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Treble bleed mod.. which one is the best?

Yoa01

Jun 18, 2012
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That pin is not connected to anything. Same with p2. In those cases you are using the pot as a rheostat, aka a variable resistor with only one input and output.
 

electronoobz

Jan 14, 2012
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oh i see... im about to do it now.. but sadly your diodes is not available here... can i use another clipping diodes?
 

KrisBlueNZ

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Yoa01, the design you show in post #12 on this thread has a number of problems.

1. Your "clipper on/off" switch is wired wrong. If you look carefully at the circuit you will notice that both sides of the switch are connected together! So the switch will have no effect, and the clipping diodes will always be connected.

2. The clipping diodes probably won't have any effect anyway, because they only start to conduct when the voltage across them reaches about 0.5~0.6V. From my experience, most guitar pickups can't generate this much peak voltage. I could be wrong in your case though.
In any case, the effect of clipping is not to make the sound warmer. It makes the sound harsh and distorted, or a bit "buzzy" if it's gentle clipping. Clipping is what fuzz boxes do.

If the effect of connecting the diodes is subtle, and you're not sure whether it's real or not, you can run an approximation of a double-blind test if you have a friend to help you. This will tell you whether you're REALLY hearing a difference, or whether you're only IMAGINING that you can hear a difference. It's surprising how easily we can fool ourselves into hearing what we EXPECT to hear. Here's how to do the test.

Get your friend to toss a coin, but not to tell you the result. In fact your friend must not communicate with you in any way. If the coin landed heads, your friend turns the diodes ON, or if it landed tails, he turns the diodes OFF. He writes down what he did on a piece of paper that you can't see.

Now, you play the guitar for as long as you want, and listen to the sound. You figure out whether you think the diodes are ON or OFF, and write that down on a separate piece of paper that your friend can't see.

Now, you repeat this process ten times, or more if you can be bothered. During all the testing there should be no communication between you and your friend, other than a signal from him that you can start playing, and a signal from you that he can move to the next test.

At the end of the test run, you compare your notes, and count the number that you got right. If you ran ten tests, and you got five right, there is no correlation between the switch position and your opinion, in other words you have failed to prove that you can even tell the difference between the switch being ON and the switch being OFF.

A higher score implies correlation and that you are successful. Obviously, 100% correlation is pretty good evidence that you can not only tell the difference, but identify which switch position is which. The more tests you run, the more confident you can be.

This is the sort of test that is not normally done by people who like to say "this sounds better". If they took the challenge, they would be able to prove that they're right, but they are often scared that they might fail. Doing the test is the only way to know for sure whether they can even tell the difference between the two options.

3. The value you have for C1, 220 nF, is FAR too high. Such a high capacitance directly across the output of a high-impedance pickup will CLOBBER the treble and turn the sound into a muddy mess. You can calculate the reactance of a capacitor at frequency f using the formula Xc = 1/ (2 pi f C). For C=220e-9 and f=1kHz, Xc is only 723 ohms. Compared to a pickup with an output impedance of say 33k, this is practically a short circuit. I would reduce C1 to around 2.2 nF and try again.

4. C2 is also probably much too high. In this case, there will be little bass rolloff. A lower value, such as perhaps 10 nF, would be better.

5. Your suggestion that the circuit is in any way like a "2-band graphic equaliser" is WAY off the mark. Graphic equalisers have filters with relatively narrow bandwidth and high Q factors; your circuit uses single pole filters, which have a very gentle rolloff, without the limited bandwidth that a graphic equaliser has. The best you can claim is that they're "tone" controls, like on old-fashioned stereos.

Edit:
6. I just looked at the data sheet for the diodes you've specified. They're great huge metal things, rated at 35 amps! They mount through a steel chassis! They're totally unsuitable for this job and will be quite expensive. If you want to try normal silicon diodes, use 1N914s or 1N4148s (they're almost the same). If you use germanium diodes, such as OA91 (if you can still get them), there's a better chance you will hear some audible distortion effects, because germanium diodes have a much lower forward voltage than silicon diodes - around 0.2V instead of 0.6V.
 
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Yoa01

Jun 18, 2012
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And this is why I usually try to stay around my computer, haha

I meant to remove those diode numbers. You can use any generally low power diodes you can find -- I personally use the roll of 50 Radioshack sells.

I'm not sure what you're asking. The only real difference between theirs and mine is I have a second filter after the "normal tone control circuit".

And about the problems: This circuit worked for me, as I said. It may not work perfectly with other systems. Here's my explanations:

1) The diodes used don't actually get turned on that much, if at all, by the output because they are rated at a higher voltage (I think like .5V or something equally tiny). This means that power will not run backwards, nor straight to ground. With higher output, however, this could be an issue.

