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I didn't see an answer to this question. Summing simply means that a stereo signal has been converted to mono by combining the L & R channels into a single monaural channel. Like when you could throw the switch on your receiver or amp from stereo to mono. You are summing the 2 channels. Receivers don't have such things anymore. joe salerno On 4/24/2012 7:08 AM, James Roth wrote: > Greetings, > > Would someone please tell me what "summing" is. > > Thanks. > Ben Roth > > -----Original Message----- > From: Association for Recorded Sound Discussion List [mailto:[log in to unmask]] On Behalf Of Art Shifrin > Sent: Monday, April 23, 2012 12:08 PM > To: [log in to unmask] > Subject: [ARSCLIST] differentiating groove walls' noises > > It's worthwhile to check if one of the two outputs of a monaural goove is, for a given side consistently inferior or superior. I just did another early 78.3 (rounded off) lateral cut lacquer (1934) for Niel Shell (Nat Shilkret was one of his Grandfathers). The two sides were, thankfully not > gouged by prior playings with steel needles. But it had been played > multiple times on those heavily tracking early systems. One of the outputs was dramatically less noisy than the other. > > For vertical cut grooves, a method that occasionally (but not consistently) is beneficial is to also digitize both outputs. Keeping the eq. flat, then apply your best available de-clicker to the two channel digital file. THEN sum them (with one channel 180 out). When summing, interactively set the two levels for a maximum lateral noise null. Whether done with early stage declicking or not, always check audibly and or visually. You'll often find that the two levels are NOT @ unity. Assuming that your preamp& cartridge combo is properly set up, then when the level 'discrepancy' occurs, that indicates that the cutter was not functioning on a precisely vertical plane. For lateral grooves, with the critical difference being that the two outputs are nominally in phase, the comparable nulling is done to suppress the vertical component. > > For grooves that are intentionally neither vertical nor lateral (i.e. Arto 78s...with their audacious knock off of Victor's "batwing' label), it's anything goes for selecting& possibly mixing outputs for the best possible results. > > AFTER the nulling is performed and two channels mixed together, then apply eq. et. al. > > Best, > Art (Shiffy) Shifrin > -- Joe Salerno