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Alembic F-1X needs repair....

CosmicRay

CosmicRay

Supporting Member
Jan 4, 2009
1,327
2,169
East Williamsburg Brooklyn NY
www.reverbnation.com
#1
Hey Now - so at rehearsal, my F-1X pre-amp lost half it's volume, after about one hour into the session.
Usually don't set it past 3-4, but even at 8-9 it was very weak.
I checked the power amp and cab with a different pre-amp and that was ok. So the issue points to the Alembic.
Could it be the tube? An easy fix maybe?
Any suggestions as to who can look at this unit in the NYC area? My amp tech retired.
Much obliged!
-Ray
 
#5
Dirk Diggler said:
Agreed the first step would be testing the tube or tubes, can't remember if there is more than one.
Your symptoms would definitely point in that direction.

In the old days you could go to any TV store or local hardware store to test tubes.
These days you need to find a local tube amp guy to do it.
Click to expand...

I remember back in the 70s you could buy tubes at are local pharmacists which also sold toys and was also a ice cream parlor I think the name was Skiffingtons.
 
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#8
gwangi said:
I remember back in the 70s you could buy tubes at are local pharmacists which also sold toys and was also a ice cream parlor I think the name was Skiffingtons.
Click to expand...
My dad would yank the tubes out of our RCA tv and we'd go to Thrifty Drugs to test and replace the duds. While you were there, you could get a skateboard, a cheeseburger, and an ice cream cone.
Memories
 
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#9
I have an F1-X also.
I experienced a loss in power also.....but I believe it turned out to be my SWR stereo 800 power amp.
The preamp sounds good through my Peavey tube amp classic 120
But....now I think I will have to re test everything.
I am sad to retire my SWR and if it is just my Alembic tube that needs replacing....well, I have plenty of those
 
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#10
logdrum said:
Walgreens liquor section is 3 times the floor and shelf space of their pharmacy. The also sell cigarettes and a cosmetics section. All forms of sweets and sugars and high carb. All of these before the actual pharmacy. So you grab things to f you up further before getting your prescriptions.
Click to expand...
Sounds like what 90% of my diet's been (or was) over the past 10 years. 2 days ago I finally paid the price for it -- had to have my gallbladder removed after 2 ERCPs, and I've got a 3rd one coming up. Stay away from that s__t, boys and girls.
 
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#11
CosmicRay said:
Hey Now - so at rehearsal, my F-1X pre-amp lost half it's volume, after about one hour into the session.
Usually don't set it past 3-4, but even at 8-9 it was very weak.
I checked the power amp and cab with a different pre-amp and that was ok. So the issue points to the Alembic.
Could it be the tube? An easy fix maybe?
Any suggestions as to who can look at this unit in the NYC area? My amp tech retired.
Much obliged!
-Ray
Click to expand...

A tube can fail randomly. I would roll a fresh 12AX7 into the preamp.

One potential problem:

In another thread the OP found out that some tubes are too fat to fit into the tube shield.
https://www.talkbass.com/threads/alembic-f1x-preamp-best-tube-replacement.1660390/#post-28685979
Here is the image I posted:
1763313808290.png

The tube shield is permanently attached to the tube socket, so it's not removable.

1763313962376.png

The top of the shield (in this image) slides down into the bottom so you can grab the tube and pull it out.

You might want to determine the internal diameter of the tube shield and see if your tube vendor can hand pick tubes that will fit.

If a fresh tube, working the controls, and inserting a jumper into the effects loop don't rectify the problem, probably time to send it to a qualified tech.
 
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#17
eniac said:
Sounds like what 90% of my diet's been (or was) over the past 10 years. 2 days ago I finally paid the price for it -- had to have my gallbladder removed after 2 ERCPs, and I've got a 3rd one coming up. Stay away from that s__t, boys and girls.
Click to expand...

I was warned of having heart disease and ended up with two angiograms (one of which was while I was on the road with my band) after massive pain, sweating, nausea, etc. When I finally switched doctors, the new one diagnosed me with gallstones within a couple of days. I had the surgery, and then went back on the road a week later on the tour from hell through the southeast, back to the midwest and ended up in a confluence of a Pacific Northwest storm and a Gulf Hurricane in southern Minnesota, after getting trapped in the middle of nowhere by mudslides and running up against a 6' 3" guy covered in tattoos named Butcher. That's just 10% of what happened on that tour. It was like a Coen brothers movie. 6 weeks later I took the LSAT....

But my F-1X was fine through it all!

These are great preamps and very easy to work on.
 
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#18
CosmicRay said:
Hey Now - so at rehearsal, my F-1X pre-amp lost half it's volume, after about one hour into the session.
Usually don't set it past 3-4, but even at 8-9 it was very weak.
I checked the power amp and cab with a different pre-amp and that was ok. So the issue points to the Alembic.
Could it be the tube? An easy fix maybe?
Any suggestions as to who can look at this unit in the NYC area? My amp tech retired.
Much obliged!
-Ray
Click to expand...

Great advice on this thread. I would definitely exercise the pots and the jacks on the back, especially the FX loop. There's a switch there that can get oxidized and will cut the signal. Pop the top and put some contact cleaner in there. DM me if you need a schematic.
 
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