ICs vs Transistors in drive pedals - differences?

Discussion in 'Burnt Fingers DIY Effects' started by parademe, Jun 10, 2017.

  1. parademe

    parademe Tele-Meister

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    Hi.

    I just finished a modified Woodrow/Trotsky Drive mongrel. Sounds great. But trying out different clipping diodes and amplifying units was kind of a déjà vu - made me remember the times when I was trying out diodes and different ICs for a tube screamer clone.

    So I was wondering, what is the difference between ICs and Transistors in sound, sonic properties and technical aspects?

    I known there are pedals where the clipping is produced by the amplifying transistor - is there a comparable IC circuit, where clipping is produced only by the amplifying IC instead of diodes or transistors?

    I'm thinking mainly of drive pedals. I don't know if it's the same with Fuzzes. I don't really know a Fuzz pedal with an IC chip.

    This is a hobby builder asking. Please forgive me if I didn't see the obvious yet.
     
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  2. matmosphere

    matmosphere Tele-Holic

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    Im not an expert on these things but it's my understanding that ICs are just several transistors built into a single package. At least the ones we use most of the time are.

    For example a jrc4558 (think tubescreamer) is essentially two silicon transistors in one case.

    There are fuzzes that use ICs including one popular version of the Big Muff that's from the late seventies. I think it has a 4558 and a lm741.
     
  3. luckett

    luckett Banned

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    There are many different types of ICs so you can't make a generic statement that ICs have a specific sound. IC is just a term to describe a circuit that is on a single silicon wafer. An IC can have any type of circuit on it and some of the different ICs used in pedals can have very different clipping characteristics. A few examples are the TL072 audio op amp, the LM386 power amp, the CA3080 OTA op amp, and the CD4049 hex inverter. They are all fundamentally different circuits and they all sound different when clipping.

    Hotcake and Red Llama are a couple of popular ones.

    The 4558 is far more complex than just two transistors.
     
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  4. wabashslim

    wabashslim Tele-Afflicted

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    Yep...

    4558.jpg
     
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  5. parademe

    parademe Tele-Meister

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    Thank you guys! That's a lot of useful information here!
    The schematic of the 4558 kind of made me understand the differences , or got me closer to understanding. I could have looked that up by myself if I only knew there even are schematics to ICs.
    That's really helpful. Imagine a post about (tone-)wood would be going that straight from question to understanding the topic : )
     
  6. matmosphere

    matmosphere Tele-Holic

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    I stand corrected, and i greatly humbled.

    I've never seen a schematic for an ic either. I've always thought of op amps basically as a series of transistors, although I didn't think any we used were quite that complex.
     
  7. jimdkc

    jimdkc Friend of Leo's Silver Supporter

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    And that's a relatively simple IC!
     
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  8. Steve 78

    Steve 78 Friend of Leo's

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    Yep, modern processors can have over a billion transistors. Yes billion with a b.
     
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  9. NotAnotherHobby

    NotAnotherHobby Tele-Afflicted

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    I'm not going to pile on here, but I can add some things for you to consider.

    Transistors vs. ICs is like comparing apples to carrots. Most of the distortions out there use opamps to amplify the signal and either clip it with diodes, over-drive it by putting diodes in the negative feedback loop, or amplify it so that the IC clips it (dives the signal past the available voltage source).

    Transistors and FETs essentially do the same thing, but they are MUCH simpler in their construction. Hence they are subject to specific variances. Kinda like using a home-made crosshairs to aim, as opposed to a laser-sighted thingamajigie. Many transistors can make up an IC, but IC's are generally not a replacement for transistors.

    Your average distortion / fuzz / overdrive is a pretty simple circuit. You take a signal, you amplify it so that the theoretical output from that amplifier is WAY greater than either the power supply powering the circuit, of the capabilities of the component itself. That's about it. Slap on a tone-control circuit and you're basically done. The difference between a distortion, a fuzz, and an overdrive is actually minute electronically. What differentiates them is how they *sound*. And it doesn't help when the terms are often used interchangeably.

    Your average fuzz circuit is usually transistor-based. It can use either germanium transistors / diodes or silicon. An overdrive usually uses tubes or opamps (I've only ever seen an overdrive circuit using opamps, but others might exist). The rest falls under the "distortion" category - usually circuits with FETs and/or opamps, and almost always using silicon semiconductors.

    In my opinion, transistors are usually used for fuzz circuits mainly because of their lower input characteristics, that often impedance-load the input (yes, that is a term I've just made up) which contributes to the "woolly" sound. Plus, transistors on their own usually have a fairly high amplification factor, and requires additional components to make them more stable under a variety of conditions.

    Opamps and FETs, because of their higher input impedances, tend to create a "crisper" sound profile, give your distortion a more "edgy" sound with less components. Hence the reason a lot of 80s circuits and Brown Sound stuff tends to use opamps and FETs.

