Best Op amp for transparent boost?

[Adventure_Audio]

Has anyone ever tried using this Texas Instruments INA103 for a clean boost?

http://www.ti.com/lit/ds/sbos003/sbos003.pdf

Not sure how I would set this up but it seems like it could be very promising. I am really interested in finding an op amp with a very low noise to signal ratio.

Thanks guys!

[clipman3]

The TL07X is a favorite, used in many circuits, and is designed for hi-fi audio. Low noise and distortion, high input impedance, and lots of example circuits. The TL072 also has two channels. Your chip is comparable, but has a wide bandwidth, which can be a disadvantage sometimes. It could be worth a shot though. If you're looking for something that's easy to deal with, the TL07X's have already been experimented with a lot, so you'll have more to go on.

Perhaps someone more knowledgeable in various Opamps will reply with something more useful

[GibsonGM]

The TL07X is a favorite, used in many circuits, and is designed for hi-fi audio. Low noise and distortion, high input impedance, and lots of example circuits. The TL072 also has two channels. Your chip is comparable, but has a wide bandwidth, which can be a disadvantage sometimes. It could be worth a shot though. If you're looking for something that's easy to deal with, the TL07X's have already been experimented with a lot, so you'll have more to go on.

Perhaps someone more knowledgeable in various Opamps will reply with something more useful

Yes, the advantage with the TL0's is the breadth of stuff done with them that you can find right online.   They're what I call "usually good enough".   I'm not a guru, by any means, but do know that our guitars are not hi-fi instruments...our amps are not designed to reproduce DC to gighertz....we're actually "of limited bandwidth", and that's how we WANT it for stability.  There's no need to reproduce what we don't want or can't hear (over 20kHz for those with awesome hearing).

So, 'super awesome rail to rail can reproduce a mosquito fart at -1,000 dB' isn't really required!   And the TL0's are quiet enough, for sure.  I suggest maybe playing around with a basic boost build around a TL071 or 72, and give it a listen!   

[Mark Hammer]

1) Don't put so much emphasis on the device itself.  The headroom afforded by the amount of gain introduced, relative to the supply voltage, tends to be a bigger factor in keeping "unwanted additions" to the signal out of the way.

2) When it comes to guitar gear, it's not clear to me that the noise contribution of a simple modest-gain booster is all that important.  The chip used could have noise specs of 5pv/root-hertz, and it would not reduce the overall audible noise reaching your amp, after the signal has passed through a plethora of other stages.  If you use any distortion, or analog delay, at all, then you will surely have far more noise coming from them than would ever be audible from a booster.  If you stick a booster after a noisy pedal, it may not contribute any noise itself, but will boost whatever noise is coming from those earlier pedals.

That said, clean boosters CAN be used to improve the S/N ratio, by providing the hottest input signal level that your pedal chain can successfully manage.  It is standard practice in audio to provide robust signal levels early in the chain (minus a small margin of safety so that no single stage along the way is unintentionally overloaded), and a wee bit of gain up front can aid in that.  But then that's not how people use them, is it?

[seedlings]

The JRC4580 has a high gain-bandwidth product (15MHz), and will give you more highs for a given gain over the TL0_2 (3MHz) with the same pinout.

CHAD

[amptramp]

If you look at the diagram they provided, this is an instrumentation amplifier, not an op amp, so you cannot drop it into a design for an op amp.  Note also that it is rated for ±9 volts minimum supply voltage so the typical power supply does not do the job.  Instrumentation amplifiers are overkill for an instrument boost that only needs a gain of about 2 or 3, but if you have them and can accommodate the power requirements, it might be interesting.  You can add feedback capacitance to overcome any stability issues but the low input voltage noise is only a bonus if you are using higher gain - see the output voltage noise in the spec.

[R.G.]

Not sure how I would set this up but it seems like it could be very promising. I am really interested in finding an op amp with a very low noise to signal ratio.

A couple of meta-themes come up here over and over. One is the word "best". Unless you can both (1) define what the scale and measurements are and (2) do the measurements, you cannot say anything is either better or best. All you can get is from one to several opinions per person, and there is no way to say that any of these opinions are worth more than any other.

Next: Every person's opinion is 100%, rock-solid, absolutely correct - to them, in their own mind. Remember that old "there can be no disagreements about matters of taste" thing? It's right. And there is no guarantee that any set of opinions you accept will in the end will tickle your own personal fancies.

Next: low noise design is tricky and involved. As Mark noted, picking a low noise part may or may not help you at all. Effective low noise design requires you to know and deal with the characteristics of your source in selecting the part that amplifies it. Guitar pickups, being a few K of resistance and two to four HENRIES of inductance as a soure impedance, further messed about with tone and volume controls, jacks, and cable capacitance, are an especially difficult source to do any generic "best" noise solution.

Finally, and more specifically, instrumentation amplifiers are often at their best with very low source impedances. A guitar pickup is not such a thing.

So there's a lot of learning and tinkering ahead of you. Welcome to design as a life work.

[Haze13]

If voltage on IC is 9 volts, you can use any audio op-amp. There won't be much of a difference...
BUT! BiPolar 15 volts power supply will show you how op-amps really sounds. For the gain less than 5 I like very much opa627 (mono), if you have to use dual op-amp than lm4562. Both unity-gain stable.
For the gain more than 5 my favorite is opa637.
Used 741, 4558, tl062/72/82, op2604, ad825, opa627/637...

[roseblood11]

I built some really good boosters around a OPA134 and a symmetrical power supply (+/- 9V) with a ICL7660S as voltage inverter. I think, for guitar you don't need "better" (= more expensive... ) parts than that.

