OT: What do you have against op-amps?!

[Paul Perry (Frostwave)]

If you open up an op amp, it is full of transistors. TRUE :!:
...except for these ones they kept on the window ledgfe at that hat company: http://www.national.com/rap/vacuumtubes.html

[gez]

Of course I know most of you use op-amps, I just wanted to encourage some of the newer members to get past some of the mojo about only using discrete devices for boosters and get stuck in and have a go.

When I first got into building effects I honestly thought that using op-amps was cheating somehow, that it was too easy and that things would sound better doing it the 'proper' way.  Nowadays, the first thing I grab is the chip that will do the job the easiest.

I'm still amazed by all the boutique boosters that use trannies though.  I can understand if someone wants to get that vintage vibe, warts and all, but if they're after transparency (and you see this in a lot of the blurb/hype)?  Each to their own I suppose...

[Ge_Whiz]

No problem with opamps, especially since I scored 30 TL062s for a dollar in Dayton last year.  

Some opamp designs seem unnecessarily complicated, when a transistor, capacitor and two resistors will do.

[StephenGiles]

It's all down to individual taste, education and breeding is it not? It's like saying that I prefer Polo to cricket (which I do of course) - they are still whacking a little white ball along a field. You hit a string on your guitar and it really matters not how it is distorted, now does it - or are the Emperor's New Clothes rearing their ugly head once more. Personally, I find transistors apain in the neck. A TLO72 does anything I need from an opamp.
Stephen

[Jason Stout]

Jason Stout wrote:
2. Most opamps require a bipolar supply.

Tone God writes:

Since when ?

Since the beginning, your article shows how to split and apply a single supply, effectively making a bipolar supply. AFIK All opamps need a bipolar supply, i.e. +V  -V and ½+V as a reference, unless they derive Vref internally.

Cool site, I like the switch de-bouncing article.

[zachary vex]

op-amps are great for creating control voltages and pushing things around that need very low-impedance driving (like transformers and LEDs and speakers/transducers.)  they're fantastic for moving the d.c. level of an a.c. or d.c. signal around, and delivering it nice and sturdy and basically looking exactly the same even during very slow signal movement.  

the flip side is that they have too many leads, need too many support components and take up too much space, and sometimes eat up a bit too much power or need negative supplies, but i always keep a reference nearby to remind me of the rules and calculations for setting them up, like the little softcover radio shack (mims) op-amp reference notebook.  sometimes you have to rely on an op-amp to solve a very specific problem so it's a great idea to study them once in a while to remind yourself of what they're good at.

otherwise, discretes RULE!  8^)

[Jay Doyle]

I'm one of those sick people that make opamps from discrete parts. I find them to be quieter and to have a smoother distortion when you overdrive them. But it is a bit of a pain to wire up...

My two main complaints with opamps are:

1 - The distortion is too "obvious". You push them to the limits and they clip, flat. No squashing, no change of gain at the headroom limits to induce distortion. Just plain old textbook clipping. Kind of sterile. Though for a booster they are pretty much perfect... Except...

2 - I absolutely HATE wiring up opamps on perf. My perf skills are pretty poor, even after all the effects that I have built, and getting all of the support parts and the opamp crammed in there is a pain. Plus you automatically have to use a jumper for either V+ or ground or cut yourself off, room wise.

I find that if I am designing and I end up using opamps, I'll build a PCB. If I am using transistors, I'll perf it. Thus transistors are more instant gratification for me; opamps I have to put in the time.

Both transistors and opamps have their place. For accuracy and/or hordes of gain, opamps are it. For a little bit of character and, to me, ease of build, transistors are great.

Jay

[Doug_H]

l;kj

[Hal]

Jason Stout wrote:
2. Most opamps require a bipolar supply.

Tone God writes:

Since when ?

Since the beginning, your article shows how to split and apply a single supply, effectively making a bipolar supply. AFIK All opamps need a bipolar supply, i.e. +V  -V and ½+V as a reference, unless they derive Vref internally.

Cool site, I like the switch de-bouncing article.

I always understood that you can use bipolar or v/2 as ref, not both.

[Fret Wire]

2 - I absolutely HATE wiring up opamps on perf. My perf skills are pretty poor, even after all the effects that I have built, and getting all of the support parts and the opamp crammed in there is a pain. Plus you automatically have to use a jumper for either V+ or ground or cut yourself off, room wise.
Jay

I know the feeling. The lead spacing is the same for pcb or perf, but I still hate perfing OA's. Op amp paranoia. As soon as I solder the socket in, I take a serrated knife and cut little trenches between the pads in all directions. Then after every jumper off the IC is soldered, I take an exacto and touch up the cuts.

That's one good thing about this forum. Sitting down and writing about it, I think I'll perf the next IC different. I'll try soldering just the pins that have no connection, or with some ckt's, clamping the socket down completely unsoldered. Then soldering both the socket leads and the jumpers at the same time, instead of re-melting the socket lead pads to add the jumpers. That way I'll be sure to get a good, direct connection from the jumper lead to the socket lead. Seems better than melting the jumper into the solder pad and hoping it connects directly. Should be less chance of bridging pads by soldering only once.

