Posted: Tue May 31, 2005 10:40 am Post subject: Variac Redux -- Variac questions for Daved
Daved,
In the photos of the red variac you're using I couldnt see if the readout is an LED display of meter. Can I assume meter?
Is it one of the 3 Amp Chinese models? If not 3 Amp, what amp rating do you use. (It looks a rather nice size).
And, finally, can you or do you trust the meter on that variac or do you read it out by separate meter?
Overall, would you recommend the one you use or do you have any other insight, warnings or advise to offer a variac buyer?
I'm interested in getting one for use in a converted barn where power gets a bit hinky at times (and, of course, venues and bar where power is ALWAYS suspect). I believe I'd be doing my old Fenders a favor by actually getting the power they want to see.
Joined: 08 Aug 2003 Posts: 943 Location: Terra Firma, Ether Sea
Posted: Mon Jun 06, 2005 10:20 am Post subject:
S,
The Variac has a small meter installed, but I like to also use a larger display (easier to see from a distance), plug-in meter (available thru RadioShack), plugged into a multsocket adapter at the Variacs output along with the main feed to Robben's rig.
I recently replaced the old Variac, which was finally deteriorating after 5 years of heavy worldwide travel, use, & abuse, with a new one I picked up at Electronic City in North Hollywood. I have seen them in black, but I like the "Danger! Trons!" red color, myself.
Though they do make both larger and smaller models, I use a 5 amp model with 3 pin, grounded, plug and socket. Less than 10 lbs., it is easy to transport in my small workbox, Lassie, with a minimum of weight issue when traveling, while still providing plenty of power. I run ONLY, but ALL, of Robben's rig, FX, and pedals thru it and it has held up well. It blows its fuse, from wear & usage, about once every 18 months, but that is easily replaced.
Robben has loved his from the very first show I used one on and actually gets panicky these days if he doesn't see it in use.
Remember, tho, it does not automatically correct so you have to keep an eye on it and manually adjust when ocassionally necessary. _________________ B C-ing U!
( }:-Daved
"This boy's diseased with rhythm!" -Bing Crosby (Road To Rio, '49)
Joined: 04 Nov 2003 Posts: 886 Location: SF Bay Area
Posted: Fri Jun 10, 2005 9:45 am Post subject: Blowing fuses
Daved, fuses should not "wear out", but your comment about them blowing every 18 months or so, makes me think of the stage senario.
What happens when Robben's rig goes off in the middle of a song? I'd bet his first reaction is to turn around and look at you. But what steps do you run though to figure out if the amp fuse has blown, the Variac fuse, the FX has cut out, or whatever? Those of us who don't have the benefit of your quick reactions at stage right, could learn from what an experienced guy does when the world goes dark. Rather than just look at the rest of the band and shrug. _________________ There are no such things as wrong notes, there's only the look on your face.
My Stuff: www.stevekirbymusic.com
Joined: 08 Aug 2003 Posts: 943 Location: Terra Firma, Ether Sea
Posted: Sat Jun 11, 2005 1:59 pm Post subject: Re: Blowing fuses
Aeolian wrote:
Daved, fuses should not "wear out",.....
I'll get to the second half of your post later when I have a little more time (I just got back home from the ABB gig at the Bonaroo Music Fest near Nashville), but I did want to address this interesting, and seldom examined, comment of yours... it is something I have thought about and do have my own opinions on (be they right or be they wrong ).
"Fuses should not wear out". This IS what 'they' say and I, too, went under this assumption for many years, but...
I have changed many, many a fuse thru the years... fuses that just out of nowhere, for no paticular reason that I can observe, decide to open up. In my earlier years, a blown fuse always put me on edge 'cause I figured "a fuse should not wear out"... therefor, there MUST be a problem! Often there is, but...
A clear percentage of the time fuses just seem to blow with a seeming amount of unexplained randomness. Maybe the cause is so quick and temporary that it can't be traced or defined (A spike? Then why did no other circuit breakers/fuses-in-common crap out?). A quick swap of fuses and, boom, the unit runs fine for years, till the next one inexplicably gives out.
I've thought about this and I've wondered...
A fuse is effectively, a resistor of sorts. Run too much current thru it, it generates heat and burns up, which is also like a light bulb... a resistive length of wire... run a certain amount of current thru it, it generates heat and does a controlled burn in a life lengthening vacuum, producing light.
Both resistors and light bulbs, because they generate heat thru resistence, gradually deteriorate and eventually fail. Some take longer than others, dependant upon their design, construction, and in-use load, but they all do eventually weaken to a breaking point.
A fuse may have extremely low resistence, dependant upon the amperage of it's designed failing, but still they DO have a resistence.
Both normal 'safe' operating voltages along with higher voltage demands or spikes (even if those voltages never quite reach the failure point) are generating heat, little as it may be.
I can't help but think that eventually the molecular structure of the resistive strip/wire inside the fuse will "wear down" to a point below what it is designed for and, like everything else in this life/world, die.
Make sense? What are your thoughts? _________________ B C-ing U!
( }:-Daved
"This boy's diseased with rhythm!" -Bing Crosby (Road To Rio, '49)
Joined: 06 Oct 2003 Posts: 70 Location: Lake Tahoe
Posted: Fri Sep 02, 2005 4:09 pm Post subject:
That seems very logical to me.. I've never thought of it that way.
Thanks for the excellent analogy Daved.
I've been wanting to get a variac myself for some time. I'm also interested in biasing my own amps, so it looks like I might be doing some research on 'scopes too. Any recommendations?
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