How to change tubes on an F-30

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louiev

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Hi Everyone,

I finally got my new set of tubes for my F-30. I was wondering if anyone can help me on the steps on how to change the tubes on the amp head.

Do I need to remove the chasis so that I would be able to replace them easily or do I just keep it on while replacing?

How do I take out the metal holders that holds the Power tubes.

And how do I go about changing the tubes? Any tips?

Thank you so much in advanced.
 
Well...the first thing you should do is set the amp on a table so you can clearly see what you are doing with out bending down, have the tubes at eye level etc.
Only remove the grill/back cover for access to the tubes...nothing else.
The metal covers are spring loaded so if you twist them they should just pop off...gently rock the tube back and forth if it proves difficult to come out...otherwise it should really just come straight out, dont force it in our out.
Allign the pins to the socket before adding to much pressure on the tube ..you will feel it locating in the socket and then push in.
Replace metal covers by turning and twisting.
I own an F50 but its bound to be very similar.
I'm sure some of the members on here have further info...but yill be grand!
Cheers
Paul
 
Paul pretty well nailed it. I might ad that the metal covers are removed by pushing up (toward chassis), and then a turn to the left (counterclockwise).
And when removing the old tubes, while pulling down, gently rotate in a small circle . . . kinda like pulling a cork out of a wine bottle.
Replacement is not too heady either. The preamp tubes have small pins. You must note where the gap is in these pins (like one is missing).
And look at the socket it is going in, line up the "gap" to the one in the socket and gently push and rotate like when you pulled them out.
The power tubes (larger) have a "key" down the side of the plastic shaft. This MUST! align with the key in the socket.
This is why it is important to set the amp where you can clearly (use a flashlight) see the sockets.
I usually lay the amp down on it's face to access the tubes.
Also, since you seem to be new to this, pull one out, replace it, pull one out, replace it, etc.

Not a big deal. You did get Mesa tubes right? No need to re bias if you did. Otherwise, you may need to take it to a tech to have it biassed.
 
makeuacaster said:
Paul pretty well nailed it. I might ad that the metal covers are removed by pushing up (toward chassis), and then a turn to the left (counterclockwise).
And when removing the old tubes, while pulling down, gently rotate in a small circle . . . kinda like pulling a cork out of a wine bottle.
Replacement is not too heady either. The preamp tubes have small pins. You must note where the gap is in these pins (like one is missing).
And look at the socket it is going in, line up the "gap" to the one in the socket and gently push and rotate like when you pulled them out.
The power tubes (larger) have a "key" down the side of the plastic shaft. This MUST! align with the key in the socket.
This is why it is important to set the amp where you can clearly (use a flashlight) see the sockets.
I usually lay the amp down on it's face to access the tubes.
Also, since you seem to be new to this, pull one out, replace it, pull one out, replace it, etc.

Not a big deal. You did get Mesa tubes right? No need to re bias if you did. Otherwise, you may need to take it to a tech to have it biassed.


Yes I was able to get tubes that we're matched for my Boogie. I bought mine from doug's tubes. It's sounding great now! The volume issues we're gone when i replaced the power tubes.
 
One bit of advice for any new F-30 owner is that EL84 tubes do have a shorter 'sweet' life than bigger bottles like 6L6 or EL34s. I recommend replacements for the power tubes every 7-9 months. YMMV...
 
How important is it to buy Mesa tubes really? Shortly after getting my F-30 a few years ago, based on advice in some forum somewhere, I switched out the Mesa EL-84's for Tesla' EL-84's with no apparent ill effects (and not much change in tone either despite the advice I was following). Also I played around with changing the 3 gain stage tubes from Mesa 12AX7's to 12AX7, 12AT7, and 12AU7 tubes from JJ and decided to stick with the JJ 12AX7's. I have not had any re-biasing done.

What would I hear of the bias was only slightly off?
 
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