[bwanasonic]

For distortion I don't have a problem with opamps, but I find I much prefer discrete circuits for "clean" boosters, most likely because they are NOT transparent in a true *scope* sense of the word. Something like the AMZ Mosfet boost or Fetzer adds a little *magic dust* factor, and keeps the organic feel and response of my playing. I would like to try a really *HiFi* style opamp booster with impedance properties like the MOsfet boost though.

Kerry M

[petemoore]

'Cheating'
 and leaving about 3/8ths or 1/2 inch resistor lead coming off the OA on top of the board.then solder the rest of the node on there...ok not quite as sturdy as having every lead short and fastened to underboard copper pad...But I forsee no trubbles, just bubbles and have been looking at and using this type of OA wiring for long time with absolutely no forseeance of problem...looks plenty sturdy to me.
 I like having Electrocaps 'in' the board, other than that I don't have much problem doing parts of the wiring atop the board, and it sure makes it EZ to see what's '?that'...also indespensible for doing neat EZ tweekz...very easy to change stuff around compared to the messes I've created 'below' when pulling parts from pad connections.
 Got all the       of room up top...why not use it? I do and can say I like it that way.
 Just trim the lead, and bend a hook in it, hook it to an 'above board lead...what could be easier?

[RDV]

I LOVE OPAMPS!



RDV

[RDV]

Warning:... Way Huge's Swollen Pickle and Red Lama contain op-amps! Disgusting! Send them to me for disposal, I will pay postage.

Ahem, neither of them contain OAs. A transistor array and a CMOS respectively.



RDV

[Fret Wire]

RDV, isn't that all op amps really are? Integrated Circuits of the above, etc.? So four 3904's in one package with the additional components is an op amp, so to speak. We could get  technical, but I thought the idea of this thread was IC's verses individual devices. That counts in the 4049 too. If its strictly operation amplifiers were talking about, ok. From a player's point of view, none of it matters when you stomp down. Then it's tone or no tone.

[Johan]

...lots of people mentioning things like 'transparency' and then they recommend someone build something that uses little feedback and introduces far more distortion than a humble op-amp design would.  

For real transparency my first choice would be an op-amp, so what do you 'all' have against them?!  Just curious...

..I think part of the problem is that people confuse transparancy with something that is in reallity not tranparent at all ...most of the time full frequency, linear boost just sound plain, dull and boring....people dont perceive it as transparent unless it has a full low end and some brilliance ( a little bit of distortion and low frequency boost ?)

Johan

[RDV]

RDV, isn't that all op amps really are? Integrated Circuits of the above, etc.? So four 3904's in one package with the additional components is an op amp, so to speak. We could get  technical, but I thought the idea of this thread was IC's verses individual devices. That counts in the 4049 too. If its strictly operation amplifiers were talking about, ok. From a player's point of view, none of it matters when you stomp down. Then it's tone or no tone.

Most of these type threads don't mean anything you know, if it sounds good, it doesn't matter what's making it sound good. My 2 main pedals right now are J201 based, but not because I'm prejudiced toward them or away from something else. They're just floating my boat at the moment.

RDV

[Peter Snowberg]

RDV, isn't that all op amps really are? Integrated Circuits of the above, etc.? So four 3904's in one package with the additional components is an op amp, so to speak. We could get  technical, but I thought the idea of this thread was IC's verses individual devices. That counts in the 4049 too. If its strictly operation amplifiers were talking about, ok. From a player's point of view, none of it matters when you stomp down. Then it's tone or no tone.

Opamps are a different animal from regular old class A transistor stages. What really characterizes the difference is that an opamp has two inputs with opposite polarity (a.k.a. a differential input stage). The output is push-pull and the object of the opamp circuit is to output a voltage that causes both inputs to be at the same voltage. Most transistor circuits don't have a differential input stage.

Arrays can give you relative consistency between devices in the same circuit which is really nice. They're my favorite.

Inverters aren't opamps either even though they do get used with feedback, they still have a single, single-ended input.

In the end, of course it doesn't matter what topology you choose in the least. It's about what sounds good to you!

[Fret Wire]

I do find some ckts interesting from a design standpoint, but it goes back to what I said earlier, tone or no tone. My bias will always be toward the player end.

I used only two effects for a long time, the RM FF and the Distortion +. Ge's and op-amps. I still like them best, and compare anything new to them. I've used them so long, I know their nuances inside out.

Still, the effect I find the best, and always return to, is a straight chord to the amp. The one and only honest effect that hides nothing.

Peter, we talked about this before, but a dream IC would be a matched JFET array for the phase 90. I'd gladly plunk another IC on that board instead of matching.

[Bluesgeetar]

Not all of us hear the same.  Anyone here who thinks he hears exactly the same as me or any other should have his head examined.  

That said I pretty much agree with Jay Doyle there.  I hate hate hate the sound of opamps.  Oooooooooooooooooooohhhhhhhhhhhh  yes opamps have their own sound and I don't like it.  Although opamps are cool if your doing 80s covers.