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CD Audio: Background Buzz

Posted on 1998-05-08
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Last Modified: 2013-11-09
I've been working with computers for many years and this is one of the strangest problems I have ever encountered. I will try to describe it in as much detail as possible because I really do not know what the problem might be.

The problem occurs on a new computer, Pentium II, 233 MHz. When playing CD audio discs, I hear a continuing buzz in the background. Everything else, including the sound card and CDROM-data, works perfectly. For instance I can play wave files (even when they are stored as files on CDROM) without any noise at all. The buzz stops when I pause or stop the CD player, and continues when I play again. All my attempts to isolate it so far have been to no avail. Here's all the evidence I could collect:

The sound is pretty much constant pitch. I even recorded it through my sound card and then ran a frequency analyzer on it, and found that the pitch is relatively fixed at around 1400 Hz, with strong harmonics at multiples of 1400 Hz. Its amplitude seems to vary, but in times it really makes it annoying to listen to music, especially quiet songs.

The sound is sometimes affected by other things going on in the computer. For instance, clicking the mouse usually changes the quality of the sound somehow, although it doesn't alter the pitch substantially. Hard disk activity also seems to affect it occassionally. This lead me to think that there is some sort of intereference between the DAC and some other devices in the computer. To check this, I tried disconnecting different parts of the computer: modem, sound card, hard disk. I also disconnected all the CD cables, except the power supply, and held the CD player in my hand as far away from the computer as the cable would go (about 30 cm), and used the CD play button to check it; but I still kept hearing the buzz! So it doesn't seem to be intereference. Besides, I can't think of anything in the computer with a frequency around 1400 Hz, and the CD is supposed to be shielded from intereference anyway.

The sound can be heard both through the sound card and when connecting earphones directly to the CD's earphone jack. Naturally this lead me to believe that the CD's DAC is defective; however I have since tried using different CDROMs and even different models, all with the same result. (I tried two brand-new BTC 24x CDROMs, and one old Acer x8 CDROM).

My next step was replacing the sound card. I replaced my Zoltrix SBpro-compatible sound card with a new Creative Soundblaster 16 Value PnP card. This did not help either.

I tried connecting the CDROM to a different computer, and it worked perfectly. Is my computer cursed? What is going on?

I am really approaching frustration and despair in this one. I would be very glad if someone had a helpful suggestion. If you want to me try anything else (although I don't know what else I can try), just leave a comment.
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Question by:Slarti
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by:Slarti
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One more thing: I know the problem is not in the computer's environment (e.g. flourescent light bulbs, etc.), because when I brought the computer to my local computer store to see if they can figure out what's wrong, the problem still persisted.
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by:mikecr
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Have you changed the cable from the Cdrom to the sound card? Have you tried a different power supply? A malfunctioning power supply can cause your problem. Do you have a case fan installed and running? Disable it and try again. Is the Cdrom set as master or slave? It could be getting interference from the hard drive if piggy backed. These are just a few suggestions. Try them out and let me know what happens.

Good luck!
Mike
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by:qnet
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disconnect the ide cable and run the cd audio thru the audio output cable only.
should problem still exist replace the audio cable.
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by:jrhelgeson
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Replace your power supply!

You have a defective filter cap.  If your system is new, it should be covered under warranty anyway.
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by:Slarti
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I really hate it when people answer a 200-point question without even reading the whole question. If qnet had read the whole question he would have seen that I already tried this and other similar things. The problem is not the CD audio cable, because I can hear the noise when I connect earphones directly to the CD's earphone jack, without the CD being connected to the sound card at all.

mikecr: As I said in the question, the problem occurs even when the CD is not connected to the sound card at all, so it can't be the CD audio cable. I do not have a case fan. I have a CPU fan but I don't want to disable it (it is a Pentium II, which are known to be $1000 frying pans). The CD is connected as master on the secondary IDE, the HD is on the primary IDE, so no problem there.

mikecr and jrhelgeson: You've both mentioned the power supply. What in the power supply could possibly cause the CD to misbehave like this? Could somebody explain in more detail what is happening?

Thanks for the replies!

-- Slarti

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by:kamall
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Slarti,
Reading your question and the comments, I can only think that the problem is in your 2nd. IDE controller. Try to operate the CD-ROM as a primary slave on the 1st. IDE controller.
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by:jlove1
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Here's what you should do:

I see that you've eliminated EVERYTHING except for the following:

Bad Power supply.
Bad CD-ROM drive.
Grounding Problem.

First, make sure that the CD-ROM drive is grounded-- You could screw a wire directly from the  case of the CD-ROM drive to the case of the Power supply.
If the problems persist, try moving the CD-ROM drive to a different power supply.

Thirdly, if the problem still persists, then it is most definately the CD-ROM drive.

