Fender Blues Junior IV Settings Guide
The Fender Blues Junior IV is a 15W EL84-powered combo with a 12" Celestion speaker and built-in spring reverb — one of the best-selling combo amplifiers of the modern era. It is compact, relatively affordable, and achieves natural power-amp breakup at volumes that are more manageable than larger Fender amps. The "Fat" switch adds additional gain and bass for a thicker, more saturated character. Used both as a practice amp and as a stage amp for smaller venues.
The best Fender Blues Junior IV settings start with: Volume at 6/10, Treble at 6/10, Mid at 6/10, Bass at 5/10, Master at 5/10, Reverb at 3/10. Adjust from there based on your amp, guitar, and room volume. For Blues (natural breakup): Volume 8/10, Treble 6/10, Mid 6/10, Bass 5/10, Master 5/10, Reverb 3/10.
⚡ Start Here — Recommended Settings
| Control | Starting Position | Range |
|---|---|---|
| Volume | 6/10 | Off → Loud |
| Treble | 6/10 | Dark → Bright |
| Mid | 6/10 | Thin → Thick |
| Bass | 5/10 | Thin → Thick |
| Master | 5/10 | Off → Loud |
| Reverb | 3/10 | None → Full |
These are universal starting points. Adjust based on your amp, guitar, and room. Scroll down for genre-specific settings and artist-documented positions.
What Each Control Does
Recommended Starting Settings
Safe starting positions for any style. Adjust from here based on your amp and room.
All values on a 0–10 scale. These are starting points — fine-tune by ear.
Settings by Genre
Volume at 8 — the Blues Junior at higher Volume settings begins to push the EL84s into natural power-amp saturation. This is the characteristic Blues Junior tone: warm, touch-sensitive breakup that responds to pick attack. At these settings, light picking cleans up noticeably compared to hard picking.
Low Volume with higher Master — keeping the preamp clean while allowing more stage volume. Treble at 7 adds sparkle for single-coil pedal tones. The Blues Junior IV is a popular platform for overdrive and fuzz pedals.
Bright clean with Reverb for country — Treble elevated, Mid and Bass pulled back for a clear, sparkly clean. The Blues Junior's 12" Celestion speaker handles Telecaster tones well at these settings. Fat switch off.
Fat switch engaged at moderate Volume — the Fat switch adds preamp gain and low-mid emphasis, moving the Blues Junior closer to classic rock territory. Mid at 7 with the added thickness of the Fat switch produces a warmer, more mid-forward breakup.
Tips & Common Mistakes
- The MK IV revision added a new Celestion speaker (replacing the Fender-designed Eminence) and revised circuit tweaks for better clean headroom and reverb quality. Earlier Blues Junior versions (I–III) have slightly different character — the IV is the most polished version.
- The Blues Junior clips at around 6–7 on the Volume knob without the Fat switch — with the Fat switch engaged, clipping occurs earlier. Many players use the Fat switch always-on for a consistently warmer, slightly more driven base tone.
FAQ
Fender Blues Junior IV — Common Questions
Best starting settings for Fender Blues Junior IV: Volume at 6/10, Treble at 6/10, Mid at 6/10, Bass at 5/10, Master at 5/10, Reverb at 3/10. Adjust from there based on your guitar, room, and playing style.
For Blues (natural breakup): Volume 8/10, Treble 6/10, Mid 6/10, Bass 5/10, Master 5/10, Reverb 3/10. Volume at 8 — the Blues Junior at higher Volume settings begins to push the EL84s into natural power-amp saturation. This is the characteristic Blues Junior tone: warm, touch-sensitive breakup that responds to pick attack. At these settings, light picking cleans up noticeably compared to hard picking.
For Clean Pedal Platform: Volume 4/10, Treble 7/10, Mid 6/10, Bass 5/10, Master 6/10, Reverb 4/10. Low Volume with higher Master — keeping the preamp clean while allowing more stage volume. Treble at 7 adds sparkle for single-coil pedal tones. The Blues Junior IV is a popular platform for overdrive and fuzz pedals.
Volume: Output volume — also drives power amp saturation at higher settings (Off to Loud). Treble: High-frequency EQ (Dark to Bright). Mid: Midrange EQ (Thin to Thick). Bass: Low-frequency EQ (Thin to Thick). Master: Master volume for separating preamp and power amp gain (Off to Loud). Reverb: Spring reverb mix (None to Full)
The MK IV revision added a new Celestion speaker (replacing the Fender-designed Eminence) and revised circuit tweaks for better clean headroom and reverb quality. Earlier Blues Junior versions (I–III) have slightly different character — the IV is the most polished version. The Blues Junior clips at around 6–7 on the Volume knob without the Fat switch — with the Fat switch engaged, clipping occurs earlier. Many players use the Fat switch always-on for a consistently warmer, slightly more driven base tone.
Got the Fender Blues Junior IV? Build the rest of your rig.
Use the Rig Builder to find matching guitars, pedals and cables for your genre and budget.