Thursday, 3 January 2013

Runoffgroove Tube Reamer

Simplified Tube Screamer workalike. ROG soundclips and info about the circuit:

The first incarnation of the Tube Reamer was developed as a stripped-down, yet edgier version of the classic Ibanez Tube Screamer. We removed the input and output buffers as well as the tone control stage, plus implemented a different gain control. Many builders enjoyed the circuit, but a number of them saw the circuit was ripe for modification. Since a majority of the popular mods dealt with the gain control and range, we decided to revisit the circuit in an effort to improve on it.

First, we reverted to the original Tube Screamer gain control. The type we used in the first Tube Reamer interacted with the bass content a bit too much for our liking and the range of available gain settings was quite narrow. We expanded the gain range and also adjusted the component values to keep more midrange frequencies in the signal. Finally, we added a second small gain stage to increase the output level of the circuit. Nearly any dual op-amp is suitable for use in this circuit, including the usual suspects: JRC4558, TL072, NE5532.



7 comments:

  1. Verified. This is incredibly bright sounding, on the verge of being a little harsh. So if anyone's building it in the future it may be worth changing the 100nf output cap to maybe a 220nf. I also swapped the clipping diode pair for an on/off/on switch with 1n4148's on one side and 1n34a's on the other, it sounds pretty nice in the centre position without any diodes too, kind of acts like a dirty boost without adding too much and the extra treble helps prevent it from being too muddy.

    Another excellent ROG circuit and another great layout :D

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    1. Excellent thanks mate, and for the Dragonfly Sparkle Boost. You've had a productive day! :o)

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  2. This is really growing on me, really nice for getting into that John Frusciante territory from around Blood Sugar Sex Magik, right now I'm getting in amongst some Funky Monks!

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  3. I built this pedal and it sounds great until I crank up the drive pot. When I crank the pot up past around 12 o'clock I get a high pitched squeal like feedback. It is not my amp feeding back because I tried it with the balanced line out into my headphones. Any thoughts where I might have messed up? The only mod I did was changing the output cap to 220nf as madferret suggested.

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  4. What if I switched all the 12k to 10k would the thing still run?

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    1. I'd guess the difference wouldn't be noticeable. but you can join a 10k + a 2k resistor in series for example, to get the same resistance.

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  5. I added a 10n cap in parallel with the 22n input cap (making it 32n). Just adds a few more bass frequencies.

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