Watt Recommendation for 8ohm Presto 1C

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skreebs
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Watt Recommendation for 8ohm Presto 1C

Post: # 47935Unread post skreebs
Wed Sep 27, 2017 1:20 pm

Hey guys,

I have been searching the forums and have not been able to find a definitive answer on what watt rating is best to use for a rewound 1c. It looks like the original presto amps were anywhere from 25 - 60 watts while I see recommendations all over the board up to 350. I currently use a 100 watt amp which really has not seem to cause any problems but I am building my own tube amp and was looking to see if anyone had any solid advice before I finalize the schematic?

Thank you all in advance!

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markrob
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Re: Watt Recommendation for 8ohm Presto 1C

Post: # 47936Unread post markrob
Wed Sep 27, 2017 2:57 pm

Hi,

You are probably OK with your current setup. Having reserve power at your disposal is a good thing as long as you don't abuse it. The 1C is pretty rugged and does not require tons of power to drive to full level. I have found that the distortion reaches bad levels long before I got into the region where the head was at risk. If you add an in-line fuse, you should be fine as far as protection goes. The head can probably handle 5-10 watts average power over a long time without burning up. 100 or even 350 watt short term peaks will not harm the head as long as you keep the average in a decent range. If you are cutting heavily limited program material, you will find that much lower peak power reserve is needed since the crest factor (peak to average ratio) is low. In that case, its easy to overdrive/overheat the head. As you try to push the high frequency response higher and higher, you need more reserve power for short term peaks and stand a chance of running into distortion and diminishing returns. Hope that makes sense.

Mark

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skreebs
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Re: Watt Recommendation for 8ohm Presto 1C

Post: # 47947Unread post skreebs
Thu Sep 28, 2017 12:37 am

Hey Mark,

Your response is perfect! Thankfully the previous owner already installed a fuse for the cutter head so we are set there. I also just found what you are mentioning in the 1-D manual and it looks like it is recommending to leave headroom of at least 10 times the amount of power needed to drive the cutter head so sticking around their original watt value in the 92a (60 watts) is the way to go. Correct me if I am wrong?

Thanks again for the help. Ill be sure to post more on the subject along with some pics once the build starts.

-Nathan

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piaptk
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Re: Watt Recommendation for 8ohm Presto 1C

Post: # 47988Unread post piaptk
Mon Oct 02, 2017 1:01 pm

I had no problem with 125-150w amps when I was cutting lacquers, picnic plates, etc. but when I started embossing plastic, I upped it to 250 (usually at 60-70% volume), because the plastic is so hard.
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