Best Op amp for transparent boost?

[samhay]

Haze13 - Did you measure the capacitance of each cap you tried?

To the OP - don't think anybody has mentioned the NE5532 yet. If you don't need really high input impedance, give on a try - they are cheap and found in just about all the mixing consoles, so will sound transparent in the sense that they should sound like everything else!

[seedlings]

I'm interested to hear more about your comparison, is there another thread?  How did you measure the capacitance of each component?  Why were the paper in oil caps the best?

CHAD

[Haze13]

1/2*Pi*r*c... in the worst case the cut off region will change slightly, and that would mean that large value will sound always better but this is wrong. Actually in the BOSS SD-1 and CE-2, Ibanez AD80, where in the input there is a 47nf (polyester) I prefer 33nf WIMA FKP2, sounds more naturaly to me...

[Haze13]

WIMA FKP2 2.5% tolerance, the rest were 5%, and the PIO were 10%. I bought more than one from each type, and changed same brand same type just to see if there is a difference. The PIO rated as 10%, from the internet they are much more accurate.
Same technique I used with BJT, IC (LM4562, OPA627/637 with PSU of +/-15 volts). Built pedals with these caps and result was always the same. Some how, I do believe after all these test that I did and to the talented engineers like Erno Borbely, Nelson Pass, John Curl and others that use these types of the caps in their builds.
You can do this to:)

Works best when there is small number of the caps in your circuit. When it's some thing like Analog Delay - it does not makes much of a difference between PIO and Polypropylene. There a lot of the 1uf's, 2.2uf's, 4,7uf's or 10uf caps. Normally people are using electrolytics for these values. They blurring every thing...

[Haze13]

Google for other threads on Hi-Fi forums, but it will take you hours and hours of reading, other opinions, similar tests... Feel free about it:)
It's never ending! There are caps that people prefer over the PIO. Teflon, Bees Wax, PIO with silver foil...  There are caps that will cost you more then 150$ for a piece. I decided to stop here and concentrate on other things.
Not in every circuit it will perform as you expect. You can't just replace all of the caps and to think that that's the best what you can do to it.
Like comparing Gibson Custom Shop with Epiphone china made on 10 watt transistor amp. They will sound the same
Resistors, semiconductors, the topology of the amplifaction (Class A, AB, Single Ended...), power supply, IC's, the design of the circuit. So much to take in to account...

[karbomusic]

Google for other threads on Hi-Fi forums, but it will take you hours and hours of reading, other opinions, similar tests... Feel free about it:)

Been there done that but moreso in the recording world (DAWs, Analog, Multi-tracking, bit depth, sample rates and so on). Many of the highfalutin audiophiles fall deathly silent as soon as they have to perform under the conditions of a proper blind ABX test. It is very difficult to get around perception bias, it's a very real issue. However, to play devil's advocate it is also very difficult for ABX testing to capture differences you notice over time which are the ones that matter to me the most, AKA listen to A for a month, then switch to B.; but most space rock toting audiophiles say they can hear the differences instantly which is what ABX solves instantly.    The thing to do is find and realize where the return vs price is a diminishing one, find that point and stop there. That's the best anyone can do, otherwise, it's for the fun and fantasy of it which is also perfectly valid, we just don't want to mix fantasy with fact.

I'm certainly not knocking the audiophile culture, there is nothing wrong with spending exorbitant amounts of cash and listening for minute differences (whether someone actually hears them in reality or not). It all comes down to being able to properly quantify why one is doing so. There are probably things I'll do that I'm enjoying doing and have no stake in it such as these nice 25.00 OPA627's I just purchased, but I don't want to be marketing them as the cat's meow unless everyone can actually hear the meow.

All that being said and for those interested in testing stuff. There is a nice ABX testing plugin for Foobar 2000. Meaning you can record various components and somewhat blindly test them yourself and see if what you hear is better than chance. If hearing a difference is important, that's a good place to start. Otherwise, I'll still build stuff with cool mojo parts from time to time, because the entire process is just plain fun.  

[12Bass]

Although I probably wouldn't recommend them for guitar pedals, I suggest trying the ADA4627-1 and LME49990, which are two of the best sounding op amps I've heard so far.  As a bassist, my rig is probably cleaner and more "hi-fi" than most guitar rigs (including a true 3-way cabinet), which makes it easier to hear subtle nuances between components.  The relatively high distortion and low bandwidth of most guitar amps likely obscures those details.  And, FWIW, I've been able to reliably hear differences between capacitor types.  What works best depends on the circuit.

[Haze13]

lme49990...  heard of these op-amps only good things. They are very expensive too, about the same price as an opa627...
ad797 goes in to the same category.
Don't think that if some body will want to buy 3 of them for just to pick one. Waste of money. These are different brands and more or less same quality. There wont be a difference like "day and night" between them, so any one of them will outperform by far any standard IC's even op2604 and ne5532.

[deadastronaut]

tolerance?..

[FiveseveN]

I'm certainly not knocking the audiophile culture

Allow me then .

There is so much talk going on about the "Sound of the capacitor", and I decided to check this thing for my self

So you were skeptical and curious and you decided to draw your own conclusions by making the same mistakes as everyone else:

• Test was not blind.
• Test was not controlled.
• Conclusion is purely subjective: what does "effect the sound" mean? Humans are notoriously bad at detecting slight distortion.

