are these noise levels normal?

Panther30 · Feb 5, 2006, 07:43 AM

This topic has probably also been done to death but I figured I would ask anyways. Since I am in the process of doing this audigy 1 and onboard ALC655 sound combination mod.

I'm using the analog cd in on the audigy for a tv tuner ( you guys had said that the ground was lifted on this so I moved from aux in on the audigy to the cd in and now I have a little less noise. with the aux in I was getting a noise of floor of -54 db. using the cd in I am getting a noise floor of about -66 db (these numbers are compared to the -106 db SNR with the ac97 muted)).

and with the onboard sond going through the cd digital in on the audigy the noise floor is -48 db (with the line in on the motherboard unmuted and the tape deck hooked up and not playing).

I am using normal shielded cd rom cables. except for the tv tuner connection (it is a shielded cable with second ground attached and bound together to the shielded cable in a sheath of electrical tape).

are these noise levels about normal for a strange setup like this?

If you think the noise level is normal I will continute in the direction I am heading with this minor mod. I'll probably add some RCA jack analog inputs next since I have room for three more analog inputs (aux in on the audigy and the aux in and cd in on the motherboard).

---Panther

Maddogg6 · Feb 5, 2006, 08:27 AM

Well - things like - having ALL AC power comming from same plug will help eliminate ground looks (TAPE DECK)

Ive also heard some noisey tape decks.

Another thing to consider is 'gain stages' - for instance..

On the tape deck (some will have adjustable outputs) - if the output is on the low side - and you compensate with higher gain on the sound cards input - will be noisier than if you send a stronger signal from the tape deck to begin with - BUT, if the deck is on the noisey side - it may not make any difference.

So, no it's not normal - not that bad - normally - but there are sooo many factors.

That extra sheilding on that cable may also do more harm than good.

Cable quality for microphone levels - starts becoming MUCH more critical.

I would suggest getting high quality shielded cables and replace what you have.
Make sure the PC and TAPE deck are pluged in same outlet.

And call me in the morning. - sorry, I had to say it.

But really, its gonna take some trial and error on your part to get to a 'normal' level - my A2 with a disconnected AUX (AC97) input is <80db.

Panther30 · Feb 5, 2006, 09:14 AM

I have the ac97 gain set at 18 to accommodate my tv tuner card (on analog cd in) because if I have the tuner hooked through the internal connectors (aux in or cd in on the audigy 1) it is very quiet at low gain levels. If I lower the gain to 0 it gets me another -11 dB putting me at -77 dB with ac97 connected. and I just checked with ac97 muted totally i get -107 dB which is expected.
I'll check out the ground loop tomorrow. I am running the PC and the tape deck off two different power strips but the power strips are plugged together in series. and I am putting a new power supply in my pc this week which will have it's own power strip and I will run more tests at that time.

thanks. I'll keep working on this.

Maddogg6 · Feb 5, 2006, 09:55 AM

yeah - setting the AC97 gain that high ESPECIALLY (its a bit noisy codec to begin with) is just asking for noise.

A preamp between the TV tuner and Aux In (or CD in) may help - as long as its relatively low noise.

My live - wil ALL AC97 sources muted - still registers ~80db - so your potential noise floor is better than this.

AC97 itself UN-MUTED...

A2 - All sources muted = Inf
Live All sources Muted = ~80db of noise

A2 - selected AUX in but not phyically connected = ~80db
Live - selected AUX in but not phyically connected = -inf

Panther30 · Feb 5, 2006, 09:09 PM

okay I took apart my double shielded cable and connected it up with only one ground. the peak metet registered an uneven noise floor between the two sides. one side was about 10 or 15 db higher than the other side. I probably should have left it alone. since I wasn't careful taking it apart I'll have to find or make another cable. in the meantime I have the tv tuner connected through the line in on the audigy and am getting a -66db with ac97 unmuted. of course as you say, it is because I have the recording gain so high.

I'll just get some more cdrom cables for the tvtuner and make sure I can find them with both sides grounded so I don't have to make one. As to your suggestion of a pre amp, I'm not really sure what to use when the tv tuner is connected internally like this.

Maddogg6 · Feb 5, 2006, 09:26 PM

TravelRec has a nice DIY one that would easily fit in your case - but, keeping it in the case will require much care in shielding the pre-amp as well.

simple modification (and 2 for stereo) found here would work nicely.
http://www.hardwareheaven.com/general-discussion/51530-cheap-easy-make-lownoise-guitar-preamp.html

But first...
Is there a jumper setting - or maybe software control to set the TV tuner's audio level?

