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'81 Brit-800 50W Amp Kit

'81 Brit-800 50W Amp Kit

'81 Brit-800 50W Amp Kit

Item # 10735
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'81 Brit-800 50W Amp Kit

About This Item

This hairy monster lives to shred.
The defining British circuit that dominated the '80s and is still rocking stages today.

This 50 watt giant created your favorite heavy rock and metal albums. Used by Slayer, Pixies, The Smashing Pumpkins, and early Metallica, the original 1981 circuit produces that screaming guitar tone that neighbors despise. With its solid-state rectification there's no sag, and the distortion created by this circuit is way more about treble than mids or bass.

This amp is renowned for its saturated lead tone that is bright and tight, with an in-your-face crunch. You can scoop the mids and have a completely different tone in an instant. Often overlooked, the clean tone is rich, full, and gives this amp unrivaled presence onstage.

Not just a one trick pony, there are so many different tones to unleash from this amp. Just listen to "Where is My Mind?" by Joey Santiago of the Pixies, "Bulls on Parade" by Tom Morello of Rage Against the Machine, "No More Tears" by Zakk Wylde of Ozzy, and "Rock You Like a Hurricane" by the Scorpions. Just turn the knobs until you feel inspired.

StewMac has lovingly recreated this timeless amplifier in our '81 Brit-800 50W Amp Kit. This is one of our Icon Kits: modern reproductions of vintage classics.

Stand out from the crowd
What makes this amp stand out from other 800-style amps? Our '81 Brit-800 is a true hand-wired masterpiece. When you wire up the amp yourself, you can customize the components and shape the sound exactly how you like it. And, hand-wired amps are easier to service—if you've ever had a PCB melt, crack, or fail, you'll love the reliability of this point-to-point head. True tone chasers say hand-wired amps have a purer, sweeter sound than PCB amps.

Take your amp building skills to the next level with this kit. The '81 Brit-800 is a perfect place to get serious about amp building. This is an involved amp and will be a satisfying challenge to complete.

If building such an iconic amp sounds hard, don't worry. We've gone to great lengths to make sure this kit has the best step-by-step directions in the industry. With hundreds of full-color photographs and illustrations, these instructions make this an easy, fun and rewarding project.

It comes with all the high-quality parts you need to complete this project in just a few evenings.

  • The head cabinet interiors are genuine 3/4" Baltic Birch
  • Superior craftsmanship on the tolex covered exteriors with perfectly aligned seams
  • Premium quality hardware
  • Top-shelf EL34, 12AX7 tubes and vintage spec Heyboer transformers to give your amp the perfect vintage tone
  • High-quality period-authentic resistors, CTS pots, reproduction mustard caps, and Cliff jacks for their authentic tone and a lifetime of trouble-free use
  • Authentic epoxy turret boards just like the ones used in vintage amps

Need Help? Our trained staff is standing by!
If you get stuck, don't worry, we're here to help. Our knowledgeable team of amp builders are just a phone call away. Our team is deeply involved with building these amps and can answer any questions you have.

You don't need a shop full of tools either!
The great thing about these amp kits is they only require a few relatively inexpensive tools. We've got everything you need to build this amp right!

Build and use this amp internationally!
This amp works wherever you are! This amazing amp is switchable from 120 to 220 to 240 volts. This means that if you are outside the USA, you can still build this amp without needing an external step-down transformer. You can also run it at the higher voltage to capture the original British tone designed in 1981.

Amp head cabinet dimensions:
Height: 9-3/4" (24.76cm)
Width: 26" (66cm)
Depth: 8-1/4" (21cm)

WARNING: Cancer and Reproductive Harm -



Product Instructions

'81 Brit-800 50W Amp Kit Instructions

The new StewMac '81 Brit-800 will be a blast to play through and even more fun to build.

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  • 4.00 average rating from 2 reviews
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Beast of a JCM800 clone!


Verified Buyer

Completed the build two days ago and am completely satisfied with the end product!

The instruction manual and schematic are about 5minutes worth of editing away from being a 10/10!

The few issues I had were;

3 of 4 turret board mounting holes had to be redrilled as they didn’t line up with the holes in the chassis.

0.1uF capacitors mislabelled as 0.01uF

47k resistor supplied instead of 56k resistor (56k is in the Mail, courtesy of stewmac, thank you!!)

Red and white wires from output transformer need to be reversed on V4 and V5 as the way it’s shown in the manual essentially turns the negative feedback into positive feedback.

Very minor issues but could be very easily rectified!

Overall, I can’t recommend this kit highly enough! Half the cost of a 30-40yr old original and imho, every bit as good!


Great Sounding Amp....Instruction Manual needs some revisions


Verified Buyer

Just finished the build and installed it into the cabinet. The amp sounds fantastic and so far there is nothing negative to say about that. The amp worked the first time I went through the startup procedures and I only had a few loose connections that were easily fixed. The High Input can go from SRV blues to crunch to 80's metal with minor adjustments of the preamp, volume and presence knobs If you're looking for a bright tone, this amp has it. The Low Input is super clean. Overall the amp is quiet even at cranked levels. All the parts are quality parts and the cabinet is well made and has a very classic Marshall look to it.

There are other amp kits out there online that appear identical and a little cheaper than this kit. You are paying a little more for the instruction manual and customer service/tech help. Matt is the only amp tech right now apparently at Stewmac so he isn't available immediately for questions but he knows his stuff, is extremely helpful and returns calls within a reasonable amount of time.

1. This kit comes In two boxes. One with the parts and the other with the wood cabinet. I received two of the same with parts only and not the cabinet. Stewmac sent me the cabinet and a return label. Also some of the small parts had fallen out of the tackle boxes used to hdsold the parts.
2. Missing parts/extra parts. Make sure you thoroughly check the parts and make sure you have everything before you start. I was missing a few items but Stewmac sent the parts needed quickly.
3. Instruction manual and schematic variances. Overall the manual is extremely detailed and laid out well. I did find some variances and mistakes in the manual and schematic but Matt took note of the variances and explained why there were some variances. I believe there is a revision coming for the manual.
4. Turret board. Two of the mounting holes on the board did not line up with the metal chassis holes. I had to redrill the holes in order to mount the turret board which left extra holes in the board. Visually disappointing but doesn't affect the performance.
5. Had a high pitch oscillation that was in the presence pot/negative feedback loop. After speaking with Matt, he recommending switching two transformer wires and the problem went away. Should probably mention that issue in the manual troubleshooting section
6. Wire leads on turret board. The measurements given in the manual need to be extended for most of the leads. I added extra length to each wire lead and still wished I would have added some extra for final assembly to the pots/tube sockets. It's easier to make a wire shorter than it is longer.
7. Wooden cabinet mounting holes were not aligned properly with the metal chassis. Had to drill out two of the holes to make them bigger in order for the screws to line-up. Also had to remove four staples from the inside of the cabinet that were holding down the gold trim piping and cut some of the piping away in order for the chassis to set far enough forward and flat down to the bottom of the cabinet. This should also be mentioned in the manual.

Overall, this is supposedly one of most difficult amp Stewmac offers for the DIYer and estimates about 18 hours to finish. I would say that is about right. Read the manual several times and familiarize yourself with the schematic before you start. Overall it wasn't difficult if you are detail oriented and ask questions. Again, thanks again to Matt at Stewmac. Great tech!