Sound issue
in [UK Mac]
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From: Adrian Tuddenham on 23 Dec 2009 06:14 Rowland McDonnell <real-address-in-sig(a)flur.bltigibbet.invalid> wrote: > Adrian Tuddenham <adrian(a)poppyrecords.invalid.invalid> wrote: > > > gavsko <gcrosswell(a)aol.com> wrote: > > > > > I run itunes from a G4 quicksilver through an amp to provide music for > > > the whole house. All the vocal sound now appears as if it is in the > > > background (for CDs aswell). I thought it may be the amp blowing a > > > channel but I tested it using a friend's machine and it's fine. Is the > > > headphone socket (from where the phonos run) or hardware damaged or > > > could it be (hopefully) a software issue? (10.4.11 OSX) > > > > A further thought: > > > > If a 3.5mm jack plug isn't fitting right into the socket, it can pick up > > incorrect channel and earth connections; that would give the effect you > > describe if the vocals were recorded predominantly on the missing > > channel. > > > > Have a look and see if the plastic body of the plug is fouling the > > computer casing and preventing the plug from going right in. > > I've noticed that my made-at-homes leads with 3.5mm jack plugs often > don't go in properly to some sockets, but that factory-made leads with > 3.5mm jack plugs so far always have. The moulded-on plugs can be made smaller in diameter than the type with the unscrewable cover which allows soldering. Some of the solderable ones are so big that they will only just go through the hole in the outer plastic casing if the cover is correctly aligned. If there is any misalignment, they will stop half way into the hole and there will be all sorts of possible cross-connections between channels and with missing earths . e.g. Skt Plug L R - L E - R E If the earth of at least one of the two systems was completely floating, this would put the right signal into both channels in anti-phase. (We have been assuming that the connector is a 3.5mm stereo jack, but I don't remember the original poster confirming that.) -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
From: T i m on 23 Dec 2009 06:27 On Wed, 23 Dec 2009 09:32:18 +0000, real-address-in-sig(a)flur.bltigibbet.invalid (Rowland McDonnell) wrote: >300Hz is a `typical highish voice tone' (I hope) > When I was with BT we talked of 'voice' paths being from 300Hz to 3300Hz suggesting 300Hz was a pretty low voice tone (if we are talking about the same things)? Cheers, T i m
From: Rowland McDonnell on 23 Dec 2009 07:16 Adrian Tuddenham <adrian(a)poppyrecords.invalid.invalid> wrote: > Rowland McDonnell <real-address-in-sig(a)flur.bltigibbet.invalid> wrote: > > > Adrian Tuddenham <adrian(a)poppyrecords.invalid.invalid> wrote: > > > > > gavsko <gcrosswell(a)aol.com> wrote: > > > > > > > I run itunes from a G4 quicksilver through an amp to provide music for > > > > the whole house. All the vocal sound now appears as if it is in the > > > > background (for CDs aswell). I thought it may be the amp blowing a > > > > channel but I tested it using a friend's machine and it's fine. Is the > > > > headphone socket (from where the phonos run) or hardware damaged or > > > > could it be (hopefully) a software issue? (10.4.11 OSX) > > > > > > A further thought: > > > > > > If a 3.5mm jack plug isn't fitting right into the socket, it can pick up > > > incorrect channel and earth connections; that would give the effect you > > > describe if the vocals were recorded predominantly on the missing > > > channel. > > > > > > Have a look and see if the plastic body of the plug is fouling the > > > computer casing and preventing the plug from going right in. > > > > I've noticed that my made-at-homes leads with 3.5mm jack plugs often > > don't go in properly to some sockets, but that factory-made leads with > > 3.5mm jack plugs so far always have. > > The moulded-on plugs can be made smaller in diameter than the type with > the unscrewable cover which allows soldering. It seems to be more the length that's wrong - the solderable ones don't reach far enough to make proper contact in some cases, at least not without minor modifications, which is how come I figured out what the problem was. > Some of the solderable ones are so big that they will only just go > through the hole in the outer plastic casing if the cover is correctly > aligned. I've never had that problem as it happens. At least, I don't recall having that problem. Hmm. Maybe I did once (memory chimes faintly) but got round it. Possibly with a razor blade/scalpel or metalworking file... > If there is any misalignment, they will stop half way into the > hole and there will be all sorts of possible cross-connections between > channels and with missing earths . > > e.g. > > Skt Plug > L > R - L > E - R > E Had that :-) - and other iffiness. > If the earth of at least one of the two systems was completely floating, > this would put the right signal into both channels in anti-phase. Hmm - yes. > (We have been assuming that the connector is a 3.5mm stereo jack, but I > don't remember the original poster confirming that.) True, but it's the audio output interface from a Mac that's most commonly used, and I suspect he'd've mentioned it if he was using an optical link. 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 23 Dec 2009 08:58 T i m <news(a)spaced.me.uk> wrote: > real-address-in-sig(a)flur.bltigibbet.invalid (Rowland McDonnell) wrote: > > >300Hz is a `typical highish voice tone' (I hope) > > > When I was with BT we talked of 'voice' paths being from 300Hz to > 3300Hz suggesting 300Hz was a pretty low voice tone (if we are talking > about the same things)? I've no idea what a `voice path' might be - but 3kHz is `overtone' territory for the human voice, not a fundamental. At least, not for anyone pitching their voice in the usual range. Hmm. "In telephony, narrowband is usually considered to cover frequencies 300–3400 Hz." Okay, so I dunno. 400Hz sounds pretty high pitched to me and telephone voices do seem to be missing the lower frequency part of the voice sounds, so I've thought for as far back as I can recall. Don't have a spectrum analyzer handy - if I did, I'd have a look. 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 23 Dec 2009 13:14
J. J. Lodder <nospam(a)de-ster.demon.nl> wrote: > Adrian Tuddenham <adrian(a)poppyrecords.invalid.invalid> wrote: > > > J. J. Lodder <nospam(a)de-ster.demon.nl> wrote: > > > > > Rowland McDonnell <real-address-in-sig(a)flur.bltigibbet.invalid> wrote: [snip] > > > > It does sound like phase reversal on one channel to me - at least, if > > > > it's the case that the only part of the signal that's common to both > > > > channels is `vocals' and only the vocals are so affected. > > > > > > Reversing the phase on both channels surely makes it worse still. > > > Seriously though, a phase reversal doesn't afffect the vocals. > > > It's the basses, below about 400 Hz, that sufffer, > > > > The bass will suffer too, but the vocals are often pan-potted mono, so > > they cancel when the phase of one channel is reversed. > > Supposing them to be centred, which is rarely the case. > What is usually done is putting most of the soloist > on one channel, and the acompaning instruments on the other. > Bass below 400 Hz otoh is always centred. > (because people may need all the power they can get) > (and because vertical amplitude had to be limited, is vinyl days) A listen to a classic Decca recording will show the fallacy of all those assumptions. [snip] > Stereo is (or should be) designed with the idea in mind > that it shouldn't be too bad to reduce it to mono, > even with the wrong phase, Why? 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 |