Maddogg6 · Feb 5, 2006, 09:29 PM

Also - something I just remebered - SOME TV programming audio is crappy - not balanced well - so make sure this isnt a factor also.

Panther30 · Feb 6, 2006, 12:31 AM

there anren't any jumpers on the tv tuner card and I have the software volume in the tv software at maximum.
I just bought a new cdrom cable that might work in place of my now destroyed custom cable. after I get it in place I will put the gain plugin in the kx dsp on the line that the tuner is on and see if that will do anything. I'm really not that great with a soldering iron so any hardware is going to have to be made by someone other than me.

and I do know that some tv prgramming does have crappy audio but it is not a factor. but thanks for mentioning that. I will keep it in mind.

Maddogg6 · Feb 6, 2006, 05:04 AM

Whats the make and model of the TV tuner card? - Maybe I can find out something on it??

Panther30 · Feb 6, 2006, 05:56 AM

www.sabrent.com It is the pci version with the philips chipset. they don't seem to have much info there. model number is SBT-TVFM. also I checked out the updated drivers, they are for the conexant chipset version of the card.

Maddogg6 · Feb 6, 2006, 07:57 AM

a question about that the cable from the TV tuner to your Audigy card -

You are plugging a stereo 3.5mm in the back of the tuner card - routing it into the PC chassis and changing the connector to be able to plug that into the audigy Analog CD in? - correct?

I would, as a test - try connecting it directly into the back of the audigy line in.
See how the levels are with a factory made cable. (Aud out of TV to LINE in on Audigy - both on back of cards - not routing into PC > into CD Analog in for now.

Note: - if you are routing this cable from outside the PC chassis into the PC - MAKE sure it does NOT gor near the tuner card or your video card.

if at all possible - DO NOT use any of the original (and thinner) CD connector wire - try to carefully remove the pins from the connector that plugs into the audigy's onboard (not rear panel, as I understand tour desire) - uncrimp the original wire - and re-crimp & solder with new shielded audio cable. Make sure you note what pin is what (left / right / ground) first. I know its not easy - but it is possible. If you have to - solder to a very short pig-tail at the CD connector end.

In other words - try NOT SPLICING 2 cables together.

Make sure any near by wires are crossing it ONLT perpindicular - and keep it way from the PC power supply and AC power cable. Dont tie wrap this audio cable to any other cables also. Tie wrap to the interior chassis.

Make sure the the AC power outlet is well grounded.

Make sure the audio cable is as short in length as possible (coiled up wires tend to become antenna)

That pretty much wraps up all I can think of to help prevent eccessive noise.

Panther30 · Feb 6, 2006, 08:08 PM

I am using the internal connectors for for the SBT TVFM card and the audigy so I am using the cd connectors and I didn't have to splice. I just had to add the second ground. I have an internal cd cable on order though that should have both ground wires in place.

without that cable I am forced to use the external connection (rear lin out of sbt tvfm to rear line in on the audigy) and there is no di9fference in gain, it is just slightly noisier than the connecting the cards internally with the cd connection (at -60db which is about the same noise as the audigy's internal aux in connector).

there is another issue that I will have to solve by using the internal connectors again but with a better, un-altered cable. (for example on three different tuner cards with a vcr hooked up to them and using the external audio connection between the tuner and the audigy I can hear the vcr's tape mechanism running over the audio cable. this doesn't happen with the internal connection).

thanks for the help maddogg. When I get the new internal cable I will test it and let you know how it goes.

and before I forget: the RCA Jack connections I talked about adding n the first post are ready-made you can find the info at this site, www.frontx.com. Someone might post this link in a different topic here.

Maddogg6 · Feb 6, 2006, 09:00 PM

Quote:

Originally Posted by Panther30

I am using the internal connectors for for the SBT TVFM card and the audigy so I am using the cd connectors and I didn't have to splice. I just had to add the second ground. I have an internal cd cable on order though that should have both ground wires in place.

Ok, the pics I seen ONLY shown 'back of card' connections.

Quote:

there is another issue that I will have to solve by using the internal connectors again but with a better, un-altered cable. (for example on three different tuner cards with a vcr hooked up to them and using the external audio connection between the tuner and the audigy I can hear the vcr's tape mechanism running over the audio cable. this doesn't happen with the internal connection).