2) They do have a minor effect. As I said, they barely turn on. If you run a higher output system through it, but then turn it down before it gets to the clipper, you'll note that it gets a slightly warmer tone, as any fuzzing system would. With a higher output, yes, it does clip, and you can tell that if you strum REALLY hard. Sadly, I don't have many friends that would know the difference. I have me and an oscilloscope and spectrometer, which do show a slightly higher level around the mid-lows, which most people interpret as 'warmth' :)

3) Again, this was just in my testing and it works flawlessly. That capacitor and resistor setup is correct, I assure you.

4) See #3

5) Re-read that, sire: "creating a kind of 2-band EQ". I never said anything about type, and honestly by this point I think you're just trying to find things to complain about, or just using my signature against me :)

6) I meant to remove the diode numbers. I use cheap Radioshack ones that I'm pretty sure have no actual number/type.

Sorry for the slow response.
 

KrisBlueNZ

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Hi Yoa01,

Yes, I did show a bit of a bad attitude in my previous post. I get irritated when advice is posted that sounds plausible but is "wide of the mark". The more widely off-the-mark the information is, and the more consistently it is wrong or misleading, the more irritated I get. I try really hard to follow a policy of "If you don't know what you're talking about, don't say anything". But to follow that policy, you have to be able to recognise when you're out of your depth.

2) They do have a minor effect. As I said, they barely turn on. If you run a higher output system through it, but then turn it down before it gets to the clipper, you'll note that it gets a slightly warmer tone, as any fuzzing system would. With a higher output, yes, it does clip, and you can tell that if you strum REALLY hard. Sadly, I don't have many friends that would know the difference. I have me and an oscilloscope and spectrometer, which do show a slightly higher level around the mid-lows, which most people interpret as 'warmth' :)

If you define "warmer" as having some high-frequency attenuation, this happens because diodes have a small amount of capacitance. You can get the same effect by replacing both diodes with a capacitor of around 33 pF.

5) Re-read that, sire: "creating a kind of 2-band EQ". I never said anything about type, and honestly by this point I think you're just trying to find things to complain about, or just using my signature against me :)

I misinterpreted "two-band equaliser" as referring to two bands that are fully defined within the spectrum. I would describe what you're suggesting as "tone controls", i.e. "treble and bass". I would not call that a two-band equaliser; I regard that as "talking it up". But it's not wrong. So, I apologise to you. I have been rather grouchy lately.
 

electronoobz

Jan 14, 2012
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hi sir.. since you recognize his scheme is not correct, could you please remake it?
 

(*steve*)

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I think the issue is not so much that the suggested modification is "wrong", as it is that the description of its effect may be inaccurate.

As I think has been said a few times, this is something you'll have to try out for yourself and see if you like the effect.

Signal level will have a dramatic effect on any circuit which uses a pair of diodes to clip a signal. We cannot tell what the signal level is at that point in your circuit (perhaps you could measure it?).
 

electronoobz

Jan 14, 2012
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hey there steve... as you can see on the link i gave (black ice)

the guitar tone pot's cap is replaced by the two clipping diodes..

hmm how could i adjust the clipping diodes tone when it's activated and use it as normal tone when it's deactivated??

could you make a scheme for me??
 

(*steve*)

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Place a SPDT switch to connect the wiper to either the end of the cap or the non-grounded end of the diodes.
 

electronoobz

Jan 14, 2012
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thanks!! what's a best diode anyway to use for a somewhat heavy/crunch (i mean metallish or just a simple crunch when the wiper is either on the right or left)

and i would like to use audio taper.. what value do you prefer? 100K? or 500K? or 250K?
 

(*steve*)

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1) almost anything. But I'd probably go for 1N914 or similar (1N4148). For lower signal levels you could use a pair of schottky diodes.

2) It depends on the impedances of the surrounding circuitry. I'd probably start with 100k if that's the smallest you have.
 

electronoobz

Jan 14, 2012
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hmm 100k looks good to me but the guitarists out there always use 250k (for singles) or 500k (doubles a.k.a humbuckers)

i'll try it.. i dont think there's schottky diodes here.. is there another name for it??

thanks anyway
 

Yoa01

Jun 18, 2012
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Kris, did... did you just apologise on the Internet? Are you trying to break the Internet??

