Recording 33 1/3 speed at 78 rpm

[Xertz]

So on my new Recordio it runs at 78 rpm, so I figured you could just pitch up music before you cut so it sounds normal at 33 1/3 rpm. What factor would you pitch this up by/how would you find it out?
- Otto

[markrob]

Hi,

You can do that, but keep in mind it will kill the fidelity. The cutter head is already pretty bandwidth limited. Perhaps 5Khz -7Khz max?? You just have to pitch the audio up by the ratio of the speeds. 78/33.33 = 2.34 times. However, if the cutter head is limited to 5 Khz, then on playback, you will have a recording limited to about 2Khz. That's pretty rotten performance, but you can give it a try.

I would stick with 78 to get started so you can get a handle on the system. Once you have this down, you can try the pitch shift process or look to modify the turntable to run slower either via modifications electrically or mechanically. Also look at 78-45 first as the ratio is smaller (1.73:1).

Mark

[Xertz]

Thanks Mark. I have the service manual, plus some old threads on lathe trolls that can help me modify the turntable speed on the lathe.

[Xertz]

In a catalog with the cutting head itself in it that says the head could go up to 10,000 hertz, so maybe if I modify the preamp I could get it up to full capacity.

[venusloungerecords]

Are using the X41 or the X26 cutterhead

[piaptk]

Another problem is that you can only get decent fidelity and noise floor at 78 by cutting lacquers or diamonds. Embossing at high speed sucks. The needle can't get a very good grip.

[concretecowboy71]

If the motor is a synchronous motor, the speed is dependent on the frequency of the power coming from the wall, not the voltage. It is a bigger challenge and more costly to change the frequency of the power than the voltage, so keep this in mind. More likely is that the capstan can be machined or replaced with a different size to change the speed by mechanical means.