This is an old topic and inherent to the 2400, but I don't think anyone really resolved it. Here's what we have on mac2400. It's from the Hardware:Reference:Sound section:
Signal Loading as a Noise Source? "My 2400 spends most of the day with the sound port plugged into an Apple Multi Scan 14 Display. The volume (on the PB) is almost all the way up. I've never had any noise or static. There is no volume control on the Monitor. Having a background in electronics, I'm prone to think that the noise problem just might be about loading. The amplifier in the 2400 designed to operate with a certain load (resistance) across its output. Haven't gone looking for specs about the proper load, but the Apple Monitor puts a 10.75 K Ohm load (per channel) on the headphone jack of the 2400. I would suspect that a significantly higher load would result in reduced output, prompting some to turn the volume up on their external speakers, and thus "pulling up" noises that are normally too far down to be heard at the proper load. I would also guess that a significantly smaller load would cause the 2400 headphone amp to "overdrive" and this would probably cause clipping (distortion) in the sounds made by the 2400 - but I don't suspect it would create the random static some folks get. Maybe there's no problem here at all, just mismatched loads - or maybe I was just lucky and got one of the quiet 2400's." (Frank Jaubert 18Aug98) Having specific sound problems? Spencer offers the following... "I don't remember if I saw this on your site but when MacFixit reported that the G3 sound problem also affected the 2400, did they report a fix other than turning your sound input source to anything but build in or line in? I found out that if I turned the volume all the way up and then put in something into the headphone port, there was no problem (i.e., no jerkiness or cutoff with sound)." (Spencer S. Chen, Esq/3Oct98) > ----- Original Message ----- > > From: "John Tree" <[EMAIL PROTECTED]> >> To: "Duo/2400 List" <[EMAIL PROTECTED]> >> Sent: Wednesday, December 26, 2001 5:07 AM >> Subject: [Duo2400] Noise from audio aout on 2400 >> >> >> > I have been using my 2400 as an iTunes player recently, hooking it up to > > my amp. > > > >> > However when no music is playing there is a high pitched hum. It changes >> > note as I do things like mouse down and open folders. >> > >> > I have the G3 320Mhz upgrade and suspect that the higher frequency of >this is causing the noise. > > > >> > Anyone else have this? Would iTunes 2 with the graphic equalizer help? >can I earth or shield anything? > > > >> > Happy Holidays. > > > Ralph Mawyer, Jr. San Antonio, Texas Associate Editor mac2400 ... http://www.sineware.com/mac2400 Your PowerBook 2400 Reference Site ---------- Duo/2400 List, The friendliest place on the Net! A listserv for users and fans of Mac subportables. FAQ at <http://www.themacintoshguy.com/lists/DuoListFAQ.shtml> Be sure to visit Mac2400! <http://www.sineware.com/mac2400> To unsubscribe, E-mail to: <[EMAIL PROTECTED]> To switch to the DIGEST mode, E-mail to <[EMAIL PROTECTED]> Need help from a real person? Try. <[EMAIL PROTECTED]> ---------- Dr. Bott | 10/100 Ethernet for your 2400 is finally here! MPC-100 | <http://www.drbott.com/prod/mpc100.html> RoadTools $30 PodiumPad available at Apple retail stores, $20 Traveler CoolPad at Staples. Both in white for iBooks at <http://roadtools.com> Midwest Mac Parts ][ <http://www.midwestmac.com> After-market parts for Macs. ][ 888-356-1104 ][ MacResQ Specials: LaCie SCSI CDR From $99! PowerBook 3400/200 Only $879! Norton AntiVirus 6 Only $19! We Stock PARTS! <http://www.macresq.com>