[karbomusic]

I built some really good boosters around a OPA134 and a symmetrical power supply (+/- 9V) with a ICL7660S as voltage inverter. I think, for guitar you don't need "better" (= more expensive... ) parts than that.

I'm currently using both sides of 3 OPA2134s in a modified TS circuit I'm designing and so far so good. I have an OPA627 and some additional 2134/2604s I'm going to try in a booster in the near future.

[roseblood11]

I'm currently using both sides of 3 OPA2134s in a modified TS circuit I'm designing and so far so good.

Interesting! Do you have a schematic? Would really like to see s.th. that might be a bit similar to my "Rose Screamer"...
It uses the mentioned voltage inverter (like the Maxon OD-820), opamp input buffer with switchable boost (similar as Maxon OD-808), a clean blend control with a summing amplifier (which also works as output buffer), a modified tone control (from Jack Orman) with added "Voice" control (like zendrive) and various clipping options, from silicion diodes (TS-9) to mosfets in the neg. feedback loop (like zendrive, but with polarity switch...), pure opamp clipping (very fuzzy) or LED's to ground (like the MI Audio Crunchbox)

[Ice-9]

Another word that crops up a lot is "transparency" In my opinion pretty much any modern op-amp should be able to give a transparent output, for the word transparent I am reading as tone and accuracy to original bypassed sound weather it introduces a boost or not.
What is more important than the op amp is the associated components that are used around it. For example by using different value resistors and caps then the freq response will change giving a different sound at the output as what is at the input, so the word "transparency" need defining correctly.

[armdnrdy]

The definition of Transparency:

Transparency is what I was hoping for when I sent away for a pair of X-ray specs when I was a child, so that I could see the cute little neighbor girl's under wear!

Non transparency: Non transparency is the fact that the X-ray specs didn't really work, this broken hearted little boy was lied to, and cheated out of $1.00!

[deadastronaut]

lol...we all got ripped off on that ,  cool graphic though .

[karbomusic]

I'm currently using both sides of 3 OPA2134s in a modified TS circuit I'm designing and so far so good.

Interesting! Do you have a schematic? Would really like to see s.th. that might be a bit similar to my "Rose Screamer"...
It uses the mentioned voltage inverter (like the Maxon OD-820), opamp input buffer with switchable boost (similar as Maxon OD-808), a clean blend control with a summing amplifier (which also works as output buffer), a modified tone control (from Jack Orman) with added "Voice" control (like zendrive) and various clipping options, from silicion diodes (TS-9) to mosfets in the neg. feedback loop (like zendrive, but with polarity switch...), pure opamp clipping (very fuzzy) or LED's to ground (like the MI Audio Crunchbox)

I don't yet hoping to draw it up soon in the next day or two. ^ Sounds similar  I added  splitter/blend sections for clean, ripped out the buffered bypass, ripped out the stock buffers and replaced, ripping out the default level control and added a volume control post blend. I'm mucking around with a handful of switchable clipping options at the moment. Currently I can switch in/out the even harmonics and will likely end up with a rotary that switches between these diode choices and a mosfet OCD type clipper. I had to change the  cap that cuts at 720hz to get some bass back. Been changing a few other things as well. So far I'm really happy but this is my mad scientist overkill circuit so may be a while before I actually get it built. Does sound like we are on very much the same page so let's keep each other updated.

[karbomusic]

I think one important point is if op amps are there, try em out. It's all a journey for me

[Haze13]

Actually, if you want the transparent booster, you have to forget about caps in signal chain... Or if there is no way around it use the best you can. For less than 1uF best that money can buy and not being too expensive is a russian k40y-9 paper in oil. For the output and the values that are larger than 1uF  - Polypropylene Film and Foil or metallized. There are more exotic and way more expansive but it will be too much.
Op-amp with Bipolar power supply, with good DC offset characteristics, good filtration in power supply an low load (more than 1kOhm) can be used without DC blocking caps. And that is a circuit in which op-amps must be compared and they are really different. Well... not if they in the same price range and similar datasheet characteristics.

[FiveseveN]

For less than 1uF best that money can buy and not being too expensive is a russian k40y-9 paper in oil.

But... why?

[seedlings]

Maybe it's time to start rolling our own caps.

CHAD

[Haze13]

There is so much talk going on about the "Sound of the capacitor", and I decided to check this thing for my self, because if my ears can't hear it  - I don't by it. So I made a simple booster based on sk170gr JFET, the one that so famous in Hi-Fi world, using the Schematic of the Nelson Pass (famous hi-fi-amp builder), bought some caps. To be more precise: Wima MKS (polyester metallized), Rifa (same dielectric as WIMA MKS) Wima MKP (polypropylene metallized), Vishay-Roderstern (same as wima MKP), Orange Drop 716P (same as Wima MKP), Wima FKP2 (Polypropylene Film and Foil), and russian mil-spec k40y-9 Paper In Oil. I needed some of these caps anyway, so it wasn't just for the "test".
SAME VALUE, but in groups.
Well... They don't sound, but when a signal goes through them some of them effect the signal more, some less. The PIO was the best, after that WIMA FKP2, than MKP (Polypropylene Metallized). The brand is not important, but the dielectric - is.
Now after the course of "Magnetic Fields" in the Institute Of technology I understand that there is some thing to do with polarization of dielectric and the square of the layer of the dielectric. May-be some other things that I will learn in the future, but the fact is that there is a difference. No Magic, no Voodoo...
The amp was JCM800 2204, with an epiphone Les Paul (replaced electronics and hardware) and 2 cables.