[78-L] NULLING VERTICAL COMPONENT

[Doug Pomeroy]

I use a mixer which allows me to hear two versions of mono:  L+R as  
well as L-R,
and so I can "fine-tune" the L-R for the best possible null.  This  
null method is the
best (only) way to get the channel outputs EXACTLY equal.  It results  
in optimum
cancellation of all purely vertical stylus motion when a L+R mix is made
.
This is very important IMHO, since there is a lot of spurious vertical  
stylus
motion due to the roughness of shellac as compared with vinyl, and  
there is
also invariably some turntable rumble.  Once the null has been found,  
I record
the channels normally knowing that when I actually combine them  
(later, in the
computer, after noise-removal), the cancellation will be optimum.
I have been on a crusade about this for many years - you will never  
realize how
much vertical noise there is until you discover how carefully the  
channels levels
must be adjusted to cancel it out!  Simply using the mono button your  
preamp is
NOT going to automatically give you an optimum result; the noise is  
different
on every disc.

I don't believe there is any harm in connecting the two hot leads at  
the cartridge.
However, I believe being able to "tune" the mix when making a transfer  
allows
for a superior result.  For the same reason, I do not use a mono  
cartridge.

By the way, I believe the post below gives too much credit to the  
Waves "Center"
plug-in.  As far as I have been able to determine, a noise in one  
channel only will
not be removed by this plug-in, only its vertical component.

Doug Pomeroy
POMEROY AUDIO
Audio Restoration & Mastering Services
Transfers of metal parts, lacquers,
shellac and vinyl discs & tapes.
193 Baltic St
Brooklyn, NY 11201-6173
(718) 855-2650
audiofixer at verizon.net
=============================================================

>> Message: 2
>> Date: Fri, 4 Nov 2011 12:48:10 -0700 (PDT)
>> From: DAVID BURNHAM <burnhamd at rogers.com>
>> Subject: [78-L] stereo/mono and noise reduction
>> To: "78-L at 78online.com" <78-L at 78online.com>
>> Message-ID:
>>             <1320436090.77628.YahooMailNeo at web88620.mail.bf1.yahoo.com 
>> >
>> Content-Type: text/plain; charset=iso-8859-1
>>
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> I have a Waves Audio plug-in called "Centre"; this is a plug-in  
>> which can reduce or increase the side elements or the centre  
>> elements independently in a stereo file. I have played a 78 through  
>> it in stereo and reduced the side elements to zero; what remains is  
>> a fairly clean signal of the music. Switching the bypass switch on  
>> and off seems to just turn the noise on and off. This works because  
>> few if any noise elements on a record are in true mono; for that to  
>> be the case, the damage to the groove wall causing the noise would  
>> have to be identical on each side of the groove but out of phase -  
>> a bump on one side of the groove would have to have a crater on the  
>> other side of the groove of the same dimensions. Just tying the  
>> channels together into mono will remove any noise which is truly  
>> vertical but doesn't achieve the same degree of noise reduction  
>> because an element on one channel only will still cause lateral  
>> displacement of the stylus and be included in the signal.
>>
>> db



Message: 20
Date: Mon, 7 Nov 2011 20:18:26 -0600
From: "Mark Durenberger" <Mark4 at durenberger.com>
Subject: [78-L] NULLING VERTICAL COMPONENT - was: stereo/mono and
	noise	reduction
To: "78-L Mail List" <78-l at klickitat.78online.com>
Message-ID: <BC6275200DB7461DBFFB6FF096FBA1C7 at MarkPavilion>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
	reply-type=original

Uhhmm...I'm not sure it's good to jumper most cartridge outputs  
together.

What I find works well is to install a proper combining pad for the  
outputs
of the preamp; set the preamp gain controls so the output is  
approximately
equal with 'Left-channel-only' and 'Right-channel-only  
tones'......THEN put
on the L-R test cut and trim one of the preamp gain controls for minimum
output.  With a properly tracking cartridge and decent test disc  
you'll get
a great null.

Regards,

Mark Durenberger

--------------------------------------------------

> I think it's best to combine the signals as near to the cartridge as
> possible because even the cables have capacitance and inductance which
> will
> alter the signal differently so it won't cancel as well when combined
> later. I put jumper wires right on the cartridge clips.  If you  
> combine
> the
> signal after amplification it will be even worse, due to distortion  
> in the
> amplifier (and they all have SOME).