Cutting Up: Stereophile's Liszt Piano Sonata LP Page 5
For the actual plating, RTI has one four-position rotary tank (which uses a rotating cathode as opposed to a fixed one) and a nine-position pre-plating tank (which uses a fixed cathode putting out no more than 20A, but circulates the plating bath more vigorously). The terms are confusing, because the pre-plating tank is actually used for fully plating most projects. Traditionally, pre-plating tanks, which use lower amperage and a lower temperature in the bath, are used to build a thin layer of metal onto the lacquer before the disc is moved to the rotary tank, where higher amperage and bath temperatures complete the job quickly. Quality plating facilities prefer to use the pre-plating tank for the entire process of forming a master, however, to prevent exposing the fragile lacquer to high temperatures. The plating process thus takes about 14 hours, as opposed to less than half that. Stampers are formed in the rotating tank, since the lacquer is not involved.
Where did RTI get their plating equipment? "Our plating tanks were built by Keysor Century, but they stopped pressing records and plating years ago," Salstrom explains. "They put the tanks in a storage locker at the back of the plant and essentially forgot about them. We were having a hard time finding equipment and, in the middle of a conversation with Keysor, this stash of gear came up. We went out to look at it, and it was all knocked over and jumbled up from the earthquake. But we were able to rebuild it with Rick Hashimoto's help."
John and I witnessed the spraying of our lacquers and watched as they were lowered into the pre-plating tanks. Then we were taken on a tour of RTI's pressing facility. RTI has seven presses, all going full-bore. It's an impressive sight, to be sure, but I think I'll leave a complete description of a record press for another time and another project. Ponder this, though: Making a record is an artisanal affair—it requires a great deal of hands-on intervention from the press operator. If records have become a premium-priced product as digital has taken over the marketplace, that is a reflection of their true nature: They are just one step removed from being handmade. As we watched the press operators baby their charges and the QC people run into the listening room to check pressings, I was overwhelmed by the realization that the technology worked at all—and even more that it works so well.
In fact, proof of this was delivered to us by way of our test pressings. Quite apart from the missing first note and our desire to recut without using the Mackie unit, we had severe nonfill (footnote 3) and pre-echo problems throughout both sides of the disc—and these were the cuts that RTI had determined to be the best! I QC'd several discs one evening—my notes of audible events averaged one page per side.
Test pressings are usually noisier than the product run anyway. You stop the press to change stampers and the vinyl in the hopper warms up, then cools off, then warms up again—all of which affects consistency. In a short run of, say, 20-50 pressings, more than enough to produce multiple copies for the client plus several file copies for the pressing facility, the vinyl never achieves optimum flow—as it would 100 pressings into a production run. When I called RTI to discuss the tests, they astounded me: the TPs I'd been listening to were the product of an extended run—they'd actually pressed a few hundred copies hoping to eliminate the nonfill by simulating real production circumstances!
The nonfill was annoying enough, but the almost constant pre-echo was extremely distressing. We all conferred and concluded that substituting a Mark Levinson No.38S for the Mackie 1202 would only take us so far. We needed to monitor cutting gain, watch the groove spread, and pray.
Footnote 2: The deposition of metallic materials upon a mold (ie, the silvered lacquer) is accomplished electrochemically. That is, the lacquer is connected to the negative pole of a DC circuit, making it a cathode; while the positive side of the circuit uses the metal to be deposited (in this case, nickel) as an anode, which is consumed as it migrates to the mold. The whole assembly is submerged in an electrolytic bath in the plating tank, which at RTI consists of nickel sulfamate.
Footnote 3: When a record is pressed, the vinyl biscuit is deposited in the center of the stampers, occupying the label area. When the stampers are forced together, the vinyl spreads from the center out toward the edges of the disc. This forces it into the inner groove wall (left channel) and, in most cases, the outer groove wall (right channel) as well. Sometimes, the outer groove wall doesn't form a perfect negative of the stamper—this is called nonfill—either because the vinyl hasn't achieved optimum consistency or because the outer groove is heavily modulated, making it too complex a form to force the vinyl into.