Rerurn to Romy the Cat's Site


In the Forum: Analog Playback
In the Thread: Copper Mat on a Micro Seiki Gun Metal Platter
Post Subject: Salad bowlsPosted by Wellington on: 10/7/2015
fiogf49gjkf0d

Interesting, but I have to say that does sound a bit problematic in several ways. For one, I’m guessing you meant to say “one mm”, or even “one quarter of an inch”, but not “one inch”. One inch is quite a soup bowl! For another, anti-skating force compensation must pull the arm toward the outside, because skating forces pull it inward toward the spindle. So you’d need an inverted bowl, higher in the center, to use gravity for anti-skating.>>

Perhaps you’re also trying to achieve a tight intimacy between LP and platter, without relying on vacuum clamping (which won’t allow the use of a CU-180 anyway). This reminds me of a simple idea. Decades ago, I bought a SOTA reflex clamp. It included a small rubber washer, which miraculously I still have after all these years. First you slip the washer over the spindle, then the LP and finally the clamp. When you tighten the clamp’s lever, the spindle is gripped and a clamping forced is exerted. So, before the force is applied, the LP is raised slightly higher in the middle by the washer, maybe 1 or 2 mm, with the LP edges drooping down toward the outer edge of the platter (barely visibly). When the clamp is tightened, it pushes down on the outer edges of the label area only, which is between the high spindle washer and the outer edge. The LP is forced to make contact with the platter first at the edges, but then all the way to the label, if you have a washer of the right thickness and the correct clamping force is applied. The idea here is to avoid the cupping problem that can occur with heavy record weights and some soft mats, where the heavy center force causes the outer edges to lift up into a shallow bowl. The SOTA clamp pre-biases the forces with the center lifting washer. BTW, the SOTA clamp works with Micro tables just as well. A simple test is, you guessed it, another rap test, only this time it’s a tap. With a (clean) fingertip, tap around the record’s playing surface while it’s clamped. You can hear any air gaps as “ticks” because the record will momentarily slap the platter when you tap over a void. After a while, I can pretty much determine how much force to exert with having to mishandle my records!>>

Rerurn to Romy the Cat's Site