PC Engine duo RGB audio hum/buzz

[Keith Courage]

so, I've been trying to figure out a solution to the audio buzz that seems to affect all of these consoles when installing RGB. I've tried all kinds of different grounds to the scart cable, tested many different amp placements, I've tried much higher quality shielded cables, and I've even run separate audio wires from the scart cable directly to the headphone jack and still audio buzz persists.

So does everyone have a hum/buzz in their audio with RGB? Anyone out there that does not?

Wondering if this is this just a byproduct of the RGB amped signal. the same audio buzz exists with 3 different RGB amp styles that I've tested over time as well.

[thesteve]

put a cap scart end across power/ground
should reduce it

[Keith Courage]

Thanks for the advice. Added a cap and it does drop the interference down a little bit but not that much. I suppose it's better than nothing though.

[L-Digital]

This is something I have been trying to get to the bottom of for a long time. I also have this issue with my PCE and SNES. I have found out two things which leads me to believe that this is something to do with the configuration of the Scart format itself. I could be very wrong though.

Experiment 1. I use a framemeister XRGB mini. I have two different input adaptors. Scart > XRGB and JP21 > XRGB

When using a Scart setup I always get the buzzing that increases with bright screens (Konami Logo is a good test). Using the same quality JP21 configuration on the same games with the same system results in what I would estimate to be around 80% reduction in buzz.

Experiment 2
I recently did a rgb mod on a White PCE and deliberately left off the audio L and R so no sound was being channeled via the Scart lead. My plan was to use the interface phono audio out to have a nice separate clean set of audio. 
What I found was even with no audio at all connected via the Scart or the interface, I still got the buzzing sound which increased with brighter images. This astonished me considering audio was not wired up at all.

Very very strange

[thesteve]

Well normally the hum is from a shared ground, when you ran it separately if it still went to the tv then it could still be ground

Sent from my VS920 4G using Tapatalk

[L-Digital]

Keith did you manage to get this sorted? How did you wire things up?

There is a buzz on mine which I am determined to eliminate

[Keith Courage]

recently spoke with Kcsims who got a better quality cable and the hum/buzz is gone. Still wondering what makes this cable better and where to possibly get a better cable to make my own in the future.

if you don't want to try to track down a better cable you can cut down the buzzing some by adding a capacitor in between the positive and negative points in your scart cable as theSteve mentioned.

I just used a 100 uf capacitor which might even be overkill but it seem to bring the buzzing down by about half with the cables I use. positive goes to the 5 volts on the scart end and negative to one of the grounds on the Scart end.

[L-Digital]

Thanks. What rating cap are we talking?

[mickcris]

recently spoke with Kcsims who got a better quality cable and the hum/buzz is gone. Still wondering what makes this cable better and where to possibly get a better cable to make my own in the future.

if you don't want to try to track down a better cable you can cut down the buzzing some by adding a capacitor in between the positive and negative points in your scart cable as theSteve mentioned.

does their cable have individually shielded wires?

i've never really noticed it too bad with the ones i make and have also never had anyone complain about it either.  Don't think there is anything special about the ones I make though.

[Vimtoman]

Normally hum is a ground loop on audio.
If possible you need to find out what the frequency the HUM is.
If you have a scope that would help.

I fi you cant try a 220uH in series with the audio supply with maybe a 10uf  cap down to ground on the either side of the coil.

[Kcsims]

Just wanted to chime in and let everyone what cable I am using and what my setup is.

First off the cable came from:
https://www.retrogamingcables.co.uk/games-consoles/pc-engine/pc-engine-pce-duo-turbografx-16-nec-core-grafx-rgb-scart-video-av-cable

I had my system modded by KeithCourage and it was an original briefcase setup.  I run rgb through a framemeister.

Using the cable from retrogamingcables seemed to eliminate all the humming in the audio.  Not sure what the difference is in the cables are, but I had ordered all my other cables from them so I gave this one a shot too.

Hopefully this can help others out looking for a cable and those looking to modify existing cables.

