Bypassing Amplifier on Presto K8 Lathe

[Retrosmith]

Guys,

If I were to buy a Presto K8 lathe, how difficult would it be to bypass the built in amplifier and just use a solid state amp to drive the cutting head? How would I kill power to the amp, but not the motor?

Any help is appreciated.

thank you,
Retro

[displacedsnail]

Hey Retro, that's pretty straightforward. I took this photo from an eBay listing. You'd just unplug the cutting head from the amp (circled), and use those plugs to instead connect to a different amp. You might have to do some work to replace the ends with something else - I usually strip the wire at the end and add spade terminals and mount a terminal brick, you can do that for about $5 with stuff from your local hardware store.

You'd still have to power the amp on to power the motor, but now you can use whatever amp to power the head.

If this is your first lathe, and depending on your budget (if you're, for example, looking at some of the K8s for sale online in the $2.5-4k range), I'd check with Mike Dixon // piaptk (recordlatheparts.com) first about what he has for sale, he can probably get you something comparable but better in terms of features, particularly if you're not going to use the amp. He offers full tech support on his restorations, too.

[Retrosmith]

Thank you very much for your reply. I appreciate it.
While I have been offered a good trade for a K8, I dont plan on using the old 1930s tube amp inside. It appears , as you say, you have to power the amp on to get powerr to the motor. I'd rather not have that old amp cooking. Also the K8 is fixed groove width.

I think I'm going to hold out for a lathe table that has different feedscrews and no amp, and use one of my spare solid state amps to drive the head. Maybe a Presto 6N or 8N. But the prices scare me!!

[mratx]

Clearly the move is to hold off on buying anything until the DinSync NC V8 is out and can be evaluated, since that looks to be an overhead with a stereo cutting head and variable pitch for a good price. Supposedly available sometime next month. If it's good, you just add a modern amp and high torque turntable and you're off to the races!

[displacedsnail]

Hey Mark, yeah, the DinSync looks really interesting! Do you think it counts as entry level for a lathe? I have to watch more videos, haha, but it looks great. I might not be able to resist getting one for myself just because I'm curious to test it out.

Retro, give Rek-O-Kuts a look, I'd say they're the machine sitting between K8's and 6N's. I use a Presto 6D and two Rek-O-Kut Challengers to make my discs, and I'll be honest with you, sometimes the ROKs sound just about as good as the Presto, but cost way less. Both have been modded to have cranks, they're fun machines that are highly mod-able and pretty sturdy.

[mratx]

Because Rek-O-Kut sold their overheads separately, it's relatively easy to find one for sale. You don't have to buy a Challenger or Imperial, you can just pick up a ROK overhead and a cutting head (ROK units usually didn't have great heads, so buying an overhead without a cutting head and buying the head separately is probably a better route.) Match it with a high torque turntable of your choice, and then just use it with a modern amp (you may need a matching transformer depending on the head impedance.) I'm with Joe, you can get a pretty good sounding cut with a ROK with less of an investment than a Presto.

But I am very serious in terms of saying you might want to wait a few weeks and check out the Dinsync. Stereo plus variable pitch, neither of which are features of the lathes you've been looking at? Sign me up!

[Retrosmith]

So.....thanks to mratx, I just checked out the videos of the Dinsync.

In a word...I am STUNNED. Customizable groove width. Stereo cutting. Cuts on plastic discs (not sure if those were PVC or not, tho.) Have they announced the price?