A few notes on the Denon DN 308 and other Denon DD Turntables.
As some of you know I restore many of the magnificent old Denon DD tables mainly the DP3000, 2000, 6000 and 80 - I turn them into these
http://pbnaudio.com/audio-components/audio-turntables/groovemaster/groovemaster-vintage-direct
There is a few mentions above about the platers on these. Please note that the rubber mat that they were originally supplied with is an integral part of the platter system , with the mat on, the platter is virtually "dead" The design of these mats vary some, the earlier DP3000, 6000 and 7000 have a circular ribbed design, the newer DP2000 have a softer but also circular ribbed design, the 75 and 80 have a almost flat but much harder rubber mat.
On the older ones 3000, 6000 and 7000 the platter it self have a raised center portion which makes it hard to use any other mat than the originally supplied mat, the 2000, 75 and 80 have a flat platter making it possible to use almost any aftermarket mat desired.
We are in the process of making copper mats with a large center holes that will make the platters on the 3000, 6000 and 7000 flat facilitating the possibility of using any desired aftermarket mat. The weight of these will be apx 4.5 lbs adding substantially to the weight of the platter. lewm above mentions that the weight of the platter should not be increased substantially because the servo control is "tuned" to the weight of the platters they are controlling, I find absolutely no evidence of this - checking the already astonishingly accurate drive systems with a phoenix engineering tachometer which displays RPM with a 5 digit read out i.e. 33,333 the added weight only makes any slight variation in speed better - the 6000 and up, after restoration, typically runs with only a one number variation on the very last digit i.e 33.333 to 33.334. For an example a DP2000 with a Micro Seiki CU500 mat and a SS record clamp increasing the weight of the platter with over 100% makes the drive system even more consistent.
The platters on the 75 and 80 are a laminated design with a light sub platter carrying a much heavier platter on three leaf springs, there is rubber dampening material applied into every other one of cavities at the circumference of the sub platter with the alternating ones having foam rubber pads that couple the platter to the sub platter. on restoring them the foam rubber obviously is replaced,
On the DN308, the drive system is quite substantial the motor is gigantic the outside rotor is apx 3/4" thick and laminated with what appear to be brass for added weight. I have procured 3 of these and will restore them into new table top machines with plinths made from Slate and Hardwood also they will be fitted with 4" custom made by Steve Blinn Isoped's. I envision them having the possibility of using two arms, I'll probably supply them with either a SME V12 or a 312S. Also since these don't have a strobe light the Phoenix Engineering Tachometers will be built in to the control interface. The platters will be damped, possibly by spraying a polymer on the bottom on them then laminating them with a copper mat. Really looking forward to this project, if any of the above DN308 owners are interested in this please let me know, as I'm already building 3 - 5, 6 or 10 for that matte is not an issue.
As far as how many of the DN308 is out there Im guessing at less than 2000 of them. Of the three I have here the oldest one is from May 1978 and it is number 472 the two other are quite newer one is from Jan 1992 # 1558 and from Jan 1993 # 1608. They are very close to identical.
On a side note restoring / "GrooveMastering" 3each DP7000 machines to be fitted with the SAT tone arm for a major cartridge manufacture, this project too will be lots of fun.
Good Listening
Peter
As some of you know I restore many of the magnificent old Denon DD tables mainly the DP3000, 2000, 6000 and 80 - I turn them into these
http://pbnaudio.com/audio-components/audio-turntables/groovemaster/groovemaster-vintage-direct
There is a few mentions above about the platers on these. Please note that the rubber mat that they were originally supplied with is an integral part of the platter system , with the mat on, the platter is virtually "dead" The design of these mats vary some, the earlier DP3000, 6000 and 7000 have a circular ribbed design, the newer DP2000 have a softer but also circular ribbed design, the 75 and 80 have a almost flat but much harder rubber mat.
On the older ones 3000, 6000 and 7000 the platter it self have a raised center portion which makes it hard to use any other mat than the originally supplied mat, the 2000, 75 and 80 have a flat platter making it possible to use almost any aftermarket mat desired.
We are in the process of making copper mats with a large center holes that will make the platters on the 3000, 6000 and 7000 flat facilitating the possibility of using any desired aftermarket mat. The weight of these will be apx 4.5 lbs adding substantially to the weight of the platter. lewm above mentions that the weight of the platter should not be increased substantially because the servo control is "tuned" to the weight of the platters they are controlling, I find absolutely no evidence of this - checking the already astonishingly accurate drive systems with a phoenix engineering tachometer which displays RPM with a 5 digit read out i.e. 33,333 the added weight only makes any slight variation in speed better - the 6000 and up, after restoration, typically runs with only a one number variation on the very last digit i.e 33.333 to 33.334. For an example a DP2000 with a Micro Seiki CU500 mat and a SS record clamp increasing the weight of the platter with over 100% makes the drive system even more consistent.
The platters on the 75 and 80 are a laminated design with a light sub platter carrying a much heavier platter on three leaf springs, there is rubber dampening material applied into every other one of cavities at the circumference of the sub platter with the alternating ones having foam rubber pads that couple the platter to the sub platter. on restoring them the foam rubber obviously is replaced,
On the DN308, the drive system is quite substantial the motor is gigantic the outside rotor is apx 3/4" thick and laminated with what appear to be brass for added weight. I have procured 3 of these and will restore them into new table top machines with plinths made from Slate and Hardwood also they will be fitted with 4" custom made by Steve Blinn Isoped's. I envision them having the possibility of using two arms, I'll probably supply them with either a SME V12 or a 312S. Also since these don't have a strobe light the Phoenix Engineering Tachometers will be built in to the control interface. The platters will be damped, possibly by spraying a polymer on the bottom on them then laminating them with a copper mat. Really looking forward to this project, if any of the above DN308 owners are interested in this please let me know, as I'm already building 3 - 5, 6 or 10 for that matte is not an issue.
As far as how many of the DN308 is out there Im guessing at less than 2000 of them. Of the three I have here the oldest one is from May 1978 and it is number 472 the two other are quite newer one is from Jan 1992 # 1558 and from Jan 1993 # 1608. They are very close to identical.
On a side note restoring / "GrooveMastering" 3each DP7000 machines to be fitted with the SAT tone arm for a major cartridge manufacture, this project too will be lots of fun.
Good Listening
Peter