[orientalexpress]

what is the best way to check speed?and the best source for strobe lights that work in daytime?Thanks

lapsan

[Wayner]

You need to have a fluorescent lamp that is run by a magnetic ballast. New CFL type lamps have circuitry in them to reduce the natural stroboscopic effect that is needed to see the results using a strobe disc.

I have a trouble light that I bought that works well. It's made by Prime and it uses a 13 watt PL lamp.

If I can find a source, I will post it.

Wayner 

[galyons]

KAB Strobe.  Does not use line power, so no frequency inconsistencies. Battery power, accurate, easy to use!

http://www.kabusa.com/strobe.htm

Cheers,
Geary

[rcag_ils]

KAB Strobe

For 100 bucks? forget that. I canned a strobe off one of the direct drive Technics and it works just fine. Or just buy a fluorescent lamp for a few dollars at your local hardware store, or just get neon bulb and it may work too.

[galyons]

...it may work too.

Exactly! Used oats are almost always cheaper than new, as well!

[BaMorin]

For 100 bucks? forget that. I canned a strobe off one of the direct drive Technics and it works just fine. Or just buy a fluorescent lamp for a few dollars at your local hardware store, or just get neon bulb and it may work too.

All that works for checking the speed via wall frequency.  If the table runs @33.33RPM at 60HZ, what is the speed then @ 59.2HZ?  How much does the frequency drift in your area? Columbus usually runs 59.7 to 60.2 at the extremes.  What is your wall frequency if you have two or more syncro motors (fridge/dryer/furnace etc) running at once? Or your neighbor's house if hooked to the same transformer?

[Ericus Rex]

What I do these days is put on a recording that I own on LP and CD.  Play both and switch between the channels on your preamp.  Adjust if the two aren't playing at the same pitch.  I haven't had great luck with strobes and pitch.

[rcag_ils]

How much does the frequency drift in your area?

Freq from the power company is dead on at 60hz, if freq drifted, the whole power grid would be drifting. Power may have occasional spikes, but the freq is dead on. Get a freq counter and measure it. Make sure you use attenuator though, so you won't blow your counter.

[BaMorin]

Freq from the power company is dead on at 60hz, if freq drifted, the whole power grid would be drifting. Power may have occasional spikes, but the freq is dead on. Get a freq counter and measure it. Make sure you use attenuator though, so you won't blow your counter.

well, it's supposed to be..........just measured mine @10:45pm edst......voltage shifting from 121.9 to 122.0 frequency measured 59.92. I'll check @10:45am.  there was a link on the VE for the grid in England. it varied as much as 2hz during the day.  The term "dead on" is a swag term..........dead on is anywhere between point A and point B. It ain't a perfect 60 always.

[BaMorin]

http://www.dynamicdemand.co.uk/grid.htm

[neobop]

Usually between 59.7 and 60.2? That's within +/- .5%. And what's the accuracy of the measuring device? Maybe in the UK it's worse. That's just takes more checking.

I don't bother with a fluorescent light. A regular old light bulb plugged in the wall, works just fine. Then compare to anything you like and set it by ear. If or when you hear no difference, there is no difference - At least not an audible difference.
neo

[BaMorin]

Usually between 59.7 and 60.2? That's within +/- .5%. And what's the accuracy of the measuring device? Maybe in the UK it's worse. That's just takes more checking.

I don't bother with a fluorescent light. A regular old light bulb plugged in the wall, works just fine. Then compare to anything you like and set it by ear. If or when you hear no difference, there is no difference - At least not an audible difference.
neo

the +/- of .5% is the swag the power companies accept.  I think the whole point behind the original question is.........how accurate are power supplies/drive systems in TTs?  It's obvious the factory mounted strobe blinks at wall frequency.......not at a perfect 60hz. You, I, nor anyone else on this board can see the strobe flashing at 59.9 or 60.01 and say its fast or slow. A hand held stobe that is built to a much closer tolerence to being near perfect 60hz generally will show the common strobe on a TT to be reacting to wall frequency.......thus speed always looks correct. Some of the exotic power supplies bought or factory installed don't re-form the wave to a perfect 60 either.........so what do they really do? For the most part they react to the the difference of what is comming in from the wall, and what is feeding back to the motor (stylus drag, spindle drag etc).  Me, I prefer a good flywheel and a 3phase syncro motor. Some power supplies simply overdrive the motor, and then use an eddy brake that can be varried to keep a constant speed.
When my wall frequency is 59.9, my "A" might be 436.......when it's 60.1 my "A" might be 442.

[Wayner]

Frequency of AC line voltage is determined by the RPM of the power plant generators, that are geared to a constant RPM. Lags may be caused by capacitive nearby loads. Mine is at 59.9 hz all the time, and that is because my Kill a watt's meter is slightly off.

Many people use a strobe disc to check TT speed. The effectiveness of the strobe disc depends on a flickering light source, like that from fluorescent lighting, which goes (in effect) on and off 60 times per second (in the US). the strobing will produce an appearance of lines standing still on a strobe disc. If the disc floats one way or another, it is too fast or too slow. The problem is that with many (but not all) belt drive TTs, there is no way to adjust speed variations.

Wayner