom

10

is there any list with differences between the different MOS/SID production cycles over the years?

Or a shematic with the inner part of PIN 1-4 (filter)?

I got another 6581 and two 8580. will try these…

btw:

I came across “Captain Hastings” website http://compiler.kaustic.net/fm/ who built a AOUT-kind-of-module (digital pot) with the Analog Devices AD5204…

What about driving an analog filter module … moog style… :smiley:

… dont shoot, just an idea.

./chrom

11

Hey…

That effects box on captain hastings sites looks quite commercial - is it?

Would be nice if he could talk about that digital pot MIOS intergration some more - Im sure alot of other mb users wud like to hear too!

Dan

12

Hey…

That effects box on captain hastings sites looks quite commercial - is it?

Would be nice if he could talk about that digital pot MIOS intergration some more - Im sure alot of other mb users wud like to hear too!

Dan

13

Yes. I think this would be a really great idea to enhance MIOS with this digital pot.

Think about:

Quite every analog fx, synth, sequencer circuit could be controlled via midi…

./chrom

14

Yes. I think this would be a really great idea to enhance MIOS with this digital pot.

Think about:

Quite every analog fx, synth, sequencer circuit could be controlled via midi…

./chrom