[neobop]

This looks like it might be a great aid to adjust speed without having to use a strobe disk.  RPM on the fly:

http://www.harborfreight.com/digital-photo-sensor-tachometer-66632.html?hftref=cj

This looks much the same for $15.
http://dx.com/p/2-2-lcd-laser-photo-digital-tachometer-dark-gray-orange-41842

Looks like you have to put some reflective tape on the side of the platter to use it.
neo

[roscoeiii]

I have one that I quite like that I grabbed for under $20. Will look up the link later.

[watercourse]

Hoo, thanks for that neobop, sure beats the $150 audiophile-approved versions you see in friends' houses. In high-impact orange too.

[plastico]

I just stumbled on this thread, and I'm glad I did. Just ordered that nice high-impact orange unit!
Cheers, Plastico

[dlaloum]

Do any of these devices actually track the speed variation? (as a %)

ie: a reading in rpm, and a % variation during the reading period (would require a lengthy reading obviously...)

I read a few of their product descriptions - but this does not seem to be something they do....

[neobop]

Do any of these devices actually track the speed variation? (as a %)

ie: a reading in rpm, and a % variation during the reading period (would require a lengthy reading obviously...)

I read a few of their product descriptions - but this does not seem to be something they do....

David,
No, not for $15 anyway.  These are really designed for all purpose applications like car engine RPM and such.  The scale goes from a few RPM to 99,999.
Accuracy is .05% +1 RPM (?), but I think the readout, although 5 digits only goes to 1 decimal point.  They do have a memory that gives you fastest, slowest, and last reading.  I suspect these are good for getting really close or seeing variations while the record is spinning and the needle is down.

For ballparking a percentage of speed deviation while the needle is up:




The 33 1/3 band has other bands above and below that are 2% fast and 2% slow. 

For greater accuracy maybe one of the $150 ones Watercourse alluded to, would do a better job or give you a percentage.  Saw these on another forum and thought I'd pass if along.  I personally have no use for these now with my direct drives, but if I ever finish my custom table one of these should come in handy.
Speaking of my future custom table, the old Sota Sapphire, I've been thinking of modding the structure instead of abandoning it for a complete custom job with a Versus motor.  It's actually more work because the suspension has to be completely abandoned and weight distribution etc redesigned. 
These thoughts were inspired by an ad for Origin Live motor and controller.  Maybe I'll just sell a few tables and arms to get the Versus and put the KD500 in the Sota wood cabinet.  What do you think?
neo

[dlaloum]

The whole belt drive thing seems counter-intuitive to me, the only way to really make it effective is to have huge platter mass to balance out the continuous expansion and contraction of the "belt" - even the best materials will stretch and contract some amount as force is applied....

I am still periodically trying to think of a way to build a new plinth for my JVC Ql-Y5F - the issue is fitting in all the electronics, which pretty much fill the OEM plinth (with the exception of the 1.5cm thick outside "box").

bye for now

David

[ptmconsulting]

I thought I had things pretty much spot on with the strobe disk, then bought a similar laser tach cheaply and found out just how off I was. No brainer for the price, and if you have a speed controller to adjust it.

[hi5harry]

By now I am sure you have all seen the irpm free app for the i phone. Just keep the phone away from the stylus. it seems really accurate and I get a big kick out of it every time.

[rollo]

I thought I had things pretty much spot on with the strobe disk, then bought a similar laser tach cheaply and found out just how off I was. No brainer for the price, and if you have a speed controller to adjust it.

+1 on that. Well worth the money.


charles

[neobop]

The accuracy aspect is interesting.  Spec for both laser tachometers is .05% +1 RPM. 

I would feel more comfortable with it if the range were more limited (like 20 to 50 RPM), and the readout was at least 2 decimal points.   Maybe the +1 thing refers to very high RPM in the thousands of revolutions per minute.
Anyone use one of those $150 tachs alluded to by Watercourse?

On the other hand, I assume you guys who bought these are getting audibly better results than with a strobe disk, so I wonder how much overkill is necessary.  I think some quartz locked DD tables might better the .05% by a hair, if they meet their spec.
This does seem like a hellofa useful tool, especially for $15.

neo 

neo

[Guy 13]

Hi all Audio Circle members.
When I went to Dung Audio in Saigon last week,
I saw a stroboscopic disc (Calibrated for 50Hz)
and I wanted to buy it, it was 8 USD I thought it was expensive
until I saw on the Internet many retail store that sell those for 25 USD+
I wonder what’s the use if I cannot adjust the speed on my
Rega P3?
If I check the speed and it’s off, then when I listen to my vinyl
I will think about the offset speed all the time
and I won’t enjoy the music.
In addition, I wonder how accurate are those stroboscopic disc?

