SID salvaging

MIDIbox SID
1

I fried the first 4 SIDs I had over a year ago and it has taken me this long to get over it and continue! I recently salvaged 8 more 6581R1 SIDs from C64s and my bad luck continues.

2 had no sound.

1 made random bleeps.

4 had working oscillators but the filters didn’t work.

1 had a filter that works, but if you changed the filter channels, it would go silent, but then if you changed the filter mode, it would work. Yet setting the filter channels caused osc 2 to be stuck on and wouldn’t shut off until you switched patch, and then be stuck on again if you played a note. Just scrolling through a patch that used a filter would cause osc 2 to stay on after a note.  >:(

I give up! I’m buying some 8580s.

My plan all along was to ultimately make a 4x6581 MB-SID, because I liked the sound samples and started off with two brown C64s really cheap (one is now my CS case). But even the two 6581s in those weren’t perfect, one had a dead osc, the other had a dead filter.

Salvaging 6581s from old C64s is a gamble. Some people are lucky, some people live in countries where most of the second-hand C64s are a good vintage. Buy one for the case and power supply and maybe you’ll get a good 6581 as a bonus. But indiscriminate buying of old C64s might lead to disappointment when the SID is noisy, or its filter and oscillators are dead, or it’s got bugs on the chip, or it’s just dead and silent.

I guess I was a little hooked on the idea of the “analog synth sound” and the impression from TK and others that the 6581 filter was preferrable to the 8580… the idea of having the original SID chips was also appealing. What I didn’t expect was the failure rate.

Something should be added to the MB-SID page highlighting the differences between the 6581 and 8580 (maybe that should be “stressing” rather than “highlighting”), and especially the point that many people end up with dead or broken 6581s (especially 6581R1). There’s the general impression that 6581s have a better filter than the 8580. This should be balanced with the negatives of the low probability of finding one good 6581 and even if you do find a good one, it’s noisy and has bugs. (Maybe TK can add that not even he has four good 6581s!!!)

I hope this doesn’t come across as complaining about the MB-SID project or that I regret starting it myself. The aim here is to allow people starting a MB-SID project should make an informed decision - not to choose 6581 vs. 8580 based soley on the sound when they work perfectly, but also consider the poor chances of salvaging a good 6581.

2

Oh, I forgot to ask: Am I just REALLY UNLUCKY to get so many bad 6581s??? What is the success rate of others salvaging 6581 chips?

3

I collected up a bunch of C64’s and have had them sitting around waiting for me to save up for the boards (now they’re just waiting on me to order from Smash :wink: woohoo!)

I’m beginning to wonder if I should be concerned about the state of the SID’s in those… But if they’re all OK, you can have some of the 6581’s. Damn, I’m REALLY curious to find out if they’re OK now!

4

Hello,

i’m very surprised reading your post, because i did’n heard that much Sidchips where fried, i thought they were verid solid  ???

I did many midibox sid (well i did 3 with different chips, and never had any problem with any)

Then about the filters, i think the 8580 r4 or r5, got much better filters than any 6581 !!!

They are less power consuming and better sounding in general !

Well i must tell you that my fav midibox sid is featuring a 8580r5 sidchip !

I must say that i dont understand how it’s possible that you lost so much chips  :cry:

5

I am embarrassed to admit I fried the first four SIDs when I changed over to use a C64 power supply - I built the power supply circuit to rectify the 9v AC and add it to the 5v DC (giving 14v). The 14v was supposed to be put through a single 12v regulator before feeding it to my 12v rail that feed the four SIDs. I forgot the 12v regulator. :-[  I actually heard them fading away…  :cry:

The other 8 I have plugged into my rebuilt power supply (nice, clean 12v rail) and I didn’t fry these, they were broken before I got to them!

stryd_one: I PMed and emailed you already, don’t you check your mail? I wouldn’t turn down a free 6581 :slight_smile: If you’re that curious, I can loan you a SID module, being friendly neighbours and all… :slight_smile:

6

To ‘smite’ Wilba or not…  ;D

M

7

If anyone wants to get rid of their semi-broken 6581’s, I can take them off your hands (ie, if you’re never going to use them, and would be happy knowing someone would).

Frankly I’m enjoying my half-broken SID synth and am considering building another (plus I’d like another semi-broken SID as a backup in case mine eventually kills itself from the pain)

Cheers,

Tom

8

To ‘smite’ Wilba or not…  ;D

I think I have already been punished for my SID-icide - cursed with only salvaging dead and broken 6581s. No need to smite.

If anyone wants to get rid of their semi-broken 6581’s, I can take them off your hands (ie, if you’re never going to use them, and would be happy knowing someone would).

I was going to do this anyway… eventually… after I’ve got my 8580s installed and have no more need for them. PM me if you want to reserve one - the price is $0 plus postage.

9

stryd_one: I PMed and emailed you already, don’t you check your mail? I wouldn’t turn down a free 6581 :slight_smile: If you’re that curious, I can loan you a SID module, being friendly neighbours and all… :slight_smile:

I didn’t get either :\ weird…

I’ll be ordering a SID module from Smash as soon as he’s open, so it shouldn’t be long now… But I’ll have to catch up sometime and give you some 6581’s :slight_smile: