Fiddled around a bit regarding pots and bowling using resistor cadence boards. It's tentative (exclusively by ear) and requires a bit more tuning. For now:
- GAIN is like dagoose described somewhere above (here on a B10k with 41 detents).
- THR is also a B10k (41 detents) with a bowing resistor for more sensitivity (logged). In my preferred operating range (ratio set to around 12 o'clock, after settling on ratio bowing resistors), one click on the THR pot now corresponds roughly to one more LED lighting up.
- RATIO is two bowing resistors, a 10k and about 1k4. Second idea was to increase the feedback of the op amps feeding the ratio pot. So a random 3k stuck across R15 (R16). That brought me closer. These should be trimmers to fine tune for pot gang deviation (I had matched the pot gangs as closely as possible, still...). However, there's really no space on the board for adding trimmers without them dangling in midair. So for now I have resistors in series feeding the pot.
I don't need the unit to create much limiting overall. A maximum of -5dB should be more than enough for my use. To my ears, anything more than max -2.5db / -3dB starts to "sound" -- which is not what I want.
I still need to investigate (waveform / scope / plotting) where the actual max ratio now sits at. Might be I do need higher ratio for extremely high peaks and sharp transients (as in razor-shaving).
The idea is to finally put all the bowing resistors and two trimmers on a tiny sub board instead of soldering onto pots or sticking them into the connectors.
Waveulator ME Saturator Construction Information
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Re: Waveulator ME Saturator Construction Information
Thanks for the update.
I knew at the time I was going to need input from users.
I'm thinking ultimately we can take the bowing resistors' effects in parallel with a linear taper and design a custom taper for a stepped switch.
I knew at the time I was going to need input from users.
I'm thinking ultimately we can take the bowing resistors' effects in parallel with a linear taper and design a custom taper for a stepped switch.
Which value is from the wiper to ground?RATIO is two bowing resistors, a 10k and about 1k4.
Re: Waveulator ME Saturator Construction Information
Would need to check, but quite certain it's from W to G.
I tried all sorts of things including bowing A100k and A10K. Then read the Uno thread and yes, it felt the best so far.
What does H stand for?
And am I right in assuming that putting a resistor in series from H will lower the max ratio? If so I might need to try different resistor values for bowing should I want max ratio at fully CW but a custom value at 12 o'clock like 2:1.
Not sure such a high resolution of only up to 2:1 for half a pot rotation makes sense, but I also want to try deep thresholds.
I tried all sorts of things including bowing A100k and A10K. Then read the Uno thread and yes, it felt the best so far.
What does H stand for?
And am I right in assuming that putting a resistor in series from H will lower the max ratio? If so I might need to try different resistor values for bowing should I want max ratio at fully CW but a custom value at 12 o'clock like 2:1.
Not sure such a high resolution of only up to 2:1 for half a pot rotation makes sense, but I also want to try deep thresholds.
Last edited by Script on Mon Dec 09, 2024 7:47 am, edited 1 time in total.
- mediatechnology
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Re: Waveulator ME Saturator Construction Information
"H" stands for Hot which is the top side of the pot.
Putting a series resistor between H to the top of the pot will reduce the range.
H=Hot
W=Wiper
G=Ground
R19 and R22, which are 49R9 build-out resistors, could be made larger to accomplish the same thing.
Putting a series resistor between H to the top of the pot will reduce the range.
H=Hot
W=Wiper
G=Ground
R19 and R22, which are 49R9 build-out resistors, could be made larger to accomplish the same thing.
Re: Waveulator ME Saturator Construction Information
Built-out resistors, yes. They sit right next to R15 and R16. Still might want a trimmer though.
I think next I'll look into the 1k4 from Hot to Wiper.
Just as an aside, I switched to dot mode on the LED graph. In bar mode, it was just flickering around wildly with too much light pollution going on for my taste. In dot mode, it's easier to read and is readable in two directions -- one LED fully lit, adjacent ones (to left and/or right) half or only dimly lit, thus revealing where the next to highest peak (next instrument peak) sits.
I think next I'll look into the 1k4 from Hot to Wiper.
Just as an aside, I switched to dot mode on the LED graph. In bar mode, it was just flickering around wildly with too much light pollution going on for my taste. In dot mode, it's easier to read and is readable in two directions -- one LED fully lit, adjacent ones (to left and/or right) half or only dimly lit, thus revealing where the next to highest peak (next instrument peak) sits.
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Waveulator Metering
I've made a minor change in the Waveulator's metering circuit to provide for 5 dB full scale when a GR-20 bargraph board is used.
For 5 dB full scale:
The GR-20 has a full scale voltage of 2.4V.
