Tubescreamer Presence Control???

[bigstomper]

Has one had any success adding a presence control to a TS type circuit.....more specifically the Son of Screamer type?  Where and how would I add that???  I'm thinking Vol, Tone, Gain, and Presence would be pretty useful.  Sorry if it has been covered before...I did a search and couldn't come up with anything.  Thanks.

[Zben3129]

Hmmm....

Perhaps a 10k pot as a variable resistor where the 4k7 resistor is in series with the .047 cap to ground/vb in the feedback loop. However I have a feeling this will impact the inverting input's impedance and therefore the gain of the clipping section. You can give it a try if you want.

[kurtlives]

^That would mess with the gain and bass...pretty sure

Check out the King of Tone schematic for an idea to add a presence control. It's kinda subtle but works well.

Maybe a cut control ala English Channel or others might work too.

[Zben3129]

Yeah, as I understand it presence is essentially treble cut. In amps, presence has to do with bleeding off come highs from the Negative Feedback Loop, resulting in more highs (less lows, really) on the output. However, tube screamers aren't amps, so we need to figure out a different way.

Maybe a 2 pot tone control would be where we might end up. I'm not sure if simply bleeding off highs (low presence) will work as it might kill the tone/gain of the circuit.


Zach

[bigstomper]

I checked out the King of Tone schematic and saw where the presence control is.  Not sure where I would incorporate that into the TS/SOS circuit.  I'm sure it's simple, but I'm still learning stuff 

[d95err]

The existing tone control on a Tube Screamer IS essentially a presence control. It boosts treble clockwise by bleeding off treble from the negative feedback path of the second opamp stage (just like a tube amp). In the counterclockwise position, it cuts treble. So, I can't see what an additional presence control could add.

I think a more useful addition would be a bass control to adjust how much bass goes into the clipping stage.

[bigstomper]

Would you add the bass control in place of the R/C combo in the feedback loop?  Also maybe I could also just adjust the size of the cap on the tone control to let more highs through?

[Zben3129]

Couple things I can think of:

   1. Are you hoping to be able to "turn up" from the current stock 'presence' or would you be satisfied if where it is now ends up being '10' on the presence knob?

   2. I think maybe controlling the presence in the clipping section rather than the tone control section may yield a different sound and is worth looking at. Kinda what I was getting at with my 1st suggestion, which was just a rough idea.

Zach

[bigstomper]

1. I was hoping to get a little more presence out of the circuit (more than there is at the moment).  To me treble and presence are different things.  Just looking to add a little presency chime on top, but without getting a really trebbly sounding overdrive.  (Yes I like adding a "y" onto words....haha)

2. I think the Menatone Red Snapper "Bite" control is in the feedback loop.  However this is the ONLY tone control....with the exception of the 4 knob versions that add a cut control (hi freq rolloff).  So maybe my quest is a bit redundant. 

[cpm]

i really like the tone control inside the feedback loop, using a pot in the RC pair that goes to gnd (or Vb)
I feel it is more effective than the usual TS tone, a deeper sweep all along the pot, and the fact it may interact with impedances and gain at the opamp is not a bad thing by itself.

[JHS]

A simple solution for a P-control (or better a treble boost control) is this:
Just add a 10k pot/trimpot in series with a 470E and a 56-100n cap and wire this combination parallel to the 4,7/50n network on IC1a.

JHS

[earthtonesaudio]

You could reduce the value of the resistor-to-ground (220 ohms I think) in the tone section, and get more treble from the fully clockwise position of the tone knob.  I used a trimpot and was able to go from a slight treble increase to serious tinnitus-inducing treble boost.  If you dial the tone knob back a little, you can't tell it's been modified.  It just adds a little oomph to the last bit of the tone control rotation.

[bigstomper]

JHS....

Couple Questions...
1. Would your suggestion be an addition to exisisting tone control?

2. You wouldn't happen to be able to show/tell me exactly how to wire the lugs of the 10k pot you suggested, would you?

[frank_p]

At first, I toughed presence control was a way of modifying distortion response in a power amp... (This is what I understand, not what I hear in my amps "at low volume").  Now, what do presence do really mean in a stompbox...  distortion response in certain frequencies... (I mean both tone and distortion shaping)
Well...  my ROG Princeton (Prof Tweed) sounds really good (crunchy) with the negative feedback loop removed, but it's not a TS.

The problem I think with the TS is that it is not the active device that is distorting, in contrast with tubes, or FETs, or "on the edge" BJTs. 

You (we) would like it to happen differently than just on the diodes.

Would a RC "tap" between the output (last opamp: tone and volume) and the clipping opamp would be a kind of a solution ?

[wampcat1]

seems like an easier solution is to connect a pot from ground to the cap after the first opamp, like shown here:
http://image69.webshots.com/669/0/98/6/2101098060089132427TWktZb_fs.jpg

[bigstomper]

Would like to check out the image, but the link says I'm forbidden to access the file.  Could you help a brother out?

[wampcat1]

try this:
http://www.indyguitarist.com/temp/TS808%20PRESENCE%20MOD.gif
You might experiment with the pot as well - a 5k may be a bit better, I'm not sure.

bw

[bipedal]

I'm following this thread as a curious lurker rather than someone who can add much substantive info -- I've learned a lot about DIY'ing via the TS circuit, so reading this is part of my ongoing training!

bistomper, could you describe a bit more about what you're aiming for with "presence"?  You noted:

a little presency chime on top, but without getting a really trebbly sounding overdrive

Sounds like you're aiming to boost a selected frequency range?

This may be getting off track, but have you tried an EQ pedal before (or after -- will give different results) your Screamer circuit?  Might be interesting/helpful...

Start with a flat EQ response, then start boosting individual freqs to see if you can get the added "presence" sound you're after.  If this works, you'll have identified the freqs to enhance/attenuate.  With this information, others might be able to chime in with additional suggestions for tweaking the screamer circuit to give you that control...

- Jay

[Ben N]

This is from a thread about eq that I saved a few years ago, but cannot find a link to now. It may be helpful:

Title: *Build own EQ pedal???*
Post by: *Mark Hammer* on *May 26, 2005, 08:18:27 AM*
------------------------------------------------------------------------
For a whole lot of players, a unit that had two bands of sweepable
quasi-parametric (i.e., just like the sweepable midrange control found
on many "metal"-oriented fuzzes), a bass shelving control (12db boost
and cut), and a variable lowpass filter, would likely cover just about
all the ground they need..  That would be essentially 6 knobs: one for
bass boost/cut, one for treble rolloff frequency (lowpass), two for
lower mid boost/cut and centre frequency (quasi-parametric 1) and two
more for upper mid boost/cut and centre frequency (quasi-paratemtric 2).

Trust me on this one.  That complement of controls is just about all you
would need to reconfigure the "personality" of an instrument
substantially.  Being able to reposition where the boost/cut occurs in
the mids and lower treble gives tons of flexibility.  Although a lot of
folks might feel a little cheated by not having a proper boost/cut for
treble, a 2-pole sweepable lowpass is a true blessing in terms of
cleaning up many "audio sins" of pedals earlier in the chain, and if you
make the frequency range of the upper sweepable mid control wide enough,
you can probably stick in resonant peaks in exactly the same spot as you
would hope a treble control would work.....without goosing the hiss.
You may want a bump at 2khz, but that doesn't always mean you want 9db
more at 10khz too.  Clever use of a sweepable lowpass and resonant
equalizer section lets you get the cake and throw away the wrapping.

[bigstomper]

Brian....that link worked....many thanks!