freestompboxes.org

It is roundabout 46M. There are two 23M resistors in series.
Thanks Kusi for drawing that schem. Looks great!
I will reassemble the pedal in two or three days to take the voltages.

By the way, i built a Dumble ODS clone. I do not know if my amp sounds
exactly like a real dumble, but i know that the howie sounds like my amp

Has anyone seen an error in my or kusis schem compared to the pics?

kusi wrote:

earthtonesaudio wrote:That's a lot of self-biased JFETs.

i could see not one...?

regards, kusi

"Self bias" in my experience refers to the JFET gate being referenced to ground. All the transistors are biased this way, at least in the .pdf schem.

...Unless you were being sarcastic, then nevermind.

hi earthtonesaudio,

for sarcastic is my english way too bad

for me, a "self-bias" needs no trim-pots for work-point-adjustment....? (like u-amps)

regards kusi

Shame they left out the preamp boost and the HRM (Hot Rubber Monkey) for the OD channels........ that really makes my Dumble shine!

Bernardduur wrote:...and the HRM (Hot Rubber Monkey).... that really makes my Dumble shine!

I have never heard of this. Please explain it to me. Is it a modification? I'm familiar with the Dumble circuits in a general sense, but I haven't heard of this.

The HRM is a second tone stack in the OD circuit that can shape the OD.

It works really well shaping and making the OD more pronounced. Love it!

The preamp boost is my fav OD pedal

soulsonic wrote:

Bernardduur wrote:...and the HRM (Hot Rubber Monkey).... that really makes my Dumble shine!

I have never heard of this. Please explain it to me. Is it a modification? I'm familiar with the Dumble circuits in a general sense, but I haven't heard of this.

Hot Rubber Monkey, or as some refer to as a.k.a. Hot Rodded Marshall. I.e. a tonestack added at the familiar Marshall location, after the preamp.

-chris

I used the HRM (Marshall tone stack tagged on the end of the overdrive stage) in a Fender 50 watt head for a customer some time ago.
he never liked it, so one day I removed the HRM tone stack - now he cannot stop raving about how great the overdrive sounds
in my opinion the HRM mod just makes it sound thin and no midrange punch.
bajaman

I have had 3 dumble clones and I kept the one without HRM. Just not into it. I love PAB though!

And what is PAB ?

Sorry for my ignorance ! I'm very bad at abbreviations.

Alf

bajaman wrote:I used the HRM (Marshall tone stack tagged on the end of the overdrive stage) in a Fender 50 watt head for a customer some time ago.
he never liked it, so one day I removed the HRM tone stack - now he cannot stop raving about how great the overdrive sounds
in my opinion the HRM mod just makes it sound thin and no midrange punch.
bajaman

The Bluesmaster is HRM but nice and fat sounding (at least my build/schematic). A lot of people only use the overdrive with PAB (pre-amp boost for the uninitiated). By lifting the tone stack with PAB the BM gives a nice mid-hump characteristic with overdrive on and all the volume/drive settings for clean signal.

That 46M resistor is part of the "local feedback" that Dumble amps use. Supposedly part of the Dumble tone, although not all models have it.

H-C reviews say it is mushy at higher gain settings. Personally, I'd use different fets, I find the 2n5457 to be tighter, or even MPF102, and increase voltage for more headroom and tighter gain.

Anyone ever play a Menatone Kar Krash? I find the Trainwreck circuits sound more rock 'n roll than Dumble and I wonder if Menatone captured that in a pedal. Dumble tones are too polished and refined for rawk.

Ed G. wrote:Anyone ever play a Menatone Kar Krash? I find the Trainwreck circuits sound more rock 'n roll than Dumble and I wonder if Menatone captured that in a pedal. Dumble tones are too polished and refined for rawk.

Then you haven't heard my Dumble

I personally feel that my Dumble can achieve a lot of different tones. Polished, yes, but also low down gain monsters are possible.......

I love my amp!

Btw; the HRM is very responsive on the setting of the HRM as on the other things in the amp. I've experimented with it a lot and found it to make my amp shine a lot! But I also heard a lot of differences side by side between models.

You know, I thought about that, that it seems that all the people who get Dumbles or Dumble clones are interested in is getting that polite, polished tone like Robben Ford. Robben amazes me with his playing but bores me with his tone. But I have considered that those amps could well be possible of more than that.

Something about the Howie schem I noticed was the 470pf cap between the drain and the source. I tried it in the bsiab and it did a nice job of shaving off the real high, razor frequencies. It's not quite "polite" but yet not as offensive to the ear. Subtle but nice.

Ed G. wrote:You know, I thought about that, that it seems that all the people who get Dumbles or Dumble clones are interested in is getting that polite, polished tone like Robben Ford. Robben amazes me with his playing but bores me with his tone. But I have considered that those amps could well be possible of more than that.

Something about the Howie schem I noticed was the 470pf cap between the drain and the source. I tried it in the bsiab and it did a nice job of shaving off the real high, razor frequencies. It's not quite "polite" but yet not as offensive to the ear. Subtle but nice.

Robben just bores me period.

Uma Floresta wrote:

Ed G. wrote:You know, I thought about that, that it seems that all the people who get Dumbles or Dumble clones are interested in is getting that polite, polished tone like Robben Ford. Robben amazes me with his playing but bores me with his tone. But I have considered that those amps could well be possible of more than that.

Something about the Howie schem I noticed was the 470pf cap between the drain and the source. I tried it in the bsiab and it did a nice job of shaving off the real high, razor frequencies. It's not quite "polite" but yet not as offensive to the ear. Subtle but nice.

Robben just bores me period.

+1 although I once saw him and I liked his style then...........

Anyone build per redraw schematic.... What's bias value for Q2-Q7.?

Made this from the vero supplied by Harold at http://www.sabrotone.com/?p=3569&cpage= ... 870,biased j201's at 4.5v and got a lovely creamy clean tone on the clean channel and a very good dumble od but a bit lacking in drive which is like all the youtube vids of this pedal,is there any way i can get a little more drive out of it?

Trying to keep the questions in the same thread so I am posting here. I recently built the Howie based on the Sabrotone vero layout which is based on the schematic from Torben3000 and kusi. I seem to have more than enough gain (too much) and when playing my humbucker 335 copy the E, A, and D strings sound like I am playing bass guitar unless the mid and treble control are maxed out and I am using the bridge pickup. It also sounds like I have a blanket over the amp. The amp is a very clean MMRD50. Any suggestions?