Right now, the only step you can do is to hook it to a different power supply.
If the CD-ROM drive has a "Play" button on the front, you can move it to another computer (don't even mount the drive) and only hook up the power cable.. use the ear phones.. if the problem is gone: Power supply is at fault.
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by:kamall
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jlove1, what is the NEW in your answer???
Did you read the question and the comments?
Also, Slarti said:
"I tried connecting the CDROM to a different computer, and it worked perfectly". Did you read it?
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by:Slarti
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Kamall, have YOU read the question? I also said that I get the same problem when the CD is not connected to either the sound card or the IDE, so there is no chance that the problem originates from connecting to the secondary IDE.

Jlove1, as kamall said, I have already eliminated the bad CDROM drive possibility. I will try hotwiring the CD to the power supply as you suggest but I doubt it will help any. If it does you certainly deserve the points. If it doesn't and I have to replace the power supply than I think it seems more fair to give the points to either mikecr or jrhelgeson, both of which suggested that the power supply might be the problem before you did.

Mikecr and/or jrhelgeson: If either of you is reading the comments here, please leave a comment, so that if I use your answer I will fail jlove1's answer and give you the points. If you do not leave a comment I will assume you're not reading these comments, and I will have to award the points to jlove1.

Again, thanks everyone for your comments, but try to read the entire question before you answer (even if it is a bit long)...

-- Slarti
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by:rmarotta
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Before changing the power supply, ypu might try a different cable from the same supply. Maybe you have one that is unused?  There may be a faulty connectio on the one you're using now.
Regards,
Ralph

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by:mikecr
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Sorry it took so long to get back to you. If you don't have a shielded power supply or you power supply is not functioning properly, i.e, running a few volts up or down, you may not notice a difference in you system now but it will eventually catch up. Because all computers nowadays use switching power supplies, it is not uncommon for a bad supply, or a poorly manufacutered one to give off interference in the power cable. This can show up as static in your speakers, pc rebooting itself for no reason, background noise on the cdrom, or your pc locking up intermitently. I can't guarantee that this is your particular problem but it sounds close. Try another power supply and see if that works first before you award anybody any points.
As for a bad on board ide, you would have noticed that a long time ago because your cdrom would have acted strangely. Another power cable for the supply, possible but I wouldn't count on it.
Test a power supply out of someone elses pc or if you have an old one and let me know if it fixed you problem.

Good luck Slarti!
Mike
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by:Slarti
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Thanks everyone for your replies. I will take the computer to the store (sign, again), and ask them to give me a replacement power supply. I hope this helps. If it does, I will fail jlove1's answer and ask mikecr to post blank answer, which I will accept.

In case anyone is interested, I have already tried connecting the CD to an alternate power socket. It did not help. I also noticed something weird: when I connect or disconnect a different power socket to a non-critical device, while the computer is running and the CD is playing, the buzz stops for about 3-4 seconds and then continues in a lower volume. This certainly seems to suggest that the power supply is causing the problems.

I will get back to you all on the results of replacing the power supply.

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by:jrhelgeson
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I mentioned the power supply first...
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by:mikecr
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That is correct jrhelgeson, and I believe that you should be awarded the points.

Slarti, please make sure the he gets awarded the points if this does fix the problem.

Thanks,
Mike
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by:rmarotta
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??????
Looks like about a three hour difference to me.   :-)
regards

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by:mikecr
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You now what Ralph, I did come in first didn't I? I just noticed that.( With your help!) Thanks Ralph!


Mike
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by:Slarti
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That is what seemed to me too - I think mike deserves the points (assuming this does fix the problem though). Anyway, you guys can make up your mind about it - it will certainly be a few days (maybe next week) before I get a chance to haul the computer to the store.

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by:ICE
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slarti if it's not your power supply, check the grounding of it
somone mentioned you may have to ground the cdrom to the case,
what used to happend with turntables before we had cd's is they used to have a seperate ground connection, this used to cut down the hiss and amp noise dramatically. now theyre commonly earthed through your power point. have a hunt around your home and check if you've got an earth spike, and make sure it's connected, if so
try a different power cord the earth lead may be damaged in it , or worse still your wall socket may not be earthed at all, some bodgey electicians will only wire the active and neutral
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by:Slarti
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Alright everyone, terribly sorry for the delay. I have run back and forth with my computer so much my now that I wish it was a notebook. Most of the delay was caused by sloppy technicians returning the computer without changing anything, saying that I should check for external interference, try other audio CDs, try other speakers - in short anything that won't require them to replace any hardware. Even after demonstrating the problem to them it still took some heavy convincing to get them to replace the power supply.

Anyway, to make a long story short, I got a new power supply, and now the CD works perfectly! As we agreed beforehand, I am failing jlove1's answer, and ask that Mike post a blank answer so that I can grade it.
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mikecr earned 200 total points
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Would you believe that it could have been something so stupid as a power supply? Sorry to put you through all the trouble Slarti. I hope everything works great now.


Good Luck!
Mike
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by:Slarti
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Yes, it is pretty incredible that the power supply turned out to be the one causing all the problem. But, all's well that ends well...

-- Slarti
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