Hi.
For an arts project I am working on I want to modify a cheap turntable to be able to play back records super slowly. From around 15RPM up to the standard 33,3 RPM.
I need the speed from 15-33 RPM to be adjustable with a dial.
I am not going for high quality playback, but more for the effect.
My thinking is adding a potentiometer inline between the regular speed selector switch and the actual motor.
Does this sound like a feasible solution?
Hope to hear back😀
For an arts project I am working on I want to modify a cheap turntable to be able to play back records super slowly. From around 15RPM up to the standard 33,3 RPM.
I need the speed from 15-33 RPM to be adjustable with a dial.
I am not going for high quality playback, but more for the effect.
My thinking is adding a potentiometer inline between the regular speed selector switch and the actual motor.
Does this sound like a feasible solution?
Hope to hear back😀
Yes as long as it is a DC motor on the T/T. You also used to be able to buy T/T's that had a 16 RPM speed as standard.
Cheers
Cheers
Audacity and most audio editors will re-record audio files at any speed you like. With or without pitch-shift (gimmick phono always pitch shifts).
AC line-lock phonos (no motor electronics, just wired to the line) can be speed-changed by running a variable freq oscillator to a power amplifier and transformed to 120VAC or 240VAC. If you are inexperienced this is not simple or risk-free. Going slower may well lead to overheating. There are for-purpose pump controllers but they cost upward of $400.
AC line-lock phonos (no motor electronics, just wired to the line) can be speed-changed by running a variable freq oscillator to a power amplifier and transformed to 120VAC or 240VAC. If you are inexperienced this is not simple or risk-free. Going slower may well lead to overheating. There are for-purpose pump controllers but they cost upward of $400.
It entirely depends on the speed control system of a particular turntable whether this is possible, and if so if as easy to implement as you imagine.
Certainly a DC motor belt-drive TT is the most promising, but an existing speed controller may not be designed for a wide range of adjustment as is, just a few percent either side of the selected fixed values.
The motor is a Hyejet-01 12V DC. I of course realize that audio can be slowed down a lot of ways, but like I said, this is for an art project - so I really need the physicallity of the turntable.
Hello Gutterne1983,
I would try to design a 12 VDC switching power supply with a very low, adjustable, switching frequency. The switching frequency would have to be determined experimentally.
Sincerely,
Ralf
I would try to design a 12 VDC switching power supply with a very low, adjustable, switching frequency. The switching frequency would have to be determined experimentally.
Sincerely,
Ralf
The Lenco L70 (and Bogen relatives) turntables have continuously variable speed adjustment from about 15RPM to over 78RPM. E
That's regulated. It will keep the "right" speed until the voltage is so low it stops spinning. You want a dumber motor.
That was my fear also, even REAL CHEAP old time portables had some kind of speed regulation to keep them stable. (sort of).
Feeding them less voltage/current only lowers torque until they stall.
Personally I would use *mechanical* means; say if belt driven I´d have a smaller diameter pulley turned on a lathe to be fitted on motor shaft.
Feeding them less voltage/current only lowers torque until they stall.
Personally I would use *mechanical* means; say if belt driven I´d have a smaller diameter pulley turned on a lathe to be fitted on motor shaft.
Hello Mark,
My expertise is in mechanics not electronics. I don't know if PWM is the same as what I have suggested. My idea basically involves applying the full 12VDC to the motor long enough to bring the motor up to a fraction of its full RPM and then turning it off, only to repeat the procedure. The rate of switching would be adjustable by a potentiometer in the control side of the circuit.
Sincerely,
Ralf
PWM is the same idea but done 1000's of times a second or more, using the inductance of the motor windings to smooth the current flow.
The motor is a Hyejet01, which has a small board on the motor itself that connects to the speed selector.
given the fact that at low speed SNR isn't that great in turntables , a cassette player can be modified much easier to work at lower speeds.Some can record at 9cm/s and play at 4.75 cm/s, mono portables or phone voice recorders allow half speed by design...
There is a lot of information on the internet on how to modify a non-quartz turntable to play 78rpm. It requires a resistor to change, and a switch so normal 33/45rpm playback is unaffected. This same technique can be used to slow the rotation, and in place of a fixed resistor a variable resistor can be used (ie, a potentiometer). Many dd turntables are suited to this conversion, many of the articles describe how it's done to a Technics SL-D2. The important thing to note that you need a non-quartz dd turntable for this easy modification. Once you are familiar with how the mod works it isn't too hard to read the schematic for different turntables to identify where the changes need to be made.