I had to make another Xmas present and after some experimentation I came up with this, it's nothing really new but it is simple and sounds great.
I started out trying to breadboard a Dan Armstrong Blue Clipper but none of the schematics seemed to work at all. Luckily, I came across the
Runoffgroove "New Clipper" and after some adjustments I ended up with what I think is better than my tubescreamer. I wanted to share in case anyone
wants to make a simple, low parts count distortion box because I think it is really good. Also, if anyone makes this but with improvements, please let
me know what changes were made. I plan on making another one for myself after I finish my never ending fuzz pedal creation.
Input cap and diodes are socketed and I ended up really liking the "big sound" of the .1uF input cap and my mysterious HP diodes.
Schemo:
(http://i67.tinypic.com/3449ldt.png)
Layout:
(http://i64.tinypic.com/cuixc.png)
Reverse Trace
(http://i67.tinypic.com/mai45t.png)
I used a row of sockets on the board and soldered another row of sockets to the hookup wires to make my own plug. The LED + goes right into a socket. My daughter did the graphics with Sharpie paint pens and then I sprayed clear engine enamel over it, I think her Grampa will love it.
(http://a66.tinypic.com/33tp8x3.jpg%20(77%20KB))
(http://a67.tinypic.com/dwf7dt.jpg%20(132%20KB))
(http://a63.tinypic.com/2i7908m.jpg%20(106%20KB))
10k input resistance and sounds good?
Quote from: Gus on December 23, 2015, 04:06:39 PM
10k input resistance and sounds good?
That's the output, I'm not sure why it is there but maybe it works with the .0033uF as a tone thing at the output?
I used a 100k pot at the input for a drive control but a 500k could be used if you wanted more "cleaner" cleans. I just wanted OD at one end of the spectrum and distortion at the other.
Anyway, yes this thing sounds great, after it is unwrapped on Festivus I will try to make a demo vid.
>> 10k input resistance and sounds good?
> That's the output
Gus is looking at the two "20K" resistors at the INput. 20K||20K= 10K.
10K loading sucks all the highs and a third of the low/mids off a naked guitar. Adding series resistance (an input pot) does change this.
If you are happy we are all happy. But it is an odd setup.
oh, ok I see. All I can say is try it out, it sounds better than an MXR Dist+ (too much highs imhop)
The original Dan A. BluClip had some kind of resistors right there but it didn't make any sound but a short, gated splutter when I tried it. The New Clipper has two 22k's right there but I just used what I had (2 20k's)
:icon_question: PRR: If I remove both 20k's will this circuit still work in theory? I can try that on my BB when I make another one.
Again, this thing sounds better than any of my TS pedals, and I've owned a lot, both stock and modded by the "Big Guys"
my "pink's clipper"
is the same, almost... the 10k onput impedance seems fine, i use it live endlessly, probably the most used pedal on my board.
i run it after my volume/wah as a lead boost, it kicks total ass and is loud as @#$% ;)
(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/pinksclipper_zpsb0a9aa1b.png)
not exactly the same circuit, but similar. i didn't even realize it was similar to the dan armstrong when i cobbled it together.
if ben's pedal sounds anything like mine (and i bet it does) i know it sounds great. ;)
and if ya think about it, doesn't a low input z equate to better interaction with effects before it?
look forward to hearing it ben ;)
Consider putting a 330-470pf cap in parallel with the 150k feedback resistor to make it warmer and less fizzy. You already have the 3300pf treble cut cap, but why settle for one pole of lowpass filtering when you can easily have two?
I salute your paint-pen work.
> If I remove both 20k's will this circuit still work in theory?
No.
How would the opamp "know" what DC level to idle at?
You can use larger values. Even 1Meg each.
There IS a better way to set bias. Rejects supply garbage, allows easy change of input impedance. Often worth 2 extra parts.
That sounds great Jimi, mine is very similar but maybe a little more distortion at the extreme and less clean at the other end. I will try to make a quick demo vid after Xmas day. BTW, it does sound very good with my Boss SD-1 or my Thomas Cry Baby in front of it.