It sounds like you house wiring has a bad ground if this is true.. I would maybe look into this also. This can be dangerous if using older power tools - I had an old drill that knocked me on my behind because of a bad ground in a house.

It will aslo DEFINITLY add to noise factors - like you describe.

Again - assuming you take care in how you route audio cables;
SEPARATED FROM VIDEO CABLES
NEVER NEAR POWER CABLES
CROSSING PERPINDICULAR ONLY when crossing other cables.

Good luck...

Maddogg6 · Feb 6, 2006, 09:05 PM

Quote:

Originally Posted by Panther30

and before I forget: the RCA Jack connections I talked about adding n the first post are ready-made you can find the info at this site, www.frontx.com. Someone might post this link in a different topic here.

I'm not seeing any 'NOISE IMMUNITY' data for their products... keep in mind, many people 'iggnorantly' put up with noise - while those 'conveniences' may prove helpful - could also add even more noise - running audio ina nd through a PC chassis is just gonna give more opportunity for noise to leak in.
I presume many people will accept that - as a consequence to the convenience it adds.

Panther30 · Feb 6, 2006, 10:39 PM

understood. I am looking into the ground situation.

As for the frontx stuff, I will hold off on it for a little while because I want to solve the tv tuner situation before doing anything else. When I am ready to add the frontx ports though I will report my results. that way everyone here will know.

Panther30 · Feb 9, 2006, 09:17 PM

okay I have the new power supply and the new cd audio cable in place now. the cd audio cable I had to swap the ground and the left channel on the little white end (these are always reversed on the little white ends probably for compatibility for the older soundcards this connector is actually meant for). and I've plugged the little white connector to the internal audio out on my tv tuner and the black end to the audigy's cd analog in connector. and I am back at -66db again where I guess I should be(without swapping the left channel and the ground on the white connector end I was getting -72db and -48db or something on the right channel). so everything is back to normal.
About the power supply: the powersupply I bout has a power strip built into it so I am going to try plugging the tape deck and maybe one or two other things into that and see if I cant rid myslef of the -48 db idle on the left channel that happens when I unmute the audigy's cd digital in. I will report back soon on that.

Feb 5, 2006, 07:43 AM	#1
Panther30 DriverHeaven Junior Member Join Date: Feb 2004 Posts: 30 Rep Power: 0	are these noise levels normal? This topic has probably also been done to death but I figured I would ask anyways. Since I am in the process of doing this audigy 1 and onboard ALC655 sound combination mod. I'm using the analog cd in on the audigy for a tv tuner ( you guys had said that the ground was lifted on this so I moved from aux in on the audigy to the cd in and now I have a little less noise. with the aux in I was getting a noise of floor of -54 db. using the cd in I am getting a noise floor of about -66 db (these numbers are compared to the -106 db SNR with the ac97 muted)). and with the onboard sond going through the cd digital in on the audigy the noise floor is -48 db (with the line in on the motherboard unmuted and the tape deck hooked up and not playing). I am using normal shielded cd rom cables. except for the tv tuner connection (it is a shielded cable with second ground attached and bound together to the shielded cable in a sheath of electrical tape). are these noise levels about normal for a strange setup like this? If you think the noise level is normal I will continute in the direction I am heading with this minor mod. I'll probably add some RCA jack analog inputs next since I have room for three more analog inputs (aux in on the audigy and the aux in and cd in on the motherboard). ---Panther

Feb 6, 2006, 12:31 AM	Thread Starter #8
Panther30 DriverHeaven Junior Member Join Date: Feb 2004 Posts: 30 Rep Power: 0	there anren't any jumpers on the tv tuner card and I have the software volume in the tv software at maximum. I just bought a new cdrom cable that might work in place of my now destroyed custom cable. after I get it in place I will put the gain plugin in the kx dsp on the line that the tuner is on and see if that will do anything. I'm really not that great with a soldering iron so any hardware is going to have to be made by someone other than me. and I do know that some tv prgramming does have crappy audio but it is not a factor. but thanks for mentioning that. I will keep it in mind. Last edited by Panther30; Feb 6, 2006 at 04:07 AM.

