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Fractal Audio AMP models: ODS-100 (Dumble Overdrive Special)

yek

Moderator
Moderator
* EDIT: Up-to-date information is available in Yek's Guide to the Fractal Audio Amplifier Models *



ODS-100: based on Dumble ODS-100

These models are based on a Dumble Overdrive Special (ODS) amp.

A Dumble is THE most expensive amplifier available, no.1 of Vintage Guitar’s list of most valuable guitar amps. They were built by Howard "Alexander" Dumble, in L.A. Every Dumble is unique because they were built on special order, specifically designed for the buyer. He retired in the 90s. They say there are less than 300 Dumble amps. More info about Dumble. Dumble (and Trainwreck) discussion forum.

Famous Dumble players include Robben Ford, Larry Carlton, John Mayer, Carlos Santana, Keith Urban, SRV, Eric Johnson, Joe Bonamassa.

There’s always a lot of talk on the forums about Robben Ford's Dumble tone. It’s an elusive tone, worshipped by a lot of jazz / blues / fusion players. It's a thick, mid-heavy, smooth lead tone, very touch-sensitive. The “note flip” is a certain tonal characteristic attributed to the Dumble and some of its clones. So what’s the note flip? Quote: “It sounds KIND of like its starting to feed back, but its not. It flips the note up so that a different harmonic order is heard, or something like that”.
That trademark tone is not for everybody: hit a power chord and it may terrible to your ears.
But there’s more to Dumble than the Robben Ford sound.​

We’ve got several models of Dumblesque amps in our Fractal devices, such as the Bludojai and Fox models.

Cliff owns an actual Dumble, serial #213, with EL34 tubes. It has a HRM circuit. The “ODS-100 HRM” models are based on this amp. Cliff:

“They call HRM "Hot Rubber Monkey" but what it really means is "Hot Rod Marshall". The HRM Dumbles have a fixed Marshall tone stack at the output of the lead channel. This gives a little scoop to the mids."​

The “ODS-100 Ford” models are based on on schematics which supposedly represent Robben Ford’s Tan Dumble, serial #102. Cliff:

“The ODS-100 Ford 2 model is not based on the HRM model with the HRM tonestack removed. Whether or not the model matches any particular Dumble is unknown as we have not been able to procure a non-HRM Dumble yet. The model is based on schematics that were given to us that supposedly accurately represent Robben Ford's Dumble. Whether or not the schematics are accurate I do not know. The voltage divider at the output of V1B is set to 0.078 which is based on the values that are indicated on the schematic for the set-point of the trimmer. As no two Dumbles are identical it stands to reason that one person's interpretation of the ideal Dumble voicing may not agree with another's. Since V1 is running clean you can get more gain by simply increasing Input Trim. It will have basically the same effect as increasing the trimmer."​

Pictures of Ford’s settings:




The amp has two inputs: FET and Normal. The FET input has a different impedance. The models are based on the Normal input.

The amp has a Preamp section and an Overdrive section.

The controls on the original amp are: preamp Volume (model: Input Drive), Treble/Middle/Bass (shared preamp tone controls), Overdrive Level and Ratio, Master/Presence (power amp). The clean channel has a bright cap on the Master Volume. This causes the tone to get brighter as the MV is reduced and vice-versa.

There are three switches: "Bright" (adds spark). "Mid" (boosts the mids), "Rock/Jazz". Cliff:

"The Mid switch, sometimes labeled "Deep", shorts out the 390 pF cap in the tone stack (which is in series with a 2 nF cap). All that is left then is the 2 nF cap. With PAB active this lowers the lowcut frequency."​

There’s also a footswitchable Preamp Bypass (PAB) which bypasses the input tone stack.

The “Ford 1” model is based on the PAB engaged. “Ford 2” model is based on the PAB bypassed. “Ford Md” is based on PAB engaged and Mid-switch engaged. “HRM Mid” is based on the Mid-switch engaged.

The OD’s gain is set through Volume and OD Level, modeled in Input Drive and Overdrive. On all amps like this the first control sets the “sensitivity” and the second one sets the amount of distortion. Cliff:

“Input Drive increases the gain amount as you rotate the knob clockwise. As the gain increases the tone is shifted from a treble and upper mid emphasis, which produces an up front sparkling tone, to a lower mid and bass emphasis, which produces a thick meaty tone.​

Overdrive increases the gain amount as you rotate the knob clockwise but with no alteration of the tonal balance.​

Different combinations of Input Drive and Overdrive settings will have a dramatic effect on the response of the amplifier and the personality of your instrument. It is easy to get familiar with the action of these controls and you’ll be amazed with your ability to make any guitar sound mellow, fat, soulful or aggressive.”​

Models with Input Drive and Overdrive controls always feel “elastic” and spongy, a real joy to play.

It’s a Master Volume amp. This means that the amp’s distortion is created in particular by the preamp tubes, not the power amp. The Master Volume, which works in the power amp section, is still very important to the tone and feel. You have to decide for yourself what setting in the model works for you best. The default setting is a good point to start of course.

The Zendrive is one of the pedals that tries to recreate the Dumble tone. Rooben Ford uses it himself through Fender amps. We’ve got a model of this pedal: Zendrive.

