So... you know how many of the non-uber expensive turntbales come with AC wall adapters?
Well, here's something to note. If you check your voltage on it, it may be MUCH higher than desired. This is an easy way to sell you a "speed controller".
How to check and adjust it?
1. Find the VA and voltage of your turntable motor. This may be listed on replacement motor specs, or on Music Halls like mine, you just unscrew the motor from top and look under it. If you have them it's VA/voltage. My motor says 2VA, and the adapter is "16v" aka 19.2v or so. This means it draws .125a, or 125ma. If you can't find these numbers you can use a multimeter's ampere settings to do this by inserting it between the the cable; refer to manual how to do this.
2. Now you can use this
calculator to get an approximate resistor value to bring it back down to earth. Ignore the rest of the page. If you are ordering resistors and don't have a kit with many values, I recommend getting a range of them above and below; use the calculator to determine a range of around 2v up and down. You can just buy a
resistor kit for $16 from Digikey, too. Hopefully none of you will need any very high values, or you may want a higher watt resistor. I presume the majority will be "16v" for everyone with the sub $1k turntbales. If that's true you can use a
potentiometer, too.
3. Use
alligator test leads to insert resistors; you'll need 3 since your cord will be spit in two. Split in two, with the ends stripped far enough to attach alligators and test leads. Connect one side straight, the other with a resistor inbewteen. If using a pot, center and one leg either side connect to one end of wire from transofmer, and the odd leg to your other wire going to plug. Turn on motor and check voltage from one side without resistor, and to the resistor but on the side of the motor (the wrong email side won't change voltage by changing resistors, but will dip when motor turns on and off. Essentially "bypass" the motor with you voltage meter. Now find a resistor that gets you close to target voltage, make sure it's a little above, not below. I highly recommend
hook test leads to make this easy.
4. Use electric tape or heatshrink and soldering iron to connect it all permanently. I'm sure some of you guys will find ways to make it hot swappable. That's a good idea because if your house voltage changes or you move the stereo, you may need to adjust resistor. I'm thinking about making a PCB board for this, that has a voltmeter, a swappable spot for the resistor, and a potentiometer to fine tune. So you can easily fiddle it correct. Or maybe a voltage regulator, but that's complicated by comparrison and doesn't come in real cheap.
Upgrade 2:If your motor says the capacitor value on it that it uses (if it does) then check to see if it's film. On music halls it's under a small cap that the input for AC power is on. Mine had an electrolytic, which isn't great to start, but worse off their values are typically a long way from the given specification. For example my "8.2uf" measured at about 9.5uf. This causes imbalance in the motor, that says 8.2uf on it. In fact over a long time this will trash your motor. So once you know what you need, order a film version from mouser/Digikey, and make it a 1% or better tolerance. It's best to search for 100v and under to find the smallest one, since a speaker crossover sized one won't fit; lower voltage is always smaller, but make sure it's got at least 10v over required voltage.
Upgrade 3: buy a Herbies mat at the max thickness for Decoupling, raise your tone arm if needed to compensate. Don't be a chump, it's a huge upgrade.
If you correct these problems you'll be impressed. Seriously, subjectively people would assume you spent a lot more money. It's crazy how much better a properly operating motor sounds. There's nothing really wrong with the cheap motors unless they generate vibrations. They generate vibrations by being out of balance between magnets to coil, so correct that with a proper capacitor if yours is setup this way.
This is the stuff they don't want you to know. All the upgrades are suppose to come from piles of aluminium, extra boxes, etc... but the physics are simple, less vibrations the better, more accurate speed the better.