How to play and record from a 78 rpm record?

Question

I can modifie a record player or fit an elctric drive to a broken wind up gramaphone.

What should the angles between lines on a strobe disc be to establish it is running at 78rpm usind a 50Hz lamp.

What pick up an needle combination is best to play the record?

or should I fit a mic to the mechanical speaker on the old gramaphone? if so what angle should I regrind the used needles to?

Answer 1

Probably easiest getting a turntable for 78 record which has a line out socket. That way you wont have to worry about the details of impedance matching.

Think there's something from signals theory that says ideally you are supposed to record (electronically) at twice the frequency you want to play back at.

I think that you can get the same effect by making the recording at 33 1/3 RPM, and then playing the recording back faster at a factor of (78 divided by 33.3333333...).

Fairly sure 78 needles are different to 33 ones. Not sure if you'd damage the record playing it back using a wrong needle (I know mono 33 needles can damage some 33 stereo recordings)

Answer 2

Remember a lamp on a 50 hz supply is running at 100hz.

So you need 100 stobe bars in the circle 3.6 deg apart

Answer 3

I know your looking for a mechanical solution but consider preserving the 78's into sound files

You can record the 78 into a sound file on your PC and use software to correct the tempo.  

Record your 78 record using a standard phonograph at 45 rpm then do a 57% time correction (42% for 33rpm) of the recorded audio file.

Many audio editing programs will do time correction. I use Acoustica version 2.5 .  You may also try open source software like Audacity

Answer 4

Get yourself a 1960s record deck that has 78 speed and a crystal pick-up with a sapphire stylus.  There are plenty around - try eBay.  The output from the pick-up can go straight to a sound card and you can use some sound editing software to tidy it up.