I can't believe that no one has posted on this....

[johnnail]

Hi All,

I posted a few days back about a problem with getting high-pitched feedback noise through a speaker under test. Standard PC running Windows 2000 (pretty much same as XP), Soundblaster Audigy soundcard using Line In and Line Out...Wallin's mic preamp, wand with Panny 60AY capsule, Sonic Impact SuperT amp. JustMLS is the software. Have done a full calibration of the JustMLS sample rates (all of them) and have reverified. Only when the speaker under test is connected does the feedback sound. Like the mic is on all the time or something. WhatTF am I overlooking here? All devices are connected to a computer-grade surge protector/conditioner...so I can't imagine it is AC line noise. Anyone? Ther are some really sharp minds out here, so don't know why no one has posted any ideas on what it might be.

Best regards, John

[Pete Schumacher ®]

> Hi All,

> I posted a few days back about a problem
> with getting high-pitched feedback noise
> through a speaker under test. Standard PC
> running Windows 2000 (pretty much same as
> XP), Soundblaster Audigy soundcard using
> Line In and Line Out...Wallin's mic preamp,
> wand with Panny 60AY capsule, Sonic Impact
> SuperT amp. JustMLS is the software. Have
> done a full calibration of the JustMLS
> sample rates (all of them) and have
> reverified. Only when the speaker under test
> is connected does the feedback sound. Like
> the mic is on all the time or something.
> WhatTF am I overlooking here? All devices
> are connected to a computer-grade surge
> protector/conditioner...so I can't imagine
> it is AC line noise. Anyone? Ther are some
> really sharp minds out here, so don't know
> why no one has posted any ideas on what it
> might be.

> Best regards, John

I know that when I played around with a mic for conversation on-line that I got feedback too if I put the mic near the speaker.

I can't remember exactly which setting it is, but the mic input is feeding the audio amp a signal, and that needs to be disabled.

I wish I could remember better, but it's been a couple of years.

[curt_c]

As is the amp. JustMLS does not, and probably has no ability to disable the soundcard in between tests. In my experience this is normal operation, and you should be able to turn the mic gain down or reposition the mic to eliminate the feedback.

Sorry John, I must have missed your original post.

C

[LouC]

Provided Link: Lou's Site


Every friggin soundcard is different, but I had a similar problem. I think there were two settings I needed to fix. There was some kind of echo or reverb setting that needed to be turned off. SB also had some kind of "WhatUHear" that needs to be disabled

[johnnail]

> Every friggin soundcard is different, but I
> had a similar problem. I think there were
> two settings I needed to fix. There was some
> kind of echo or reverb setting that needed
> to be turned off. SB also had some kind of
> "WhatUHear" that needs to be
> disabled
Hi Lou....I think this popped into my head about the time that you posted.....the "what you hear"...since I don't have the control panel pop-down on the screen, I didn't see that and so "out of sight, out of mind" as they say. So, how do you disable the "what you hear"? Is there a properties somewhere that allows this? Or do I just make sure that "what you hear" is set to anything other than mic? I would think that "what you hear" must be some kind of monitor looping...correct? I have the basic soundblaster drivers installed, but none of the EAX extra crap...so I don't think there is any environment sound effects in play....at least I was smart enough to do that...sheesh...been pulling my hair out on this one.

Thanks,

John

[ericy]

I think I may have the solution to this feedback Issue. Creative has a pdf saying a fix for it, at least with regard to my specific audigy that I use for measurement. It requires manually turning some original sound thing for the input to 0% on some slider somewhere. I am at work right now and don't remember exactly how at the top of my head. Please send me and email and I'll let you know later today or tomorrow.

Eric

Also, I tried using the regular T amp for measurement before never with any success. But that's probably because of the limitations of the basic amp or that I was doing something wrong. All the other amps I use seem to work though.
> Hi All,

> I posted a few days back about a problem
> with getting high-pitched feedback noise
> through a speaker under test. Standard PC
> running Windows 2000 (pretty much same as
> XP), Soundblaster Audigy soundcard using
> Line In and Line Out...Wallin's mic preamp,
> wand with Panny 60AY capsule, Sonic Impact
> SuperT amp. JustMLS is the software. Have
> done a full calibration of the JustMLS
> sample rates (all of them) and have
> reverified. Only when the speaker under test
> is connected does the feedback sound. Like
> the mic is on all the time or something.
> WhatTF am I overlooking here? All devices
> are connected to a computer-grade surge
> protector/conditioner...so I can't imagine
> it is AC line noise. Anyone? Ther are some
> really sharp minds out here, so don't know
> why no one has posted any ideas on what it
> might be.

