Audio Driver For Presto Cutter Head?

[hawkweed]

I own a working RCA Victor Lathe with a Presto cutter head. I recently bought some of the guts from an old Presto suitcase record lathe on ebay but its missing the electronics to power the cutterhead. Can I use a normal radio amp speaker output to power both heads by hooking the 2 heads together one left and one right so I can cut 2 records at the same time from one source?

[markrob]

Hi,

Yes, providing the Presto head is 8-16 ohms. You can get a good idea of the head impedance by measuring the DC resistance with a multimeter. If the resistance is under 16 ohms, you are good to go. Some of these heads were wound for 500 ohms and would read 100 ohms and up. You can use a matching transform to allow a solid state amp to drive a 500 ohm head. Do a search here to find some info on that if you need to do this.

Mark

[rsimms3]

I was watching that one on eBay. You have the basics of a K10 model. Lots of missing pieces including 2 of the 4 worm gears (assuming there was one on the platter with the other under the platter as pictured). Most folks only use 2 of them anyway, the two that control cutting from outside in, the other two are for inside out. The advance ball tip is also missing. I was interested in the platter and especially the rubber tire, it looked to be in good condition. I haven't looked into fixing/replacing mine yet but it's on the to do list.

[hawkweed]

Thanks for the help! How many watts can I run into it? I started rebuilding this with out the amp but I would like to set this up to add a 1/4 plug that connects to the meter then the cutter head. That way I can try different amps. Here's a picture of my presto rebuild. I used a vintage shoe/hat case for the new case

[Snakeheadfishlab]

I have been jumping out my presto 8k with a line 6 Spyder amp but you really have to watch it so you don't burn the cutterhead up.had some good sounding polycarbonate discs so far.


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[Jccc]

Hello, nice suit case for the k8! As for the wattage for powering the head any 20 to 100 watt amp will work . The higher the wattage the more volume you will be able to record. as long as the output impedance matches he cuttinghead. I believe the 5c is 8ohms as is stated in the k8 manual.

Also put a fuse protector line with the cuttinghead as it connects to the amp as to protect it from not burning out. Especially if you are going to run a higher wattage amplifier.

A vu meter will help out as well to give a rough area to see how hard you can push the head before the fuse blows out.

[hawkweed]

Thanks for the information. I have a vu meter inline and will add the fuse. I have a 120 watt sony amp I'm thinking of using. I'll keep you all updated on the progress

[audadvnc]

Back in the day, cutters used small public address amplifiers as cutting amps. A 10-30 watt tube amp would be plenty for your needs - any more is likely unnecessary and risks burning up the head winding.

As far as a VU meter is concerned - what level would you set as "0 dB"? I believe you'll need to compare a cut from your machine versus a standard reference disk (any commercial LP of the past 40 years will do). When you find the playback level on your cut disk is similar to one of those, dial in your meter appropriately.

[hawkweed]

I think I'll try a smaller amp just to be safe. As for setting up the vu meter I was going to get all levels set on my RCA victor lathe then connect my new meter and cutter head then adjust the vu meter to read the same levels as the victor. Am I trying to over complicate my setup? Could I just run the 2 heads off the amp of my victor by connecting to the same terminals?