PRR- I will try my next one with some of The ideas I saw in Kipper's latest links.
Quote from: Mark Hammer on December 23, 2015, 10:42:37 PM
Consider putting a 330-470pf cap in parallel with the 150k feedback resistor to make it warmer and less fizzy. You already have the 3300pf treble cut cap, but why settle for one pole of lowpass filtering when you can easily have two?
I salute your paint-pen work.
Thanks Mark, will definitely try that, sounds easy. Artwork is by my daughter... just making sure credit is given where due :)
nice diode bridge, ben. be nice to the other half of your opamp, tho.
Quote from: duck_arse on December 24, 2015, 09:05:52 AM
nice diode bridge, ben. be nice to the other half of your opamp, tho.
Thanks Duck. Umm... someone said I should run the ground line right up across all three unused legs of the IC... is that what you mean by "be nice"?
Quote from: PRR on December 23, 2015, 06:02:05 PM
>> 10k input resistance and sounds good?
> That's the output
Gus is looking at the two "20K" resistors at the INput. 20K||20K= 10K.
10K loading sucks all the highs and a third of the low/mids off a naked guitar. Adding series resistance (an input pot) does change this.
If you are happy we are all happy. But it is an odd setup.
not to be a jerk, but imho most distortion designs i've built that use a high input impedance often have way too much high end to them.. particularly in combination with any other dirt pedals. how much treble does one really need?
all comes down to if it sounds good, it IS good. reminds me of a few years back a tc electronic multieffect. turned out some shop had been modifying them with a lower input impedance, and they had a rep to sound great. tc investigated, and found the modded circuit, altho "the rules" say it shouldn't sound as good, in fact sounded better and began shipping modified units at a higher cost if people preferred it.
how many times has someone picked up say, a stock ds1 by boss, been amazed at the crappy tone "that's right" and modded it to better suit their needs ears and tonal requirements?
just playing devil's advocate ;)
Quote from: Ben Lyman on December 23, 2015, 11:22:59 PM
That sounds great Jimi, mine is very similar but maybe a little more distortion at the extreme and less clean at the other end. I will try to make a quick demo vid after Xmas day. BTW, it does sound very good with my Boss SD-1 or my Thomas Cry Baby in front of it.
PRR- I will try my next one with some of The ideas I saw in Kipper's latest links.
Quote from: Mark Hammer on December 23, 2015, 10:42:37 PM
Consider putting a 330-470pf cap in parallel with the 150k feedback resistor to make it warmer and less fizzy. You already have the 3300pf treble cut cap, but why settle for one pole of lowpass filtering when you can easily have two?
I salute your paint-pen work.
Thanks Mark, will definitely try that, sounds easy. Artwork is by my daughter... just making sure credit is given where due :)
i look forward to hearing it in action ben!
yeah, mine is less distortion sorta... i use it as a big "cleanish" boost. lotta compression and enough nuts to overdrive anything else. live, i barely crack the gain on.... mayyyyyyyyyyyyyyyyyybe 9:00, and the output pot similar. when i step on that sucker i could part a deaf guy's hair at the back of the room. very loud, very creamy. it sounds more like this in actual context, which is my ever present fuzzface into my clipper with a les paul
You see that 8.2K right after the 4.7uF at the output, just before the clipping diodes? Temporarily replace that with a 1K and a 10K pot, then twiddle the pot while taste-testing.
Hmmm.... I think I am going to experiment with lower input impedance.
