HAO Sole Pressure

[josepqr]

thanks for the reply, but that's not what I asked.

changing the values of 1u and get 2,2u change the values of the "normal" position and "warm" (position 1 and 3 switch),
but I wonder how give a little more brightness (... but only a little) to position "bright".

thx.


any suggestions ????

[rocket88]

Actually I did answer you're question. You want more "brightness" or treble to come through and less bass in the "bright" setting of the switch. The way the switch works is by changing between 2 different output caps, one that let's more bass through, 2.2uF, and one that cuts the amount of bass that comes through, 1uF.

By changing these values you will alter the frequencies that you will hear in the different positions of the switch. The lower the cap the more bass is cut, ie the "brighter" it will seem, while the larger the cap the more bass comes through, ie the "warmer/darker" it will seem.

So, as I said to you before, if you want it the be "brighter" in the bright setting the lower the value of the 1uF cap. If you want to change the overall "brightness" of the effect you will have to make more changes to circuit.

Now, in the bright setting on the effect completely removes the output cap from the circuit. So, if you really want the "bright" setting to be brighter you're going to have to make changes in the tone section of the effect, or apply the same concept I explained to the input cap. If you lower the input cap you will block more bass from entering the effect, larger allows more. The problem is that you're going to run the risk of making it very trebley and ice picky since the output cap is removed in the bright setting. My 2cents.

Btw, this is part of the whole argument for buying expensive low capacitance guitar cables, and using shorter cables.

You might want to do some reading on moding effects, there's a thread with resources posted here on the forum, to help you further.

[josepqr]

Thanks for the reply !!!

really "desist" I surrender !!!

Not if I do not understand well or not really understand me.


As you well say, changing the capacitors of 1uf or the 2,2uf modficas tone, but ONLY the "normal" position and "warm", but NOT the "general" glow around the pedal.

there is a switch with 3 positions: ON - OFF - ON


Position 1; "warm" -> affected by the 2.2u capacitor
Position 3; "normal" -> affected by the capacitor of 1uF

Position 2: "bright" -> NO affected by any capacitor.

I understand that you can change (and play) with different capacitors, but I wonder:

How to change a little more "general" brightness, ie the switch in position 2 ??

[rocket88]

Hey buddy. No need to "surrender," it's hard to tell tone of voice throught text. I  don't want to see anything happen like what happened towards the end of last year, just trying to help. The comment about reading is really to help you better undertand circuits o you can get exactly what you want out of each circuit. Keep in mind as well that you're drescribing the tone, which is suggestive, it's no different then saying you want to warmer, tube-like, etc. so it's very hard to gather what you're looking for. Ya know what I mean?

So, let me try again. There are multiple things that control the overall tone of a circuit, as in the amout of bass and treble you hear. Two of which are the input and output caps. The input cap control show much bass enters and hits the circuit, while the output cap controls how much leaves. The higher the value the more bass you'll get. This is why those of us that play bass will usually change these to suit our instruments. Now, there are other things, like high pass and low pass filters which will cut either lows or highs, some circuit you can alter values in the gain stage to alter what frequencies get distorted, and there's even more.

With this cuircit in the bright mod you are completely removing the output cap, which is cutting a lot of high end. You may want to change the input cap to a lower value to cut some more highs. Now it's a fine line you need to walk. If you go too low the effect can have too much treble and be ice picky. You need to all find a value that you'll like wiht the other settings on the switch as well. When it comes to getting more bass out of a circuit you have to be careful of letting too much bass in and out, because you can end up with an effect that is too muddy.

[jaredcohen]

Hey John,

Please forgive my stupidity, but I'm trying to compare veros to schematics so I can start learning how to read schematics better.  In the schematic it looks like VS+ goes to pin 7 of the TL072, but in the layout, it looks like it goes to pin 8.  

Also looks to me like input should go to pin 2, but here it goes to pin 3.  It's late, maybe I just need sleep.

Just curious and hoping to learn more.  Thanks.

[induction]

A few corrections are needed here.

The switch does not select the output cap. The output cap is the 10u attached to the op-amp output (pin 1). The caps on the switch form a low pass filter with the 100k resistor. So the result is a little different to how you described it: In the center ('bright') position, there is no cap to ground, and therefore no low-pass filter, and the sound will be brighter rather than darker. You are right though, that increasing the size of those caps will make the sound darker, but this is not because it cuts less bass, but rather because it cuts more treble, in other words, moves the corner frequency of the hi-pass filter to lower frequencies.

Rockett is correct that anything you do to increase treble in 'bright' mode, will change the response in the warm and normal modes. But you can experiment.

As Rockett points out, you can decrease the input cap, but this will change the frequencies that get affected by the distortion, so instead of tone shaping, you will be reshaping the distortion, and you may end up with a very different sounding unit. The general rule is this: EQ before (or during) distortion changes the distortion flavor, and EQ after distortion acts like normal frequency shaping. So if you like the sound but just want more treble, I wouldn't mess with the input cap.

The simplest solution would be to reduce the 10u output cap. This will make all three modes brighter. Try 1u and then go up or down from there until the 'bright' mode gives you what you want. Then increase the 1nF and 2n2 caps on the switch until the 'normal' and 'warm' modes are dialled in.

However, in this case, most if not all of the clipping is coming from the leds, which are actually after the output cap, so you may still end up changing the distortion characteristics if you reduce the 10u output cap. So another idea is to leave the circuit stock, but use a DPDT on/off/on for the mode control. Then you could use the second pole to cut some bass in bright mode. This could be done by inserting a smaller cap between the diodes and the treble attenuator caps, or by adding a resistor in parallel with the 100k output resistor (the one between the output cap and the level pot). You'll have to play with the values to see what works for you.

Your best bet would be to build two versions of the circuit on the breadboard, with a switch to select between them. Make sure they sound identical, then start modifying one of them to improve the 'bright' sound. That way you have a reference to compare your mods to.

Jared: The pins are labeled incorrectly in the schematic (pins 2 and 3 should be swapped, and pin 7 should really be pin 8, check the pinout on a datasheet to see what I mean). Trust john's layout and ignore the numbering on the schematic.  

[alex.s]

If I'm not mistaken the bright setting is the one without any caps going to ground. The addition of a cap dampens the highs, which means that by tweaking them you will be able to change the frequency response of the normal and warm settings, but not that of the bright setting, as it is basically the "stock", unaltered sound.

Perhaps trying a (much) smaller value in place of the 10u cap between the opamp and the 100k reistor? 10u seems a huge value, and if you don't mind losing some low freqs in favour of a brighter tone you could try 47n or lower. That said, such mod would make the pedal very much a guitar OD and not much of a bass OD anymore, since a decent slice of beefy lows would be pulled back a fair deal.

EDIT: completly missed page 2 altogether...! Didn't realise the same had already been discussed better and more clearly by others before me... D'oh! :)

[rocket88]

D'oh, I forgot output was at pin1 in this effect.

[jaredcohen]

Great sounding OD. Thanks for posting this John.

If anyone else is wondering, this one really needs the 500k anti-log pot.  Tried it with a linear pot and there's basically no gain until the end of the rotation when it all kicks in at once (and sounds awesome).