how to power a presto k10

Post: # 17822Unread post **secretmessagemachine** Thu Jan 26, 2012 1:52 pm

I recently purchased what I believe is a presto k10 cutterhead that I want to mount on my homemade lathe for embossing. Does anyone know how I can power the cutterhead? What is the ohm / wattage required for this? Since I don't have the amp that originally was part of this machine, is there a type of amplifier out there that would do the job? Any information would be much appreciated.

Post: # 17824Unread post **markrob** Thu Jan 26, 2012 2:51 pm

Hi,

You can get a rough idea by measuring the DC resistance of the coil. The actual impedance will be in the order of two times higher. So, if you measure 4 ohms, figure its an 8 ohm impedance unit. Most heads were either 8, 15 or 500 ohms. The first two, should be able to be driven by a modern solid state power amp. 10-50 watts is fine. 500 ohm is a bit tougher to drive with a solid state amp. You might need to add a transformer.

Mark

Post: # 17829Unread post **audadvnc** Thu Jan 26, 2012 5:35 pm

Add plenty of garlic to y... oh, you said Presto?

Never mind.

Post: # 17838Unread post **Jesus H Chrysler** Fri Jan 27, 2012 12:51 am

stock head for the k-10 was a 5-c I believe. If it is from a k-10 it should be 8 ohms.

Post: # 17869Unread post **maniman** Sat Jan 28, 2012 5:56 pm

Yes its labeled 5c , I try to use the K many times my 1C 15ohms and really i dont know if its mismatching impedance problem or what ... but the original k10 head achieve better results for me , if that "5C" (only rear side labeled) its a 8 ohms head i can explain that effect with my 1C.

And I take to throw a "bounce" question about the K , any info about the shaft right diameters for 33.3@50hz and/or 45@50hz for a 60 hz motor in a 50 hz mains ?

That diameter can be the same as a standard 1800 rpm 60 hz to 50 hz "idler wheel style" shaft ? i have one of it , and the diameter of the 33 rpm part of the shaft is similar of the one I can imagine taking in care the 33 (naked shaft) and 78 shafts @ 60 hz.

The K its a awesome device.

Post: # 17889Unread post **secretmessagemachine** Sun Jan 29, 2012 1:45 pm

thanks, it is a 5c cutter and i have it connected to a solid state amp. it rattles like crazy when the level is turned up. is this normal? also, is 50 watts the maximum this can handle? it seems that if i want to get any kind of volume from the cut (embossed) i have to turn it up above this point. its rattling like mad and i'm afraid of blowing it.

Post: # 17898Unread post **markrob** Sun Jan 29, 2012 6:35 pm

Hi,

It should only take a few watts to get a decent level. Are you doing any EQ or just trying to cut flat? Flat won't work. You need to at least try to simulate the RIAA curve. Try rolling off the bass below 500 hz and boosting the highs starting at 2Khz and level off around +13db at 10Khz. That should get you in the ballpark. Its possible that the damping material inside the head has hardened and will need to be replaced. The Presto heads are pretty easy to work on. There are some re-builders out there.

Mark

Post: # 17903Unread post **secretmessagemachine** Sun Jan 29, 2012 10:46 pm

yeah, i have applied the riaa curve and boosted the high end some. the overall eq is coming across well, but i have to really crank it to get any kind of volume out of it. it sounds great once i really turn it up, but don't want to keep it at that level. it starts to smell hot. perhaps that the damping material is hard. is that the plastic like material in front of the head? would this keep the volume lower than normal or is that a symptom of something else such as the magnet or coil.

my homemade cutter head has better volume over sustained periods, but the quality of the sound seems to be less precise (a bit more distortion / less clear). if i could get the volume of my homemade cutter with the clarity of the presto i would be happy.

Post: # 17904Unread post **Jccc** Sun Jan 29, 2012 11:06 pm

It could be that your cutting head has to be rewound. I have a Audax cutting head that was like that.

Then i sent it to Gib at West tech and he fixed it up. It cuts so much louder now

Post: # 17910Unread post **maniman** Mon Jan 30, 2012 4:07 am

Don't kill the messenger so early.... WHAT STYLUS ARE YOU TRYNG ? WHAT BLANK ARE YOU TRYNG ? If the system works .... are you tryng to use something more sharpened as stylus ? , if you are embossing with inox tip (i.e) the groove can be cutted / embossed easily (more or less) , but the freedom move achieved with a really sharpened stylus isnt the same as an emboss tip , for me that was be the reason of low cutting levels , y try to cut a very very superficial groove with a sapphire stylus on PVC and sounds 30 times better than a inox tip (AND ITS A MISMATCHING MATERIAL PAIR.....) , WITH A HEATED DIAMOND.... I'm sure the things gonna go in a very different way.

If you are tryng to cut strictly acetate / sapphire your head have a problem , but In any other case (not gem stylus or lost shapeness , harder material blank ... ) that result isnt representative of head problems. not ? , always is a relation between stylus sharpness and blank hardness , more sharpened stylus less weight on cut , more high end response , less surface noise ...

No Shaft diameter Info ? NO ONE IN A 50 HZ MAINS COUNTRY HAVE A K10 AND USE IT TO CUT LIVES ? I CAN'T BELIEVE IT...