Need helpo getting a Presto up and running

[lodubsrecords]

Hello all! I'm a a long time reader of the Lathe Trolls for the most part due to basic curiousity, but as I started looking into doing poly cuts as a aspect of one of the record labels I run, I started thinking about it more seriously, and then a presto appeared in front of my eyes (Well, on Craigslist...).

It's a K8, and although I've done a lot of digging on the site, I can't seem to find much information on them! I've been talking to JayDC about it a bit (He kinda kicked off my interest, and I just released a 12" of his stuff). PIAPTK also has provided me with a bit of insight.

I am hoping I can get this going, and figure out what I will need to do to get decent cuts off with it. From what I understand, it is best to set it up with some sort of bypass of the amplification it was designed with, along with some sort of EQ to adjust the input signal.

I guess I am hoping I can find someone here who has worked primarily on techniques for use with this model, and can maybe suggest to me a good amp, setting it up, etc.

It came with a few styluses, and some other bits (Picture below) one looks like sapphire, but I couldn't really say.

Any suggestions as to what direction to go would be very helpful. Thanks!



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[markrob]

Hi,

A lot depends on your skills. Are you good at working on mechanical and electronic equipment? With a little bit of restoration work, you should be able to get this up and running. As to the quality, I would not expect the results to compete with the higher end lathes (even a 6N/1C combination). I assume you been to Alan Graves Presto site.

http://www.prestohistory.com/Presto.htm

You can get manual re-prints from him and perhaps some guidance on restoration.

Of course, you can pay sombody to do this, but it could get costly. Using external electronics is a great option as this will eliminate the need to restore the old tube electronics. You might even be able to recoup some money by selling them on ebay. If you go that route, then you only have to consider the mechanical restoration. I think that might be easier to understand.

Mark

[opcode66]

Hey, good for you Jon! You're in for a long road ahead man. Basics...

You need to figure out what is working and what is not. Does it power up? Does the platter spin smoothly? Might need some oil. Does the platter motor work? Do the pucks for speed control work? Does it actually spin at 33.3 or 45? When fed a signal, does the VU meter ping? When fed a signal, does the cutterhead vibrate? When the cutting arm is engaged and the platter is spinning does it make a smooth migration from the outer edge to the center of the platter? Does it get stuck anywhere along the path or slow down anywhere?

These are the basic things to start checking. Once you have checked and fixed anything electrical and/or mechanical and the lathe functions appropriately you can move on to the next steps.

Does the cutterhead function, not just vibrate, but function? You can use the built in amp as long as all the tubes are working. If not I can tell you a good source for old new stock of tubes. This will at least tell you if the head works. After making some test cuts into acetates you'll be able to tell if it is in working order. If it doesn't work or sounds horrible you might need to have it rewound by Gib at westtech.

Then you can start to figure out a replacement for the amp. I'm fairly certain you need an amp that is 8 ohms for that cutterhead. You only need mono, but a stereo amp is fine. We can look that up that spec down the road when you get there. It would be in stated in the specs for that cutterhead. And, yes, if you want to cut standardized masters you would need an RIAA EQ Curve implemented in your mastering chain.

But, a few things to take into considerations here are... This will only cut mono records. This cutterhead has an upper frequency cap at something like 10Khz. Not exactly sure on this. But it is certainly at or below 15K. Again, we could find the specs and determine. The point is, you'll be missing the upper high end. There is no way to setup suction on a lathe like this so if you are cutting, your chip will always be falling on your cutting surface. You'll need to brush it towards the middle as you cut. This sort of counterbalance for the head doesn't allow you to adjust or add downward preasure so I don't think you'll be able to cut plastic. Even with a diamond cutting stylus. I think you'd be able to emboss plastic at best. This cutterhead can not handle excessive volume. You will not be able to make hot cuts. You would smoke the head if you tried.

That's all I can think of off the top of my head. There are a number of people who are cutting on old portables like this one. I'm sure you'll find all the help you need here on the board. I think it's great that you have the ambition to give it a go yourself. Best of luck!

[lodubsrecords]

Thanks for the checklist! yes, it is a fully functioning unit, other that the speaker being disconnected as the chord was all rotted out. The platter spins true, and is set at 33 right now, and the arm seems to be migrating smoothly.

I need to feed it a signal (I tested in when I bought it and it was getting signal through the meter and the head), and figure out something I can use to do a test cut to, so I can go to the next step. Any suggestions on what kind of material to try out on it?

[shawnborri]

First of all it is from the late 30s, early 40s. Know that all of the capacitors should be replaced the electrolytic and waxed paper foil kind. The cutter head needs to be cleaned and adjusted, and the power wire to the motor is probably dry rotted, all other wires being cloth covered are usually fine. I just re capped the amp on Innerspeaker's K-8 and the amp is quiet, it plays records fantastically cleaned the pots and adjusted the cutter. I even have a low Z to high Z adapter so I can plug my RCA 44bx ribbon microphone.

[rsimms3]

You said the platter runs true, does it have any flat spots or indentations on it? Also, did it come with the 78rpm adapter or possibly the 45rpm adapter (45 adapter is tougher to find and usually included with K10 models). Also, you should be able to run the motor without turning on the amp. When not in use, make sure to pull the motor back so that the capstan doesn't sit on the rubber tire and cause a flat spot from sitting engaged. If your rubber tire is a bit cracked, you can turn it inside out to improve the surface qualify if the inside is better than the outside. You should also check the long bolts that hold the motor to see if they are bent. If they are, the capstan may not engage the tire flat with even pressure, but based on your pictures it looks squared as it sits. As mentioned, pull the motor and clean it up/re-lubricate it.

[Snakeheadfishlab]

Nice unit,I have the same one,had it re capped and new tubes.let me know if you need a guy to do that.
Peace
Jb


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[EvLoutonian]

Nice looking unit.

I have a similar machine, but I think it's older (brown colour-scheme) but also marked as TYPE K on the front panel.
Mine was unfortunately in advanced "ratty" condition when I got it recently, so I'm slowly trying to work out what restoration is needed to get it up and running.. Beginning with just re-gluing the ply laminations on the case, and glueing loose tweed style fabric covering back down securely! ha
Inside it looks reasonably clean, but the surface of many of the components shows corrosion also.. hmm.. may or may not be fruitful in the end.
I'll start a proper thread about it here one day.

Meantime, shall be very keen to hear more about your project, and how you're going with it!
Please post an update when you get time?

All the best,
Evan.

[EvLoutonian]

PS. mine looks like the one on the left in this pic:
http://i4.photobucket.com/albums/y108/Karlfalcon/Audio/STA70522_zps999c5fd4.jpg

- Except mine is more "road worn", and the brown crinkle paint is flaking off the metal base section (which the platter is mounted to), and the head is Audax rather than Presto (but with no styli installed)..