On Tuesday 15 January 2008, Bill Unruh wrote: >On Mon, 14 Jan 2008, Gene Heskett wrote: >> On Monday 14 January 2008, Bill Unruh wrote: >>> On Mon, 14 Jan 2008, Tom Enderlin wrote: >>>> Hello, >>>> I'm having a heck of time trying to figure this out and could really use >>>> some help. >>>> >>>> Problem is that I'm able to use an old (crappy) labtec microphone, but >>>> the two different headset microphones I tried, don't pick up a thing. >>>> I've tried the headsets on another computer so I know the headset mics >>>> are working. >>> >>> Does the labtec have a battery? It sounds like a power issue. An electret >>> mic needs a power source, and it may not be getting the right power. >> >> The electret condenser mics do need a battery, but lets clarify something >> here. They need the battery to run a buffering amplifier which converts >> the many megohms source impedance of the mic capsule down to something >> that can be fed down a cable and into a <=50k ohm load of the typical mic >> input. The > >Agreed. But they need power. A buffering amp with no power does not do >much. > >> capsule itself is permanently charged to a quite high voltage, which is >> where the 'electret' in the name comes from. FYI, its ultimate high >> pressure sound level response, if one were to record a gun going off, is >> generally such that a 44 magnum can be recorded without clipping from a >> point 6" below the muzzle of that formidable arm. The buffering amplifier >> in it would probably clip at a much lower spl. The original condenser mic >> I've some experience with, an Altec M-21, could do that to a civil war >> cannon, and did so for the Mercury recording of the Overture of 1812 50 >> years ago, but needed a plate voltage of 150 volts applied to the 6AT6 >> tube used as that buffering cathode follower to do that. Which was the >> std voltage used also for the condenser bias since this predates the >> electret technology by about 35 years. More recent, and several hundred >> dollar cheaper electrets, of the teeny AAA cell battery types, will limit >> the clip point to about a volt of output, which I can easily do with my >> voice. >> >> I also have 2 varieties of headsets that I use with skype and friends, >> that do not have any batteries in them and work just fine. In fact I've >> not seen any > >The Mic input on soundcards have power -- try putting a volt meter across >the gound-> live inputs of the mic input to the soundcard. Unlike the Line >in. Ie, they do not need batteries but they do need power. Now if his mono >had a battery it would not need the power from the soundcard, while if his >other mic did not, it would. >Note that it is his mono plug that works, and his stereo that does not. > >> for sale at Staples, circuit city, wallies, et all, that do have >> batteries, so I'm inclined to think its more likely the OP has a jack >> incompatibility such as can happen when plugging a mono circuit plug into >> a stereo jack and one side of the stereo is shorted out by the mono plugs >> contacts not being in the right place on the barrel. That has been the >> case for me a few times. > >Except it is the stereo plug that does not work and the mono that does. I've not seen a headset boom that was stereo, so I read it the other way around and the OP didn't actually state. I have seen headsets that use a stereo plug though. The ring is some cases is the earpiece! Intended for cellphone use I think. You may be right Bill, but that's how I read it. >>>> Hardware: ALC888 on a Shuttle XPC SN68SG2 using the snd-hda-intel >>>> driver with a model=6stack-dig option. >>>> All the other functions on the soundcard that I've tried are working. >>>> >>>> Software: Debian unstable. Tried both the debian packages (Alsa >>>> 1.0.15) and compiling Alsa 1.0.15 from source. >>>> >>>> Tried moving all the mic and mic boost sliders in alsamixer to their max >>>> settings and it still didn't record any audio, just background static. >>>> >>>> Also plugged the mic into the line-in jack on the back of the computer >>>> and same thing: the old labtec mic worked but the newer headset mics >>>> didn't >>>> >>>> I'm totally at a loss here. The old microphone has a plain mono plug >>>> and the headset has a stereo plug but I didn't think that should matter >>>> since it's just a mono signal anyways. This is a new computer so it >>>> should definitely be able to accept an off the shelf headset. >> >> But if it is the sort that parallels the stereo right at the input jack, >> the mono plugs longer sleeve with cause the ring contact of the >> tip,ring,sleeve type jack to short the signal out. Gently pull the plug >> out slowly, testing as you do, and I'd bet a bottle of suds you'll get >> something at some point. >> >>> Depends on the soundcard, but the mic in input on some have the power on >>> one of the stereo pins and the input on the other. If your mic is not >>> wired up for that, it will have trouble. >>> >>>> Looked around and found various asoundrc files with input >>>> configurations, but nothing has worked so far. Tried all the different >>>> snd-hda-intel module options with no success. >>> >>> If the labtec produces sounds into the mic in input, then it is not a >>> soundcard/alsa issue, it would seem to me. >>> >>>> Any ideas at all would be appreciated. >>>> Thanks. >>>> Tom > >------------------------------------------------------------------------- >Check out the new SourceForge.net Marketplace. >It's the best place to buy or sell services for >just about anything Open Source. >http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace >_______________________________________________ >Alsa-user mailing list >Alsa-user@xxxxxxxxxxxxxxxxxxxxx >https://lists.sourceforge.net/lists/listinfo/alsa-user -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) The major difference between bonds and bond traders is that the bonds will eventually mature. ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
