can VMS 70 get as good as a VMS 80?

[Johanz]

Hi all,

I'm trying to find out if you can pimp a VMS 70 in a way it can give the same quality as a good VMS80? I mean, do the mechanic differences like more or different bearings still matter after upgrading the VMS70's with a good pitch computer etc. Think I need a VMS 80 but they're hard to find, so I wonder how far I could could get with a VMS70 to get the same quality/lenght.

Thanks
Johanz
Ballyhoo Studio Mastering

[Phinster]

not really...the 80 is a total re think of how pitch and depth function..anything you can do to make a 70 more efficient ain't gonna be a bad thing tho...

there are still loads of 66's and 70's about, they're fine..easier to fix...80's are hideously expensive if you can find one, and can exhibit mysterious problems..

good luck and have fun

[dmills]

The 80 is a fine example of what you can do with an infinite quantity of 1980s 4000 series cmos logic, hideously complex does not even begin to cover it.
Everything I have seen of the drawings says the original electronics are going to be a serious headfuck.

There is actually, so far as I can see, little to stop someone making a 70 do the same pitch and depth logic as the 80, and with modern electronics you could trivially run all the control logic, depth and pitch on a PC or even something like a raspberry pi. The patents have expired, so...

You would want something better then the original Lyrec motor and would probably need to slightly re jig the pitch drive arrangements (A modern servo drive or some sort seems indicated).
About the only thing that would be difficult in a computer based setup is the actual feedback error amp, mostly because group delay is the enemy of stability in feedback systems, but all of the preview driven depth and pitch logic is not exactly hard.

[jjgolden]

With the 80 another thing to consider is the efficiency of the groove nestling do in part by the direct drive pitch motors as apposed to the belt system on the 70

[Johanz]

Thanks all. So with a (upgraded) pitch and depth control added and possibly a replacement of the motor you would be there? I read somewhere the 80 is utilizing more bearings and is therefore also more stable? Maybe a perfectly modded VMS 70 should be satisfying too these days? So with a modern pitch depth control I could do the same minutes of cutting as on the VMS80? Or is this one still more efficient with pitch and depth control, because the hardware is offering more stability? I have time to wonder about this while laquer shortage reaching it’s peak since the US company burned out.

[dmills]

Well both machines cut a reasonably low noise disk (With the 80 possibly being slightly quieter), but that issue is >30dB below modulation, so I don't see it making much difference to the pitch and depth controls.
Probably want to replace the pitch drive with a modern servo motor and maybe something like a strain wave reducer (Which are really nice for this sort of thing, high ratios and zero backlash).

If you pick your new main motor correctly you can probably get pulses out of the motor drive to provide clock synchronisation to the audio delay doings, modern servo drives are good like that.

The lacquer (and stylus) thing does rather suck.