Hello to all, I have a problem about the weight of my Omnitronic dd 4750, because the platter isn't very stable.
Now, which solution choose ? Add a metal ( alloy, copper, or other ) mat, or... ??
add weight turntable lathe platter ?
Moderators: piaptk, tragwag, Steve E., Aussie0zborn
Re: add weight turntable lathe platter ?
Inertia, through mass, is helpful at de-jittering analog. I always think about Lester Polsfuss's Cadillac flywheel turntable.studiorp wrote:Hello to all, I have a problem about the weight of my Omnitronic dd 4750, because the platter isn't very stable.
Now, which solution choose ? Add a metal ( alloy, copper, or other ) mat, or... ??
For what it's worth, CD4Cutter pointed out that the Scully LS-76 turntable I have is composite - machined aluminum outside with a sort of formica? core. I think the total weight is supposed to be around 40 lb for this floor model lathe's turntable platter. Whereas, the dd 4750 seems to weigh in at about 20 lb for the whole maschine.
...
- Chuck Spindle
Last edited by Serif on Sun Sep 02, 2012 6:48 am, edited 1 time in total.
Wonder if it's related to turntable "runout." This can be adjusted on some platters if, say, there are screws which can be tightened or slightly loosened to make differences iron out the rotational vertical undulations down to a target of acceptable variance, using a dial indicator attached with a depth "feeler" (plunger valve) that is made to be deflected more or less from a known needle position while moving the table by hand. The spirit level should be consulted first for the coarse adjustment.
If the vertical variance you experience? is close to the spindle, rather than at the outer radii (e.g., the L. J. Scully The Lathe turntable runout adjustment is done at around 1" from the edge, which would be a radius of around 7.5" from the spindle), then it could be something else. Can the platter be removed without damaging the thing? If you needed to replace a thrust ball or get into that shaft for any reason, is this field-servicable? It appears well clad.
Is it looking like this version, mit... Ooo - Ess -Bay...
http://www.andromedya.de/images/product_images/popup_images/1573_0.jpg
Good luck to sort this out. TubeFan has an interesting YouTube of one of his lectures called, Taking Things Apart.
http://www.aeemsu.com/AEEchannel/taking-things-apart-by-dylan-constan-wahl
You can learn a lot by doing this. Only, of course, always take clear close-up pictures and videos of the items, including any other documentation, in all states of assembly...
Cordially,
Garrard Thorens
If the vertical variance you experience? is close to the spindle, rather than at the outer radii (e.g., the L. J. Scully The Lathe turntable runout adjustment is done at around 1" from the edge, which would be a radius of around 7.5" from the spindle), then it could be something else. Can the platter be removed without damaging the thing? If you needed to replace a thrust ball or get into that shaft for any reason, is this field-servicable? It appears well clad.
Is it looking like this version, mit... Ooo - Ess -Bay...
http://www.andromedya.de/images/product_images/popup_images/1573_0.jpg
Good luck to sort this out. TubeFan has an interesting YouTube of one of his lectures called, Taking Things Apart.
http://www.aeemsu.com/AEEchannel/taking-things-apart-by-dylan-constan-wahl
You can learn a lot by doing this. Only, of course, always take clear close-up pictures and videos of the items, including any other documentation, in all states of assembly...
Cordially,
Garrard Thorens
Last edited by Serif on Sat Sep 15, 2012 12:07 pm, edited 1 time in total.
No, cd4cutter was an engineer who cut on a Neumann lathe 'back in the day' as it were. He would be able to elaborate on which studio he used to work at etc. I haven't seen a posting from him in a long time, hopefully he's all right.
I'm tubefan... (After a month with actual artists I completely hate that youtube lecture. But whatever.)
CD4cutter's introductory posting:
-------------------------------------
Hi all. I just discovered this board and began reading some of the posts. Hmmm, I'm seeing a fair amount of guesswork, misinformation, and just plain old wives' tales being passed on here. So I'll try to fill in the blanks from what I know from my disc mastering experience at RCA Records during the time that I was employed at the manufacturing plant in Indianapolis, Indiana from 1973 until I turned the lights out way after we pressed the last records at the end of 1987. We were the tail end of the long legacy of Victor Talking Machine Company and RCA Records.
Among my engineering projects, I cut all the custom RCA test records which we manufactured for a number of clients during my years there. RCA maintained a large catalog of test records which nobody these days seems to know about. too bad I didn't "liberate" copies of more of these when we shut the plant down. They'd be useful to me now. I was also the developer of the RCA Quadulator which was the disc mastering signal encoder required to cut the only discrete 4-channel disc analog record ever manufactured, the CD-4 process. The Quadulator was about one tenth the size of the massive three-relay-rack system developed by JVC who invented the system. Toward that end, I did a LOT of disc mastering at 1/2.7 speed and 1/2 speed, both in my Indy lab and in our New York studios which were the only two CD-4 mastering locations maintained by RCA. My equipment in Indy consisted of a Neumann am32b lathe with SX-68 and SX-74 cutter heads and Neumann SA-66 (if I remember right) amp set, an old Scully lathe that I can't remember the model number of and several older vintages of Westrex and Western Electric cutting heads and amps.