If anyone has any questions, please let me know, happy to help out however I can.

[mickcris]

well there is nothing special about those cables.  i assumed you guys were talking about the slight buzzing that happens when there is a lot of white on the screen but maybe this is something else.

[Keith Courage]

well there is nothing special about those cables.  i assumed you guys were talking about the slight buzzing that happens when there is a lot of white on the screen but maybe this is something else.

Yes, but it's also noticeable when playing hu card games that have low volume. Meaning you can slightly hear the buzzing coming through even when music is playing because the music is not loud enough to drown it out. You need to listen real hard though. Then you can really hear it when music stops for a moment until it fades away. Especially in the original bomberman.

in all honesty it's not that big of a deal to me personally. I've just had others ask me about it and was wondering if anyone else who had dealt with this had found a solution.

could just flat out be that lots of people are using cheaper cables where the gauge of wire is way too thin causing some kind of audio buzz. I know generic thinly wired composite video cables do this as well so most likely the issue.

[ClodBusted]

Thank you so much for your suggestions. Both the hum as well as jailbars are so annoying when dealing with RGB.

I experienced the same hum/buzz noise when using third party RGB Scart leads for the SNES, Turbo Duo and Genesis. I found out that more often these cables do not have seperate coax shields for every video and audio signal lines. Using modified first party RGB Scart cables (e.g. for Nintendo GameCube or Xbox 360) helped, since they incorporate these coax shields.

Another possible solution would be using RCA leads for the signals, since they're coax. If they need to look neat between console A/V plug and the SCART plug, you could use thin silicone/rubber tube wrapped around the bunch of wires.

I'll also try the cap fix once I build my custom cables.

[thesteve]

as far as the freq of the hum its 60Hz, from the blanking on a white screen
the cap reduces it by half as it doubles the effective grounds in the cable

[deubeul]

I tried the 100uF cap thing and it din't reduce the buzz

@ Keith: Is there a groung better than the other for this? do you link all the grounds together?

[Keith Courage]

Well I can hear a drastic change if I try the cable without the cap and then hold it on there for testing. Buzzing won't go away completely but you should hear a small difference. Make sure to put the positive end on the 5V pin. Not the lower voltage end that is after the resister. I always put it here. 8+ and 4 -

[deubeul]

Thanks for the drawing effort Keith!

I was putting the cap's positive directly on the pin16 of the scart, so AFTER the resistor(I don't use pin8)

I'll do tests tonight.

[deubeul]

No change

I wired the scart the exact same way, exept I have separate L and R sound, even if I assume you too and that you used the SMS/MD shematics for illustrational purposes.

I tried with different cap values and didn't hear any difference

[thesteve]

shorten you cable or use better wire/more ground wires

[deubeul]

I'll try that but the cable is already only 1,5m long ...

[vitaflo]

I had a similar problem and bought a better cable from Retro Console Accessories on eBay.  It reduced the buzz by probably 80%.  The cable has no caps in it so it could probably be reduced further with the methods described above.

The biggest difference between the Retro Console Accessories cable and the original one I had was the shielding and grounding.  Shielding is much better and every ground point on the Scart end has a connection to ground.

One thing I found when experimenting with the noisy cable was that on my set up (briefcase), if I ran audio out from phone output on the CDROM² to the same receiver the IFU was inputting audio to, the hum/buzz was very drastically reduced.  Note, I wasn't using the CDROM for actual audio, but in essence it seems like it was most likely getting rid of a ground loop (it's the only explanation I can think of).

So if you're having issues I would do that as a test, just to see if you can minimize it that way.  It's hokey but it did work.

[csgx1]

Installed a cap in my scart plug and it seems to reduce the hum on my set up.  It's still there but definitely not as loud.  Thanks for the tip.

[gtsamour]

This RGB buzzing is really getting into my nerves.
All of my PCEngine consoles are RGB modded (and we're talking about 7 consoles) using the classic 4 channel transistor amplifier (full cirquit), that I make myself using panasonic capacitors. The picture is just amazing, crystal clear and after the two ceramic caps fix, no jailbars at all.
I make the scart cables too using high quality scart connectors and cable (made in Germany but not with individually shielded wires).

