Remind me again why interactive tone controls are so great

Discussion in 'Glowing Bottle Tube Amp Forum' started by Digital Larry, May 14, 2019.

  1. Digital Larry

    Digital Larry Tele-Afflicted

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    I think some of it boils down to a misunderstanding which nobody wants to clarify. Some people might think the interaction is with THEM, the user. "Wow I really have a wide range of adjustment!" vs. interaction of controls with other controls, e.g. "when I turn down the treble, my bass also drops quite a bit". Maybe you'd really like the bass to stay where it was, but too bad. It's interactive therefore you must love it.

    I have similar problems with the word "resonant" but I'm saving that rant for another time.
     
  2. gusfinley

    gusfinley Tele-Holic

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    Interactive tone controls = Just a way for marketing to relabel a design feature into something that consumers could precieve as having value.

    Take the Vox Top Boost Circuit- The original circuit puts the "mid resistor" in parallel with the Bass control, so if you crank the bass pot the mid resistor goes to "zero" and you get a tight mid scoop. Talk about interactive!

    The new "Custom" Series of amplifiers "fixes" this quirky circuit by putting the "mid" resistor where it should be in a TMB tone stack. Yet, I still here the new "Custom" Top Boost circuit as being described as "interactive." I haven't heard anybody selling it as being "less interactive."

    For those who think that their Vox doesn't quite sound like what they feel a vox should sound like restoring the original circuit usually produces the effect they were looking for - interactive tone controls.
     
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  3. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    All true WRT where the feature actually resides.

    I like my room resonant and my tone woody.
    If the room is woody and the tone is resonant I'm taking my toys and going home!
     
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  4. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    I have a Vox style amp with just a tone knob and a cut knob.
    Can't dial in a tone I like to save my life.
     
  5. Digital Larry

    Digital Larry Tele-Afflicted

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    On the other hand, I can respect this sort of thing as a creative decision. The more you tighten down the adjustability of settings, you constrain the amp to a more specific range of sounds or personality. It takes a certain level of moxie to put out a product like that rather than one that can sound like the 3 top brands or model everything under the sun.
     
  6. anthrotony

    anthrotony Tele-Meister

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    Thanks for this. I'm going to have to (yet again) look at the two circuits to see just how much I'd need to change relative to my BOM and ultimately just make a decision. Problem is that like these darned interactive controls, I've never actually played such an amp, nor am I able to, so I won't actually know if the amp I build is the right first "one" until I actually do it!
     
  7. Digital Larry

    Digital Larry Tele-Afflicted

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    A good example at 1:50 here

     
  8. printer2

    printer2 Poster Extraordinaire

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    Interactive tone controls just means that the dip or peak changes, and the different places it ends up changes the character of the sound. As far as normal hifi, flat at 12:00 tone controls goes, they are non-interactive, assuming a gain stage and two resistor and capacitor networks. But then put in a mid control and they interact a little with the corner frequencies for the bass and treble or the mid control shifting depending how the others are set. But unlike hifi controls the guitar frequency range is less wide and the control frequencies closer together. And this causes them to interact more with each other. The way to get around this is to have each control to have its own gain stage (now days normally an opamp) and the controls will stay in their places.

    So the interactive nature can be used as an advantage if you want to mess around with your controls and then remember if the bass is at 6, mid at 3 and the treble at 8 with the guitar volume at 7, you have your favorite sound. Now if you are playing live and you just want to add some treble without messing up your mid scoop, maybe a non-interactive control might do you better.
     
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  9. gusfinley

    gusfinley Tele-Holic

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    For a quick visual example, download Duncan's Tone Stack Calculator. You can see the effect of the controls on the amps frequency response.

    For extra credit check out the Vox circuit at full bass and treble, then set the Marshall circuit to vox values to see the difference.
     
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  10. Digital Larry

    Digital Larry Tele-Afflicted

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    I get why the design is interactive and I'm not even trying to claim that interactive tone controls as found on so many amps are bad, but let's take this ridiculous example.

    I design an amp with interactive tremolo and reverb and gain controls. If you turn the reverb up from 0 to 50%, the tremolo speeds up. Reverb above 50%, the gain starts to go down. That may or may not lead to some really great sounds, but it sure as hell is interactive! As a marketer I don't know what to make of it other than to say "HIGHLY interactive reverb, tremolo, and gain controls!!!!" The guy in the Rob Chapman video I posted clearly doesn't even understand what he is talking about but he mentions it anyway.

    I do DSP effects design for fun and occasional profit and sometimes you have something you want to allow people to do but you don't have a spare knob for it, so you double up the function of a single knob. Putting speed and width (inversely scaled) on a chorus adjust is a really common example. The width auto-scales with the speed so you avoid slow/narrow and fast/wide settings. I view it as either a creative decision (because that's the range of sounds you really wanted to allow, at the expense of not having the other ones available), or you were backed into a corner by technical or cost considerations and just had to make do. Possibly a combination of those two things.

    OK I'm done pummeling my point to oblivion. You've been a great interactive crowd.
     
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  11. mexicanyella

    mexicanyella Tele-Holic

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    Interesting perspective on this post, and what you said about choosing whether to double up functions of controls reminds me of an interview I read with the ZT Lunchbox amp guy, where he mentioned that the odd not-quite-reverb “ambience” control came as a result of a chip specified in the original design was no longer available when stocking up for production. The replacement they found didn’t have the processing power to pull off reverb, so they did what they could with it and relabeled the control.

    Henricksen, in Arvada CO, makes jazz-oriented amps with EQ controls that seem like graphic equalizers with the slider functions transferred to rotary knobs.

    https://www.henriksenamplifiers.com/product/jazzamp-ten/

    The JazzAmp Ten manual shows low, low mid, high mid and high controls from 100 Hz to 1.6 kHz and a presence control at 3.5 kHz. Never played one, but I’d like to try one and see how interactive the tone controls are.
     
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