And, as it usually happens with these things...

large value will sound always better

You're confusing aesthetic preference for objective performance.

[anchovie]

If you use audiophile parts in your guitar gear, does that mean you can only ever play to an audience of one person who has been placed in the optimal listening position?

[Gus]

The interaction with the guitar or bass matters. 

The supply voltage(s) matter This limits the gain before clipping(this is for the common one opamp circuit you will often find being used for boosters)

A common jfet input opamp circuit should be fine at the guitar or bass frequency range set at a max gain of 3 using a 9VDC supply

Set it up with a 1meg input resistance, add stability circuity, add a RF filter(s), use good layout, select you input highpass frequency, select you output highpass frequency and make sure not to load the opamp output beyond it's specifications

[anotherjim]

I don't think any human sense is laboratory standard. But you really can't argue against anyone's faith in their own senses.

My own suspicion is that the idea of "Transparent Boost" of a guitar is actually asking for a trick to be done. It can't be a simple amplifier - no matter how clean. In a stomp box running on 9volt, boost more than x3 or so and a good strong whack of a chord will clip at the initial peak. But the gain is so low, it'll sound weak, not much boost at all, for the rest of the sustain. Ok, so let's go to a higher voltage. Might as well be +/-15volts bipolar. We can now boost by more than enough - except that we don't want to overdrive the next item to much, so we turn the boosted signal down. What have we gained? Not much in my experience.

This is a subjective area, the requirement here isn't going to be something that's lab perfect, it's got to be something of a fake.
A compressor is called for I think. Not strong enough to sound artificial, but enough to sound clear and open with improved touch sensitivity.
It will "sound" like clean boost - but it's a trick.

[Mark Hammer]

1) All guitar amplifiers have front ends designed around anticipated input levels from "normal" guitars.  They have to, in order to be able to aim for something approximating an acceptable S/N ratio.  It doesn't take all that much to exceed that input level.  What this implies is that what emerges untainted from the booster will likely not emerge untainted from the speakers.

2) I will remind folks, yet once more, that audiophile wisdom regarding optimal processing of complex wide-bandwidth multi-source signals may be entirely sensible, but that does not mean it bears all that much relevance to limited bandwidth single-source guitar signals.  If one is attempting to reproduce a complex multi-source signal, whose content stretches out into the 18khz+ domain, then faster slewing, and anything you can do to allow harmonics and fundamentals from different instruments to align properly and be "assigned" by your brain to the appropriate source, will reduce listener fatigue and the mental labour associated with hearing a complex sound-field coming out of a couple of cones.  Much of that doesn't matter when you dwell in the world of 6khz and under, and your amp only processes ONE instrument.

3) Placing all the emphasis on a single semiconductor is assigning a little too much blame if you ask me.

4) The reason why there are so many different op-amps on the market is because they are all designed in anticipation of slightly different operating circumstances, and optimized to match those circumstances.  A device that works fabulously under conditions XYZ may perform in mediocre fashion in circumstances QRS.

[Haze13]

 To Fiveseven:
Who said I was alone? When you A/B-ing you can hear very well the Difference, and I am not alone in this world...
Just like in a big tube amps, if you want a good sound you will use good parts. What are these Orange Drops that Soldano, Bogner, Mesa and others use? A capacitor with a Polypropylene as a dielectric... Famous "Mustards" in the Marshalls? Polyester Film and Foil type...
That's what Sozo uses to recreate that sound of these caps.
If you don't believe me, I'm ok with that, but I believe to what I hear.
I probably could try to write all the Physics that can explain why dielectric effects the current that passes trough it between 2 conductors but it will take too much writing and so much formulas and what is the most important - not interesting. Believe me, I'm not trying to be smart, just writing what I heard and experienced.
You can compare them too! Physics works - I've checked

Totally agree with Mark Hammer, but wanted to add that good headroom is what we like the most, and these are low frequencies, so most of what Hi-Fi conductors and semiconductors are offering to us we actually CAN hear...

Like delay based on MN3005 that first works of 9 volts, and then you bump it to 15... No difference still? Only voltage has changed and the result is - Ibanez/Maxon  AD-80, ELH DMM, Maxon AD900, BOSS DM-1, BOSS DM-100, Yamaha e1010 and more.

[FiveseveN]

You can compare them too! Physics works - I've checked

Of course there are differences in dielectrics, tolerances, constructive details, age etc. Modelling or measuring them is one thing, being able to hear and identify them, in different circumstances, is another.
I only said your test methodology can not support the conclusions you've offered. And my objections have not been addressed.

[Haze13]

Okay... *Humans are notoriously bad at detecting slight distortion you say? Odd and Even Harmonic Distortions. Transistors have Odd harmonic distortions the most, and the Tubes have the Even harmonic distortions the most. Some how people do hear the difference between them

[FiveseveN]

This is quickly turning into the Audiophiles Say the Darndest Things thread  .

[electrip]

...Transistors have Odd harmonic distortions the most, and the Tubes have the Even harmonic distortions the most. ...

Thats nonsense.

[Mark Hammer]

This is quickly turning into the Audiophiles Say the Darndest Things thread  .

Actually, audiophiles buy (and sometimes build) the darndest things.