S40 - 5881

Vintage Tweed Grit. Modern Power. Hand-Wired Character.

The S40 – 5881 is Marla Amplification’s powerful take on the beloved low-watt Tweed amps of the 1950s—built not just to emulate the past, but to push it forward. Don’t let the name fool you—this amp is loud, raw, and unapologetically expressive.

While its layout mirrors the S20V, the S40 uses a pair of 5881 power tubes to deliver a tighter, punchier, and more articulate version of that 5E3-5F6A style growling overdrive. The result is a tone that retains the creamy breakup and rich midrange of classic Tweed designs, but with enhanced clarity, headroom, and responsiveness.

Key Features:

• Output Power: ~40 watts (clean), with natural breakup that kicks in beautifully at stage volume

• Power Tubes: 2x 5881 

• Preamp Tubes: 2x 12AX7

• Rectifier: GZ34 for dynamic sag and classic feel

• Channels: 2 fully independent channels (Channel A and B)

• Inputs: High and Low sensitivity inputs for each channel

• Jumping Capable: Use a jumper cable or ABY switch to blend both channels for rich overdrive and tonal complexity

• Tone Character:

• Channel A: Fat and focused with a strong mid-push—perfect for driven rhythm and bluesy leads

• Channel B: Brighter and slightly more open—ideal for edge-of-breakup cleans or jangly rhythm

• Cabinet: Finger-jointed pine for natural resonance and vintage mojo

• Controls (per channel): Boost, Volume, Tone (Bright Switch for CH1)

• Dimensions: Approx. 22" W x 22" H x 9" D

• Weight: ~34–38 lbs

• Finish Options: Hand-applied finishes upon request

• Hand-wired in the USA using turret board construction and top-shelf components

Raw Materials Used:
Orange Drop 715 Series, Sozo NexGen Yellow Mustard &
Sozo NexGen Blue Molded Coupling Caps
Metal Film and Metal Oxide resistors
Mojotone KingCap Filtering Caps
Hammond 290 Series Power Transformer
Hammond 1750 Series Output Transfomer
Switchcraft Jacks
Alpha Pots
Marla Speaker Cabs and Chassis are also Made in North Carolina

Voicing
The Marla Amplification S40 - 5881 is my take on popular low-watt Tweed Era amps, brought to life in a gut punching and louder-than-necessary combo. At first glance the S40 looks much like the S20V's big brother, but in some ways, it is actually the louder little sibling. The S40 gives you a beefy but creamy 5E3-like tone at a volume level that all guitarist desire in order to fill the room. The S40 is equipped with two channels, both having low & high sensitivity inputs, meant to give players a wide variety of jumping off points for crafting their signature sound. The two channels are independent in voicing and early signal path, so they need to be jumped with an ABY Box or Jumper Cable if you would like to blend both worlds. Jumping the two channels will create a sensational amount of midrange overdrive and top end creamy drive. 

Channel One
A bright and warm full spectrum guitar tone. Every bit of the guitar is elevated with this channel. This makes a great crunch and clean tone. Perfect for stacking fuzz and timing or tuning modulation. Channel One is biased slightly hotter in the preamp section to add more separation between the two channels. Pull the Channel One Volume Pot for a cathode bypass boost and pull the Tone Pot to engage a bright switch for Channel One!

Channel Two
Focused and mid-forward. This is the sound that American Rock was founded on. Hook up your favorite drives, fuzzes, and distortions to push this into wicked heavily clipping territories. The attached wide-sweep tone pot will help roll off or enhance the top end needed to stand down or stand out in the mix. Pull the Channel Two Volume Pot for a cathode bypass boost!!

Speaker
The Mojotone Anthem makes its return in the S40 - 5881. This American Classic speaker was a no-brainer choice when designing an amp intended to highlight the best tones of the 50s and 60s.

Tube Layout
The S40 - 5881 ships with a pair of JJ 12AX7’s for the Pre-Amp and Phase Inverter. The power section hosts two JJ Electronics 5881 tubes. With the adjustable bias and internal Pin Wiring, the S40 can be updated with 6L6s (46w) or EL34/E34Ls (38w). The S40 ships with a JJ Electronics GZ34 rectifier tube, giving players access to high plate voltages and low SAG. If players would like a tamer sound and less top end hair on the overdrive, then a 5URGB will drop the voltages, creating a more modern and compressed sound without losing any notable power.

Cabinet
The S40 sports a 20”x20”x9” solid pine cab with a 5/8 semi open back baffle. The oversized cab produces a robust low end, the solid pine keeps top end pronounced and the semi open back contributes to the feel of notes being more resonant than anticipated. Additionally, if you’re in the studio, mic the speaker from the front and from the back – it’s a cool trick from the 70s and hearing a mix of cab and speaker cone makes the recording sound like a freight train!