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Dumble ODS question for Steve A, & others.

9/20/1999 9:43 AM
Mark Abbott
Dumble ODS question for Steve A, & others.
Dear Steve  
I've just seen the new circuit 1.2, and I have a few questions, (1) How come the 22Meg/0.05uF feedback circuit was omitted? Of late people have been saying what a great idea this is. (2) Secondly, could you give me a bit more info regarding the FET stage (where to find it at your site). From what I've seen of Dumbles in ads you can choose either the FET input or the normal I/P is this correct?  
(3) I also down loaded the notes and I thought the clean master volume had a 47pF bright cap which isn't in the circuit, is this correct?  
This isn't the Spanish inquistion, this is an amp I'm very much interested in building and I'm trying to get the info straight to get the best possible result.  
Has anyone built one yet?  
I couldn't help but feel the clean tone would improve without the clean master volume.  
In closing, thanks for your help and suggestions. Mark.
9/20/1999 12:07 PM
Cardinal Richeliu
9/20/1999 4:57 PM
Victor Van Beetoven
I have built one according to the 1.2 schematics and it does have a british tone but does have the 77 vibe as far as the articulation goes^ The tone stack does add punch and adjustable scoop, but if thats what you desire go for it! ^ I like the old model with a tone stack switch better.>>
9/20/1999 5:59 PM
J Epstein

"Not the comfy chair!"  
9/20/1999 10:21 PM
Victor Van Beetoven
But oh yes young Squire!
9/21/1999 2:26 AM
Steve A.

    It was with great pains that I removed that 22M/0.05uF "local feedback loop" but several reports mentioned that the current models don't use it anymore. And you probably missed this in the plethora of Dumble posts on the "Open Forum" but I mentioned that I will be drawing up an advanced version of the schematic that includes the rock/jazz, mid-cut, bright and boost switches (along with the bright cap for the Master Volume control which I was told affects only the Clean channel- since the OD channel is not as loud with the second tone stack after the OD stages as it was in the earlier models...) BTW I have a pre-PI MV in my project amp with the Dumble-ized Normal channel and it sounds okay to me...  
    The amp has two inputs, with the FET input mainly intended for plugging in an acoustic with a piezo pickup (although I guess you could crank it up to overdrive the initial gain stage like with a Tube Screamer). The FET input will be included on the "advanced" drawing, too.  
Steve Ahola  
P.S. You got something against the Spanish Inquisition? (I've been "racking" my brain trying to think of a good joke about that, but I will resist the temptation... < g >)
9/21/1999 4:47 AM
Mark Abbott
Much thanks
Dear Steve  
Thanks for your reply. Also thanks for letting Monty Python rest in peace. Some of these surely deserved the Holy Hand grenade! Thanks  
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