I had all of the parts ready to make another Dumbleator and then got inspired by Martin's miniaturized version. Using a chassis box I had on hand for building power supplies for some of my audio gear, I thought it would be interesting to use a prefabricated tube effects loop using a subminiature tube and pack everything into a 5-3/4" x 8" x 2-3/4" box.
The power supply filter nodes are reduced (could have dropped one more but decided to use a choke between the 47uF and 22uF caps. Adjusted the B+ dropping resistor and added dropping resistors to the heater supply to drop the voltage from 7V to 6.2V, since the tube effects board draws so little current. Also removed the trimmers from the board and substituted with pots.
It sounds excellent. More neutral than my more standard Dumbleator, very clean and clear, despite some obvious but minor frequency distortion as shown in the o-scope picture. All in all, very satisfactory, despite the higher cost due to using a pre-fabbed buffer board, but nice to have in a small package. The labels are rather cheesy, but serve for now.
Different Take on Dumbleator
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Different Take on Dumbleator
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- martin manning
- Posts: 13404
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: Different Take on Dumbleator
Nicely done! I find the independent gain and buffer stages can be used in other ways too.
Re: Different Take on Dumbleator
Looks great!
-Dan
-Dan
Re: Different Take on Dumbleator
Thank you!
Please say more, Martin.martin manning wrote: ↑Sat May 28, 2022 11:23 am I find the independent gain and buffer stages can be used in other ways too.
- martin manning
- Posts: 13404
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: Different Take on Dumbleator
You have a gain stage and a CF stage with 1/4" inputs and outputs, so you can have a booster and/or buffer out front to overdrive the amp's input stage, or use them for experimenting with other circuits on your bench.gktamps wrote: ↑Sat May 28, 2022 1:55 pmPlease say more, Martin.martin manning wrote: ↑Sat May 28, 2022 11:23 am I find the independent gain and buffer stages can be used in other ways too.
Re: Different Take on Dumbleator
Good points, Martin. Hadn't really considered using it in the input of the amp, but could also be a great way to drive non-buffered pedals. And I didn't think of using it for other circuits on the bench. Thanks!
Cheers,
Greg
Cheers,
Greg