But the best setup was the Ortofon DSS-731 cutter and matching GO-741 200 watt cutting amps. The 731 cutter was specifically designed by Ortofon to cut CD-4 at half speed. It had the widest frequency response of any audio disc recorder ever designed and could easily cut up to 30kHz in real time. But that performance still wasn't good enough for real time cutting of CD-4 which required response up to 45kHz with minimal phase shift between the the two channels, so we used the 731 at half speed with wonderful results. The stylus and collet assembly was very small compared with the clunkier Neumann mounts which went a long way toward providing the wonderful high frequency performance, but changing the stylus was much more of a challenge. Anyway, there's much more to relate about that experience if anyone is interested in it.
For now, I'm curious if there are any more of us old codgers on this board who have professional cutting experience from back in the 70s and 80s. Anybody out there? Anyone with experience cutting DMM in copper?
I'm tubefan... (After a month with actual artists I completely hate that youtube lecture. But whatever.)
CD4cutter's introductory posting:
-------------------------------------
Hi all. I just discovered this board and began reading some of the posts. Hmmm, I'm seeing a fair amount of guesswork, misinformation, and just plain old wives' tales being passed on here. So I'll try to fill in the blanks from what I know from my disc mastering experience at RCA Records during the time that I was employed at the manufacturing plant in Indianapolis, Indiana from 1973 until I turned the lights out way after we pressed the last records at the end of 1987. We were the tail end of the long legacy of Victor Talking Machine Company and RCA Records.
Among my engineering projects, I cut all the custom RCA test records which we manufactured for a number of clients during my years there. RCA maintained a large catalog of test records which nobody these days seems to know about. too bad I didn't "liberate" copies of more of these when we shut the plant down. They'd be useful to me now. I was also the developer of the RCA Quadulator which was the disc mastering signal encoder required to cut the only discrete 4-channel disc analog record ever manufactured, the CD-4 process. The Quadulator was about one tenth the size of the massive three-relay-rack system developed by JVC who invented the system. Toward that end, I did a LOT of disc mastering at 1/2.7 speed and 1/2 speed, both in my Indy lab and in our New York studios which were the only two CD-4 mastering locations maintained by RCA. My equipment in Indy consisted of a Neumann am32b lathe with SX-68 and SX-74 cutter heads and Neumann SA-66 (if I remember right) amp set, an old Scully lathe that I can't remember the model number of and several older vintages of Westrex and Western Electric cutting heads and amps.
But the best setup was the Ortofon DSS-731 cutter and matching GO-741 200 watt cutting amps. The 731 cutter was specifically designed by Ortofon to cut CD-4 at half speed. It had the widest frequency response of any audio disc recorder ever designed and could easily cut up to 30kHz in real time. But that performance still wasn't good enough for real time cutting of CD-4 which required response up to 45kHz with minimal phase shift between the the two channels, so we used the 731 at half speed with wonderful results. The stylus and collet assembly was very small compared with the clunkier Neumann mounts which went a long way toward providing the wonderful high frequency performance, but changing the stylus was much more of a challenge. Anyway, there's much more to relate about that experience if anyone is interested in it.
For now, I'm curious if there are any more of us old codgers on this board who have professional cutting experience from back in the 70s and 80s. Anybody out there? Anyone with experience cutting DMM in copper?
tubefan wrote:No, cd4cutter was an engineer who cut on a Neumann lathe 'back in the day' as it were. He would be able to elaborate on which studio he used to work at etc. I haven't seen a posting from him in a long time, hopefully he's all right.
I'm tubefan...
Hi Tubefan - Glad to know you didn't have to change your name after selling the testarosa (DSS 731). It is great, btw, but it's only mated to a two-channel 1x system, presently. No quad dreams, here. Lateral mono is still ne plus ultra, imho (but I'm using a belt!).
The transistor version of the GO 741 is 550 Watts. Was CD4Cutter using a tube version that had the same model number? His eBay activity is recent. Just bought himself a beautiful fish scale. Guess I better check my carriage brake's coefficient...tubefan wrote: CD4cutter's introductory posting:
-------------------------------------
...
But the best setup was the Ortofon DSS-731 cutter and matching GO-741 200 watt cutting amps.
- CD-tooth-ruster