Guy 13

[rollo]

The accuracy aspect is interesting.  Spec for both laser tachometers is .05% +1 RPM. 

I would feel more comfortable with it if the range were more limited (like 20 to 50 RPM), and the readout was at least 2 decimal points.   Maybe the +1 thing refers to very high RPM in the thousands of revolutions per minute.
Anyone use one of those $150 tachs alluded to by Watercourse?

On the other hand, I assume you guys who bought these are getting audibly better results than with a strobe disk, so I wonder how much overkill is necessary.  I think some quartz locked DD tables might better the .05% by a hair, if they meet their spec.
This does seem like a hellofa useful tool, especially for $15.

neo 

neo

  Si Senor. The Kuzma StobiS never sounded better.


charles

[Delacroix]

By now I am sure you have all seen the irpm free app for the i phone. Just keep the phone away from the stylus. it seems really accurate and I get a big kick out of it every time.

+1. I just downloaded this and tried it on my SME. I was worried the phone would spin off the platter but it did not. My strobe set speed proved a little fast, 33.8/33.9 (the iRPM seems to flit between) but my 45rpm, which I rarely use and can't remember setting was up over 46rpm. Small adjustments got both very close -- my 33.3 setting now reads 33.2-33.4 as platter spins, not sure I can get it any finer or to stick dead on 33.3. That could be the app variance, my belt, minor variations in motor speed as it spins, but am happy enough. Not sure such small measures are audible but I feel the setting now is more accurate than I achieved with strobe and light. It's certainly way more convenient.  And it's free! Thanks for the reminder, hi5Harry.

[neobop]

Check out this video.  Sutherland Engineering

http://www.youtube.com/watch?v=RF2XieUlzvk

neo

[Guy 13]

Check out this video.  Sutherland Engineering

http://www.youtube.com/watch?v=RF2XieUlzvk

neo

Hi neobop and all Audio Circle members.
Nice unit, but I could not find on the Internet how much poorer
I will get if I buy one of those.
Anyone know ?

Guy 13

[neobop]

Hi Guy,

$399.  The price to drive yourself crazy.  Of course you can also use it as a spindle weight.  Considering, I've seen plain old weights advertised as much as $600 (beyond belief), it's a bargain.    If you have more money than you know what to do with, or you're already crazy.....

Seriously, it would be interesting to see the same demonstration on a quartz locked direct drive table.  On the other hand, if you have such a table and it's functioning properly, you don't need the laser weight thingy.  Even a servo controlled DD table will have a built in speed display and you can see any difference in speed with the needle down.  What the Sutherland device does is magnify the display so any minor fluctuation is readily observable every 1.8 seconds.
neo

 

[Guy 13]

Hi nebop and all Audio Circle members.
I paid 1,000 USD for my Rega P3 with an Exact mm cartridge,
I would be crazy to pay 399 USD plus Canadian custom and transport
(More than 500 USD) for a gizmo like that.
I wonder how much offset in % before you can notice a change in the sound?

Guy 13

[neobop]

I wonder how much offset in % before you can notice a change in the sound?
Guy 13

It usually depends on whether the speed variations are a steady amount, fast or slow, or wow and flutter types, which are much more readily heard.

Even people with perfect pitch usually have perfect relative pitch which tells them if one sound is in tune with another.  If they can sing middle A to tune up the choir, it's because they've memorized that pitch and can sing it on demand (usually).   

A table can run a steady 1% fast and it will tend to sound "lively" and most people wouldn't realize the speed variation unless it was measured.  If it ran 1% slow it would sound kind of dead or sluggish.  My old LP12 ran fast and I got used to that.  When I replaced it with a Goldmund DD I had to get used to correct speed.  Wow and flutter is a different story. Warp wow or an off-center record is usually not heard if it's minor, but readily heard if it's more than a little.  I can't really quantify the amount, it seems to vary between individuals.
neo

[BobM]

I can adjust my speed pretty acurately with my laser tach, and I prefer it between 34-35 rpm. Just a little bit faster. That's not even half a pitch in tone, for the perfectionists here, but enough to give the music extra life and sparkle.