Author Topic: F-1X replacement Tube (Read 283 times)

markhvn · « **on:** December 05, 2005, 10:04:16 AM »

Hi. My F-1X is 8 years old and I am wondering if I should replace the Tube. Since it has worked fine for that long, what is the opinion of replacing the Tube for Sonic purpose; that is how the sound could improve. I would only want one that is built as good as the original (12AX7 i recall). Any suggested specific brands would be appreciated. Mark H

David Houck · « **Reply #1 on:** December 05, 2005, 11:31:30 AM »

Hi Mark; there was a recent thread on this very topic. If your F-1X is only eight years old, the tube probably doesn't need to be replaced unless you're just wanting to experiment with the tone.

bigredbass · « **Reply #2 on:** December 05, 2005, 11:48:34 AM »

DHouck

I've always wondered:

As regards the tube in an f1x/f2b ( or any of the tube pre / solid state power amps ), is there a biasing involved in the tube replacement, or do you just change them like a light bulb (provided it's the right bias tube)?

J o e y

David Houck · « **Reply #3 on:** December 05, 2005, 12:12:14 PM »

I have no idea. The last tube I had changed was in a Hartke head, and that was done at the factory eight years ago. Before that would have been maybe 25 years ago changing the tubes in a Fender Bassman head; and I don't remember anything about that at all.

In the FAQ section, Mica just says that the tube is easy to replace. There is a shielding sleeve you slide down, then pull the tube straight out... Once the tube is out, you can push the new one in and slide the sleeve over it. The only thing to be mindful is that some tubes are made too fat and the sleeve may not fit.

markhvn · « **Reply #4 on:** December 05, 2005, 01:14:40 PM »

Thanks, I will see the recent thread.
Well, maybe I should keep it as is!
thanks
Mark H

dfung60 · « **Reply #5 on:** December 05, 2005, 03:59:00 PM »

Joey -

Preamp tubes don't require biasing. The signal levels are low in the preamp stages and a single amplification stage in the tube handles the entire signal from maximum positive to maximum negative (that's class A configuration).

In the power amp stages, voltage and current required to drive the speaker is high, so the signal is split between a pair or multiple pairs of tubes, so a single power tube covers only half the output. For even higher power (this means only more than 100w, so it's not that high!) there are multiple pairs of tubes in parallel. In this kind of amp configuration (this is class AB), you need to adjust the bias to properly set the mid point between the tube pair (or pairs).

Since a single tube handles the entire signal in class A and most of the signal is amplified in the sweet spot of the tube's response, it has the purest and sweetest sounding tone of any amp configuration. But for power stages it would limit you to only about 30w RMS and is very power ineffecient as well.

The 12AX7 tube used in preamps actually has two indepenent amplification stages so a single tube can do two channels or (more commonly) handles multiple amplifications stages in the preamp.

David Fung

bigredbass · « **Reply #6 on:** December 05, 2005, 04:47:18 PM »

Thanks, David !

J o e y

cosmic · « **Reply #7 on:** December 07, 2005, 05:46:20 PM »

Mark,

i swear by JJ tubes. I have them in all my Fender amps and my Eden head. Personally, I would not consider any other tube.

You can get them at Eurotubes.com. If you email Bob via the website, he will pick out a tube specific to your amp/needs. He is very responsive to what you want.

For example, on a Fender amp I had, he picked out specific preamp tubes and power tubes to match the breakup I was looking for on the clean channnel.

JJ tubes are excellent and much warmer and harmonically richer than your standard sovtek/groove tube/generics.

kmh364 · « **Reply #8 on:** December 08, 2005, 05:20:57 AM »

I've got the JJ's (Tesla) in my custom Straub Cantus amp (50W hot-rod Plexi-style amp)...both 12AX7's and EL-34's. The amp was voiced around these tubes after a lot of hand-picking, listening and tweeking by Harry Straub. It sounds awesome! Despite all that, Harry swears by the Mullards (pre-amp tubes)...he tried them and ended up using them in his daughter's amp, which is similar to mine. They're very pricey, however. The JJ's are good bang for the buck.

gare · « **Reply #9 on:** December 08, 2005, 06:28:47 AM »

JJ tubes are excellent and much warmer and harmonically richer than your standard sovtek/groove tube/generics.

I'll second that, I have JJ's in a M-2000 and 400+ preamps, and they were a nice improvement over the originals. I also just recently put JJ 12AX7 and EL-84's in my Studio Caliber amp as well and very happy with the results.
Their tubes are reasonably priced as well.
One day when I get the time, energy, and money I'd like to try Mullards/Telefunkens etc.
But, like Kevin said, the JJ's are alot of bang for the buck. I think the 3 tubes for the M-2000 were $37 including shpg and I had em in my hands in 3 days.
Good luck.
Gary

gare · « **Reply #10 on:** December 08, 2005, 07:41:28 AM »

Oppps..double post...darn sunspots

(Message edited by gare on December 08, 2005)