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#0755545

Mojotone Custom 50 Guitar Tube Amp Kit

The design was a labor of love that started in a garage in New Malden, England. It quickly grew in local popularity, and made its way to the stage behind big names like the Who, Pink Floyd, Jethro Tull, the Moody Blues, and Manfred Mann. The legendary DR504 is synonymous with big, clean, and powerful.

Skilled amp builders, try your hand at recreating this sonic icon with our Mojotone Custom 50 amplifier kit.

The kit comes with everything necessary to build a working unit, including resistors from Ohmite and Vishay, Mojotone Dijon capacitors, Heyboer transformers, Belton tube sockets, and potentiometers by Alpha.

Also included is a full-color wiring diagram which provides a faithful road map of all the right angles and mil-spec techniques which were documented from studying two original examples from the early seventies.

If this kit shows as out of stock please check here for more information.

Please read our article 'Mojotone Amp Kit Building Primer' along with our amp kit disclaimer located in the Specs tab before buying this kit.
$1,020.00
Shipping calculated at checkout.
Only 1 left in stock. Order soon.
$5 U.S. shipping over $99
 Real support from real techs
Trusted by guitarists for 25+ years
SPECS

Weight: lb

* Note: If shown as out of stock, most amp kits ship within 2-3 weeks. Our team will contact you if we anticipate a longer lead time.

  • Class Type: AB All Tube Amplifier
  • Output: ~50 Watts
  • Circuit: 1970-1972 DR504 Custom 50
  • Bias Type: Fixed Bias
  • Build Time: ~8 hours
  • Preamp Tubes: ECC83/12AX7 (3) & ECC81/12AT7 (1)
  • Output Tube(s): EL34 (2)
  • Rectifier Tube: None - Solid-state Rectified
  • Transformers: Power - Hiwatt 50W (MOJO786), Output - Hiwatt 50W (MOJO785)
  • Hardware:Mojotone Custom 50 Small Parts Kit, Custom 100 Chassis, Front & Rear Faceplates, Octal Base Clamps, 10' Removable Power Cord

Disclaimer: Some of the parts contained in this kit are subject to availability.

Mojotone reserves the right to change or substitute any and all of the parts contained in this amplifier kit without advertisement or notification to the buyer. Part substitutions made by Mojotone are guaranteed not to affect the integrity or operation of your amplifier kit. Time estimates listed are from start to finish. If you are new to tube amplifiers, additional time may need to be factored.

 When purchasing a kit from Mojotone, you will receive the following documentation.

1. Schematic

2. Wiring Diagram / Layout

If you purchase a kit from Mojotone and do not receive these documents, you can obtain copies by emailing tech@mojotone.com or calling 800-927-6656. The Mojotone staff is available Monday through Friday from 8:30 a.m. to 5:00 p.m. EST unless otherwise closed.

 Mojotone kits include the best quality parts that are available at the time of purchase. If a substitution is required, our team will use parts that are of equal quality to ensure the integrity of the kit build remains the same.

Building a fully functional amplifier kit is not an easy task. Before building a kit, one should have the ability to properly solder as well as read and understand a schematic and wiring diagram. While we do our very best to ensure all documentation is current, the included documentation is meant to serve as an overall guide to building the amplifier. Simply following the schematic and wiring diagram does not guarantee you will have a fully functional amplifier. In fact, post build troubleshooting is a common issue across all builds.

 Our staff is available to assist with basic troubleshooting needs. There are plenty of online videos available that are helpful with most post build issues. Technical staff is available via email by sending a message to tech@mojotone.com. You may also call our sales team to discuss build problems, dial 800-927-6656 and press 1 for sales.

 Building a tube amplifier takes time, dedication, resources and most importantly... Skills! The experience of building an amp can come with some frustration, the reward of completing the build is definitely well worth your time. Please review the wiring diagram, schematic and manual (if applicable) prior to making your purchase. Mojotone will not accept any returns on amplifier kits and/or parts that have been assembled, soldered or modified.
DOCUMENTATION

This amp kit also comes with the following documents. Please feel free to view and/or download them:

Custom 50 Schematic

Custom 50 Wiring Diagram

Custom 50 Power Transformer Wiring Diagram

Custom 50 Output Transformer Wiring Diagram

Overall rating: 4.8333335 / 5 from 6 reviews.

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Reviews

Great kit! With some suggestions for better product.

