Which Direction for Great Cleans

[s2]

I'm interested in building a Dumblesque amp just for clean tones. With all the information here, I'm not exactly clear on which direction would get me there.

So if you Dumbly experts were only interested in building the best possible clean channel, how would you proceed?

[Structo]

How about a AA165 Bassman circuit.
Isn't that what Dumble ODS are based on anyway?

http://www.schematicheaven.com/fenderam ... _schem.pdf

[s2]

Well, I have to admit to being inspired by some clips I've seen of the John Mayer 2-Rock played clean...

And I've only built D'Lite kits for other people. I've never done anything in Dumbleland myself and this seems like a good excuse to mess around there.

[phsyconoodler]

S2,
Good to see you here!
Just build a blackface AA864 bassman and add the dumble local negative feedback and maybe a mid-boost and there you are.I have added the local feedback network to a few fender amps and they sound incredibly dumblish after.The cleans are fatter and the headroom is extended a bit.Very jazzy if you want it to be and when you gig in the notes bloom.

[s2]

Forgive my dimwittedness, but what is the local negative feedback loop to which you refer?

[d95err]

Forgive my dimwittedness, but what is the local negative feedback loop to which you refer?

Many Dumble amps have local negative feedback on the second gain stage. It is a resistor (typically 22M or 44M) from the anode back to the grid (through a coupling cap). You'll find it on many of the schematics posted here.

[Funkalicousgroove]

The first questions I'd ask are:
1) What is your main guitar?
2) What type of speakers do you intend to use?
3) What style of music do you play?

If you can answer those It'll be easier to suggest a circuit or 2

[jaysg]

If you can answer those It'll be easier to suggest a circuit or 2

Funk, to your ear, does Mayer's amp sound more like a standard ODS tone stack, Skyliner, or Bluesmaster? I hear it as the standard.

[Funkalicousgroove]

to me it sounds like a classic (100k slope, .05 mid cap) but I could be wrong!

[guitarsnguns04]

d95err Posted: Tue Aug 26, 2008 7:37 pm Post subject:

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s2 wrote:
Forgive my dimwittedness, but what is the local negative feedback loop to which you refer?


Many Dumble amps have local negative feedback on the second gain stage. It is a resistor (typically 22M or 44M) from the anode back to the grid (through a coupling cap). You'll find it on many of the schematics posted here.


I have seen in some layouts where they have deleted the local negative feedback loop. It was in a dlite build...what difference would it make to that circuit?

[brownnote]

If you remove the local feedback you have more 'raw-ness' and bite.

[s2]

Forgive my dimwittedness, but what is the local negative feedback loop to which you refer?

Many Dumble amps have local negative feedback on the second gain stage. It is a resistor (typically 22M or 44M) from the anode back to the grid (through a coupling cap). You'll find it on many of the schematics posted here.

D'OH! I suppose I should bother to look at the schematics before I ask bone-headed questions.

Does anyone have any preferences as to the 22M or 44M options? All I have handy is a few 33M resistors, so I'll give that a go first.

[dogears]

Try a 4.7M and a 33M. Most of the DUmbles with the LNFB have a total of 40M feedback. 4X10M resistors and a .05uf cap.

Forgive my dimwittedness, but what is the local negative feedback loop to which you refer?

Many Dumble amps have local negative feedback on the second gain stage. It is a resistor (typically 22M or 44M) from the anode back to the grid (through a coupling cap). You'll find it on many of the schematics posted here.

D'OH! I suppose I should bother to look at the schematics before I ask bone-headed questions.

Does anyone have any preferences as to the 22M or 44M options? All I have handy is a few 33M resistors, so I'll give that a go first.

[stratcat62]

Did Dumble use LNFB across the board, for all his amplifiers? Could I (or somebody) modify a Twin in that way to get me closer to that Dumble clean sound?

[Structo]

Is your Twin a straight Twin or a Twin Reverb?

I think you would have to change more than that.
If you compare tone stacks between the two amps you will see a difference along with the bypass caps/resistors and coupling caps.

Not to mention the phase inverter.

Fenders typically use 25uf bypass caps where Dumble used 5-10uf.

Leo also liked using 100K plate resistors.

I think you would have to compare the two schematics to see the differences.

Ice-Racer modded a Super Twin Reverb to Dumble specs.

https://tubeamparchive.com/viewtopic.php?t=5396