> Best regards, John

[zobsky]

> Also, I tried using the regular T amp for
> measurement before never with any success.
> But that's probably because of the
> limitations of the basic amp or that I was
> doing something wrong. All the other amps I
> use seem to work though.

Could be because of the floating ground on the T-amp. I've had issues using it for impedance measurements before.

Re. the Creative "what you hear" setting, you should be able to locate it on the sound card RECORDING (not playback) tab.

Try ARTA, .. it works for me with a panasonic capsule/preamp fed into the line-in input.

[ericy]

I already use both speaker workshop and arta with three different amps with success.

> Could be because of the floating ground on
> the T-amp. I've had issues using it for
> impedance measurements before.

> Re. the Creative "what you hear"
> setting, you should be able to locate it on
> the sound card RECORDING (not playback) tab.

> Try ARTA, .. it works for me with a
> panasonic capsule/preamp fed into the
> line-in input.

[DaveBurke]

John,

On your taskbar double click the Creative Volume control, far left will be "what U hear". You'll aslo need to disable any EAX effects, the equalizer, CMSS 3D and make sure you are out of surround sound (all controls and windows at the bottom, and in EAX follow the arrow for more buttons such as CSMM). Set your line in and wave volumes around 80% then set your master volume to start. JustMLS has a resistor jig you should have hooked up but it sounds like already mentioned, too much mic gain or a grounding issue with that T amp. You can set the software for 20dB mic sens as well as have that option on a Wallin pre so check both.

Dave

[DaveBurke]

[dancarroll]

<A HREF="http://en.wikipedia.org/wiki/Methuselah">http://en.wikipedia.org/wiki/Methuselah</A>

[johnastockman]

Just think of the speaker technology and SQ he'll be able to see/hear...if your ears still work when you're that old.

John A.

[Andy_G]

[johnk]

Make sure the everything except Wave/MP3 is muted in the Play Control and make sure you have selected the correct input (Line In) for the record control. Also, it may help if you go to the systems control panel and turn off all system sounds. It sounds to me like you may have the Line In unmuted selected on the Play control.

[johnk]

If the amp is bridged it could be a source of the problem or if there is a ground shorted to the input. If one of my probes touches a ground on the amplifier side of things I get a very loud screech.

[johnnail]

> If the amp is bridged it could be a source
> of the problem or if there is a ground
> shorted to the input. If one of my probes
> touches a ground on the amplifier side of
> things I get a very loud screech.
Thanks, John....it isn't a screech, more like a constant high-pitched whistle sound. The amp, I don't think, has provisions for bridging....though I haven't really looked....but it is hooked up stereo fashion...inputs and speakers, both.
John

[ericy]

I'm not sure if this is the problem, but I found the pdf I was talking about.

<A HREF="http://www.trueaudio.com/downloads/audigy-setup.pdf">http://www.trueaudio.com/downloads/audigy-setup.pdf</A>

I hope it helps

Eric

> Hi All,

> I posted a few days back about a problem
> with getting high-pitched feedback noise
> through a speaker under test. Standard PC
> running Windows 2000 (pretty much same as
> XP), Soundblaster Audigy soundcard using
> Line In and Line Out...Wallin's mic preamp,
> wand with Panny 60AY capsule, Sonic Impact
> SuperT amp. JustMLS is the software. Have
> done a full calibration of the JustMLS
> sample rates (all of them) and have
> reverified. Only when the speaker under test
> is connected does the feedback sound. Like
> the mic is on all the time or something.
> WhatTF am I overlooking here? All devices
> are connected to a computer-grade surge
> protector/conditioner...so I can't imagine
> it is AC line noise. Anyone? Ther are some
> really sharp minds out here, so don't know
> why no one has posted any ideas on what it
> might be.

> Best regards, John

[jonpike]

Provided Link: RMAA site


> I'm not sure if this is the problem, but I
> found the pdf I was talking about.

Yep, beat me to it... It's from the Right Mark Audio Analyzer site, (RMAA) great tool to have for checking your setup as well. They have a few other's for other cards.

The issue is that some cards have a "monitor out" feature, that takes some of the line in and feeds it out to the output. You can hear yourself sing/play when you do so out of your speakers, while recording. This you DON'T want when doing testing, even if it dosen't get to feedback levels, it will wierd out your frequency response and you will have bad data. Many cards have this, some like the CL SB cards had it on as a default.

Just learn if yours has it, and how to disable it.