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Marshall ST-20H Studio JTM Guitar Amplifier Head Amp 20w (JTM)

IN STOCK - Ships today if ordered before 1pm AEST

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Product Information

The unrivalled number one is here, just smaller. Reproducing the legendary, warm and smooth tones of the original Marshall JTM, the Studio JTM packs a punch. Swap between 20W and 5W at the flick of a switch and let the era-defining sound of the JTM steal the show, whether it’s playing at home, or on stage. Make sure to pair the ST20H with one of our Studio cabinets for a small but perfectly formed Marshall rig.



An unmistakable sound that is recognised all over the world, the ST20H is a loving homage to the amp that responded to the rock’n’roll revolution. From its legendary warm and smooth tone to blending the voices for a combination of crunch and clean, the ST20H brings the outstanding sound that Marshall is so well known for.


Accurately recreating the iconic look seen across thousands of stages over the years, the ST20H has the power of a classic Marshall amp in a new, more compact design. Packed with the same vintage tones you know and love, just in a smaller package. Features such as a DI out and FX loop have been added, bringing the JTM into the present day.


Whether you're playing at home or an intimate gig, swap between 20W and 5W at the flick of a switch thanks to built-in power reduction technology. The 5W mode allows playing at a lower wattage without compromising on tone.



  • Model: ST20H
  • Range: Studio
  • Technology: Valve
  • Channels: 1 with 2 voicings


  • Output wattage: 20W (with power reduction option to 5W)
  • Outputs: 5 x 1/4” jack sockets (16Ω load / 8Ω load / 4Ω load)
  • Inputs: 4 x 1/4" jack instrument inputs (high/low sensitivity)
  • Controls: Treble, Middle, Bass, and Presence
  • Effects: None
  • Effects loop: Yes, send/return


  • Preamp valves: 2 x ECC83, 1 x ECC83 (phase splitter)
  • Power amp valves: 2 x 5881


  • Cable: Detachable power cable included
  • Speaker cable included

Dimensions (Including Feet and Handle)

  • Weight: 9.25kg / 20.4lbs
  • Width: 500mm / 19.7"
  • Height: 240mm / 9.4"
  • Depth: 230mm / 9.1"


1 Year Warranty

Shipping & Delivery

All orders over $100 will be automatically eligible for FREE Shipping Australia Wide, if you order is under $100 there will be a flat rate of $10.

Belfield Music is well known for its top online customer service. We treat all online customers with the same excellent service we give to our in store customer. We will ensure that you receive all the support you need while your goods are in transit and ensure the goods arrive promptly. All of our shipments have tracking numbers available and we cover every single unit by our own shipping insurance.     

Online orders are normally processed within 1-3 business days. Once processed, your order should take between 1-8 business days to arrive depending on your location. Please note that your order may take up to 10 business days to arrive from the day you place your order. 

If it transpires that the product is out of stock due to a stock discrepancy and/or there will be a delay in shipment, we will contact you within 2 business days of placing your order and give you the option of waiting or cancelling your order. The products we advertise online should show if they are in stock or not. We do our best to keep the website stock count up to date, but there may be an occasional error.

If you wish to utilize an Express Delivery Service to receive your item, please contact us for a shipping quote before you place your order at admin@belfieldmusic.com.au or by using the Chat icon on the bottom right of the page.           

Deliver is made during the hours from 8:00am till 5:30pm Monday to Friday. As such, please ensure you nominate an address which is capable of receiving goods during 8am and 5.30pm.  Given the restrictions on PO Box deliveries we cannot deliver larger sized items to a PO Box.

If for any reason our selected carriers don't service your area we will contact you before processing your order if this applys to you.

Returns Policy

If you wish to return an item which is not damaged or faulty in any way and you have simply changed your mind or made the wrong decision, you must let us know within 7 days of receiving the item.  We will not agree to refund an item because you simply changed your mind or made the wrong decision if we have not been advised of your intention within 7 days of receiving your item. Once we have provided a return authority, it is the buyer’s responsibility to return the item, at their own costs within 30 days from original purchase. If the item is returned with any damage or alteration to its original packaging, we will refund the item subject to applying a minimum 15% restocking fee.  We will not refund the costs of the initial shipping charges.

It is in Belfield Music best interests to keep our customers happy with their purchases. If you are not happy with your purchase, please talk to us first. We will always attempt to resolve any problems you may have as best we can. To contact us please email us at admin@belfieldmusic.com.au or by using the Chat icon on the bottom right of the page.