I've seen a lot of squaring/fuzz that have low input impedance. It must help reduce the "harmonics of harmonics" fizz in the fuzz and let the squarers track the fundamental better. But it ceases to help if you have any buffer between it and the guitar.
sometimes, you DON'T want a buffer between your guitar and effects... put a buffer in front of a true fuzz?
heresy.
buffers often tend to make stuff sound very hard and very bright. they are by all means useful, but too many can destroy your tone.
it depends on where in the chain it is.... first in line is useful to have a lower z as the guitar will interact more with the circuit (fuzz face as example)
and in between a bunch of other effects it can be handy too, as a lower z not only allows less high end response and brittleness than a high z one, but also makes it less susceptible to picking up noise, which high z inputs EXCELL at.
really depends on application and what you consider to be good tone, as well as where "in the chain" the effect is located.
another example is boss volume pedals. those designed for guitars have a much higher impedance than those designed as exp pedals... the lower z "plays nicer" in the middle than at the front. less noise, smoother sweep. of course this is all subjective to the rest of your rig and your own personal style,
but to me still, the best sounding box ever built is the fuzzface... i get a LOT of mileage out of mine, and play everything from folk rock to classic metal with it a couple shows a week. when i'm playing, it's almost always on...
and the worst pedal to my ear is the tube screamer.. which represents everything i personally don't like in solid state guitar technology. too bright, too nasal, way too obviously buffered for my taste...
one can always add a buffer if they need to. but as we all know, buffers sometimes are awesome, and sometimes, with their too high treble response and high input z they totally destroy your tone. ;)
but i'm a weirdo, and i have a different approach than some folks do, being a bowed instrument guy originally. i like a longer attack, personally... but that's all apples and orangutans.
also depends on whether the box in question is an opamp or transistor, whether fet based or uni, darlington, ge or si... the list goes on.
i'm mos def not saying i'm right... but i AM saying, if it sounds good, it IS GOOD.
peace and merry christmas to those of you who celebrate that, to the rest, have a kewl yule ;)
Since you have a series diode going from the battery to the effect, the shunt diode to ground, if used at all, should come after the series diode so it prevents voltage from going too high due to leakage in the series diode. That way, you don't discharge the battery if you put it in the wrong way.
A capacitor across the 220K feedback resistor may be necessary to avoid oscillation. 47 pF will give you a cutoff of 15400 Hz and maintain stability. You can reduce this value slightly to compensate for the diode capacitance.
The 10K biasing resistors to ground and +9VDC should go up by at least an order of magnitude and possibly as high as 1 megohm. The 5534 takes a fair amount of bias current, so you may have to adjust values to get the bias point at 1/2 Vcc. The 10K in series with the input is too high if you increase the bias resistors. I would put it at 100 ohms to 1 K so you can add a small capacitor of up to 100 pF to ground after it if it picks up radio frequency interference.
The series connection of 10K and 0.047 µF at the input does not give you the high frequency rolloff you may want because the connection to the 4.7 µF feedback cap may give dramatically different results depending on the series ESR of the electrolytic cap.
Quote from: amptramp on December 24, 2015, 02:32:03 PM
Since you have a series diode going from the battery to the effect, the shunt diode to ground, if used at all, should come after the series diode so it prevents voltage from going too high due to leakage in the series diode. That way, you don't discharge the battery if you put it in the wrong way.
hi ron, i'm assuming your referring to my circuit from reading this, not ben's. thanks for the tip on the diodes. ;)
Quote
A capacitor across the 220K feedback resistor may be necessary to avoid oscillation. 47 pF will give you a cutoff of 15400 Hz and maintain stability. You can reduce this value slightly to compensate for the diode capacitance.
zero problems i've encountered with this. 15.4k is pretty high.... guitars don't have much above maybe 6k, so i don't see what the point would be of needing the filter cut off so high?
Quote
The 10K biasing resistors to ground and +9VDC should go up by at least an order of magnitude and possibly as high as 1 megohm. The 5534 takes a fair amount of bias current, so you may have to adjust values to get the bias point at 1/2 Vcc. The 10K in series with the input is too high if you increase the bias resistors. I would put it at 100 ohms to 1 K so you can add a small capacitor of up to 100 pF to ground after it if it picks up radio frequency interference.
that may indeed be valid by an EE standpoint, but 10k sounded great. i started with 100k, tried 1 meg, 10k gave the best response and interaction with the guitar knobs. to me, any dirt box that doesn't clean up well from the guitar is absolutely pointless. the 10k in series may be too high if you increase the bias resistors, but it made a tremendous difference in tone and response on the breadboard, so i kept it. if changing the circuit makes it so it may need a cap to bleed rfi to ground, how is that necessarily an improvement?
