Tilt Control Center Freq. and Usefulness

[Bill Mountain]

I'm working on a boost pedal with some graphic EQ bands that would allow for some decent tweaking.

I was thinking about adding a tilt control on the end for quick adjustments in different rooms or with different guitars/amps.  What I don't know is how realistic that is.

Scenario 1: After I spent all night getting my tones, I go to a jam and I don't have enough low end, instead of adjust my EQ I just nudge the tilt control a little.

Scerario 2:  After I leave the jam session I go to the club and I'm too boomy.  I just nudge the tilt control back and little.

It seems feasible but I'm thinking the tilt control would not be flexible enough for room/rig/guitar adjustment but I was hoping to make a set-it-and-forget-it EQ section that I didn't have to change every time I plugged it in somewhere different.

So assuming this is a good idea then I need to figure out how to implement it...Is the BMP style sufficient (no mid-scoop) or do active tilt controls work/sound better?

Then once I figure that out what would be a good center frequency?  600Hz 1000Hz???

Thoughts?

Criticisms?

Ideas?

[samhay]

When I think tilt control, I think of the active (1 op-amp) version that gets used in HiFi amps. In this case, the frequency response is flat over most/all of the audio range, but can tilt (not a great description I'll admit), making the centre frequency somewhat arbitary - the point with gain = 1, I guess.

Something like this - http://www.edn.com/design/analog/4368935/Implement-an-audio-frequency-tilt-equalizer-filter

[merlinb]

Then once I figure that out what would be a good center frequency?  600Hz 1000Hz???

500Hz is a reasonable centre for distorted sounds, but for clean sound go lower, say 300-400Hz.

[Kipper4]

The amz presence control is great for modding.

[Kipper4]

Here you go
http://www.muzique.com/lab/tone3.htm

[Kipper4]

Is this the kind of thing you talk of Sam

http://sound.westhost.com/articles/eq.htm

I wasnt sure if Bill meant Jon Pattons recent thread about a tilt control

www.http:I tried the search but drew a blank.com

[samhay]

Yes, Figure 20.

I see Rod is not a great fan. I like the design, but have never built one.

[Mark Hammer]

One needs to start out by pondering what is standing in the way of the desired tone.  As Bill notes, it could be the room, or it could be the speakers.

A tilt control is a reasonable wholesale way of changing too-much-o'-this-too-little-o'-that.  But the question comes up as to whether too much of one always means too little of the other.  A tilt control is reciprocal; are the listening environments and rigs of the sort where the deficiencies are reciprocal?

My own guess is no.  One approach is to use a Baxandall-type shelving EQ for bass and treble, with the corner frequencies selected to avoid getting unwanted midrange shriek or lower-end honking while in the pursuit of a little more clarity or body, or conversely losing bite or body when trying to eliminate undesirable sizzle or boominess.

The BMP-type approach can actually be useful and suitable, if you do the following:

• use separate level pots for the two paths (bass side, treble side), prior to mixing
• give yourself a couple of corner frequencies to choose from with a 3-way toggle to select different cap values, and
• add suitable gain recovery to compensate for the passive loss

Such a circuit provides only cut and no boost, but since the purpose is merely to remove what there is too much of, it's good enough for a lot of applications.

[garcho]

I wired a "James EQ" to a dual gang pot with the HPF signal going to terminal 1/gang 1 and the LPF signal going to terminal 3/gang 2. Basically a "cheat" tilt tone control. High goes up, low goes down, and vice versa. Not active, needs a recovery stage. Can make for quick dramatic changes in tone while leaving 'noon' on the pot sounding fairly flat.

[Bill Mountain]

Thanks for the discussion so far.  This is all just a symptom of me always overthinking things.

I've seen room balancing EQ's on amps before but never thought about what they might actually be controlling.  That seems worth investigating.

I like the active tilt circuit because the passive BMP loses signal at noon which is were I plan to leave it most of the time.  This would require a makeup stage.  If I'm adding a stage why not an an active one (with the benefit of actually boosting lows or highs if need be)?  It's a shame ESP hates them so much but I'm often at odds with HiFi folks.  I imagine he dislikes the lack of flexibility.

I get the desire for bass and treble controls but It would look ridiculous to have a full on EQ to EQ my EQ.

[Kipper4]

What about the Bosss FA1 active tone control.
IIRC its a single op amp but is tied to Vb, so maybe use one half for a buffered Vb and the other half for the active tone control.
Just thinking out loud.

[midwayfair]

Here's a super simple passive one -- you can practically build it right on a 16mm pot itself. There is no signal loss with this, except to the extent that turning up or down the treble means that there's more or less treble.

http://www.diystompboxes.com/smfforum/index.php?topic=112009.msg1032327



You can do the standard calculations to figure out the cutoff frequency you want to use, and it has an optional stopper to make it a shelf. Someone on Madbean did a sim if you want to see the sweep.