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#1 2009-03-27 14:37:18

PIGSNOOT
Nibbler
From: Belgium
Registered: 2009-02-08
Posts: 44
Website

Equal output levels on S2S, removing R8?

Hey I just Read Flemming's post on getting even output levels on Sid2Sid, I too notice that Sid2 is weaker, and therfore also the feedbackmod on Sid2 is weaker....
Is removing R8 from the S2S board the best solution?
I was thinking of installing a volume pot on SID1 to match the level of SID2..

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#2 2009-03-27 15:10:11

Flemming
The Last Ninja
Registered: 2008-11-27
Posts: 291

Re: Equal output levels on S2S, removing R8?

Hi Snoot....

Removing R8 does help, but it's very VERY little effect you'd gain - my real breakthrough was to stuff my S2S with 2 6582A SIDs. After much experimentation i discovered that it was my 3 8580 SIDs that all had different output level sad this was the head cause of the problem... one of my 8580s had a datecode pretty close to the 6582As and it has exactly the same output level as the later 6582As. My point is that if your SIDs are close regarding date then they should output alike, if not then try to switch the two SIDs to check if the result is the same or the weak channel gets switched... if the weak channel switches because of a SID switch then you can be pretty sure that the difference in output is not because of S2S....

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#3 2009-03-27 15:48:24

PIGSNOOT
Nibbler
From: Belgium
Registered: 2009-02-08
Posts: 44
Website

Re: Equal output levels on S2S, removing R8?

Hey Flemming thanx for your quick post!
I too have 2 6582A's in my S2S,But I noticed Sid2 sounds a little brighter and a lot quieter...
So I guess I'll have to start swapping and searching for the chosen pair:)
Is it really not worth the effort removing R8? if It's just a mini tiny boost I'll leave it in there..
Anyway I like the 6582A's a lot!! Nice filters!

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#4 2009-03-28 00:46:37

Flemming
The Last Ninja
Registered: 2008-11-27
Posts: 291

Re: Equal output levels on S2S, removing R8?

Well, if you're using two identical 6582A SIDs with the same datecode they should sound exactly the same!!! does your mainboard have a resistor at R8? if not, it makes sense to remove it from the S2S too to give the second SID the same environment as the first SID has... at least that's what i think smile i'm curious to what you will find out from swapping the SIDs... i forgot something else that might be of importance; i ripped all parts for the S2S from another C64 mainboard (to make sure for equal sound) did you get the exact parts stated in the S2S manual or were you forced to compromise??

Where did you get your 6582As ????

I can tell you that i love the filters too... i installed new filter caps, 1% polyfilm smile it's really worth the effort!!

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#5 2009-03-28 16:20:42

PIGSNOOT
Nibbler
From: Belgium
Registered: 2009-02-08
Posts: 44
Website

Re: Equal output levels on S2S, removing R8?

I used the exact components from the S2S manual, Works fine on it's own but in comparison to the other Sid it's totally different... But I'll have to check what components are used in My mainboard...
But I'm pretty sure the 6582A's are from the same batch and brand new too, as I had to bend and adjust the Legs to fit the socket, looked they were never fitted before...I got them from Ebay, but pretty expensive as I thought it were the ultra rare 6582's, I payed 10 euros a piece...
Anyway R8 is quite controversial it seems smile
Have to check those caps you're talking about....

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#6 2009-03-28 19:51:50

Flemming
The Last Ninja
Registered: 2008-11-27
Posts: 291

Re: Equal output levels on S2S, removing R8?

PIGSNOOT wrote:

Anyway R8 is quite controversial it seems smile

Not really... it's only me who finds it interesting it seems smile

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#7 2009-10-25 23:43:16

D Vibe
The Last Ninja
From: Sweden
Registered: 2007-02-03
Posts: 254
Website

Re: Equal output levels on S2S, removing R8?

Hmm! So R8 is not really needed? Actually, when I extracted components from my second C64C board, I saw that there were no R8 installed at all! Is this common?

Does this prove that it isn't actually necessary at all?

Edit: I just checked.. The R8 is not installed on my first c64c board either (which is the one I want to install the SID2SID on ...).

Last edited by D Vibe (2009-10-26 12:09:30)

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#8 2009-10-26 19:10:23

D Vibe
The Last Ninja
From: Sweden
Registered: 2007-02-03
Posts: 254
Website

Re: Equal output levels on S2S, removing R8?

Now when I've got everything up kicking, I noticed that the output of the sid chips are equal. At least no audible difference is spotted. (Edit: This is with R8 removed.. I've not tried with it though since removing it was one way of debugging what was wrong smile..)

Although this would be less problem since I feed both of the sid chips to one channel each of the mixer anyhow..

Last edited by D Vibe (2009-10-26 19:11:28)

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#9 2010-01-08 21:16:03

deathstarchris
Nebulus
Registered: 2009-05-17
Posts: 64

Re: Equal output levels on S2S, removing R8?

Removing R8 brought Sid2 up to a more acceptable level.  It still is not 100% as strong as SID1, but it is a huge improvement.
Thanks for recommending this!

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#10 2012-11-08 17:49:54

MadModder
Bomb Jack
Registered: 2012-11-03
Posts: 31

Re: Equal output levels on S2S, removing R8?

Sorry for the bump. I haven't found a rule saying bumping very old threads is not allowed though, so, here goes...

If you look at the C64 schematic here: http://www.zimmers.net/anonftp/pub/cbm/ … -right.gif
and read note 8 to the right under the SID, it says: "R8 resistor should be removed for 8580 SID."
So, removing it if you have two 8580s is the right thing to do. wink

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