ok i have a fender blues junior-awesome amp,
but i have a problem,

when i turn up the volume , i get gain, and the overdrive is O.K.
i mean its great for blues and shit but how do i get more distortion.

im looking for like purple haze distortion, jimi hendrix overdrive kinda stuff/

How could i get my amp to sound like and overdriven marshall amp( sounds amazing), without buying a pedal.
youll ned a fuzz pedal to get hendrix type sounds. and a feder wont sound like a marshall without some heavy modding.
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I was gonna say "get a overdrive pedal" when I read the last sentence. Maybe active EMG's ? Why dont you want to use a pedal?

Peavey 5150 head
Marshall 1936 Lead 2x12 Cab
'06 Jackson SLSMG
Dean Hardtail Select
ISP Decimator
Planet waves tuner
Weber Mini Mass
Ibanez Delay & Chorus

time is like a fuse; short and burning fast -- James Hetfield
Are you really asking for your amp to sound like a different amp without pedal help? Ridiculous.

You'll need to do one of several things...

1. Add an overdrive pedal to your mix. If it's good enough for Hendrix, SRV, and thousands of other guitar heroes it's good enough for you.

2. Sell you amp and buy a different one, in that price range you'll have to consider hybrids like the Vox AD or Roland cube series.

3. Accept the fact you have a great amp for cleans and blues and save your pennies to buy another amp that meets you requirements. Ceriatone builds Marshall Superlead clones for under $700 that rock.

4. Pay an amp tech to mod your amp for more gain.
It's a fine line between clever and stupid.
Basically, you're gonna have to spend money to get more gain outta a Blues Junior. A good OD pedal is the easiest way.