ROG Tube Reamer Mod?

[Zben3129]

Hi guys,

I breadboarded the ROG TR, and I found that, as per description, it was edgier than a tube screamer. I was wondering, if I were to remove the 51k resistor in the FB loop all together, would this make me able to turn the gain pot all the way down and have no distortion at all, and also have the range of the distortion generally milder?


Zach

[B Tremblay]

Try using a 27k or 33k resistor to start, then decrease the value if there is still too much gain when the pot is at its minimum.

[nooneknows]

BTW B Tremblay, the TR 2.0 has officially become a part of my sound chain. A great pedal for my type of fingers and sound.

Ciao

[Zben3129]

+1

I love the warmth It gives my sound, great pedal. Especially for how easy it is!

And I tried the 33k, and I liked it, but I did end up going down to no resistor. When I turn the pot all the way down, There is little to no breakup, only if I smash the strings. On 2, I can play "Clean". If you asked someone what I was playing on 2 they would say clean, but it has a nice little warmth to it (Think Texas Flood). On 5 (My favorite setting), I get some nice, smooth, gentle overdrive (Do you feel like I do?). On around 7 or 8 is where I play my zeppelin, Still plenty of drive without the 51k, sometimes I ratchet it up to 10 for some fun, but definitely not neccesary to get some serious drive


Zach

[nooneknows]

I'm using it pretty clean, gain at 9/10 o'clock, then I use a booster to push it in case of fire: best of both worlds.
So I have at least 4 really different sounds with only 2 pedals with this setup, very useful.
The Reamer just gives that kind of crunch I need, I can hear the pick nuances on the string still sounding distorted, I like it.

[stm]

An unnoticed feature of the Tube Reamer 2 is that the second stage has a rather high gain (5x above 200 Hz or so) which introduces additional clipping for hard hit notes and chords.  In this sense, this circuit is more sensitive to the opamp type than a regular TS.

Reducing the 51k feedback resistor allows less gain, but won't allow absolute cleanup even with the GAIN pot at min since the 5x gain of the second stage is likely to clip the peaks anyway.  Further guitar pot vol reduction would be neessary if no clipping at all is desired.

Notice also that the 1k resistor at the output of the first opamp can be used easily to implement a tone control.  One possibility consists in lowering the 22n cap to 10n, then adding a 5k pot in series with the 1k resistor.

[bipedal]

Slight hijack:

I'm curious if anyone has substituted FETs in place of diodes in the tube reamer circuit?  If so, how'd it sound?

If I'm reading the "FETs as diodes" section of http://www.diystompboxes.com/cnews/mods.html correctly, one could replace the 1N914 diode pair in the TR circuit with a pair of FETs, shorting the gate and source leads on each transistor...  (I'm sure some adjustment of cap values would be needed.)

- Jay

[wampcat1]

Slight hijack:

I'm curious if anyone has substituted FETs in place of diodes in the tube reamer circuit?  If so, how'd it sound?

If I'm reading the "FETs as diodes" section of http://www.diystompboxes.com/cnews/mods.html correctly, one could replace the 1N914 diode pair in the TR circuit with a pair of FETs, shorting the gate and source leads on each transistor...  (I'm sure some adjustment of cap values would be needed.)

- Jay

fets do have a unique sound... they sound "fetty" I guess 
a little smoother more compressed tonality. However, if it was me on the TR I would lose the last opamp stage and insert an eq stage instead (gyrator) at around 150 hz or so and another at around 2.5k or so. But that's just me.

bw

[MikeH]

Hi guys,

I breadboarded the ROG TR, and I found that, as per description, it was edgier than a tube screamer. I was wondering, if I were to remove the 51k resistor in the FB loop all together, would this make me able to turn the gain pot all the way down and have no distortion at all, and also have the range of the distortion generally milder?


Zach

It also has no tone control.  You could add a simple low-pass type tone control on the output to take off some of the "edge" as well.  it's a great little circuit, and rife with modding opportunities.

[nooneknows]

I've just finished adding a tone control to the tube reamer 2, now it's almost perfect!
I used a Mark Hammer's "Stupidly Wonderful Tone Control" (SWTC) (http://hammer.ampage.org/files/SWTC.gif) using this values:

R = 1K8
P1 = 22KA
C = 10nF

It works, give it a try!

Ciao,
Marcello

[Zben3129]

Nice! I may try this

[nooneknows]

An unnoticed feature of the Tube Reamer 2 is that the second stage has a rather high gain (5x above 200 Hz or so) which introduces additional clipping for hard hit notes and chords.  In this sense, this circuit is more sensitive to the opamp type than a regular TS.

It might be true, I tried different opamps and there seems to be slight differences, the best sounding to my ears is the JRC4558D I finally mounted

[wampcat1]

An unnoticed feature of the Tube Reamer 2 is that the second stage has a rather high gain (5x above 200 Hz or so) which introduces additional clipping for hard hit notes and chords.  In this sense, this circuit is more sensitive to the opamp type than a regular TS.

It might be true, I tried different opamps and there seems to be slight differences, the best sounding to my ears is the JRC4558D I finally mounted

You might try the LM358 too - I really like this one! It's a little darker and smoother IMO.

all in all, the TR is a great, simple circuit, and very easy to build for the newer diy'er. Great stuff ROG!!

bw

[Zben3129]

True, or my personal favorite, the LF353. I use these in all of my builds now, they sound the warmest and smoothest to me!

Zach