Feb 6, 2006, 07:57 AM	#11
Maddogg6 Tail Razer Join Date: Jun 2005 Location: Bernyurass, AZ - USA Posts: 4,027 Rep Power: 0	a question about that the cable from the TV tuner to your Audigy card - You are plugging a stereo 3.5mm in the back of the tuner card - routing it into the PC chassis and changing the connector to be able to plug that into the audigy Analog CD in? - correct? I would, as a test - try connecting it directly into the back of the audigy line in. See how the levels are with a factory made cable. (Aud out of TV to LINE in on Audigy - both on back of cards - not routing into PC > into CD Analog in for now. Note: - if you are routing this cable from outside the PC chassis into the PC - MAKE sure it does NOT gor near the tuner card or your video card. if at all possible - DO NOT use any of the original (and thinner) CD connector wire - try to carefully remove the pins from the connector that plugs into the audigy's onboard (not rear panel, as I understand tour desire) - uncrimp the original wire - and re-crimp & solder with new shielded audio cable. Make sure you note what pin is what (left / right / ground) first. I know its not easy - but it is possible. If you have to - solder to a very short pig-tail at the CD connector end. In other words - try NOT SPLICING 2 cables together. Make sure any near by wires are crossing it ONLT perpindicular - and keep it way from the PC power supply and AC power cable. Dont tie wrap this audio cable to any other cables also. Tie wrap to the interior chassis. Make sure the the AC power outlet is well grounded. Make sure the audio cable is as short in length as possible (coiled up wires tend to become antenna) That pretty much wraps up all I can think of to help prevent eccessive noise. Last edited by Maddogg6; Feb 6, 2006 at 08:03 AM.

Feb 6, 2006, 08:08 PM	Thread Starter #12
Panther30 DriverHeaven Junior Member Join Date: Feb 2004 Posts: 30 Rep Power: 0	I am using the internal connectors for for the SBT TVFM card and the audigy so I am using the cd connectors and I didn't have to splice. I just had to add the second ground. I have an internal cd cable on order though that should have both ground wires in place. without that cable I am forced to use the external connection (rear lin out of sbt tvfm to rear line in on the audigy) and there is no di9fference in gain, it is just slightly noisier than the connecting the cards internally with the cd connection (at -60db which is about the same noise as the audigy's internal aux in connector). there is another issue that I will have to solve by using the internal connectors again but with a better, un-altered cable. (for example on three different tuner cards with a vcr hooked up to them and using the external audio connection between the tuner and the audigy I can hear the vcr's tape mechanism running over the audio cable. this doesn't happen with the internal connection). thanks for the help maddogg. When I get the new internal cable I will test it and let you know how it goes. and before I forget: the RCA Jack connections I talked about adding n the first post are ready-made you can find the info at this site, www.frontx.com. Someone might post this link in a different topic here. Last edited by Panther30; Feb 6, 2006 at 08:55 PM.

Feb 5, 2006, 08:27 AM	#2
Maddogg6 Tail Razer Join Date: Jun 2005 Location: Bernyurass, AZ - USA Posts: 4,027 Rep Power: 0	Well - things like - having ALL AC power comming from same plug will help eliminate ground looks (TAPE DECK) Ive also heard some noisey tape decks. Another thing to consider is 'gain stages' - for instance.. On the tape deck (some will have adjustable outputs) - if the output is on the low side - and you compensate with higher gain on the sound cards input - will be noisier than if you send a stronger signal from the tape deck to begin with - BUT, if the deck is on the noisey side - it may not make any difference. So, no it's not normal - not that bad - normally - but there are sooo many factors. That extra sheilding on that cable may also do more harm than good. Cable quality for microphone levels - starts becoming MUCH more critical. I would suggest getting high quality shielded cables and replace what you have. Make sure the PC and TAPE deck are pluged in same outlet. And call me in the morning. - sorry, I had to say it. But really, its gonna take some trial and error on your part to get to a 'normal' level - my A2 with a disconnected AUX (AC97) input is <80db.

Feb 5, 2006, 09:14 AM	Thread Starter #3
Panther30 DriverHeaven Junior Member Join Date: Feb 2004 Posts: 30 Rep Power: 0	I have the ac97 gain set at 18 to accommodate my tv tuner card (on analog cd in) because if I have the tuner hooked through the internal connectors (aux in or cd in on the audigy 1) it is very quiet at low gain levels. If I lower the gain to 0 it gets me another -11 dB putting me at -77 dB with ac97 connected. and I just checked with ac97 muted totally i get -107 dB which is expected. I'll check out the ground loop tomorrow. I am running the PC and the tape deck off two different power strips but the power strips are plugged together in series. and I am putting a new power supply in my pc this week which will have it's own power strip and I will run more tests at that time. thanks. I'll keep working on this.

