Re: [looper's] RE: Tube amp HUMMMMMMM...Ground?

[Dave Stagner <dave@spnz.org>]

On Tue, 2003-04-01 at 12:09, Mark Sottilaro wrote:
> I will try that for sure, couldn't hurt.  I've always wondered how long  
> will a 12ax7 preamp tube last?  I've got a Digitech 2112 (that's been  
> upgraded to the 2120) that's got the original tube it came with.  It's  
> got to be almost 10 years old at this point.  I don't use it as much as  
> I should, but when I do it seems to work fine and it sounds good to me.

A 12AX7 will probably last effectively forever, if it lasts the first
ten minutes. Life is pretty good for low-current preamp tubes. Power
tubes are the ones that suffer. And power tubes suffer mostly due to the
complete disregard amp designers showed for their design ratings in
order to get more power. For example, a Fender Deluxe operates the 6V6
power tubes at 425v, 75v over their design limit! Old Marshalls made
similar abuses. High-quality older tubes can survive this, but cheaper
modern ones cannot. :(  Another power tube problem is guitarists not
matching impedances properly, which can increase load on already
stressed tubes. 

And overworking the tubes isn't necessary for good tone, either. The
best-sounding amp i ever played was a Dr Z Route 66, which positively
babies its tubes. Wish i could afford one!

If you can easily swap the tube in your Digitech, get your hands on
several and taste-test them.  There's a lot of variation in 12AX7
sounds. Play loud to test for microphonics, tho. 
-- 

-dave

"...'cause she knows that it's demanding to defeat those evil
machines..."
 -The Flaming Lips, _Yoshimi Battles the Pink Robots pt. 1_