I've decided to move my ongoing discussion here to share a comprehensive view of my third-generation Dumble amp build. This includes all the details—layouts, photos, and a video demonstration of the tone.
**Background:**
As long as I’ve been alive I’ve wanted to play an ODS and i honestly never thought that day would come. After finding this forum around 5 years ago i went balls deep and made a few Fender circuits and eventually more complex builds and even “attempting” to design my own, all with the ultimate goal of making an ODS. This project has been in the works for over a year, with meticulous planning and iteration.
**Build Process:**
Starting with a custom layout using my drawing app (which doubles as a layout creator), I developed to-scale chassis drawings to serve as templates for drilling and assembly. My component choice and layout were entirely taken from Tony's third-gen layout and M.Roberts schematic, though I made several modifications:
- Added a power amp out jack.
- Changed the overdrive resistor from 1.2M to 1M.
- Used a 100pF bright cap
- A 0.015uF 715P OD mid cap.
- A 1.5uF Poly accent cap
**Component Choices:**
The build features a mix of NOS and modern parts:
- NOS Draloric resistors in the signal path
- Modern Dale CMF60s
- NOS TVA bypass capacitors (authenticity of TVAs uncertain).
- A few Koas and OM series CFs
- 6PS ODs
- Hammond transformers.
I am not the guy to believe that NOS resistors could sound different enough to be worth the trouble. When i replaced the OM CFs with NOS Dralorics from Jelle, it was a very noticeable improvement . It seemed to sweeten the high end, it was not subtle. I wish this was not the case but it was. I have a very controlled listening environment, My mics and cabs are far away in my live room and i listen on reference grade phones. Its extremely valuable to be able to hear exactly what the recorded tone will be in the mix or just to swap a value and hear the change without the room sounds.
For tubes:
- V1: RCA Blackplate 12AX7
- V2: Tesla Telefunken ECC83
- V3: Balanced GE 12AT7
- V4 and V5: Sovtek WXT+
**Cabinet and Aesthetics:**
The head cab is made from solid pine with dovetail joints, featuring a maple crossbar and supports. It's finished with black pig suede and orange cow leather, this was a first for me.
**Challenges and Modifications:**
Early in the build, I stuck closely to the original design but was encouraged to experiment with component values, “thanks Xtian”. I tried 130k, 150k, and 160k slopes. 0.015uF, 0.02uF, 0.03uF, and 0.04uF mid caps, same with the bright cap, plate and cathodes of every stage, ect…. I ultimately reverted to the original specs, other than the few noted above. There is something so harmonious about the response, its as if the harmonic content stacks and layers in a perfectly musically pleasing way. I can sit in front of a cab and let the sound wash over me and its so incredibly rich and beautiful, not even a trace if harshness. It just resonates with something deep in me. Im starting to sound like the man himself
**Outcome:**
The amp records beautifully, offering a clarity that cuts through the mix like nothing I’ve ever heard. The tone is exactly what I envisioned, proving this build to be my most successful and satisfying yet.
**Final Thoughts:**
Despite a few minor hiccups, like having to adjust faceplate holes and replacing a faulty jack, the build went remarkably smoothly. The detailed planning and quality component selection have truly paid off.
Note: my FET didnt function at first, i found Ians build and his problem was identical to mine, he ended up replacing the jacks with the period correct ones so the solution wasn't exactly found. It seemed like the FET jack would be the culprit especially because the only one i had found was ebay nos. Nope, brand new switchcraft jack from mouser and the switch wasn't making contact, Ive had this happen before a few times. Replaced it and bam, cool feature.
Attached below are the layout, boards, photos, and a video showcasing the amp. The video was a lot of work and i mostly made it to share with you guys, no one else in my life wants to here the word Dumble ever again. I recorded and wrote a song that was an attempt at revealing the span of tones from blues to rock. The second half of the video is the amp solo as i switch through the settings and noodle. All of the guitar parts were recorded with the ODS even half of the bass signal. I appreciate this forum in a way that i cant really quantify, without the work so generously shared this could not of been possible. Thank you and enjoy!
