Turntable speed accuracy

Halcro: "Perhaps the key to the accuracy and consistency of many DD turntables.....is their inbuilt ability to monitor the platter speed against a quartz crystal timing device......and make instant corrections for any deviations."

While I am a fan of direct-drive but I am not sure that's a good thing about servo making "instant corrections for any deviations." Any error has to be detected first before making correction so it's after the fact and sometimes if treating it with an iron fist approach it can cause unnecessary jitters and possibly that sterile sound we associate with DD tables. I think the key to good sound in DD, other than motor quality, is how the designer approaches this servo or corrective system in a sensible way. If the outside disturbance of the speed is too large, I see no need to correct it and just let it be. For example, if I were to tap the platter rim with my palm while spinning and I don't see the need for the platter trying to hold speed. It comes down to how smooth the correction is. I don't think servo response time have to be so quick. A gentle approach is probably more pleasing to the ear than a brute force one. I can be wrong and there are probably good sounding DD tables (TT-101?) out there using the quick fix approach.

I understand stylus drag is not a constant resistive force, neither is music. Perhaps the torque should be set just high enough to plow through the most demanding musical passages (1812, anyone?) and leave it at that so the servo does not have to do tap-dancing all the time? Of course, it's impossible to do instant servo on belt-drive of course due to the elasticity and time delay of the belt but its gentleness probably offers a pleasing sound.

______

Hiho, Well said. The L07D is among those that use the servo feedback sparingly or gently, whichever term fits best. But since I cannot understand any of the feedback circuits without a tutor, it is hearsay evidence coming from me. I am reporting what is implied in the owners manual for lay persons to read.

Halcro, I tried to test the L07D with the Timeline today. It's the first time I had this unit up and running. But sadly the test could not be done, because the Timeline will not fit over the L07D spindle. Apparently, L07D has a "fat" spindle like my Lenco. The L07D ran spot on with the KAB strobe, however and for whatever that is worth. Sutherland should make some sort of adapter to accommodate each of the 3 possible spindle diameters. it would not be difficult.

Have been following and reading all the posts since I posted back in November.

Here is my follow up.
Since my post I have made it a ritual to use my Verdier and Timeline every time I start to listen to vinyl.
Experimented with various different threads and settled on the J&J unwaxed dental floss.
My ritual is to place a record on my Platine, turn on the air for the tonearm, place the Timeline at the speed of the LP's rpm and then turn on the Verdier motor.
When I start tracking the speed with the Timeline on the wall behind the table I can clearly see if it is running slightly fast or slow. Have a piece of grid paper taped against the wall with blue painters tape. The grid paper has black ink lines drawn every 1/4 inch vertically.
The laser dash on the wall is approximately 1 1/4 inch long. My Verdier spindle is 18 inches away from the spindle and 16.5 inches from the timeline.
I adjust the speed in order for my "laser dash" to stay constant. After about 2 minutes of staying put " good dog spot" had to throw that in..... It is then that I start playing my music.
After playing numerous Lps and it time to get things wrapped up for my listening session I then check to see if the Verdier is still holding speed.
Timeline strobe light not drifting.

Now it gets interesting.
When I have my next LP listening session, I go through the same ritual and sometimes I have to adjust the speed on the Verdier.
Ever so little about a 1/16" to 1/8" of inch" of adjustment on the dial is all that is required so that the timeline doesn't drift.
What is causing this ? Don't know. Line voltage, slippage, stretching ? Time for the battery set up for the Verdier.

When I play LPs on my Denon DP 6500 the speed does not drift while playing LPs with or without tonearm engaged.
Just for S&G decided to play the Denon with the Timeline but with no tonearm engaged. Left this playing for one hour (iPhone timer) the timeline laser dash was still in the exact same spot.
I did not stay there for the whole hour but was there for the first 20 minutes, son did the next watch for 10 minutes, I returned and finished up the last 30 minutes. This is such a fun hobby starring at a red line ............

Speed stability the DD DP 6500 first place, tread drive Verdier second place.

Sound comparison and conclusion.
The Kuzma tonearm stays on the Verdier. The FR64 can be inter changed between the Denon and Verdier and the set up takes about 30 minutes for an "equal" comparison. The protractor used is Dertonarm's.
Which table brings me more emotion and gestalt ?
Result is still the same. Even with the extra steps required The Verdier is the table that I go to 99.9% of the time.
Knowing that it needs to be tuned to be accurate is not a biggy for me. Effort is worth the result. Curious how a heavy platter DD would sound.

IMO my ritual with my Verdier is like my days of tuning multiple Webers on a car. Anyone remember those days?
Get it right and you are rewarded with the glory of the exhaust note and the response of a fine tuned engine.
Music to my ears. My other passion.

Take care all,

> Lewm: "The L07D is among those that use the servo feedback sparingly or gently, whichever term fits best."

I don't know enough of electronics to decipher servo circuits but I do know one DIYer in another forum tinkered with the servo on a heavily modded unit of a stock Technics SL-Q3 turntable with the following:

"I modified the negative feedback loop network to make the whole thing under-damped. As it is from the factory, it is over-damped and after doing some A/B test by switching instantly between the factory network and the new one, it is obvious the change in sound. The modded version is much more relaxed and clear and all the distortion (similar to jitter in digital) in mids and highs is gone."

Now, I wish I can do that to my Technics table...

> Lewm: "But sadly the test could not be done, because the Timeline will not fit over the L07D spindle. Apparently, L07D has a "fat" spindle like my Lenco."

Maybe you can raise the Timeline above the spindle with, say, a piece of styrofoam or a roll of electrical tape, center it and hold it with double-side tape? It's a little mickey mouse but it can be done...... that is, if you have the time and energy to entertain us. :-)

_______

Unoear:

No, I did not get a chance to try a Timeline with Rockport Sirius lll while it was here last year. However; Tim Sheridan, was here late last year for a visit before I shipped the Rockport to its new home...where it joined a few other Rockport TT siblings in the UK.

I can hardly believe after all the work and effort you put into obtaining the Rockport you sold it. Your post is the first I've heard about that.