    Overdrives are a different animal. Most overdrives are used to simulate tube distortion circuits, as tubes have this funky sort of thing they do when they amplify a signal greater than the tube can reproduce. Instead of hard clipping, it tends to flatten and slightly round-over the signal past the breakover point (maybe linearize?). Some have found ways of reproducing this with FETs, and most notably using back-to-back diodes in an opamp's negative feedback loop, to reproduce this effect. Hence the reason why the more famous pedal is called a "Tubescreamer."

    Now as far as clipping goes, the harder you amplify the signal, and the lower you clip it, the more radical-sounding the sound is. This is the reason why some fuzz boxes sound like your old Atari 2600 when you play through them. Cut back on the amplification, and raise the clipping level, and you'll go from blips and burps, to light crunch. That's the general principle. Different diodes have different clipping voltages. There are different ways of clipping transistors. And, with some creative use of capacitors, you can smooth off the hard edges of as clipped signal to get a more "reed-y" like sound, or warmth. Believe you me, it's not just the clipping that gives your distortion a distinctive sound.

    So, I hope that helps a little in clearing up some confusion.
     
  10. parademe

    parademe Tele-Meister

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    Aiming with crosshairs and laser at my question and every shot a hit, no more questions left on the range.

    Thank you very much!
     
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  11. TeleOrLes

    TeleOrLes Tele-Meister

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    You at least picked a great time to be a hobby builder. With the web, you have more info & drawings that you could ever build in a single lifetime. That Elektra/Trotsky drive alone has so freaking many cool mods that you'll keep your breadboard busy for quite a while. Go to the Muzique.com site! Jack Orman is one of the masters & shares some of the stuff that makes effects magical. Just by changing that NPN transistor alters your sound with each swap. There's tons of info about your clipping diodes as far as different diodes, adding a pot with the diodes, & many other configurations. Along with Muzique, you can spend hours (days) until your eyes bleed with other awesome (and some not so awesome) stuff. Look this stuff up & have fun! ;)
     
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  12. TeleOrLes

    TeleOrLes Tele-Meister

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    And the 4558 doesn't use JFETs & that's a horse of a different color.
     
  13. TeleOrLes

    TeleOrLes Tele-Meister

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    And yet a FuzzFace just uses two transistors! Yes two with a 2. Sorry, deep fried Tim Tams have messed my head up. :rolleyes:
     
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  14. wabashslim

    wabashslim Tele-Afflicted

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    Electro-Harmonix' very first product I believe was the LPB-1, a "Linear Power Booster", just a clean boost in a little box (not a pedal) with a slide switch and a volume knob. Inside was a single transistor & a couple resistors suspended by their pigtails between the input & output jacks. Cost around $20, could be built with Radio Shaft parts for <$3 which is what I did to counter this perceived ripoff. Never bought another E-H product. My loss, probably...
     
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  15. TeleOrLes

    TeleOrLes Tele-Meister

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    The problem years ago when "The Shack" was one of the only places to buy small quantities of parts was their lack of selection & their prices. Now with the internet, I weep when I see the prices on some of the parts. E-H in their defense, did make some pretty cool stuff that some of us poor musicians could afford. My first E-H was a Small Stone phase shifter. It was the coolest of my 4 pedals. I wish I still had all 4 but that's another story. Now we can build LBP-1's to our heart's content and more. Gotta get back building! Not an LBP-1, a vacuum tube/fuzz face hybrid! Wish me luck! :confused:
     
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  16. parademe

    parademe Tele-Meister

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    Yes! Thanks! I used his "wonderful stupid tone control" in the past. Great site!
     
  17. reddesert

    reddesert Tele-Meister

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    Electronic components have never been the majority of the cost of a pedal, except maybe for a few exotic ICs or a vacuum tube. It used to cost more than $3 in labor to assemble $3 worth of parts (before automated pick-n-place and SMT soldering). When I build a pedal, the enclosure is likely to cost more than all the components (and I find drilling the enclosure more tedious than assembling the electronics).
     
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  18. metalosophy

    metalosophy Tele-Meister

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  19. waparker4

    waparker4 Doctor of Teleocity Ad Free Member

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    In 1949 Leo Fender built an amp straight out of a Radio electronics manual book, just a couple bucks in parts, but now worth thousands of dollars! What a rip off! :p
     
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  20. NotAnotherHobby

    NotAnotherHobby Tele-Afflicted

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    Component cost is actually pretty small. The main cost is usually marketing, sales, overhead, and various Q/A processes, all of which are long, and labor-intensive.

    I used to work at a place that produced automotive diagnostic boxes. Getting boards produced correctly, RF compliance, and so on was the majority of the cost. Then there was the time they got stung with counterfeit parts of a rare memory chip that was pretty much nothing but painted clay with leads coming out of them. They managed to recover most of their purchase, but they still took a huge hit.

    Then there was they time some genius bought a bunch of non-returnable signal converters that were the wrong type. So stupidity factors into the price as well...
     
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