PROPHET64 & MSSIAH Userforum

What's the closest you can get to 500K? You should be fine as long as it's close.

When using the feedback mod, you do not want Audio In to be grounded directly like you have now. You won't need it.

Thanks guys.. i'm very insecure towards this mod, so excuse me for asking too much also it will be my first mod involving a potmeter

I got a 500k pot from a guitar-store (damn expensive!!) i was thinking if this looks correct???

dschohennes wrote:

no, don't do any connection to the ground! thats what you dont wanna do. EITHER you ground the input (noise reduction) OR you connect it to the output via pots (feedback).

If you want to do it for both SIDs you could use a stereo potentiometer or 2 mono potentiometers - you would have to connect each SID's ouput to it's input.

So the middle leg on the pot is to be ignored?? and if i swap the in and out on my photo i have the correct solution ??

InactiveX wrote:

No, he was talking about grounding the audio in, not about legs on the pot!

Oh, i see... so i will forget the grounding, but still.. what to do with those 3 legs   i tried googling for a pot-related wiki thing, but i only found one in dutch, hehe..

i agree

Hmmm, i guess i'll never learn this nevertheless the pot works on the TV using the RF-out.. i can hear (primarily the last 1/3) of the pot is adding to the resonance of the sound. but in my audio out jack the sound is the same.. should i connect the output jack to the pot??

What i did..
Pot
- Leg1 connected to Leg2 and Audio out on mainboard
- Leg2 connected to Leg1
- Leg3 connected to Audio in on mainboard

Audio out jack (it's a stereo TRS jack)
- T connected to R
- R connected to T and Audio out on the mainboard
- S connected to ground

Another weird thing; when i plug in headphones in the Audio out jack, the volume of the sound from the TV is decreasing..

While the pot only works 1/3 of the way i suspect it to be logarithmic.. wolud a linear pot stretch the range so finer adjustment is easier?? If not, i'm thinking about just using a switch for feedback instead. In that case, Would a 500K resistor be a substitute for the pot?

Last edited by Flemming (2008-12-10 00:35:05)

dschohennes wrote:

as i said, i also have only 1/3 of the way ... and my pot is linear!

yeah, i see... but do you have an idea how to fix my problem please ??

Can't see anything wrong with what you've described, but it's late here and I'm tired!

Also I should point out I haven't done the feedback mod myself, so I'm only theorising.

Keep trying.

Last edited by InactiveX (2008-12-10 01:55:26)

dschohennes wrote:

hm... you GET sound our of your trs jack, but you won't hear a difference concering feedback there? Don't know why this could happen, sorry... but there sure will be people 'round here to help you!

And sorry, i didn't have much time when posting the last entry, so i could not think about your problem

Well, i hope you get some time later i saw you did the feedback mod yourself so it must be very easy for you to point out my boo-boo, or just explain to me how you hooked it up yourself and i will find my boo-boo myself according to your explanation

Is it normal that the volume of the RF-output decreases if you connect something to the Audio out jack ?? It does here, even when no pot is involved

My feedback pot only works with RF-out, but when i connect my earphones to Audio out jack the feedback dissapears - no feedback in either RF-output or audio jack like the load is shared between the two outputs.. If i turn down the pot i can hear the ground-noise

Last edited by Flemming (2008-12-10 14:38:25)

sorry for digging up old topics but I wonder if Flemming found his solution and got his feedback mod to work with his jack outs. it's a pity this topic ended unanswered.

I also did not understand AlphA's feedback schematic and followed the answers here.
I want to try this:

Pot
- Leg1 connected to Leg2 and Audio out on mainboard
- Leg2 connected to Leg1
- Leg3 connected to Audio in on mainboard

but which 'Leg' do I need to connect to my mono jacks (jack for audio OUT and audio IN)?
doesn't Leg 2 have to go to my output jack instead of connecting Leg 1 and Leg 2 together?

hope someone can help me out.

alright, i got the feedback mod working at one of my SID chips.
but when i try to do the same with the other one (SID #2) it decreases the volume instead of distorting it.

what did i do wrong?

please respond. i really want to have this working. thanks!

hi I'm also working on the feedback mod
I've built mine in a breakout box with audio in/out and video out.

seems to work ok but I can't work out how to activate MIX in in mssiah?