The Nobel/Noble Tube Screamer

[Mark Hammer]

Thanks.  Did not know that.

[Rob Strand]

Thanks.  Did not know that.

The actual values for the RC network were not posted/known but I made some estimates at the time.  Aion's clone has a pot instead of a switch.  As I recall, with the input HPF present, it pushes the response of the first stage closer to the TS-9.  In the context of this thread, a switch with that response would be too subtle as it's too close to the TS-9.   In a sense the BC switch does the reverse of your mod by giving the ODR-1 a TS-9-ish option - at least for the first stage, as the rest of the circuit is quite different.

Having spending zillions of hours on this type of thing in the past my gut feeling is the (non BC) ODR-1 response with the HPF present would suit more people.   Too much LF boost can get bottom heavy, like Stallik found.    It's not so obvious from your video but over time I found myself eroding more low-end off these things.  For your original diagram that would mean a smaller cap for the 1uF.  maybe start with 220nF,  but people need to play with the value.

[Mark Hammer]

I guess this means I should probably test out mods using something more than an 8" speaker in a 5W amp.

[stallik]

Maybe, but knowing how to tune the response is a valuable lesson. And your mod makes for a great loudness button when playing quietly even if it's too much at stage volume (or with a bass player)

[Rob Strand]

I guess this means I should probably test out mods using something more than an 8" speaker in a 5W amp.

Yes you might see more of a difference.

Maybe, but knowing how to tune the response is a valuable lesson. And your mod makes for a great loudness button when playing quietly even if it's too much at stage volume (or with a bass player)

The ODR-1 values on my schematic try to balance the volume.  It's only ball-park from memory.   Everyone will chose slightly different values for "equal volume"

While we're at it I thought I'd throw the Timmy RC network into the pot for a few Bass pot settings.   As you can see the high end is in the BB1/RAT/ODR1 region.  You can see how the Timmy bass pot does broadly covers all the low end possibilities.

A small point is the Timmy flattens off the low end - for the dual RC network that's a large cap then vary the low-end resistor. Whereas playing with the low cut cap on the dual RC network will roll-off the low-end a lot more (depends on the resistor).   Timmy with a smaller bass cap and set to 15:00 would match the RAT (and as it turns out close to the ODR-1 w/HPF when the Timmy is at 12:00); bass cap around 56n.

[Rob Strand]

Here's all the common circuits with the circuit values for simple RAT style parallel RC networks.
That's all the circuits below the middle band - pretty obvious these use the RAT form of the circuit.
Two settings for the Timmy (V2) Bass control, 12:00 and 15:00.

Schematics:


Response:


You can:
- compare the f1, f2, fz parameters of the circuits
- compare the ratio of the larger resistor to the smaller resistor
- comparisons are on near equal grounds due the roughly normalized gains

Notes:
- I didn't plot the response of all the circuits as some are similar to others.
- For the ODR-1 BC the values are my best guess with the information I have.
  (not plotted due to uncertainty and to minimize clutter.)

[Mark Hammer]

Good chart.  Informative summary.  Thanks for that.  Like I say, the bass rolloff of the original Maxon circuit was a "first approximation", intended to achieve roughly equivalent clipping for wound and unwound strings across the fingerboard.  It more or less achieved that, but at a cost of some "guts".  Can't fault the engineer for being first out of the gate.

[Rob Strand]

I've updated the schematic and response so the ODR-1 has a 100nF HPF cap.

Good chart.  Informative summary.  Thanks for that.  Like I say, the bass rolloff of the original Maxon circuit was a "first approximation", intended to achieve roughly equivalent clipping for wound and unwound strings across the fingerboard.  It more or less achieved that, but at a cost of some "guts".  Can't fault the engineer for being first out of the gate.

The Maxon/TS9 values are certainly close to the money.   I'm almost embarrassed to say how many times I've tinkered with all sort of variations of networks, tweaking pedals over time, only to go back to the TS9 values and leave it.    The good thing about the switch option is you can leave the TS9 setting alone and tinker with the other one  .