Audio "buzz" in the background that increases on white or particularly clear picture

yami

Mr. Big's Thug
Joined
Oct 15, 2004
Posts
208
Audio "buzz" in the background that increases on white or particularly clear picture

Hi,
I noticed that with my CMVS on a Sony Trinitron CRT there is an audio "buzz" in the background, which increases when the picture is particularly clear (eg. Neogeo at boot logo on a white background).
I do not know if it's a problem of CMVS, or TV.
May depend on what?

Thanks
 

xsq

Thou Shalt Not, Question Rot.,
Joined
Jan 17, 2013
Posts
7,415
I'm guessing you're using the speakers integrated in your TV, right? If so, try getting the sound directly from your CMVS with earphones or separate speakers. That will help you figure it out.

Even though it's unlikely: did you check the wires you're using?

My best guess would be that your TV is getting old... do you have the same issues watching shows or using another console? Could still also be the caps on your Neo...
 
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yami

Mr. Big's Thug
Joined
Oct 15, 2004
Posts
208
Hi,
it is right, I'm using the TV speakers. Unfortunately I did not consolize the MV-1B so I can't use earphones or separate speakers (maybe with a special SCART RGB cable with RCA out?).

I will test this evening with a PS2.

Thank you
 

Xian Xi

JammaNationX,
Joined
Dec 1, 2005
Posts
27,679
If you get buzzing when using a stereo receiver and the TV then it is something with the CMVS.
 

bustedstr8

Trollbox Trade Federation,
Joined
Oct 15, 2007
Posts
943
Sounds like crosstalk may be coming from the flyback. Flybacks will often hum with relation to power being used, so a black screen will be fairly quiet and a pure white screen can be pretty loud.
 

kuze

Maxima's Barber
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Apr 20, 2013
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Yeah it sounds like there could be a grounding problem
 

channelmaniac

Mr Neo Fix-it
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If you have a white screen on a TV and a buzz coming through the speakers on the TV, it's not abnormal. It's an overmodulated signal or a signal that is too high in voltage.
 

yami

Mr. Big's Thug
Joined
Oct 15, 2004
Posts
208
Hi and thank you for all your answers.
I've tested the same TV with a PS2 via SCART RGB cable, same SCART input, ad I do NOT hear the buzz.

So it happens only with the CMVS... it would be great if the audio of the CMVS could have more "gain"... the is an easy fix? (I am NOT the author of the CMVS).
 

xsq

Thou Shalt Not, Question Rot.,
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Hm, I'm just guessing here, but you might want to look into putting some 75-100 ohm resistors or 250 ohm potentiometers in the RGB lines of the cable you're using to connect the CMVS to your TV, that might "dim" the picture a bit so your TV doesn't buzz anymore.
 

yami

Mr. Big's Thug
Joined
Oct 15, 2004
Posts
208
Hm, I'm just guessing here, but you might want to look into putting some 75-100 ohm resistors or 250 ohm potentiometers in the RGB lines of the cable you're using to connect the CMVS to your TV, that might "dim" the picture a bit so your TV doesn't buzz anymore.

Hi, I spoke with the author of consolization.

He said that I can't control volume on the board 'cause of 5V mod. I think he is referring to an attenuation circuit?
So audio is lower than normal.

It is correct? Will I solve anyway with resistors on RGB cable or a better shielded RGB cable?

Thank you.
 

Xian Xi

JammaNationX,
Joined
Dec 1, 2005
Posts
27,679
Hi, I spoke with the author of consolization.

He said that I can't control volume on the board 'cause of 5V mod. I think he is referring to an attenuation circuit?
So audio is lower than normal.

It is correct? Will I solve anyway with resistors on RGB cable or a better shielded RGB cable?

Thank you.

Not audio, video.
 

xsq

Thou Shalt Not, Question Rot.,
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Jan 17, 2013
Posts
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Will I solve anyway with resistors on RGB cable or a better shielded RGB cable?
Shielding won't change anything, you need resistors in the cable. Also, you don't need to worry about the audio level, that is not what is causing your issues.
Please note that dimming the RGB signal down is not a fix I can guarantee you to make the buzz go away completely, but it is worth a try and will most likely at least attenuate it.
 

VaNDAL_UK

Neo Bubble Buster
Joined
Apr 11, 2007
Posts
45
I have this on a 2 slot (MV2F) I get the buzz (quite loud). Using a LED TV through RGB scart, stero soldered to the headphones as per Jamma Nations tutorial on the 2 slot.

Funny thing is that if the headphones slider is all the way off the buzzing still happens. It does seem like a grounding issue!?

Even though the buzzing is there it does change tone as the screen changes contrast.

However when the normal game sound is on the buz isn't noticable.

Using head phones there is no buzz.

I may solder to the headphones socket as a test and report back!
 