Quote
The series connection of 10K and 0.047 µF at the input does not give you the high frequency rolloff you may want because the connection to the 4.7 µF feedback cap may give dramatically different results depending on the series ESR of the electrolytic cap.
you need to understand, i am no EE. i don't really care about "rules" too much. i sit there with my breadboard and dick around til it sounds good to ME. if it sounds good to me, i'm good with it. as i recall, the high end roll off is fairly natural sounding. i've built 10 or 12 of these things now for customers and friends, and for what it was designed for (if you can call 10,000 monkeys x 10,000 years designed) it works great. this was intended to be used AFTER all dirt boxes etc to give a big boost for leads and whack the bejesus out of anything after it... works pretty well for that. it's the last thing in line before my flanger and delay, and when i kick it on, it screams. generally my guitar will only be on 2-3 when i use it anyways... but all the "metal" guys who sit in ALWAYS turn it on and leave it on. it's a simple circuit, try it on a breadboard before trying to over engineer it. it's meant to be simple, cheap, and toneful. if it sounds good, it is good...
i'm betting ben's idea kicks total ass and am looking forward to hearing it.
like i said, just cuz something is "right" doesn't mean it sounds any better. peace!
Quote from: anotherjim on December 24, 2015, 01:46:23 PM
I've seen a lot of squaring/fuzz that have low input impedance. It must help reduce the "harmonics of harmonics" fizz in the fuzz and let the squarers track the fundamental better. But it ceases to help if you have any buffer between it and the guitar.
Which is pretty much why I suggested the additional cap. Trimming the high end is the goal to achieving what you describe. One can do that by tweaking the input impedance, OR by trimming the treble from the signal that drives the clipping mechanism. Tone-shaping in the op-amp is key here.
but there's a bit of a dif in application still. one is more of a tone control, the other affects the interaction of the guitar and effect more.
to me, the goal is as much interaction READ:dynamics as possible. the "feel" is affected as well as the tone i think with the impedance more, cap alters tone by filtering the feedback somewhat. . different ways of accomplishing similar things.
remember, we're purposely distorting stuff, not necessarily trying to make it happen in a traditional or linear way. we're seeking to abuse the stuff to find that tone that makes your pants too tight. ;)
sorry if i'm questioning everything but i'm questioning everything, and have been learning a lot more about implementing high and low pass filters... especially in guitars. it's all about the tone, so if it ssounds good and fills a pocket...
Seems I've opened a can of worms here ;D
Sorry, not my intention but thank you all for the helpful hints... now I'm very eager for Poppy to unwrap his gift so I can plug into it again!
Ben Lyman
Look into what you should do with the not connected pins of the other opamp in the dual opmap
Look into noise and opamps.
Think about noise and gain of the stage
OK Gus, it looks like I am supposed to ground all 3 unused pins. That should be easy with my layout because the ground already links with pin 4.
Thanks
Let me run this one by you all, I want to see if I am understanding any of what you are saying.
(http://i66.tinypic.com/2v0hj6h.png)
Oops, I think I didn't mean to put that extra 10k at the input... or did I?
The extra 10K at the output is what gives you treble rolloff with that cap across the volume control. As it sits now, it starts cutting at about 4.8kHz, neglecting the oddity effects when the diodes are not conducting.
Note that the 330pF and 150K feedback resistor are already starting to roll off treble from the amplifier at 3.2kHz, but that is before the diodes have clipped whatever is there. The 10K/3.3nF is rolling off both signal and clipping products.
> ground all 3 unused pins
NO!!
Tie Out to -In. Tie +In to Vref.
> imho most distortion designs i've built that use a high input impedance often have way too much high end
Granted, but....
"Low input impedance" does not equal "less highs" EXCEPT the special case of a guitar. Which maybe was not so special long ago, but today we often get buffered signals from active guitar, wireless, or other pedals.
IMHO: Take the signal verbatim (hi-Z), then whack-down the highs yourself.
