Skip to main content
Mad Professor

Mad Professor Old School 21RT 21W Tube Guitar Amp Head Black and Beige

SKU #L28793000001000
Add To Wish List
$1,699.99 1199.97 $1,199.97 Save $500.02 (29%)
25 $25/mo. with 48 months financing*
Limited time
More ways to pay:
Lease-to-own with Progressive Leasing. Learn more
Loyalty Points Icon
Loyalty Points Icon
Earn 9,600 reward points
($96.00 in credit)
Inventory Msg Check Mark Inventory Msg Exclamation In Checkout Promo Inventory Msg Download Icon
In Stock & Ready to Ship
Most orders placed before 3 p.m. ET ship same day (except weekends and holidays).
  • Free Shipping
  • Flexible Financing
  • Lowest Price
  • Ships Internationally
Product Warranties Icon Product Warranties Icon

Gold Coverage Protection

Protect your gear

Chevron Right Icon

Get classic tube tone from this straightforward, modern head.

With the Mad Professor OS21RT tube head, you are able to get legendary tones from both sides the Atlantic that suits country, blues, pop, rock, reggae, soul, hard rock, alternative and every other style-name the clever marketing people at record companies come out with.

No need for channel switching as these classic tones from clean to distorted are easy to get by adjusting your guitar’s volume and tone knobs.

Coming from a pedal manufacturing company this amp takes pedals VERY well.

The amp has built in Reverb and Tremolo for the final old school touch.


  • 21 watts of classic tones from jazz to rock
  • Very good master volume, sounds great with any volume level
  • Unique yet familiar tone, little Fender, little Marshall and bit of Vox in it

Call or click to order today!


Old School 21RT 21W Tube Guitar Amp Head Specifications:

  • Power: 21W (tube)
  • Tubes: four 12AX7 (preamp); two 6V6 (power amp)
  • Single channel
  • Single input
  • Built-in reverb and tremolo
  • Outputs: 4, 8, 16 Ohm speaker outputs
  • Universal power switching between 100/120/230/240V
  • Dimensions: 19.09" x 10.25" x 10.25"
  • Weight: 30.64 lb.

Questions & Answers

Do you have questions about this product?

Shop with a Friend
Free Shipping
  • Free Standard Ground shipping (48 contiguous states, some overweight and Used/Vintage items excluded).
  • Orders placed before 3 p.m. ET usually ship the same business day.
Learn More
2-Year Free Warranty on Guitars

Every guitar or bass you purchase from Musician's Friend (electric or acoustic, New or Open Box) includes two years of protection from manufacturer defects.

Contact Us for Details
We're Here for You

Our Gear Advisers are available to guide you through your entire shopping experience. Call or Chat for expert advice and to hear the latest deals.

Contact Us
gear adviser
Want to customize your own bundle?
Our Gear Advisers are ready to help.
Our contact center is currently closed.
Request a Callback
Proactive Advisor Support Chat