VaNDAL_UK

Neo Bubble Buster
Joined
Apr 11, 2007
Posts
45
Hi,
I noticed that with my CMVS on a Sony Trinitron CRT there is an audio "buzz" in the background, which increases when the picture is particularly clear (eg. Neogeo at boot logo on a white background).
I do not know if it's a problem of CMVS, or TV.
May depend on what?

Thanks

Sorry this isn't a thread hijack to help me it's more as a log of my issue as it's a bit similar and to shoot out ideas!
 

ikaruga007

Timid Neo Newbie
Joined
Jul 9, 2012
Posts
6
I have no experience with CMVS but this is a common problem on SNES. It's definitely a cable issue. I've got 4 RGB SCART cables for SNES and out of those, it's only the official GC (PAL) cable that doesn't have this issue. All cheap 3rd party cables I've tested have the buzzing on bright screens even if built according to spec. Provided your CMVS outputs correct voltage levels on the RGB-lines, this is usually down to a badly shielded cable in my experience.
 

Xian Xi

JammaNationX,
Joined
Dec 1, 2005
Posts
27,679
I have this on a 2 slot (MV2F) I get the buzz (quite loud). Using a LED TV through RGB scart, stero soldered to the headphones as per Jamma Nations tutorial on the 2 slot.

Funny thing is that if the headphones slider is all the way off the buzzing still happens. It does seem like a grounding issue!?

Even though the buzzing is there it does change tone as the screen changes contrast.

However when the normal game sound is on the buz isn't noticable.

Using head phones there is no buzz.

I may solder to the headphones socket as a test and report back!

If you took it from the slider then the audio source will be kinda low. Taking it from the headphone jack will be a better level.
 

xsq

Thou Shalt Not, Question Rot.,
Joined
Jan 17, 2013
Posts
7,415
It's definitely a cable issue. I've got 4 RGB SCART cables for SNES and out of those, it's only the official GC (PAL) cable that doesn't have this issue. All cheap 3rd party cables I've tested have the buzzing on bright screens even if built according to spec.
There are slight differences between Gamecube and SNES RGB cables as well as SNES PAL and NTSC RGB cables. If you haven't already you might want to open up the ones you have and see if they are build correctly for the console you're using them with - here's some more info on that topic.
 
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ikaruga007

Timid Neo Newbie
Joined
Jul 9, 2012
Posts
6
Yup, I know :) The PAL GC cable is the same as an NTSC SNES cable, which is what I'm using. I've opened one of the 3rd party cables and it looked correct (for NTSC SNES), but had the buzz on bright screens.
 

xsq

Thou Shalt Not, Question Rot.,
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Alright then, I may have been wrong in posting that "shielding won't change anything". @OP:You could try a better shielded cable!! ;)
 

VaNDAL_UK

Neo Bubble Buster
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Apr 11, 2007
Posts
45
Yeah I took it from the Jack and it better. Once the game sound kicks in it isn't noticable.
 

dougal

Twinkle Star Sprite
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Oct 21, 2013
Posts
33
I have the same problem exactly with my MV1-FZ + Supergun MAK Strike. Buzzing sound especially on the Neo Geo startup logo.

It's not the TV as my SNES and Megadrive both work fine via RGB. Its not the SCART cable either as I tried two, one of them brand new and gold plated.

The volume on the MVS is cranked up to full. There is no headphone jack on my model.

Things i have not tried yet: Another TV + taking audio directly from the phonos on the Supergun.
 

GadgetUK

Robert Garcia's Butler
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Sep 27, 2013
Posts
1,280
I have the same problem exactly with my MV1-FZ + Supergun MAK Strike. Buzzing sound especially on the Neo Geo startup logo.

It's not the TV as my SNES and Megadrive both work fine via RGB. Its not the SCART cable either as I tried two, one of them brand new and gold plated.

The volume on the MVS is cranked up to full. There is no headphone jack on my model.

Things i have not tried yet: Another TV + taking audio directly from the phonos on the Supergun.

How are you taking the sound to the TV? I've got the same board as you and the same problem, and in my case I am pretty sure its because the video cables aren't shielded so when you get a white picture etc where the signal is strong you get interferance on the nearby sound wires. At some point I need to get some cable with some shielded pairs in it or something, then I can either shield the RGB and sync, or the audio.
 

UDb

Timid Neo Newbie
Joined
May 8, 2021
Posts
8
Audio "buzz" in the background that increases on white or particularly clear picture

Hi,
I noticed that with my CMVS on a Sony Trinitron CRT there is an audio "buzz" in the background, which increases when the picture is particularly clear (eg. Neogeo at boot logo on a white background).
I do not know if it's a problem of CMVS, or TV.
May depend on what?

Thanks

I know it's a really old post but, as my just bought Mv1FZS has exactly the same issue,
Does anybody found a solution in the end ?
Thanks.
 

ChuChu Flamingo

We have purposely, trained him wrong, ...as a joke
Joined
Nov 23, 2010
Posts
2,298
If this is a supergun/cmvs chances are it is your poorly shielded scart cable video coupling and causing interference on your audio lines. White screens will show this the worse.
 
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