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R13 on Dragonbeard Jr

Started by danfrank, July 20, 2024, 04:07:48 AM

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danfrank

Hi everyone!
I haven't been here in a long time but I did want to check in with something I found out about the Dragonbeard Jr, this also applies to the original Dragonbeard.
R13 on the schematic (last resistor at the output) shows 1K1 (1100 ohms) but the actual Expandora uses an 11K resistor here at this position.
I was having a lot of trouble with the original Dragonbeard, where the sound would get quieter the harder the guitar is played. The LEDs for the four modes would also start to flicker. It just seemed odd to me. Anyway, I compared with an actual Expandora and found that difference. I also took out all the flashy LED circuitry to make the Dragonbeard an exact clone of the Expandora. Now the Dragonbeard acts and sounds like an actual Expandora.
I don't know if anyone else had a similar problem or if it's been discussed here before but I thought I'd add my two cents here.

madbean

That does appear to be a typo/wrong value. 11k is fine there. Even 10k. A 1uF/1k1 will create a HPF filter @ around 140Hz so it's cutting out some low end. I'm a bit surprised that it was the source of your other problems, but I guess the proof is evident here. I'll make that change to the build doc and also the DragonBeard Jr, since I used the same schematic as the basis for it.

Thanks for bringing this to my attention!