Meta Luddite.
When I was a kid the family stereo was a Panasonic thing with a turntable on top a cassette on the right and a tuner in the middle.
(I found this picture on the Net. This is not our old one)
I found the model number by searching images online. Panasonic RS-257s.
My sister still has it! She still uses it! This is very Luddite. I asked her about the needle as I doubt it has been changed in 50 years. I went on a search for new one using my dim memory of what it looked like. It was one of those flipping ones on a crystal pickup.
That was a trip! My very first records were played on this beast. If I liked the music I would immediate record it to cassette and put the vinyl away. Remarkably little damage actually.
This thing has a crystal or ceramic piezoelectric cartridge. You can tell them as the needle could flip over to play 78s. Aside from the speed the groove in a 78 is very different than an LP and needs a point like a pencil lead, like 1mm. Carpentry nails are sharper.
It gets weird as there is a lot of, lets call it muddy, information on the internet. Many experts confidently claim as fact things that just aint. That is what I want to discuss.
Electrical signals in all magnetic cartridges are made by magnets or coils moving relative to one another to make a current in the coil wires. A magnet sitting by a coil makes no current. It has to move to create a current. Hence it is reading the velocity of the motion. These experts then say that causes the frequency response to vary as velocity is different that displacement.
A crystal pickup uses a piezoelectric device that reacts to displacement which is not the same thing they say. So the thesis says you do not need the same frequency response curve as a magnetic cartridge so you do not need to plug them into phono preamps. What was that line in Star Wars? "Everything you just said is wrong."
If you displace a piezoelectric crystal a voltage is created. But that depends on the displacement moving. If the motion stops the voltage stops. If that were not so we could have infinite electrical power by putting crystals in vices. So the voltage varies with the motion just like the current varying with motion.
The only real difference is one makes voltage the other current. Even that is not really different. Current and voltage are directly related V=IR.
This is not the same as a strain gauge which does not generate either current or voltage but varies resistance (in non-linear fashion). Lets not go there please.
So both of these methods depend on motion over time which is the definition of velocity. Now it gets fun. In mathematics the representation of displacement over time is the first derivative of position with respect to time. Pos dt=Vel. Sound waves can be modeled with Sine waves with the proper mix of frequencies and amplitudes. The derivative of a Sine wave is a Cosine wave of EXACTLY THE SAME SHAPE AND AMPLITUDE. The only difference is a phase shift of 90 degrees. So velocity or displacement, bottom line is it sounds exactly the same to our cave man ears.
Now when an LP is recorded with the RIAA curve (or other similar curves) the bass is cut and the treble boosted. The bass is cut to reduce the width of the grooves so all that music will fit on a 12" disk. It also means the stylus is subject to less low frequency violence that could throw it out of the groove. The low frequencies have the most amplitude and power in a music signal. That "correction curve" has nothing to do with what type of pickup is used. As the curve used in the cutting process is the exact opposite of the curve used in a phono circuit it is strong evidence that any device that plays acceptably well into a phono circuit from an LP is actually quite linear.
Some of these guys claim the RIAA curve is to compensate for the inherent non-linearity of magnetic pickups. WRONG. WRONG WRONG!
The ideal goal is the signal that comes out of the phono preamp circuit is exactly the same as the signal that went into the RIAA circuit and into amplifier and lathe that cuts the disk.
If a crystal pickup can be used in a linear input (not the phono) that is because it has a non-linear response that is close to the RIAA curve. None really have that. Many old stereos like the Panasonic RS 257 have custom circuits to make the response OKish.
I have heard this nonsense from several respected golden ears. They are not bound by logic. That is so limiting!
I found a source for a new needle so if she wants to not damage more records more than they already are she can refresh the thing. That would bring it up to be as bad as it was new.
A fun thing is during my trip back in time and space I found that there were quite a few of these old beasts out there. Some were picked up from garage sales others from thrift stores even granny's attic. I was surprised by the praise many had for them. They did not even grow up with them! Zero nostalgia content.
I knew it was crap when it was new.
