Interference from cassette player
in [UK Mac]
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From: Martin S Taylor on 17 May 2010 12:10 Jaimie Vandenbergh wrote > plus any 3G data devices you > might have lurking around (GPS, iPads, 3G data USB things, whatever). I should be so lucky. I'll give it a while and see what happens. MST
From: Jaimie Vandenbergh on 17 May 2010 12:14 On Mon, 17 May 2010 17:10:08 +0100, Martin S Taylor <mst(a)hRyEpMnOoVtEiTsHm.cIo.uSk> wrote: >Jaimie Vandenbergh wrote >> plus any 3G data devices you >> might have lurking around (GPS, iPads, 3G data USB things, whatever). > >I should be so lucky. > >I'll give it a while and see what happens. T i m ' s suggestion of a shielded 3.5mm stereo cable may be all that's needed. Or, to Peter's point, the coil is sensitive but also pretty directional: You may be able to either turn the tape player around, or stand it on it's side, to avoid the interference. Funny how these things happen. I'd never have thought that phones would kill off the (original) Walkman through interference. Cheers - Jaimie -- "The more wrong a guy gets, the louder he yells at the person trying to help him. Which, inevitably, makes him even wronger. But less helped." -- Merlin Mann
From: T i m on 17 May 2010 14:43 On Mon, 17 May 2010 16:40:09 +0100, Martin S Taylor <mst(a)hRyEpMnOoVtEiTsHm.cIo.uSk> wrote: >T i m wrote >> Yes, what is the construction of the cable you are using for the audio >> from the player to the Mac? I'm presuming it's a 3.5mm stereo jack at >> the cassette player end and possibly the same at the Mac end. However, >> there are screened and unscreened types and they might look the same >> from the outside. > >It's one of these: > ><http://www.maplin.co.uk/Module.aspx?ModuleNo=1170> Hmm, if it's actually one of those (not just looks like) then indeed it suggests it's screened. > >Moulded (so there's no way in) and circular in cross section. Ok. The only thing I'm not sure about now is the fact that the lead is mono, (as probably is the cassette player) but the input to the Mac is probably stereo. However all that should mean is the contact on the 'ring' of the input on the Mac (as opposed to the 'tip' contact) would be shorted to ground so effectively muted. Out of interest is it recording on just one channel ... do you have any control over that. The only thing I might try is using a 3.5mm stereo to mono converter (or lead) and see what that does. Or, try pulling the jack out a mm or two at either / both end? http://www.maplin.co.uk/Module.aspx?ModuleNo=1227 If the output of the cassette player was stereo (even if the unit itself was mono) it may have a stereo output jack so you would effectively be shorting one output out using a mono lead (not the same as a stereo to mono adaptor). A stereo lead would probably also work but may be more likely to have the issues you mentioned (one input un terminated at the cassette player end so acting like an aerial). Again, not something I would have though would have happened via a screened cable. Do you have any other things you could use as a audio source as a test. Something with a 'line' rather than 'headphone' out would be preferred as well. Cheers, T i m
From: Rowland McDonnell on 18 May 2010 04:22 Martin S Taylor <mst(a)hRyEpMnOoVtEiTsHm.cIo.uSk> wrote: > I've been trying to transfer some old cassette tapes onto the iMac by > plugging a cassette player into the audio input and using Amadeus to record > the output. > > You know that "Bzzzzz-bzt-bzt-bzzzzz-bzt-bzt" noise you get from time to time > when a mobile phone is too near the Mac's external speakers? Well I'm getting > that on all the recordings I make. I've taken the iPhone out of the room, but > it seems to be the tape recorder itself which is causing the interference, as > the sound only happens when the motor is running. > > At first I thought it was just affecting the speakers, but the sound is on > the recording, too. Moving the cassette player further from the computer > helps, but not enough. > > Any thoughts? There's a fault condition. Hum tends to be caused /not/ by unscreened cables in short lengths. Earthing failure around/near the high-sensitivity circuitry, that'll do it. What you've got sounds like some sort of earthing failure to me. Poke around, see what you can see. Start at the signal sockets - are they sound? The wires properly attached inside? If the cassette recorder is double-insulated rather than `case properly earthed via its own mains lead', you'll want to be making sure that your signal lead has a continuous earth connection. Aha! What you say you hear, I've heard when plugging kit into Mac audio ports. Yeah, I remember now. Yeah. This is what I remember meeting: Some Macs, the audio sockets, they don't quite fit some of the plugs I've used. Dunno what, but I've had hum, yeah, hum due to an apparently perfectly okay lead that, due to either the Mac 3.5mm socket or the `non-Mac' 3.5mm plug being slightly out of spec, the plug didn't reach far enough in to make proper contact. Iffy earth connection is what it gave me - twiddle and fiddle and I could sometimes get it working okay. Different plug, and it was fine. Rowland. -- Remove the animal for email address: rowland.mcdonnell(a)dog.physics.org Sorry - the spam got to me http://www.mag-uk.org http://www.bmf.co.uk UK biker? Join MAG and the BMF and stop the Eurocrats banning biking
From: Rowland McDonnell on 18 May 2010 06:07
Woody <usenet(a)alienrat.co.uk> wrote: > Martin S Taylor <mst(a)hRyEpMnOoVtEiTsHm.cIo.uSk> wrote: > > > Peter Ceresole wrote > > > Have you tried with another cassette player? > > > > I would, but it's the only one I own and so few people have them these days. > > I bought this on eBay specifically to transfer my tapes. > > > > I'm not sure it's a motor fault, anyhow, since the problem is reduced when I > > move the cassette player further from the computer. Would you expect this > > from a motor fault? > > This noise, exactly how is it? You said it was like a phone noise, but a > phone noise is a series of short buzzes in a pattern, followed by a long > one, That particular pattern is not the one I get from my phone interfering with the radios here, although there is definitely a quite unique sound that the cellphone interference causes. > and is unique to phones (that noise isn't generated by anything > else). Yeah. > If it is a motor noise it would be like a high pitched constant > noise. Not /necessarily/ high pitched. >if it is a mains loop, Earth loop, you mean - via the mains wiring is the usual way it happens in domestic audio. > which I think is less likely on a mac, it > will be a constant mains frequency buzz. Yeah. > I think the type of noise will tell you where it is coming from. There's the `plain old-fashioned dodgy earth connection' to consider. Rowland. -- Remove the animal for email address: rowland.mcdonnell(a)dog.physics.org Sorry - the spam got to me http://www.mag-uk.org http://www.bmf.co.uk UK biker? Join MAG and the BMF and stop the Eurocrats banning biking |