@tubestyle, there is a great post over on the Lenco Heaven forum on the Russco Studio Pro, the 2 speed industrial broadcast cousin of your QRK that has a lot of great information and tips that are applicable to your table as well.
One of the latest discussions is how much the motor noise is reduced by dropping the incoming voltage. All very interesting stuff.
BillWojo
One of the latest discussions is how much the motor noise is reduced by dropping the incoming voltage. All very interesting stuff.
BillWojo
Reducing the voltage will increase the current, resulting in heat issues.
Not advised.
And unless a variac is used, the drop method will cause irregular rotation.
Not advised.
And unless a variac is used, the drop method will cause irregular rotation.
"Reducing the voltage will increase the current, resulting in heat issues."
I agree if the motor had a big load on it but it's a huge motor and it's just coasting along. So far no negative reports.
Big motor is there for instant startup, a broadcast thing.
BillWojo
I agree if the motor had a big load on it but it's a huge motor and it's just coasting along. So far no negative reports.
Big motor is there for instant startup, a broadcast thing.
BillWojo
The second part was HOW the speed is reduced.
And also how much, and the advantages gained by doing that.
And also how much, and the advantages gained by doing that.
"The second part was HOW the speed is reduced."
It's a synchronous motor, locked to line frequency so the speed doesn't vary. Since it's an idler I'm sure you understand how the speed is reduced between the motor and platter.
These are not the tiny toy motors used in the belt drive TT, these are big industrial motors made by either Bodine or Nidec, a Japanese company.
My buddy that is one of the guys doing testing said he didn't notice any reduction in torque either. Of course these have a ridiculous amount of torque to start with.
The only real load on the motor is the start up torque needed to get a heavy 7 lb platter up to speed in about 60 degrees of rotation. The rest of the time it's basically idling along.
These Russco Studio Pro TT are incredibly well built, 3/4" spindle shaft just to give you an idea.
BillWojo
It's a synchronous motor, locked to line frequency so the speed doesn't vary. Since it's an idler I'm sure you understand how the speed is reduced between the motor and platter.
These are not the tiny toy motors used in the belt drive TT, these are big industrial motors made by either Bodine or Nidec, a Japanese company.
My buddy that is one of the guys doing testing said he didn't notice any reduction in torque either. Of course these have a ridiculous amount of torque to start with.
The only real load on the motor is the start up torque needed to get a heavy 7 lb platter up to speed in about 60 degrees of rotation. The rest of the time it's basically idling along.
These Russco Studio Pro TT are incredibly well built, 3/4" spindle shaft just to give you an idea.
BillWojo
You will reduce the volts and restrict the amps HOW?
Volts x Amps = Watts
Force x Force Arm = Torque...
If nothing changes, you have done nothing.
Volts x Amps = Watts
Force x Force Arm = Torque...
If nothing changes, you have done nothing.
Well, I'm not an EE but I have real world experience, mostly with industrial 3 phase gear. If I measure the voltage/current draw on a unloaded motor the current draw is minimal, however as I apply load the voltage stays close to the same but the current goes way up.
So what your saying is that at idle if I reduce the voltage the current goes up. Well, I would need to measure that. Either way if it consumes the same number of total watts the temperature should remain the same.
I did plug my TT into a variac and tested the motor for vibration at both 124 wall voltage and than at 90 VAC. Huge difference in vibration. Now I need to find a transformer that will allow me to buck the voltage 34V. Any ideas?
Since these motors date back to the late 50's early 60's I'm thinking the line voltage was much lower back then. But I think 110VAC was pretty much the standard back in that era.
But the important thing here is the massive reduction in vibration as was reported by two other Russco owners.
BillWojo
So what your saying is that at idle if I reduce the voltage the current goes up. Well, I would need to measure that. Either way if it consumes the same number of total watts the temperature should remain the same.
I did plug my TT into a variac and tested the motor for vibration at both 124 wall voltage and than at 90 VAC. Huge difference in vibration. Now I need to find a transformer that will allow me to buck the voltage 34V. Any ideas?
Since these motors date back to the late 50's early 60's I'm thinking the line voltage was much lower back then. But I think 110VAC was pretty much the standard back in that era.
But the important thing here is the massive reduction in vibration as was reported by two other Russco owners.
BillWojo
Just chatted with my buddy Andy and he said that at 90VAC he didn't feel like it was running hotter or cooler so it probably consumes the same number of watts. He also said that he thinks the sweet spot lies around 100 to 110VAC. I will test that when I get a chance. It would make perfect sense considering that when these were made the wall voltage was around 110VAC.
So to get from 124VAC to 110VAC I think a 12.6VAC filament transformer with a rated input of 115VAC might work, I think it would get me pretty close used in the buck mode. Any comments?
BillWojo
So to get from 124VAC to 110VAC I think a 12.6VAC filament transformer with a rated input of 115VAC might work, I think it would get me pretty close used in the buck mode. Any comments?
BillWojo
A Variac is a better option, or an IGBT pure sine wave motor drive.
Do not use triacs, or any other chopper.
You could try a series capacitor, 1 uF, 400V, or so, those are used in higher values, 4-4.5 in fan speed controllers.
How they distort the wave, if at all, I have no idea.
Do not use triacs, or any other chopper.
You could try a series capacitor, 1 uF, 400V, or so, those are used in higher values, 4-4.5 in fan speed controllers.
How they distort the wave, if at all, I have no idea.
"A Variac is a better option"
Buck/Boost transformers have been around forever. Are you saying that they will distort the wave form? Usually there is very little load on a transformer used in that mode so the core should never reach saturation levels.
BillWojo
Buck/Boost transformers have been around forever. Are you saying that they will distort the wave form? Usually there is very little load on a transformer used in that mode so the core should never reach saturation levels.
BillWojo
Buck boost is adjustable like a Variac?
Then no problem.
If fixed, you are a little limited by that.
Then no problem.
If fixed, you are a little limited by that.
Buck Boost is limited by the taps on the secondary, no adjustments. Use the variac to see what voltage works best and than select a transformer with a tap on the secondary that will give you the correct voltage. It's dedicated to the piece of gear that your trying to correct the voltage on. Better than tying up a good variac and no chance that someone will "spin the knob" possibly damaging something.
I've mostly used them on industrial 3 phase power, usually to reduce voltage to a piece of machinery.
+ or - 10% of name plate voltage is used as a general guideline for industrial equipment, anything beyond that calls for correction.
BillWojo
I've mostly used them on industrial 3 phase power, usually to reduce voltage to a piece of machinery.
+ or - 10% of name plate voltage is used as a general guideline for industrial equipment, anything beyond that calls for correction.
BillWojo
The turntable is in a place where lots of people pass by?
Try the capacitor trick too...
Read up on ceiling fan regulators with capacitors, the motor ratings are not far from your table.
That will save you a transformer, and it is not easy to tamper with.
Try the capacitor trick too...
Read up on ceiling fan regulators with capacitors, the motor ratings are not far from your table.
That will save you a transformer, and it is not easy to tamper with.