| davidlzimmer |
I recently bulit a chipamp (form Brian Bell) and the thing has absolutely surpassed my expectations of quality and power. The problem is with my soundcard. I get a buzz/hum only when using the PC as a source. No one else notices it, nor does it effect the enjoyment of listening. But, I know it's there and it bugs me. I have made all the standard ground loop test and subsituded sources and cables to come to the conclusion that the noise is generated from the soundcard it's self.
I downloaded a "freebe" analizer and found that with everything muted, the card is generating a 66hz signal at about .18 volts. This is a CHEAP built in soundcard but is the buzz a result of the switching power supply?
Would a quality soundcard help or would I still get the buzz because of the power supply? How bout a USB sound card with it's own separate PSU?
Thank you in advance for sharring in knowledge or experience. |
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| Bazukaz |
Switching power supplies usually work in the range of 30-50kHz.
Normally , PC sound cards don't generate noise.Try plugging in headphones.If the problem persists , buy a new sound card.
I would't go for a USB sound card.Its quality may be questionable , especially if it is cheap. |
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| Eva |
This 66Hz signal is the vertical retrace of your monitor :)
It may be picked up in several ways, though. It may be coming either from your monitor or from your video card, so the first test to perform is to check whether the noise persists with the monitor turned off and/or with the VGA cable unplugged.
Tell us your findings. |
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| Bazukaz |
| One more advice : try mutting all inputs , especially mic. |
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| davidlzimmer |
Eva
Tried with monitor off and with video disco'd. Still got the hum. The video card has a fan on it. Could that be the cause?
Bazukas
Everything is muted.
The hum doesn't start until the sound card is activated.
The hum is not that prominate and wouldn't even bother me so much if the amp wasn't perfectly silent with no input or with a stand alone cd player. But, I built it for my PC.
Thanks for the suggestions. Any more would be greatly appreciated. |
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| neutron7 |
| have you muted the microphone and line inputs as well? as all the other inputs. it might be monitoring an input thats not even copnnected to anything. |
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| davidlzimmer |
Everything is muted.
Only thing pluged into soundcard is the amp. Everything including master volume is muted. The hum starts when the soundcard is activated at boot up with everything muted.
The sound card is a cheap AC97 chip on board the MB. |
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| neutron7 |
not driver problem. the noise happens right on boot. could be 66hz is measured by the software instead of 60 because of the steps of resolution in the software..maybe ther eis no 60 and 66 is the closest one.
it may be "good enough" by the motherboard designer and nothing you can do about it. |
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| EWorkshop1708 |
Well in my experiences with onboard sound, you can hear the mouse making sounds in your speakers when you move it, and you hear different sounds as the computer processes. My PC with a soundblaster 5.1 is fine, but my brother's PC with onboard sound, you can hear little noises when you move the mouse, and my computer did the same thing with onboard sound before I got my soundblaster.
Onboard sound is C R A P and picks up all the noise from signals generated in the motherboard, which gets sent to your amplified speakers. :smash:
Get a soundcard if you want to use your computer for playing with audio. :att'n: |
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| davidlzimmer |
Eworkshop.
Thanks. That's the kind of info I was looking for. I was going that way but wanted to here from someone that had the same experience.
Guess I'll start shoping for a good soundcard! |
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| davidlzimmer |
OK folks. I borrowed a cheap PCI soundcard from a freind who admitted it was a crapy card but, I thought what the heck. I installed it and the hum was almost gone. But now I have a hiss! :)
But it proved to me that sound cards can really make a difference. Actually the hiss is less a problem with this card as it seems to put out about 20% more volume. Turning down the amp to achieve same level almost intirely eliminated any hiss. But, the guy was right. It's a crappy card. Noises and pops when Media Player starts and noise when adgusting volume on TV tuner card.
So.... I'll be looking for a GOOD, but cheap, soundcard for awhile.
Any suggestions?
Thanks to all for helping out! |
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| Bazukaz |
| Good and cheap is inconsistent :) |
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| davidlzimmer |
"Good and cheap is inconsistent "
I know Bazukaz. But I'll look for a bargain! :-) |
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| Bazukaz |
I would just recommend not to go with the cheapest solution.