This also avoids the problem of the hi-cut changing on every guitar you own. You can pick the tone for musical reasons, not compromise with your gear.
True, this may mean an added stage. However *this* plan is using half a dual op-amp.
> sometimes, you DON'T want a buffer between your guitar and effects...
OK, but....
> put a buffer in front of a true fuzz? heresy.
Because so many antique (and copycat) fuzz pedals took no consideration of buffered signals. But some of us don't like to live in 1967 any more. (Says the proud owner of a 1967 Ford backhoe.)
Quote from: PRR on December 24, 2015, 08:36:38 PM
> ground all 3 unused pins
NO!!
Tie Out to -In. Tie +In to Vref.
Ok... I think I get it now... sort of. I can do all that easily enough but I am unclear what is happening if I do it. Why does the unused half of the op-amp need to have VR to +In?
Quote from: PRR on December 24, 2015, 08:38:00 PM
>
This also avoids the problem of the hi-cut changing on every guitar you own. You can pick the tone for musical reasons, not compromise with your gear.
but.... i must counter, why would anyone want all their guitars to sound the same thru their rig? i appreciate generic rock distortion tones as much as the next guy, but i always prefer pedals where you can tell which guitar you're playing with it. personally, i
WANT every guitar i own or play to sound different, that's the point of maintaining so many of 'em ;)
An un-used not-connected opamp *may* find a way to make trouble. They have large gain far beyond the audio band. They will amplify any stray signal, even their own self hiss, to infinity (or till slamming the power rails).
It's like having dogs. Sometimes they just lie there. Sometimes they go berserk. It is good practice to set things up so they don't make trouble: leashes, fences.
By wiring Out to -In, you say "do what the +In does!". By wiring +In to Vref, you say "Stay at +4.5V and don't move!"
Vref is not critical. It can be any steady voltage within the input common-mode range. However most opamps don't handle zero or +9V well. Some even do a wrong thing. Vref is handy and safe.
Actually, if this is a '4558 project, the un-biased bipolar inputs will probably drift to an extreme and jam-up fairly harmlessly, unless there is huge stray signal which brings them out of the jam. But a distortion pedal has large signals to go astray. And you might want to try a BiFET or CMOS opamp, and these can hover in the "active" zone pretty freely.
Quote from: PRR on December 24, 2015, 10:59:51 PM
An un-used not-connected opamp *may* find a way to make trouble.
isn't there any single op-amps equivalent to the 4558? if there is only one already distracted amplifier, it can't possibly get up to hijinks.
>Let me run this one by you all, I want to see if I am understanding any of what you are saying.
Your gain control isn't going to work very well now. At the moment, it will be almost max to max gain.
To get the same voltage divider effect, you would have to scale the value of the pot up by 100 x (470k vs 5k), which isn't feasible.
Quote from: pinkjimiphoton on December 24, 2015, 01:59:38 PM
sometimes, you DON'T want a buffer between your guitar and effects... put a buffer in front of a true fuzz?
heresy.
buffers often tend to make stuff sound very hard and very bright. they are by all means useful, but too many can destroy your tone.
Hummm... you can use buffers to take the impedance issues out of the equation, and then work on the equalization network inside the Fuzz circuit to get rid of the brightness and harshness.
We should also remember that the great Fuzz Face, Muff & etc tones we hear on our beloves 60s and 70s records (Hendrix anyone?) are in fact heavily post-processed by the recording engineers and producers, so we just DONT HEAR the true, raw Fuzz Face sound on those records. Modern-day FF builders should take this into account and maybe re-create this whole chain of processing inside the pedal. This way we can get the tones we hear on the record when playing live.
Just my tuppence.
Quote from: samhay on December 25, 2015, 09:41:07 AM
>Let me run this one by you all, I want to see if I am understanding any of what you are saying.
Your gain control isn't going to work very well now. At the moment, it will be almost max to max gain.
To get the same voltage divider effect, you would have to scale the value of the pot up by 100 x (470k vs 5k), which isn't feasible.
sam, couldn't he just swap out the 150k pot in the feedback loop for a 100k or 250k pot to vary the gain?