Cliff’s Dumble cabinet with EV speakers has been captured in IRs. Look up the 4x12 Rumble stock cabs.

Cab Pack 17 provides more IRs of this cabinet.​





 
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ethomas1013

Forum Addict
"Dr. D"? Seriously? LOL...

I have never cared for Dumble amp sims in the past, but I recently stumbled upon the ODS-100 HRM preset in the AX8. Really digging that one. I like a lot of Robben's tones, but was never able to make these amp models work for me. Guess I'll have to give the rest of them another shot now.
 
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steadystate

Fractal Fanatic
Judging from that interview, I wouldn't think the guy could design a toothpick. Can't judge a book by its cover; or it's views on crystal lattices.

While the amp is not by bag, I want to thank yek for his incredibly useful list of amp descriptions. Reading them helps me to know what I should be trying to achieve with each model, rather than auditioning models and blindly adjusting parameters. I also like learning the history of each model. Great work!
 

Rocket Brother

Forum Addict
Love the Dumble ODS-100 HRM in the Axe for both clean and lead tones, the clean is very tight and balanced and works great for very clean parts and for funk rhythm and the lead is just great for blues, fusion and classic rock.

I haven't got much experience with the ODS-100 Ford models, which is strange considering how much I love Robben Fords playing - guess I really have to make it a priority to set time aside to dive into the ODS-100 Ford models.

@yek - One "correction" to the OP though - they are/were build by Howard "Alexander" Dumble.
Howard started calling himself Alexander when his amps started to really get in demand, and he became an "artist" who choose his customers as much or more than they choose him/his amps.
He signed a lot of his amps HAD.
 
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Sleestak

Forum Addict
That is such a weird and idiosyncratic amp. I played an ODS in the studio several years ago, and it was very interesting. Single notes and simple intervals spoke nicely, and the overall amp behavior was to "bloom" notes into greater complexity after the attack. It seemed similar to me to the behavior of a tube amp with unstable tubes, except instead of harsh oscillation, the amp tended to extrapolate the harmonic content of what I played. I recorded with it, mostly just to say that I had done so. I also used my Boogie Lonestar on that session. As much as I appreciate the uniqueness of the ODS, I would have needed a lot more time with the amp to really learn how to play it.

Given my very limited exposure to that amp, I can't say whether the ODS model in the AxeFX is definitively authentic, but I'm inclined to believe that it must be, because everything else in the AxeFX is so well done. Also, using the ODS model in the AxeFX means I don't have the studio owner nervously hovering over his holy grail to make sure I'm not "plugging in too hard". He insisted on carefully inserting my guitar cable into the amp as if it were docking with the space station, rather than allowing me to do it with my brutish muggle hands. Entirely understandable. I'm 5'6" and weigh 155 pounds... a total wrecking machine. :)

Nigel Tufnel: Don't touch it!
Marty DiBergi: We'll I wasn't going to touch it, I was just pointing at it.
Nigel Tufnel: Well... don't point! It can't be played.
Marty DiBergi: Don't point, okay. Can I look at it?
Nigel Tufnel: No. no. That's it, you've seen enough of that one.
 

Teej

Regular
People always list Eric Johnson as a Dumble user, which is true, but I don't believe he ever used an ODS. He did use a Steel String Singer for a number of years for his dirty rhythm/fuzz tone, but I heard that it broke down and it was never repaired. After that he just threw another Plexi in to replace it. When I saw him live two years ago, he had an old Park in that spot.
 

bradlake

Axe-Master
People always list Eric Johnson as a Dumble user, which is true, but I don't believe he ever used an ODS. He did use a Steel String Singer for a number of years for his dirty rhythm/fuzz tone, but I heard that it broke down and it was never repaired. After that he just threw another Plexi in to replace it. When I saw him live two years ago, he had an old Park in that spot.
Ask @Tex Axe
 

Smittefar

Fractal Fanatic
Had a good play with this amp today.

I only played with the HRM models and the clean model. I used the rumble cabs. I find it to be a quite dark amp. I had the bass almost off although I reduced both input and master volume.

But my oh my the sustain this thing brings to the table. It sounds very good.
 

kartman

Inspired
Inspired me to do a clean patch with the ODS Clean - absolutely love the clean channel of this amp!
I did the same last night... messed with IRs a bit and settled on one of the new OH 112 DLXRVB options just cuz it's new and near the top of my 'recents' list. Didn't tinker too much as, frankly, I was busy playing. :)

Anybody have IR suggestions that pair well with the clean model?
 

zenaxe

Fractal Fanatic
I liked the OP simply because it included the infamous 'crystal lettuce' YT clip. I like to rewatch that clip every once awhile because it reminds me what a dumb, strange, and weirdly wonderful all at the same time place the universe is. Fun Fact: Watching that clip five times in succession has the same medicinal value and psychological effect as two adult benadryl tablets.
 

Brownmatthall

Forum Addict
I liked the OP simply because it included the infamous 'crystal lettuce' YT clip. I like to rewatch that clip every once awhile because it reminds me what a dumb, strange, and weirdly wonderful all at the same time place the universe is. Fun Fact: Watching that clip five times in succession has the same medicinal value and psychological effect as two adult benadryl tablets.
It's simple physics really
 
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