Message Sort: Post Order or Asylum Reverse Threaded
Speed accuracy on vintage belt drive TT with "electronic speed control"
184.90.51.10 |
||
Posted on January 13, 2017 at 23:02:46 | ||
Posts: 6622
Location: Eastern Massachusetts Joined: July 4, 2000 |
I have a Philips AF877 table, which was built in the late 1970s. It is belt drive with electronic speed control (the subsequent AF887 had quartz lock control, but not this one). I bought it on Craig's List for $49 a few years ago for a second system and I think it sounds great. I just downloaded the Turntabulator app on my iPhone and it showed the average speed initially as 33.16, which is 0.5% slow. I left it spinning and checked about every 15 minutes over the course of about an hour, and the next three readings were 33.13, then 33.14 and then 33.13 again. So, between 0.5% and 0.6% slow. The app does not test for variations - only average speed over about a 15 second period. In John's post below, he and others reported observing the average speed of belt drives increasing over time, most likely because of bearing lubricant viscosity. But I gather that I should not expect that kind of a change on my table since it has electronic speed control built in (and claims to have a self-lubricating bearing in any event)? This table also has pitch adjustment, but even the smallest adjustment brings the average speed above a +0.6% deviation, so that's not a "solution". Any sense of whether a technician could micro adjust the speed control? The service manual is on Vinyl Engine, but I can't make sense of it because I'm not electronics-smart! It's really an academic question because I really enjoy what I hear, but I'm nevertheless interested. Finally, and perhaps more importantly from a performance standpoint, are there any apps out there that measure the stability of the speed as opposed to the average accuracy? It would be fun to see if the table is in spec as I have the owners manual from Vinyl Engine.
|
RE: Thanks everyone! Slight update and a question . . ., posted on January 14, 2017 at 10:31:47 | |
here is a whole page to look through. |