Feb 5, 2006, 09:55 AM	#4
Maddogg6 Tail Razer Join Date: Jun 2005 Location: Bernyurass, AZ - USA Posts: 4,027 Rep Power: 0	yeah - setting the AC97 gain that high ESPECIALLY (its a bit noisy codec to begin with) is just asking for noise. A preamp between the TV tuner and Aux In (or CD in) may help - as long as its relatively low noise. My live - wil ALL AC97 sources muted - still registers ~80db - so your potential noise floor is better than this. AC97 itself UN-MUTED... A2 - All sources muted = Inf Live All sources Muted = ~80db of noise A2 - selected AUX in but not phyically connected = ~80db Live - selected AUX in but not phyically connected = -inf

Feb 5, 2006, 09:09 PM	Thread Starter #5
Panther30 DriverHeaven Junior Member Join Date: Feb 2004 Posts: 30 Rep Power: 0	okay I took apart my double shielded cable and connected it up with only one ground. the peak metet registered an uneven noise floor between the two sides. one side was about 10 or 15 db higher than the other side. I probably should have left it alone. since I wasn't careful taking it apart I'll have to find or make another cable. in the meantime I have the tv tuner connected through the line in on the audigy and am getting a -66db with ac97 unmuted. of course as you say, it is because I have the recording gain so high. I'll just get some more cdrom cables for the tvtuner and make sure I can find them with both sides grounded so I don't have to make one. As to your suggestion of a pre amp, I'm not really sure what to use when the tv tuner is connected internally like this.

Feb 5, 2006, 09:26 PM	#6
Maddogg6 Tail Razer Join Date: Jun 2005 Location: Bernyurass, AZ - USA Posts: 4,027 Rep Power: 0	TravelRec has a nice DIY one that would easily fit in your case - but, keeping it in the case will require much care in shielding the pre-amp as well. simple modification (and 2 for stereo) found here would work nicely. http://www.hardwareheaven.com/general-discussion/51530-cheap-easy-make-lownoise-guitar-preamp.html But first... Is there a jumper setting - or maybe software control to set the TV tuner's audio level?

Feb 5, 2006, 09:29 PM	#7
Maddogg6 Tail Razer Join Date: Jun 2005 Location: Bernyurass, AZ - USA Posts: 4,027 Rep Power: 0	Also - something I just remebered - SOME TV programming audio is crappy - not balanced well - so make sure this isnt a factor also.

Feb 6, 2006, 05:04 AM	#9
Maddogg6 Tail Razer Join Date: Jun 2005 Location: Bernyurass, AZ - USA Posts: 4,027 Rep Power: 0	Whats the make and model of the TV tuner card? - Maybe I can find out something on it??

Feb 6, 2006, 05:56 AM	Thread Starter #10
Panther30 DriverHeaven Junior Member Join Date: Feb 2004 Posts: 30 Rep Power: 0	www.sabrent.com It is the pci version with the philips chipset. they don't seem to have much info there. model number is SBT-TVFM. also I checked out the updated drivers, they are for the conexant chipset version of the card.

Feb 6, 2006, 10:39 PM	Thread Starter #15
Panther30 DriverHeaven Junior Member Join Date: Feb 2004 Posts: 30 Rep Power: 0	understood. I am looking into the ground situation. As for the frontx stuff, I will hold off on it for a little while because I want to solve the tv tuner situation before doing anything else. When I am ready to add the frontx ports though I will report my results. that way everyone here will know.

Feb 9, 2006, 09:17 PM	Thread Starter #16
Panther30 DriverHeaven Junior Member Join Date: Feb 2004 Posts: 30 Rep Power: 0	okay I have the new power supply and the new cd audio cable in place now. the cd audio cable I had to swap the ground and the left channel on the little white end (these are always reversed on the little white ends probably for compatibility for the older soundcards this connector is actually meant for). and I've plugged the little white connector to the internal audio out on my tv tuner and the black end to the audigy's cd analog in connector. and I am back at -66db again where I guess I should be(without swapping the left channel and the ground on the white connector end I was getting -72db and -48db or something on the right channel). so everything is back to normal. About the power supply: the powersupply I bout has a power strip built into it so I am going to try plugging the tape deck and maybe one or two other things into that and see if I cant rid myslef of the -48 db idle on the left channel that happens when I unmute the audigy's cd digital in. I will report back soon on that.