R65, which was previously 10K, becomes 3K32.
This raises IC19B's gain to "4."
The internal VCA scale factor is 120 mV/dB so: 0.12V/dB x 4 x 5dB = 2.4V.
When the GR-20 is directly connected to Vout it will display full scale at 5 dB gain reduction.
To make it switchable from 5 to 10 dB full scale:
The GR-20 has a 10K input resistance.
To provide a switchable 5dB/10dB full scale meter, insert a switchable 10K series resistor in the GR-20 input line from the Vout terminal.
The switch is a SPST with the 5 dB position shunting the 10K.
When the 10K is in circuit, the full scale is 10 dB; when the 10K is shunted the scale is 5 dB.

Current outputs for use with mechanical meters:
The output of IC19A is 1.2V at 10 dB gain reduction.
For a 1 mA meter to display full scale with a 1.2V source the total resistance needs to be 1200 Ω.
The meter has an internal resistance. Assume a 200Ω Rmeter.
The value of R66 = 1200 - Rmeter = 1KΩ.
At 5 dB gain reduction IC19A is producing 0.6V.
For 1 mA of current a total resistance of 600Ω is required.
The value of R67 = 600 - Rmeter = 400Ω.
The nearest E96 value is 402Ω.
If you don't know the internal resistance of a meter simply measure it.
For 5 dB full scale:
The GR-20 has a full scale voltage of 2.4V.
R65, which was previously 10K, becomes 3K32.
This raises IC19B's gain to "4."
The internal VCA scale factor is 120 mV/dB so: 0.12V/dB x 4 x 5dB = 2.4V.
When the GR-20 is directly connected to Vout it will display full scale at 5 dB gain reduction.
To make it switchable from 5 to 10 dB full scale:
The GR-20 has a 10K input resistance.
To provide a switchable 5dB/10dB full scale meter, insert a switchable 10K series resistor in the GR-20 input line from the Vout terminal.
The switch is a SPST with the 5 dB position shunting the 10K.
When the 10K is in circuit, the full scale is 10 dB; when the 10K is shunted the scale is 5 dB.

Current outputs for use with mechanical meters:
The output of IC19A is 1.2V at 10 dB gain reduction.
For a 1 mA meter to display full scale with a 1.2V source the total resistance needs to be 1200 Ω.
The meter has an internal resistance. Assume a 200Ω Rmeter.
The value of R66 = 1200 - Rmeter = 1KΩ.
At 5 dB gain reduction IC19A is producing 0.6V.
For 1 mA of current a total resistance of 600Ω is required.
The value of R67 = 600 - Rmeter = 400Ω.
The nearest E96 value is 402Ω.
If you don't know the internal resistance of a meter simply measure it.
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Waveulator Makeup Gain
Waveulator Makeup Gain
To reduce the 0 to +12 dB range of the makeup gain control, scale the values of R55 and R56.
For a 0 to +6 dB range make R55 and R56 536KΩ.
For +5 dB make R55 and R56 634KΩ.
To reduce the 0 to +12 dB range of the makeup gain control, scale the values of R55 and R56.
For a 0 to +6 dB range make R55 and R56 536KΩ.
For +5 dB make R55 and R56 634KΩ.
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Re: Waveulator ME Saturator Construction Information
Finished my Waveulator yesterday and have been loving the way it sounds.
I know this is the "zero Attack Zero Release" limiter... But I couldn't help adding some release. Its so easy. Just add a cap across R13. (R14 for the other side)
No cutting traces no pulling up any parts. I've played with everything from 0.47uF to 100uF. I'm putting in a six position switch for sure. Sounds soooo good:)
Caveat:
I don't know if this could possibly damage the THAT300 transistors, maybe adding 47-100 ohm resistor in series with the timing capacitor might be a good idea.
Try at your own risk...
Thanks for an amazing project!
Ian
I know this is the "zero Attack Zero Release" limiter... But I couldn't help adding some release. Its so easy. Just add a cap across R13. (R14 for the other side)
No cutting traces no pulling up any parts. I've played with everything from 0.47uF to 100uF. I'm putting in a six position switch for sure. Sounds soooo good:)
Caveat:
I don't know if this could possibly damage the THAT300 transistors, maybe adding 47-100 ohm resistor in series with the timing capacitor might be a good idea.
Try at your own risk...
Thanks for an amazing project!
Ian
- mediatechnology
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Re: Waveulator ME Saturator Construction Information
Thanks Ian!
I'll have to try that.
I'll have to try that.
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Re: Waveulator ME Saturator Construction Information
After playing with values for a bit. Something like 4.7uF to 20uF is a good range...