Odd that this phasing observation should arise now.
I have been transferring some mono 1930s ARC test pressings in stereo
and noticed that the two signals were seemingly out of phase. I
initially thought it might be an incorrectly wired cart, but that turned
out not to be the case. Next I looked at the record groove - normal.
Then I looked at the signals on the computer again. The run-in to the
musical content IS out of phase (that's where all the rumble shows up),
but the musical signal itself is in phase!
Shelving at around 80 Hz and notching at both 60 and 120 Hz should do
the trick without adversely affecting the program content. I'm going to
Tom Fine wrote:
> One possibility is that the 78 transfer captured enough rumble to set
> the computer speakers flapping. That would make them sound distorted
> because most of the mechanical energy is drained off making the
> speaker "plut". Headphones and car speakers might have no energy
> transfer at the rumble frequencies and thus be immune to the problem.
> My experience is that a rumble filter is always a good idea with 78's,
> and it's better to use it at the same time you're finding the optimum
> turnover and rolloff settings because killing off the rumble effects
> other frequencies, and overall loudness of the musical content.
> Apparently, some of the rumble elements are out of phase to certain
> musically-relevant elements, so when those elements are not partially
> or wholly cancelled, they are louder.
> -- Tom Fine
> ----- Original Message ----- From: "Ted Kendall"
> <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, May 14, 2009 5:48 AM
> Subject: Re: [ARSCLIST] Technics SP-15 to computer nightmare
>> Your computer speakers or amp are evidently at fault here - maybe
>> they can't handle the surface noise from the 78 - I'd not be inclined
>> to worry about it...
>> Ted Kendall
>> ----- Original Message ----- From: "gary atkinson"
>> <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Thursday, May 14, 2009 10:23 AM
>> Subject: Re: [ARSCLIST] Technics SP-15 to computer nightmare
>> Sometime ago I acquired a Technics SP-15 deck. I took it, at the time
>> as a
>> "stand by" and it has been "standing by" waiting for it's big moment to
>> arrive. A few days ago that moment arrived and I transferred a 78rpm
>> from it. As it hit the amp it sounded wonderful, both through
>> speakers and
>> headphones. As it went through the Tascam CC-222SL and onto CD it
>> splendid. Play the CD back on the Tascam, Marantz, Pioneer and even
>> the car
>> CD player and everything is beautiful. Play it back through the computer
>> (desk top and lap top) and the sounds terrible; very distorted and
>> All the more odd is that when I play back from the computer (either
>> the CD
>> or going in directly through and Edirol interface), through an
>> external amp,
>> it sounds fine, yet when I turn up the computer speakers at the same
>> what comes out of them directly from the computer is very distorted.
>> Anything else played in the same way through the computers; vinyl from a
>> Thorens, tape from a Teac, any other CD from the Tascam, radio, DATs,
>> Minisidiscs etc are all fine. After having tried just about every
>> permutation of phone leads and sockets that I can think of I am
>> homing in on
>> the SP-15 deck. The computer seem to doesn't like it directly and though
>> other CD players and amps are happy playing the test CDs that hold
>> recordings transferred from the deck, again, the computer is not
>> happy when
>> it comes to tracks taken from the SP-15. (I created a CD with tracks
>> various sources and all played fine in the computer other than those
>> from the SP-15).
>> I am about to set off and get the deck tested and it might be worth
>> that the power lead goes to an AC Converter as this piece of
>> equipment was
>> from the U.S.A but now resides in the U.K.
>> Any advice on what could be the cause or how to resolve this
>> conundrum would
>> be greatly appreciated.