All jokes aside, I do see where you are coming from. Like I said, there's a slight peak (boost) in the mid-low range, no attenuation. Very slight. And you're right, they are essentially tone controls. I was inspired my the Korg MS-20's filter setup, but thinking about it it really is more of a tone control than an EQ, as that sets volumes of certain bands whereas this simply filters stuff.

electro, like I said, this worked for me. It might work with you, might not. May as well try it and see instead of basing everything off of theory :)

Steve, you're right, I did misdefine the function. Everything after the 20k pot is simply for tone and tone only. I also have no idea what the actual output is as none of my measuring devices can actually measure the signal! Sad, I know.

electro, the best diode setup I've found (and am actually using in a passive 'distortion' pedal) is a series of two diode clippers using 1N4148 diodes. It creates a really harsh, fat distortion, but you may need to play kind of hard. Also, as for the pot to use, just use whatever works. 20k works for me, 1M might work for you. Most Gibsons use a 500k because they have a pretty high output.
 

electronoobz

Jan 14, 2012
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i'll modify my amp again. haha

lpb1.gif



assuming it is 680 not 360 and 820k not 830

i'll put an spdt switch on the output.. ( the first side to the diodes and the other to it's normal path)

then on the input i'll put on a switch so my treble bleed (on my guitar) would go to the amp's vol when activated or use it as normal treble bleed when deactivated.


i will mount my preamp on my guitar. wahahahaha
 

KrisBlueNZ

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Kris, did... did you just apologise on the Internet? Are you trying to break the Internet??
LOL!
Actually, I've apologised on the internet before. I think the damage is only localised, and the internet's self-repairing properties kick in. Soon enough, the insults are flying just like normal.

All jokes aside, I do see where you are coming from. Like I said, there's a slight peak (boost) in the mid-low range, no attenuation.
I suppose it's possible that the inductance of the pickup coils is forming a tuned circuit with the capacitor and giving a broad boost to the signal in the mid- to low-frequency audio range. But there's no need for diodes. A capacitor will do the same thing, and more consistently. You'll also avoid the possible clipping at high volume. Also, a typical audio cable a few metres long will have much more capacitance than the diodes. So I doubt the effect is real.

electro, like I said, this worked for me. It might work with you, might not. May as well try it and see instead of basing everything off of theory :)
The trouble is, of course, that it's impossible to test in a consistent, reliable or meaningful way, because your signal source is not consistent, unless you replace the pickup(s) with a signal generator such as an MP3 player, or perhaps couple a repeatable signal into the pickup magnetically.
If you want to have your claims taken seriously, you need to provide proper measurable evidence of them, or if they're not measurable, then you need to at least pass a double-blind test as I described in an earlier post. "That which can be asserted without proof can also be dismissed without proof."

electro, the best diode setup I've found (and am actually using in a passive 'distortion' pedal) is a series of two diode clippers using 1N4148 diodes. It creates a really harsh, fat distortion, but you may need to play kind of hard. Also, as for the pot to use, just use whatever works. 20k works for me, 1M might work for you. Most Gibsons use a 500k because they have a pretty high output.
If you want clipping at a lower voltage, you can use Schottky diodes as suggested by Steve. A common Schottky diode is 1N5817, although it's over-rated for this application. Search on Digikey or Mouser. You could also use germanium diodes such as OA91 (as I mentioned in a previous post), which have an even lower forward voltage, and a "softer knee", so the clipping will not be as harsh.
 

Yoa01

Jun 18, 2012
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hey, Electro, don't use that schematic. If you can even get it to work you'll get next to no output, and you'll also have to worry about power.

Kris, you're fking awesome. lol

You're probably right, but I'm using Alumitones, which don't use coils. All I know is that if you remove the diodes it sounds different, so there's definitely some bit of magic going on there.

You've got a point. I'll just stick to my designs and if anyone else has a problem, they can deal with it :)

Random question: who's better overall, Mouser or Digikey?
 

KrisBlueNZ

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Thanks Yoa01. Sorry I was rather scathing to you. I like your attitude. You were very restrained in your responses. That's something I try to do myself.

Re Mouser vs. Digikey, from my limited experience, it seems that Mouser have a wider range of different types of components than Digikey, and within each category, they have a much wider range of component types. This is based on a few searches I did for MOSFETs and JFETs. Mouser's parametric search doesn't filter on as many fields as Digikey's, but it shows you the number of matching components while you apply the filters, which is very helpful. With Digikey's search, I sometimes find that when I select options for several columns then click Apply Filters, there are no matches, and I have to start the filter again. Mouser doesn't have this problem.

Also, Digikey seem to focus on components only, whereas Mouser also sell lots of tools, sprays, etc.

Both of them charge a ridiculous amount for shipping to New Zealand. USD 39 for both of them, I think.

I'd like to hear other opinions on Mouser vs. Digikey. Also, what about Jameco? And are there any other companies that have a wide range of components and will ship worldwide?
 

Yoa01

Jun 18, 2012
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I'm a YouTuber and I speak my mind too much on Facebook, I'm used to it :)

That is freaking rediculous shipping, but I would have to agree with your findings.
 
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