5F4 - FAT mod

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bluesfendermanblues
Posts: 1314
Joined: Tue May 22, 2007 12:57 pm
Location: Dumble City, Europe

5F4 - FAT mod

Post by bluesfendermanblues »

Dear all,

I'm new to this forum - this is my first post, but I have already read a lot of the 'old' posts.

I have recently build a 5F4 Tweed super clone - very close to stock, using hammond transformers and a chassis from TAD.
Speakers are a pair of Weber 10A125, (which I used to use in a RI Bassman 59 - so they are well played in)

As you probably all know, a 5F4 is a pretty simple and straight forward amp, and it worked flawless at first power up.

However, a 5F4 is one of the more bright tweed amps and is often referred to (on the clone companies websites) as the perfect humbucker amp. I'm a strat player, so what do a guy do?

I searched a lot of forums - this one included - in order to get some tricks to fatten up the tone. Have tried all tricks in the book:

After a lot of experimentation I have arrived at the following fat switch - (BTW I didnt 'invent' this feature, but am only posting to share my personal experience that this is a usefull to mod the tone stack in a 5F4):

Fat switch:

Installed an on-off-on switch with a 500p Mica cap and a 1000p Mica cap - between V1 and V2 below the chassis - that can put none of one of the caps in parallel with the 250p treble cap. It provides you with the following sound options:

Pos 1 (adding a 1000p): sounds like a big fat Tweed Twin 5E8a
Pos 2 (no extra cap): stock 5F4 circuit
Pos 3: (adding a 500p): sounds like a 5E5 pro


Cathode Bias Switch

I have also used the 'ground' switch for cathode bias with a 250 ohm parallel by a 50uF cap - this option sounds very close the sotck fixed bias option.

Paul C mod

Have also tried the Paul C mod, but IMO it didn't do anything for the tone of this amp (same goes for a new build 5E3). Paul C used this mod on a Princeton Reverb, but according the himself never on a tweed: http://www.firebottle.com/fireforum/fir ... x&enter=go

Hope this info is usefull to some of the 5F4 cloners out there!
Diva or not? - Respect for Mr. D's work....)
bluesfendermanblues
Posts: 1314
Joined: Tue May 22, 2007 12:57 pm
Location: Dumble City, Europe

Re: 5F4 - FAT mod

Post by bluesfendermanblues »

Tried another 12ay7 in V1 - major difference. Now the amp is full and Balanced.

The above mentioned switch is still a nice feature. And if you want tweak the tone stack in a 5f4, upping or lowering the 250p has a major impact on the tone.
Diva or not? - Respect for Mr. D's work....)
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M Fowler
Posts: 14017
Joined: Wed Jan 16, 2008 2:19 am
Location: Walcott ND

Re: 5F4 - FAT mod

Post by M Fowler »

Welcom to TAG,

I haven't built this particular amp but have you tried different rectifier tubes since this one is 3A 5U4 you could try some other 2A varieties.

How about jumping the two input jacks like an old Marshall or 5f6 Bassman?

Mark
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