The interaction with the guitar cable and effect can make a differences as well as if a effect is between them.
I did tests years ago with friends and found under 220K input resistance and some RC highpass often did not sound good with an overdrive or buffer this was a compromise for a possible guitar/bass and cable or another effect between with say a 470K input resistance
NOW with that posted
Fuzz and distortions are a little different depending on what could be before them a guitar/bass or another effect of unknown output Z and voltage and current drive
Quote from: Hatredman on December 25, 2015, 09:49:02 AM
Quote from: pinkjimiphoton on December 24, 2015, 01:59:38 PM
sometimes, you DON'T want a buffer between your guitar and effects... put a buffer in front of a true fuzz?
heresy.
buffers often tend to make stuff sound very hard and very bright. they are by all means useful, but too many can destroy your tone.
Hummm... you can use buffers to take the impedance issues out of the equation, and then work on the equalization network inside the Fuzz circuit to get rid of the brightness and harshness.
We should also remember that the great Fuzz Face, Muff & etc tones we hear on our beloves 60s and 70s records (Hendrix anyone?) are in fact heavily post-processed by the recording engineers and producers, so we just DONT HEAR the true, raw Fuzz Face sound on those records. Modern-day FF builders should take this into account and maybe re-create this whole chain of processing inside the pedal. This way we can get the tones we hear on the record when playing live.
Just my tuppence.
well stated on the post processing, but that's more true with the ff full on with the guitar cranked. to me, that's only a barely useable sound most of the time. with me it's all about the interaction of the guitar and fuzz. there is every single shade of classic rock and blues distortion you've ever heard capable with one that's good. (when it works, of course, lol).
i've built a bunch of silicon ones with buffers and various trims and filters but none of them sound the same or right... they all lose the interaction with the instrument. a buffered signal is gonna do that... it's the reason for the season, to electronically isolate the two circuits or parts of the circuit. but a proper fuzzface or tonebender needs to be driven right from the guitar itself, so the fuzzed guitar can drive the amp. i dunno about you, but i tend to play my amp and effects more than i play my guitar itself.
i have yet to find a solid state fuzz i've been happy with. i realize my tastes in tone and sound are different from a lot of peeps. i'm not interested in the sound of the fuzz cranked up with my guitar up all the way luxuriating in square wave mud... i like the sound of the fuzz cranked, and my guitar between barely on and maybe 6 or 7. freakin magical. that's why i tend to cobble together things the way i do so they suit my ears, i make no pretense about being any form of EE, i am strictly a 10 toed freak of a monkey playing with a breadboard, but i do tend to find some cool sounds out of things and def take the left hand path of circuit molestation and abuse. i'll smoke some components if i have to til i figure out how to get it to sound right. ;)
my two cents ;)
Quotezero problems i've encountered with this. 15.4k is pretty high.... guitars don't have much above maybe 6k, so i don't see what the point would be of needing the filter cut off so high?
The 15,400 Hz filter is not there so much for the effect it has on the audio, it is there to ensure you do not get into RF oscillation that may not propagate through your system but may limit the dynamic range and voltage handling capability for itself and the next pedal. You need a scope to spot it properly and sometimes oscillation only occurs on part of a waveform. The 47 pF capacitor as suggested cuts the gain of the amplifier stage at high frequencies and keeps the phase response from going to 180 degrees before the gain drops below 1. This is the condition for oscillation and since the 5534 works at RF frequencies, you may not be aware of it - it may just cause some muddiness at high inputs that you can't find without a scope.
Quote from: pinkjimiphoton on December 24, 2015, 10:30:52 PM
Quote from: PRR on December 24, 2015, 08:38:00 PM
>
This also avoids the problem of the hi-cut changing on every guitar you own. You can pick the tone for musical reasons, not compromise with your gear.
but.... i must counter, why would anyone want all their guitars to sound the same thru their rig? i appreciate generic rock distortion tones as much as the next guy, but i always prefer pedals where you can tell which guitar you're playing with it. personally, i
WANT every guitar i own or play to sound different, that's the point of maintaining so many of 'em ;)
The points that you Pinkjimiphoton, and Paul (PRR) are trying to make, are actually the same, just two very different approaches.