Unless I have made some kind of mistake with the cable wiring (which I doubt after the things I read here) I really don't know what else to try except maybe the cap in the scart connector (which I will).

I bought a cable from www.retrogamingcables.co.uk for the GameCube and desides being only 1.5m (too short) the cable was really high quality and gave excellent picture and clear audio on the GC.
This guy is really trying to "hide" some components he's using to make his cables (at least the GC cable I have experience about). Using a multimeter I came to the conclusion that there has to be resistors inside the GC side of the cable in the part that can't be opened.

Anyway, I have no idea why his PCEngine RGB cable manages to eliminate the buzzing on the PCE consoles (as someone here said) but I wouldn't be surprized if there was a coil inside the male DIN connector.

Since I brought this thread back from the dead, is there any progress made that someone could share about the issue?

[thesteve]

i havent messed with it in awhile
the reason the cap works, is it makes the 5V wire another signal ground
the issue is the wire gauge used being too small in the cable allowing for voltage drop
another way to mask it would be to add an amp to the audio and drop resistors in the cable (same concept as the cables with the 75ohm resistors on video)

[gtsamour]

Well actually the cap didn't do much for me. I do hear a slight buzzing reduction but not even close to 50% at least according to my assessment. Also the cap introduces a slight ringing sound that is hardly audible but I can hear it.

I tried 100, 220, even higher capacity caps to the same end.

I'm not yet convinced that this buzzing is due to cable picking up interference and a high quality shielded cable would eliminate it. Crappy cables yes, they would make it worse.

Anyway, I ordered a triple shielded SCART to SCART cable that i will cut one end and add the DIN8 connector.
It supposedly has the following caracteristics

"Gold-plated connectors with compact plug Metallic foil shielding for protection against electromagnetic noise and interference with magnetic shielding bronzed ferrite of high purity pipes without oxygen OFC.
High precision manufacturing Using 75Ohm double aluminum foil and high density plentaz plus a ferrite is used on the cable at the end that connects to TV, for absolute rejection of EMI and RFI interference.
Robust terminals that withstand mechanical stress.
Specially constructed dielectric by maintaining the cylindrical geometry of the cable by holding the mains always aligned."

If that doesn't eliminate the buzzing, I don't know what will....

[gtsamour]

I discovered something yesterday and thought I should let everyone know....

I have a TG-16 which I have added an amp externally taking the signals from the expansion port. Attached the amp inside the removable case on the back and installed a connector on that removable casing.

The connections on the pins of the expansion port are not soldered but easily removable.

So.... I noticed the following....
If everything is connected and I disconnect the sound (L and R channel) console side, from the pins of the expansion port of the console, the buzzing is still there and even gets louder when disconnected.
Now... if i cut the sound wires (L and R) from within the scart connector this time (console side sound wires still connected), the buzzing is COMPLETELY gone, complete silence.

The test was performed by having loaded a game (Everdrive), pause it (no music or sound) and have the TV on maximum volume.

So that leads me to believe that the buzzing is caused by interference picked up by the sound carrying wires, INSIDE the cable, obviously from the RGB signal carrying wires.
External shielding will NOT solve the problem. Individually shielded wires cable (if there is such a cable I haven't seen one) WILL solve it entirely and that would be the ultimate solution.

Individual shielded pair cable for the sound (running outside the main cable) will solve it as well (but its not pretty).

Good quality cables will definitelly make it better but don't know if its possible to completely make it go away.

[Johnpv]

I get a little bit of an audio buzz/hum on just certain games.  Most the time it's minor and only noticeable if the volume is turned up a bit, except in Ys IV where its just there all the time.  Would it be worth it to get different cables for me?  Keith, you did my RGB mod on a PC Engine Duo, would the cables from the UK site that KCsims posted work on myset up as well?

