Vintage DD turntables. Are we living dangerously?

When I owned "only" the SP10 Mk2A and the Denon DP80, both in very similar slate plinths, I gave a slight edge to the DP80 and eventually sold the Mk2A.  But I agree, the Mk3 surpasses both by a considerable margin.  Prior to applying the Krebs mod to my Mk3, I would have said that the L07D was slightly preferred, not that I could hear anything wrong with the Mk3. The two were just different flavors of goodness. The Krebs mod seems to make the Mk3 sound as fluid and open as the L07D with slightly more "drive" than the L07D.

JP, can you amplify on your cryptic comment about the effect of a heavy platter mat? "Drive gain"?  I was thinking last night that I wished I could modify my statement that a heavy mat might mess up the servo mechanism. Obviously it's also about the motor and its torque.  I thought that the original designers had to match platter inertia with torque and servo action, a triumvirate of factors.

Also, you guys, my concern about a heavy platter mat was not about bearing wear.  It was about the possible effect of a very heavy mat on speed accuracy and constancy. See above.  I'd give the CU-180 a try on the TT101, based on Halcro's comment, but pigskin too. 

lewm
03-15-2016 12:10pm

JP, can you amplify on your cryptic comment about the effect of a heavy platter mat? "Drive gain"?

Okay, but I’m more than rusty on root locus and complex conjugates. :)

My very hasty research this morning indicates rotational mass isn’t going to have an affect on the PLL if the drive is compensated. It may not have a meaningful effect regardless.

Increasing the rotational mass means a given correction to be performed in the same amount of time will require more energy. If not the reaction time will be slow. Note the sync position timing for the MK2A and MK3 are the same, yet the MK3 platter is just over 3x heavier. Most of that mass is inboard but it’s still a significant difference.

I think this is one of the reasons these DDs can be so polarizing - there’s no way to tell how different techs are calibrating them without measuring one first-hand, thusly no way to really know that they’re performing the same. A MK3 can be dialed back so far the motor will actually overshoot and bounce off phase lock 2-3 times before settling, or set over-critically such that the drive MOSFETs will self-destruct in seconds. I’ve mentioned I’ve seen these running in belt-drive emulation mode before - that’s wasn't a joke.

I haven’t measured a MK3 or MK2A with additional platter mass. On the MKII the W&F measurements were negligible, but I don’t think that’s a spectacular measurement for how a drive system reacts to real-world conditions anyway; more of a steady-state baseline.

The TT-101 at a block level is really no different than an SP-10 aside from what it takes to drive their coreless motor, so I wouldn’t expect a little extra mass is going to have a broad affect on what you hear. The motor will not be as critically controlled, though depending on the mass that may be negligible, or actually preferable.

dd
The Denon DP-80 has the saucer shape like the Victor TT-101. In fact the Victors copied the Denon look. I have a copy of the DP-80 mounting template.

Was it the chicken or the egg with regards to the copying.
But we won't get into just who did the manufacturing and design not that it matters.

JP, Thanks very much for your informative response. If you ever do get to do some additional experiments with DD’s toting heavier-than-OEM platters, let us know. 

Here is a question that maybe Totem or Peter can answer, particularly Peter: Will a TT101 fit into a plinth made for a DP80? Here I am asking only about the hole in the top deck and the placement of the bolt holes. My DP80 is sitting in a very nice slate plinth cut for it. I might like to try the TT101 in that same plinth, but not if it requires modifying the slate. Obviously, I could just try it, but that requires me to do work.  Hate that. Thanks.

Lewm, 

Unfortunately the metal casing that house the electronics on the TT101 is larger in diameter then on the DP80 (DP80 =10.5" Diameter) (TT101=11" Diameter).

I'll be making a very nice plinth for my TT101  maybe you want one too :-)


Good Listening


Peter