Tube fuses

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corndog71

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Tube fuses
« on: 21 Apr 2013, 06:15 pm »
Roger,
At the end of the bio on your home page you briefly mention putting fuses on power tubes.  Can you elaborate on this practice and offer any tips to the DIY builder?

corndog71

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Re: Tube fuses
« Reply #1 on: 2 May 2013, 08:22 pm »
I'm guessing this is somewhat proprietary or something because I've spent the last week poring over hundreds of posts here in the MR forum and have found very little information.  It seems this is something only Roger does although I haven't studied other high end manufacturers extensively.  I've gathered a little bit of intel from my observations but this only gets me so far.  As someone interested in DIY tube audio it would be nice to include this feature in my projects.  If it saves tubes or the rest of the amp then why not?  I don't mean to sound like some blind follower regurgitating an idea simply because someone like Roger believes in it.  I really want to learn and understand the application. 

I built my first tube preamp roughly 15 years ago off of an old Glass Audio project posted by Eric Barbour which is essentially the same as the one Roger shows in his excellent video.  I wish I could've had that video and known more about Roger back then.  He does seem to be a good teacher and just by reading his posts here I've learned a great deal. 

I've rebuilt several Dynaco amps as well as a Bottlehead amp and a few preamps.  I understand a lot but am still catching up on all of the math behind it. 
After reading a good chunk of this forum I've learned a lot in the last few days and I think it's even starting to sink in. :thumb: 

My current and ongoing project is a modified version of the Dynaco ST35 which uses the driver circuit by DIYTube.com and includes the EFB mod from Dave Gillespie as well as a tweak or two by me.  Next I want to take a stab at building Bob Latino's ST-120 but again with some changes/tweaks.  Nothing too fancy.  A different chassis and layout so as to allow for different parts.  I just want to put a little bit of my own spin on what others have started.  I would love to get my hands on one of Roger's amps but they're just a little bit out of my reach.  That's the nice thing about the dynaco designs:  I can build them piece by piece if need be. 

Roger A. Modjeski

Re: Tube fuses
« Reply #2 on: 19 May 2013, 02:45 am »
nothing proprietary here. Just get some high breaking fuses, we have them here. Put one in the B+ leg or individual cathode of your dynaco. If you don't mind some exploding glass just use a 1/2 amp fast glass in an open clip holder, otherwise you might melt the holder when the element vaporizes. if you put the fuse in the cathode circuit it is less likely to explode. Its really no big deal but manufacturers who don't do it are just lazy or stupid. And of course no TUNING FUSES, they have zero protection because they are really stupidly made.

corndog71

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Re: Tube fuses
« Reply #3 on: 28 Jul 2013, 10:14 pm »
I had a question but I think I found the answer to it.  :thumb:
« Last Edit: 6 Aug 2013, 02:13 am by corndog71 »