[thesteve]

just a note, reducing the current in the RGB lines will reduce it notably
it will also make you pic less vivid

[Keith Courage]

I get a little bit of an audio buzz/hum on just certain games.  Most the time it's minor and only noticeable if the volume is turned up a bit, except in Ys IV where its just there all the time.  Would it be worth it to get different cables for me?  Keith, you did my RGB mod on a PC Engine Duo, would the cables from the UK site that KCsims posted work on myset up as well?

Get a cable from mckcris here in the forums. His are good quality like the ones from the UK site. They drop the audio buzz significantly. It won't be gone altogether but definitely a huge improvement over cheaper made cables. https://www.pcengine-fx.com/forums/index.php?topic=18903.0

Also some devices(RGB upscalers) don't suffer from the audio buzz as much as others. So it can be different depending on the setup one has as to if a cheaper cable works okay or not.

[gtsamour]

I tested a cable from www.retrogamingcables.co.uk yesterday. To my surbprise the buzzing is almost non existent.

With the volume at maximum and adventure island game at pause, there is only a slight background noise that doesn't classify as the regular hum/buzz thing of the rgb modded pcengines.

I opened the scart and din parts of the cable.... nothing special there. The cable shielding part goes to the sound ground and the pin ground on the composite ground pin of the scart connector. No other ground connections anywhere else in the scart connector (metal shell, RGB grounds etc).

The cable part doesn't look like the super high quality ones (individually shielded wires).... Its not thick and the wires inside it are not particularly thick either.

Maybe afterall it has to do with being of good quality and it being only 1,5m instead of the longer ones I have made myself and experimented on (3m) using high quality cable.

[edomatic]

Is there anyone here who has found a way of eliminating or reducing the high frequency whine emitted by the huc6280 chip?
I find that whine really annoying , if the volume is up during gameplay (and heck, it's always up! :-) )..then it is clearly noticable
I am using a decent cable ( RGB-Sync to scart) that does not produce to much hum/buzz but this high frequency whining is terrible

[edomatic]

Nobody?

[Keith Courage]

I'm not sure if others here know what sound you're talking about. including myself.

[gtsamour]

I think he's referring to the buzzing sound on RGB modded consoles...

[edomatic]

Well,specifically is was referring to the high frequency interference heard when playing games like bomberman '94, ninja spirit,son son 2 and many others, its like a whine or something
I tried hooking up (soldering) the audio cable seoerate to the video direc from din connector to my audio amp and it still there
I tried with a 31 band equalizer but have to really cut nearly all to get rid of it so that it ruins the audio
I think i read somewhere that its caused by thr huc6280 directly

[Keith Courage]

Well,specifically is was referring to the high frequency interference heard when playing games like bomberman '94, ninja spirit,son son 2 and many others, its like a whine or something
I tried hooking up (soldering) the audio cable seoerate to the video direc from din connector to my audio amp and it still there
I tried with a 31 band equalizer but have to really cut nearly all to get rid of it so that it ruins the audio
I think i read somewhere that its caused by thr huc6280 directly

What scart cable are you using?

[mario64]

Glad to hear I'm not the only one with this issue. I'm going to order a high quality coax cable from retro console accessories but it sounds like even that may not help? Is the consensus now this is a hardware issue?

[Keith Courage]

No, it's most likely the cable. What kind are you currently using?

Mickcris here in the forums sells good quality scart cables that work great. hardly any hum or buzz to be heard using them. https://www.pcengine-fx.com/forums/index.php?topic=18845.0

[mario64]

No, it's most likely the cable. What kind are you currently using?

Mickcris here in the forums sells good quality scart cables that work great. hardly any hum or buzz to be heard using them. https://www.pcengine-fx.com/forums/index.php?topic=18845.0

I've tried both retrogamingcables.uk and retro console accessories. Both have the issue. I'm looking into the shielded coax cable from retro console accessories next

[Gypsy]

I think he's referring to the buzzing sound on RGB modded consoles...

Probably. But PCE audio is noisy anyway, even on untouched systems. This has been my experience with multiple PCE systems anyway.