"Pretty good kit. Well packaged. Complaints... 1) Wire is not good for soldering. Sleeving shrinks too easily. 2 seconds of exposure to iron (700F) and they shrunk. 2) Heat shield is still too close to can caps. Hard to install. 3) Preamp tube sockets came with defects in the pin sockets. Had to drill out to get tubes to seat properly. 4) Need to include metal hole caps for unused hole(s) in chassis rear. 5) Add a build guide. Helpful for knowing how to run wires on turret boards. 6) Add an optional bias pot circuit. This amp stock biases way too hot. 7) Maybe add more than one of each fuse."

— Forrest (4/5)

Great Hi-Watt sound, great beefy clean sound.

"This was my third build from Mojotone. This is labeled as a difficult build. I think maybe its listed that way because the diagnosing of problems may be a little more challenging (unfamiliar?) compared to other amps. I didn't find it very hard to follow at all. Plenty of room to work on everything. Luckily all voltages were correct, and everything worked wonderfully on first start up. The thickness of the clean is just great. When you can play a signal note and it sounds full and then play a chord and all the notes actually come through cleanly. One of the filter caps was sent incorrectly, and the wiring diagram was missing, but Mojotone has been absolutely great to deal with and their customer service is top notch. Now I have a serious problem, and can't stop building these amp kits."

— Sasha (5/5)

Blown away with this build...

"This amp will absolutely rip the balls off a charging rhino at 100 paces. This was my very first amp build and its been a blast. The wiring diagram and the schematic are excellent and hard to mess up if you are meticulous about your work. I am a retired I.B.E.W. Journeyman Wireman with a mountain of controls experience that came in handy. The folks at Mojotone are the best support group I have worked with. They are very professional and passionate about what they do. Any future amp builder would be wise to work with these guys, they know their gear. The Custom 50 has an incredible tone stack that produces unreal crystal clear tones at any level, including high volume. This amp keeps it tight. I invested in this beast for a pedal platform after researching the finest amps ever built. For me, I feel like I nailed it."

— Steve A. (5/5)

Legit kit, worth the effort.

"This is a great kit. I usually drill my own chassis and stake my own boards and do my own thing, but being unfamiliar with Hiwatt type stuff I just wanted an “easy” way to get there. Very impressed with the quality of materials, the exceptional packaging, and the attention to getting things right. This build is a lot of work (especially if you’re OCD like me and wrap the turrets instead of poking) but the result is excellent. Only two faults that were east to resolve: one end screw hole on the main board didn’t match the chassis hole spacing, and there was an extra 100-ohm resistor that freaked me out for a minute when I was done, ha. Also, be ready (and equipped) to either swap out the bias resistor or add a trimpot. I only got about -32v from the included value, which gave me a toasty 71ma per tube. Easy enough to fix. Sounds great. Really fun amp. Very loud. Can’t even imagine the 100…"

— Matt (5/5)

Beautiful kit, some notations.

"Am currently rebuilding my old Peavey 5150 mk 1 head, but i wanted to try my hand at a hiwatt circuit. The Custom 50 is plenty for my needs & this will hands down be the first amp i build. As of writing this review, am in build process of the kit, but i wish to clarify a few things: Bias circuit will need some altering to keep the power tubes a little bit cooler than they would be with the stock "vintage" scheme. Triple check you have all your components, & when assembling verify all fit without hitch in or out on the chassis. My kit was missing a few parts, & my chassis' heat shield sat too close to the can caps. Mojotone's customer service swiftly resolved the missing parts, & sent my concern of the heatshield placement to have it corrected in future chassis (i made no request to swap my chassis as all else fits, & two holes to drill isn't a bother). Overall, great kit, superb build quality. Highly recommend. Take your time to build, the journey is enjoyable!"

— PK (5/5)

Great Amplifier, Great Kit!

"Thrilled from the moment I unpacked the shipping boxes! Mojo's packing deserves special mention: exceptional padding, all parts neatly organized and labeled. Suggestions: take your time! Make copies of the layout diagram to mark off components/connections as they are added. Triple check everything before soldering. Before power on, re-check against layout diagram; use a DMM to look for shorts/cold solder joints and continuity. It sounds great! Despite their reputation for being obscenely loud, Hiwatts do have a very useful master volume. At least for clean tones, it's surprisingly usable at "bedroom" volumes. Only nitpick is the lack of an adjustable bias. Mojo's goal was to be true to the originals, which did not have an adjustable bias. Today's tubes are not as consistent as the tubes from 40 years ago, and therefore adjustable bias is a must. (The adjustable bias mod is not particularly hard, and well documented.) In short, I'm delighted with the kit!"

— Greg R. (5/5)

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