When I'm designing effects, I like to make sure that they have a high input impedance (~1MEG), with minimal band limiting until after the input buffer so that I can then tailor any frequency shaping to a known source impedance (that of the buffer). This means that my designs will sound the same regardless of whether they are connected directly to the guitar, or through a buffer.
Many classic designs such as the Fuzz Face or Dallas Rangemaster use the source impedance as part of the frequency shaping, and this means that if they follow a buffer, this frequency shaping is effectively eliminated, and they sound different to how they were intended (usually terrible).
A solution to this is to add a buffer in front of the Fuzz Face, but give the buffer an output impedance that resembles a guitar! To really do this properly, it's a complex impedance, and requires inductance, series resistance, parallel capacitance... etc. That can be done http://www.muzique.com/lab/pickups.htm (http://www.muzique.com/lab/pickups.htm), but is usually more effort than you want (or need) to go to.
Instead, if we're designing from scratch (or just tweaking an existing circuit), we can just set all these tonal characteristics after the input buffer, and the circuit will behave as expected regardless of the source (guitar or buffer).
You've made the argument that you want to hear the difference between different guitars when plugged into your circuit, with the implication being that the low input impedance of the posted circuits helps with that. In fact, it does exactly the opposite. The complex impedance of a guitar has a strong resonant peak, and the Q and frequency of this peak is the most defining characteristic of different pickups. However, as a guitar is more heavily loaded, this peak is damped, and the frequency response of even very different pickups quickly starts to look very much the same much below about 300k. At 9.9k like the input impedance of the circuit posted at the start of the thread by Ben, pretty much all pickups are going to sound approximately the same.
Now, he could have used the other half of the 4558 as a high input impedance buffer (although the 4558 being a bipolar input opamp can have a minimum input impedance of 300k, but typically 5Meg, it's maybe not the best choice for a high input impedance buffer compared to a jfet input opamp like the TL07x with typical 1TeraOhm input impedance), and followed that with a 10k-ish series resistor on the output
(EDIT: to approximately mimic the output impedance of a guitar), and the circuit would probably sound pretty much the same, but would work with a buffer in front, and would actually retain more of a particular pickup/guitars sonic characteristic.
I'm not going to say that the low input impedance trick is wrong, but it is certainly unpredictable, as you've observed. I like my designs to work exactly as intended, regardless of what's in front of it.
Anyway, hope my ramblings are of some use to somebody!
Thought I should add something to better illustrate my point.
The attached image shows the frequency response of two different (simulated) pickups, a single coil, and a humbucker.
The top teal trace is the frequency response of a single coil loaded with 1Meg.
The red trace below that is a humbucker loaded with 1Meg.
You can see that there is a fair difference between the two, with the resonant peaks having different Q's, amplitudes and frequencies.
Below that is the green trace, the same single coil circuit loaded with 10k, and the bottom is the humbucker loaded with 10k.
As you can see, the response of the previously fairly different pickups now looks surprisingly similar to one another. There are differences, sure, but it's mostly in the very high frequency roll off, far beyond the frequency range of a guitar or amp, and the resulting pickups end up sounding very similar. This is one good reason to use a high input impedance buffer to deal with unknown source impedances, and then do your tone shaping post buffer, when you have a known and fixed impedance.
(http://i1065.photobucket.com/albums/u389/Gregorykrobinson/Pickup%20response_zpsannv1fzr.png)
Hope this helps.
EDIT: Here's the plots overlaid on top of each other for a more direct comparison.
(http://i1065.photobucket.com/albums/u389/Gregorykrobinson/Pickup%20response%20overlay_zpsrtxg75rf.png)
Only had a minute to spare today and soon the Blues Blaster will be headed to San Diego
> isn't there any single op-amps equivalent to the 4558?
Read your history.
'4558 is a dual improved '741.
