Tuesday, October 30, 2012

Tumble and Drive - the Rougue Dumble


The Runoffgroove Tumble Drive (Umble)
For those of you who are following this blog and my recent posts, it is probably clear that, although our main point of concern is the magical sounds of fuzz circuits, a great of interest is being paid to the accompanying peripherals, which have a great deal to do with the overall guitar sound. What I mean by this long phrase is that every time I think I have understood the fuzz sound of a certain pedal I am amazed to discover how different it sounds and behaves when you play with it through different amps.
That was the main reason I began building amp emulation pedals like the English Channel (emulation a VOX AC30 top boost channel) or the Thor (The Marshall 100W Superlead). You have probably noticed that when it comes to amp emulation I am very fond of the Runoffgroove design, and that is mostly because they just sound great and they definitely evoke the characteristic sounds of the amps they aim to emulate.

On of the most sought after sound of guitar amplifiers is the unique sound of the Dumble amps which have been made since the 60's in California by Alexander "Howard" Dumble. Although I have never played through a Dumble in my life, nor do I believe I will ever do, it was interesting to hear what the fuss was all about. The list of Dumble users includes some major players like Santana, SRV, John Mayer, Al Di Meola and Ben Harper and many more. Probably the most recognized user of the Dumbles is Eric Johnson who made the amps famous with his singing Fuzz Face going through an heavily overdriven Dumble.

Unlike many of the ROG designs which I built in order to get the well known classic sound of a certain amp, on this build I just wanted a good American  sound which would get me from clean to crunch with some nice lead tone and good tone control. I even asked the ROG guys about a Fender like design that would get me close to a Vibroking or a Super-Sonic sound and they recommended their Dumble-like design, called the Umble, a cascaded FET based overdrive. 

I quickly started gathering parts and had the circuit running in a few days....and YES....another great sounding overdrive by the amazing guys at ROG. This is a very versatile unit which got me playing for days getting some wicked tones. On the lower end of the DRIVE knob it's capable of some really sweet clean tones. Single coils come cleaner but with proper use of the tonestack you can get Humbuckers to sound clean too. I really love low gain pedals because I love the warm drive you can get from them. This pedal does it all, warm, punchy or razor sharp, it's all there. Once you get the DRIVE up it becomes a monster and reaches Fuzz territory towards the end. While lowering the Tone stack knobs cleans the sound, increasing them gives you more drive and half way through the dials you are already speeding on the freeway.

I called it Tumble Drive because it sounded better then Umble to me and it drives so smooth and nice.
The one thing which I really love about this design is that it also serves as an excellent booster before a second overdrive like the Supreaux Duo ("1st Page" on my blog). It sounds really good and gives you the Eric Johnson tone if you put a Fuzz Face in front of it. Actually, every fuzz I hooked up with it sounded great and so it isn't just another amp-like pedal. Although the Tone stack is a little strange to work with it sounds good: The TREBLE knob adds some BASS as you crank it, and the BASS is quite subtle.

The final thing I did just recently was adding a simple switch to bypass the first FET gain stage so that I can now get even cleaner sound on low DRIVE settings. Now it's just perfect and I really like the paint job which I got in the end with the IGNITE toggle switch.
The gain switch which bypasses the first stage gain FET (in red)


Umble with Gain switch

Again....don't pass out on this design if you are serious about american sounding overdrives. The schematic can be found here.

Below are 2 demos of my lousy playing on my ES335 clone guitar and the pedal through a soundcard and some amp with room simulations. The first is a demo with different settings and the second is a mix of 3 tracks, Riff+rhythm+solo, with various settings showing the versatile sound of the effect on a single guitar. It's quite an amazing pedal with its capabilities as a low gain overdrive, high gain overdrive, full on distortion and a great fuzz character with the BASS knob fully cranked. The tone stack have a huge effect on the sound of the pedal.



9 comments:

  1. Sir,
    From tagboardeffects.com, you posted, "I wanted a lower gain option for more versatility so I discussed it with the guys at ROG and they suggested a switch for bypassing the first gain stage. Did it and it was great, especially for humbuckers." I am building this board now and am hopeful you can share the method for bypassing. Mirosol suggested a SPDT between Input and the drain lug. Thanks in advance.
    pete

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    1. Lift the ground connection of the 4u7 cap on the source of the first gain FET. Use a switch and a 1M resistor between the SPST switch lugs to prevent a pop upon switching.

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  2. Thank you and done. For clarification and my own peace of mind, there are four FET's, left to right on the TBE layout, and I am assuming the leftmost FET is the one we are talking about. To clarify, the (-) side of the 4.7u connects on the same row to a 1.5K on the left and 1.5K on the right which then goes into the source leg of the next FET over and eventually feeds out to the leads of Master 1 & 3. Thanks and appreciate your help and patience.

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    1. Yes. Just lift the (-) of the cap from the ground row. You should notice, if you do it while you play, a decrease in gain. It's not a huge difference but it's enough to get you cleaner tones from humbuckers and hot pickups on the lower gain settings. Good Luck! You can do it with many of the ROG designs. It is super useful.

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  3. I had originally posted this to TBE, and it was suggested that I wait until you see the post there. I elected to go this route and if you do not mind, I would like to post your answer. For your info, I placed a cut at 5/11, and countersunk the hole at 4/10 to remove minimal copper around the hole. I then soldered legs 1&2 of a 3-pin SIP together underneath the plastic and then soldered leg pins 2&3 of the SIP to the board. The cut at 5/11 does not interfere with the circuit even though it shares a row with leg 1 of the trim pot and allows greater holding of the SIP, two legs are better than one. The removal of copper at 4/10 keeps the unsoldered pin from shorting.
    The 4.7 cap then is soldered back into 4/8 and pressed into hole 1 of the SIP. I then ran wires from the switch to holes 2&3 of the SIP and viola. Thanks again.

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    1. No problem. Post whatever you want. Make sure you credit ROG for the mod as it was suggested by them. Enjoy.

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  4. Added some audio clips if anyone is interested.

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  5. I am getting ready to build this pedal. Any chance you could post a pic of how you wired the low gain mod?

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    1. I have added a little schematic modification from the original ROG design which shows the FET switch on the 4.7uF cap to ground connection.

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