I neutered my F50

F-30, 50 and 100's

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Mark II
Posts: 83
Joined: Mon Feb 23, 2009 7:09 pm

I neutered my F50

Post by peedenmark7 » Mon Jan 29, 2018 9:31 am

I've had my F50 going on 9 years now , and I still love this thing !

What I have found though is that with each successive tube change [3rd to date], the amp sounds less and less like it did when i first picked it up.

The amp when it came to me had Mesa STR430 [green] in it with Russian 2 pre-amp tubes [I mainly use this amp for soloing, the contour is why I bought it]
It had that extra kick that my 70s Master Volume Marshall amps don't achieve without running my BOSS FA-1 in the chain.
Granted , I use RCA or GE 6550 which naturally have more headroom.

My first replacement was STR440 [red] and SPAX7 across the board. Sounded a bit bright to me, but after a break in period all was well.
Second tube replacement I did the same, with pretty much the same results.

This time I went with STR440 [yellow] and the amp is a total stranger to me. The gain is the same but it is a bit uncontrollable , and note articulation is really lost, the amp is sterile and brittle to me. Same pre-amp tubes were used.

So as Winged C stock is disappearing , I decided to give them a try and bought a quad.
The first thing I noticed is that note articulation is crazy clear, it's wonderful , but the wild contour gain that drew me in to the F series initially, seems like it's at about 70%, The low end thump the Mesa power tubes provided is diminished big time, and I feel as if I neutered the amp. I did buy the same Mesa SPAX7 pre amp tubes .

I then decided to try some tube rolling with some vintage glass as that is all I have. [damn cork sniffer]
I tried RCA 7025's, GE and Sylvania Military spec 12ax7 tubes, Amperex, RFT, Raytheon and even a Telefunken, in V1/2 , and eventually landed on
an early 70's Mullard Ecc83 in V2 which dramatically opened the amp up.
The sound stage for what ever that term is worth is absolutely glorious compared to what it was. I'm liking it.

Still, I am not loving the Winged C's 6L6, and am disappointed that I am feeling this way, because I love their 6550 power tube.
I guess the only way I can describe it is that my amp went from being a rectifier to almost sounding JCM800 which I detest.
The amp no longer has that F series grind.

I ended up putting the STR440's back in the amp and the thump and gain are back, and the Mullard in V2 has really brought some life to the amp that has been sorely missing with each tube replacement .

Seems like the smallest of changes can make a positive difference in a modern amp, same as in the old ones.
'64 Fender Concert Amp
'71 Fender Super Reverb
[2] '78 Marshall 2104 Combo's
Custom F50 head with matched 3/4 back 1x12
Custom F50 Combo
'87 Roland Cube 60 keyboard CK60
'88 Roland Cube 100 Keyboard CK100

Mark I
Posts: 22
Joined: Fri Jul 27, 2007 4:01 pm
Location: Los Angeles, CA

Re: I neutered my F50

Post by blackmonday » Thu Oct 18, 2018 11:05 am

I had the same experience - it didn't sound the same after a retube with JJs. I need to contact Mesa and get NOS tubes for it.

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