The main thing that represents quality of sound card is D/A converter and filter. |
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| davidlzimmer |
Bazukaz,
I know very little about soundcards. How bout a Sound Blaster Audigy 2 ZS (Model SB0350)?
I might get one fairly cheap. |
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| Bazukaz |
| Well, i have no experience with the model you have shown.It should be better than integrated solution anyway. |
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| davidlzimmer |
Well. after listening further, (been busy) I had just as much hum on the PCI card as the onboard chip. It was masked by the hiss. I told ya it was a crapy card. :-)
Did a lot of searching and phoning. Heard an example of a guy with an M-Audio card that for an un-related reason bought a better power supply. The result was hum!
A freind suggested and I tried this: Took my Son's MP3 player and hooked it up, with no battery, into the USB port . Used the earphone output to feed the GainClone. Result: NO HUM! Even at 100%!
I'm sold!
I'm going USB. Preferably one with it's own power supply! :-)
Any suggestions?
Warnings? |
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| tiltedhalo |
| Hum is a common problem when interfaceing a sound card to a stereo or amp. You computer is grounded youre PCI card uses a uni-polar configuration, ground is tied to V-/ single ended PS. This cause voltage variances to be applied to the G / V- to the amp inturn Hummmmm, Lift the ground or isolate the input to the amp with a high quality transformer like a Jensen. |
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| davidlzimmer |
The output of the soundcard is un-balanced. Sheild of output cable measures ZERO to puter chassis.
Tried lifting ground on amp, puter and both. still got the hum when the card was activated at boot up.
Thanks |
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| quickshift |
You also find that certain types of cooling fan introduce noise, usually the cheaper ones IME. It's best to go for fanless cooling systems if possible but these can be expensive and a PITB to fit if you aren't used to messing about with pooters.
Some fans can produce RF interference too! I have a fan by Evercool that produces interference from 98FM to 103FM!
I'm using a Vantec stealth case cooling fan and that is both quite and doesn't introduce any noise as far as I can tell.
Oh, re soundcards... I tested the SIS onboard card on my laptop and it rolls off the low end starting at 300Hz and is 30dB down at 30Hz - not good! I was going to test the FR of some speakers in the garden with the laptop but somehow I don't think the results will be accurate ;) |
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| EWorkshop1708 |
Fans do introduce noise, but inside a computer I doubt that fan noise would go out the sound port.
However, I have learned that if you build an amp with fans, that if there's a fan near the input wires (volume control) the amp will pick up noise emmited from the fan :mad: However a solution that works most of the time is to ground the fan grill. |
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| quickshift |
If you have a combination of certain fans and sound cards they can introduce noise which is audible through the speakers or headphones. In the old days when it was still possible to build PCs and make a few quid I knocked up maybe 200+ boxes and some, particularly onboard soundcards and some cheaper brands of card did pick up fan and HDD noise. I haven't found it a problem with sensible soundcards though.
Maybe it's worth shielding fans in amps with copper foil tape and connecting it to the grounded fan grill too? |
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| billdinva |
| try connecting a 10pF capacitor across the inverting input and non-inverting input connections. I am breadboarding a preamp circuit and this worked for me. |
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| neutron7 |
good and fairly cheap = EMU 0404 amazing for the price! (around $100) i got mine for $80 on ebay.
it wont do 4.1 or anything though just good stereo.
some games may not work though. what i did was enable the onboarsd sound and plug the onboard sound output to EMU input and just turn the volume up when i need it. and you can tell how much noisier and crappy the onboaerd output is just by turning those levels up! |
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| davidlzimmer |
neutron7,
Thanks for getting back on topic. Since I determined the noise source was not originating in the card itself and the USB device was totally silent (paused) with volume at 100%, I concluded getting a USB soundcard would be much easyer than experimenting with souncards, powersupplys, fans,ect.
I orded a well known USB soundcard and it should be here in a few days. At the moment I don't even want to mention the model because I know their are plenty of guys pounced and ready to tell me how crappy it is ';)'
I'll let you all know if it solved the problem. |
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