Turning a pair of Afterlifes into a tone control...

[btml]

But how about a different approach-
Could I use an Afterlife's Vactrol as the variable resistor in a tone control instead of for controlling the afterlife's gain?
Because I really like Ampegs use of the Baxendall in their B15, and I was going to be shooting for that voicing anyway-
If I don't need the resistor side of the vactrol hooked up as drawn in order for the afterlife to control the vactrol, would I be in business?

[btml]

Except that it would then be an expander.. brain is scrambled.

[kothoma]

Except that it would then be an expander.. brain is scrambled.

It would depend on how you hook up that vactrols. You can get expansion or compression in the resp. bands.

But for that Baxandall you would need 4 vactrols and the pairs would need to be complementary, i.e. (Rpot - Rldr) + Rldr, if that makes sense.

[btml]

I was just looking at that- It would be a nightmare to tune two vactrols to act like two halves of a pot-

I could compress the full signal conventionally and get slightly more compression on highs by using the vactrol as a tone knob, essentially.

Too many ideas, need breadboard.

[Vallhagen]

I don't understand why there is a phase shift of this type in the first place, but there's probably some math involved?

Yep, math is involved... but math is - in this case - "only" a way to explain physics/reality.

Verrrry simplified: Each time* you put a C or L (in this case, C) and some R in a signal chain, you will cause a time delay. And time delay=phase shift, just expressed in different units chosen by context. This time delay is related to the time it takes to charge/discharge a capacitor in a given circuit.

...so what happens here in your filtering is that the LP part of the circuit cause a time delay, and your HP-circuit cause another time delay. And the difference between those time delays will, at one specific (the crossover-) frequency, equal to a 180 degrees phase difference, causing a complete destructive interference when you mix them to eachother.  When You add a perfect positive peak to a perfect negative peak the result will be nothing...Just as 1+(-1)=0.

My reasoning here is based on the Linkwitz Riley 12dB/oct filter. Funny: Now as i see it and type it, the further developed (better!) Linkwitz Riley 24dB/oct filter must cause a 360 degrees phaseshift between the LP and HP sections. And 360 degrees means... we are in phase again, just that the LP is a cycle late (and we can live with that). No dip, no notching!!

So, yea, this takes me back to square one, THcustoms Pro-cessor is probably exactly your thing. I encourage you to try it:)

hehe, you see i changed my mind?

Cheers
***



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* okokok, maybe not EACH time, but again, simplified example...

[alanp]

Yep, math is involved... but math is - in this case - "only" a way to explain physics/reality.

Math is always a way to explain reality

[kothoma]

Yep, math is involved... but math is - in this case - "only" a way to explain physics/reality.

Math is always a way to explain reality

At least it allows to make models of reality that can be used to make predictions.
Not sure about explaining anything.

[btml]

Yeah- I've tried doing more advanced maths and surprised myself- But the only way I can do it is to find a visualization that jives, otherwise I'm lost.

I'm definitely going with the Pro-cessor so I can have conventional results, but I also want to see where this other idea goes cause it would invariably sound different than anything else out there. Two Builds-

So, the Vactrol controlling a tone knob thing-

In the AL, the LED idles at low (or off?), and when a loud enough signal is applied, the LED brightens lowering the resistance in IC1a's negative feedback loop, and this turns the loud notes down.

At least that's how I understand it-

Instead of resisting less in a feedback loop to turn down the signal, Id like to resist more in the signal path.

Is it possible to have the LED idleing high and send it less voltage when a loud signal happens? I don't see it in any schematics for compressors... Is that just because it would eat batteries, or is it not possible?

Cheers~

[kothoma]

Instead of resisting less in a feedback loop to turn down the signal, Id like to resist more in the signal path.

You could use it as is resisting to ground, like many tremolos do.

Is it possible to have the LED idleing high and send it less voltage when a loud signal happens? I don't see it in any schematics for compressors... Is that just because it would eat batteries, or is it not possible?

You could flip the curve around with simple op-amp-mathematics, that's what they were invented for anyway. But there could be simpler methods. Sure it would need more current that way.

[btml]

I can't use resistance to ground with this particular eq-

I guess it's the math for me.

I had the thought that if I were to go nuts and replace the pots with pairs of LDRs, A) they could do the compressing, but I could use pots to control the 'idle' voltages, and they would essentially set the default tone knob values. Which I think is spiffy.
And B) Id never make it work.

[kothoma]

I still have trouble trying to understand what you want to achieve.
I know what multiband compression does to a mix.
But I can't quite imagine what compressing highs and lows separately on a single note would sound like, especially on bass. And mids stay uncompressed?
What would be different from mixing an eq'ed and compressed signal with the dry signal?

[btml]

Kothoma- It's just multiband, but as it relates to the bass guitars spectrum and my playing style.

I don't like much compression anyway, but I do like the option of slightly more compression on my highs.
Say, if I wanted to slap or do something percussive- I like to have balanced tone, but that means when you do anything percussive, those things just poke out and clip more in the higher frequencies than I would like(especially if I've been DI-ed into a PA, and the vitamin root perm sound man assumes I want to sound like a machine gun).
As for the lows, I like to palm-mute a lot and go for a lower frequency percussiveness- as in mimicking the shorter attack and quicker decay of a note played on an upright. I'm pretty good at getting that bouncy swingin feel from my notes, but if I compressed that like I do the highs, it would get all smoothed out.

So- I use multiband compression to support the range of playing techniques I use. Does that make sense? I'm just looking for a version of that which is tailored for what I do rather than have 17 knobs.

The mids aren't a separate band to me- that would be going a bit nuts. On a conventional multiband I would keep mids with the lows- matter of taste I suppose. The baxendall idea is a whole different thing though, I'm not sure where that will take me.

Actually- I have tried eq + comp in parallel with dry- Read about Motown doing their vocals like that. I always felt like it was working against me though-

[kothoma]

I do like the option of slightly more compression on my highs.
Say, if I wanted to slap or do something percussive- I like to have balanced tone, but that means when you do anything percussive, those things just poke out and clip more in the higher frequencies than I would like(especially if I've been DI-ed into a PA, and the vitamin root perm sound man assumes I want to sound like a machine gun).

So in essence you want a limiter for percussive playing. But you only want to limit the highs? But aren't the highs mostly in the attack anyways, so a limiter should do? Or is it really compression you want?

As for the lows, I like to palm-mute a lot and go for a lower frequency percussiveness- as in mimicking the shorter attack and quicker decay of a note played on an upright. I'm pretty good at getting that bouncy swingin feel from my notes, but if I compressed that like I do the highs, it would get all smoothed out.

You want a milder compression for that.

OK, I get basically you want to be able to play funk slap bass and palm muted jazz walking bass (or similar) with the same compressor setting? So you don't have to switch between two different compressor settings?

[btml]

Exactly- except for limiting, I always felt that's the nuclear option.

Some use two compressors, and A/B between them-
One could compress the full signal, then compress the highs more-
You could do the motown parallel trick you described-
Some try sidechaining an eq-

Tried it all and I prefer the multiband approach- except that multibands are pretty much all 4 knobers, and those things never sound as musical to me as the simpler circuits like you see in ancient compressors like the Altecs, or in certain guitar pedals which we could geek on for days.

But yeah, it's all about having a setting that I can forget about and just play-

[kothoma]

OK then, for two-band compression the easiest way should be to go with a Pro-cessor.
You only need to find the right corner frequencies.

This will yield 5 knobs, but you probably can eliminate the blend pot.
(I guess it would be more tricky to dial in your setting if you throw out the level pots.)
Still 4 knobs.