Lead in groove length.

Topics regarding professional record cutting.

Moderators: piaptk, tragwag, Steve E., Aussie0zborn

User avatar
Dub Bull
Posts: 64
Joined: Fri Apr 05, 2013 4:53 pm

Re: Lead in groove length.

Post: # 27605Unread post Dub Bull
Tue Nov 05, 2013 8:23 pm

..as for the length of the Lead In groove, it depends on the disc diameter of the target pressing. The target pressing's disc diameter also affects the blank's disc diameter of the Cancel Finish trip which makes the lockout spiral (inner circle) at the end of side so as to park the pickup after the end of program and allow the listener time to get up and lift off the needle when using a manual player. The different disc diameter pressings use differently sized labels, so it's best to adhere to the target recommendations for Finish cancel tripping, especially.

From the L. J. Scully manual from 1978:

Disc Diameter (in inches)____________Disc Diameter position (in inches) of cutting stylus at time of event:

7________________Cutter_drop______6-15/16

12_______________Cutter_drop______11-15/16

7________________Lead-In_cancel___6-9/16

12_______________Lead-In_cancel___11-7/16

7________________Finish_cancel_____3-7/8

12_______________Finish_cancel_____4-3/16


As indicated above, the 12" Lead in groove length is one half inch. But for 7", the Lead in groove length is 3/8". Many records are serviceable which don't adhere perfectly to these recommendations, but following them assures compliance with expected events. (which are classified, of course)

Praise Hymn, daily,

- Father Jose'

User avatar
boogievan
Posts: 142
Joined: Thu Feb 21, 2013 3:43 am
Location: Dutchess County, NY

Re: Lead in groove length.

Post: # 27616Unread post boogievan
Wed Nov 06, 2013 9:10 pm

Back in '90, I drove from LA to SF to visit an old girlfriend. Without telling me, she and some friends went to a rave. When I arrived at her street in the morning, she was still out partying, so I had to have a neighbor buzz me into the building. When I got to her door, it was ajar, so I went in. The cat had fled, and the record player was still playing the lockout groove from the night before. For the sake of that record player, I'm glad I didn't cancel my trip.

- boogie

User avatar
Dub Bull
Posts: 64
Joined: Fri Apr 05, 2013 4:53 pm

Re: Lead in groove length.

Post: # 27683Unread post Dub Bull
Wed Nov 13, 2013 5:35 am

Hey, above? it's ok, but you have to read that stated "half-inch"-Lead In groove length (for 12" pressings) as being both in "disc diameter" inches (which is half inches for every stated inch, making it 1/4" in reality, I mean, radius))... It's the head trip to the lead in cancel spread. ):


- Father Jose'

Post Reply