The "improvement" may have been significant when new but seems insignificant now.
'741 used to be THE op-amp. Many-many-millions sold.
Funny thing is: today a '741 is hard to source. Everybody and his brother-in-law introduced "improved '741". One popular improvement was putting two in one chip for less than double-cost. Duals now cost the same (even less) than singles.
So yes, you can find '741, and you can probably source TL071 (half a TL072). Won't save any money ('741 may cost premium), won't save any space.... it is useful to know how to safely "idle" half a dual chip.
BTW: grounding the output is usually very wrong. Depending on various factors, it is liable to dump LOTS of current through the chip. A happy dual chip pulls about 3mA. A ground-shorted opamp may pull 30mA, on top of that 3mA. Eleven times the battery drain, supply load, internal heat, for no good reason.
Quote from: Ben Lyman on December 25, 2015, 02:39:25 PM
Only had a minute to spare today and soon the Blues Blaster will be headed to San Diego
that sounds pretty much as i expected it too. nice bro. nice playing, too. it does seem to have a good interaction with the guitar. your circuit is a little more transparent sounding, which to me is good, mine is a little creamier and thick, but pedal sounds smashin' to my ears. ;)
Thanks Jimi! Colonel Grampa loves it, he played Inna-Godda-Davida on it and it sounded perfect for him.
I plan on making another for myself, gonna play around with everybody's suggestions on the breadboard first.
I wonder if the Blue Clipper is biased the way it is because Dan Armstrong was just doing what he knew how to do and maybe using an IC chip was kinda new to him.
try it with a fet based opamp like one of them ne553X like i used bro, you may like it. different sound, but good.
i think i'm gonna try one of these (yours) on my breadboard later, i really liked the demo... has a nice bite to it that's a bit different from mine, more of a nice transparent yet gritty overdrive like the way things used to be. i can dig it. and ya can literally almost build the entire thing on the back of a chip socket and stuff 'em in a 1590a.
time to whip out the old veroboard gizmotron and work up a layout. thanks ben!
Cool Jimi, I want to know what changes you make and how it sounds.
My main goal here was to make something fast with as few parts as possible, that's
why I started with the DA Blue Clipper.
I figure any beginner can make one of these and put it in a big enclosure easily with
room to spare, it's a good way to learn how to wire up a pedal with all the bells and
whistles: 3PDT w/LED, switched input jack, battery and switched DC jack.
Of course, I know a lot of you guys can easily squeeze this thing into a tiny
little box no problem.
I want to make my own soon but I have got to finish my Ge fuzz first. I also wanted
to make a Dan Armstrong Orange Squeezer but now I'm having second thoughts,
I don't know if it has weird, unorthodox wiring to it as well.
google up "mictester's really cheap compressor".... opto comp, couple parts, sounds great... so clean you almost can't tell it's on ;)
Quote from: pinkjimiphoton on December 26, 2015, 02:21:56 PM
try it with a fet based opamp like one of them ne553X...
553x is worth trying, but is not a FET opamp. Actually the opposite, as FETS have very high input impedance and 553x has very low input impedance for an opamp (300k typical). Based on the ongoing discussion, maybe that's why you like it. :)
i like 'em mainly cuz a bud gave me a huge bag of 5532's and 5534's. other than that i just buy whatever's cheap usually. that said, i'll be using these ne's for YEARS still..
i bought a few of the oplxx whatever kinda chips i heard people rave about, and heard no particular difference.
i mean... we're talking distortion here ;)
i still like 741's. great for a lot of things. and sometimes the best sounding.
but i'll agree in part with all of it... just disagree as a design absolute that ANYTHING ever has to be "just this way".... particularly when the objective is to distort the poo out of an electric guitar. ;)
there's different ways to achieve similar goals. i argue form over function i guess, and prefer to worry about toneful more than correct. ;)
I don't have any of those but I will try to get some next time I order. The only op amps I have are JRC4558, TL071 & TL072. I also tried a lot of different Ge and Si diodes and I think a big part of the sound that I like is coming from those HP/Motorola diodes