Fender Blues Junior – what does the "Fat" switch do – technically?

[nosuch]

I use mine as a solo boost (with a footswitch) as it adds a bit (for me: just the right amount) of volume, fatness and compression. Personally I like the tone of it better than the boost side of my box of rock, any tube screamer or the EHX soul food used as a boost.
I'd like to know what goes on technically when I hit that switch just out of curiosity ...

 

[=JL=]

It probably brings in a cathode bypass cap on V1, that was certainly a common amp mod for years and it certainly sounds like that to me.

 

[danlad]

It does look to be exactly that. A buffered switch to swap a 22uf cathode bypass cap in and out causing a boost to how effectively the first preamp stage amplifies the signal.

Most preamps have it hardwired in, so maybe is more accurate to say the Blues Junior lets you reduce the preamp gain!

 

[nosuch]

You mean switching off the fat switch effectively reduces preamp gain?

 

[danlad]

You mean switching off the fat switch effectively reduces preamp gain?

Looks like it, yes. Compared to your common or garden Fender Blackface type preamp anyway with cathode caps right through the preamp.

 

[Lobomov]

So you guys are saying that playing with the fat switch on gives a normal amp construction, while having it off is actually a type of mod?

 

[flyswatter]

So you guys are saying that playing with the fat switch on gives a normal amp construction, while having it off is actually a type of mod?

Yes, which is basically what all switches do (unless operating some type of active circuit with a separate power supply, like a reverb circuit). Switches stop things from happening that would normally happen if the switch wasn't there. If you took the power switch out of an amp and reconnected the wires, the amp would be on all the time.

 

[rwhite219]

Thanks for the excuse to keep it pushed in forever! It does sound better but can be noisy.

 

[Henry Mars]

Thanks for the excuse to keep it pushed in forever! It does sound better but can be noisy.

FWIW the fat switch is always on when I play my Jr .. it just sounds better to me.

 

[Paul G.]

Old trick, giving you what you already have and telling you it's "more".

Fender did that on the old Blackface and Silverface Bassman heads with a Deep switch that attenuated the bass drastically when pushed down. So push it up for Deep tone, which was already there if the switch wasn't in the way.

P

 

[rwhite219]

Been using the "fat" Channel for the last couple hours. Really cures the boxyness problem. I wonder how many people have ditched the amp without trying this. Mine is the tweed/Jensen version and it's much rounder sounding. I wish fender would have left it out now.

 

[=JL=]

I honestly can't imagine that anyone would have ditched a 500 dollar amp without seeing what that little button did.
Many of us just think the Blues Junior sounds vile, whatever the control settings.

 

[nosuch]

I wonder how many people have ditched the amp without trying this.

Seems like many don't know that it can be operated with a footswitch. The plug is a bit hard to find – beneath the speaker out. Any standard footswitch will do, even a true bypass pedal like the joyo vintage overdrive as I found out (connect the output to the plug) can switch it.
I use the Fat function for the few songs I need a little "more" than my usual clean with a bit of hair tone. Not worlds apart, but a little more grease.

 

[john_t]

Just adding to this thread. I have the NOS version with the Jensen which sounds a little less muddy than the standard. I always had the FAT switch on - it was a no brainer. You turn it on - get badass sound, turn it off and get something that sounds awful in comparison. However, I've been experimenting with keeping it off the past few months and I really like it. Much cleaner sound, without the forced boost of the amp taking over the clarity of the sound. The amp can be manually driven and adjusted to be FAT - the switch seems like a rough shortcut IMO.

 

[burntfrijoles]

Many of us just think the Blues Junior sounds vile, whatever the control settings.

LOL. Well that's pretty harsh. It's a $500 15 watt amp so it depends on the amp used in comparison. Honestly how many great $500 amps are out there?

I think the Blues Junior is really a "pedal" amp. On it's own, it's nothing special but it doesn't get in the way of pedals which is what it is: an inexpensive foundation amp.

 

[=JL=]

LOL. Well that's pretty harsh. It's a $500 15 watt amp so it depends on the amp used in comparison. Honestly how many great $500 amps are out there?

It was a little harsh to be fair, all I would add is that it's nearer to the equivalent of $750 dollars over here, which starts to look expensive for a boxy little mass-market practice amp, making the Hotrod deluxe (for only about 30% more) an absolute bargain in comparison.

 

[rdwhitti]

It was a little harsh to be fair, all I would add is that it's nearer to the equivalent of $750 dollars over here, which starts to look expensive for a boxy little mass-market practice amp, making the Hotrod deluxe (for only about 30% more) an absolute bargain in comparison.

I've often wondered about that, especially since the Deluxe (HOT ROD or Blues) is usually about the same price or even cheaper used. About $450-550 for either B Jr NOS or Blues Deluxe or Hot Rod Deluxe.

 

[telefunken]

Seems like many don't know that it can be operated with a footswitch. The plug is a bit hard to find – beneath the speaker out. Any standard footswitch will do, even a true bypass pedal like the joyo vintage overdrive as I found out (connect the output to the plug) can switch it.
I use the Fat function for the few songs I need a little "more" than my usual clean with a bit of hair tone. Not worlds apart, but a little more grease.

Thanks for the tip about using a true-bypass pedal as a way of turning on/off the fat boost. I actually just tried out an old true-bypass looper pedal I had.......and it works like a charm!!!

 

[Sonicboom1]

I find the sound cleaner with the fat switch off.