Quality Opamps
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Samuel Groner
Well-known member
Both the 990 and the Forsell's don't go below 1 nV/rtHz, but they come close.
But LT has two:
* LT1028
* LT1115
Samuel
But LT has two:
* LT1028
* LT1115
Samuel
[quote author="Samuel Groner"]Both the 990 and the Forsell's don't go below 1 nV/rtHz, but they come close.
But LT has two:
* LT1028
* LT1115
Samuel[/quote]
thanks, those look like great parts. Jensen claims that the 990C is below 1nV although I haven't seen what John Hardy's specs say.
But LT has two:
* LT1028
* LT1115
Samuel[/quote]
thanks, those look like great parts. Jensen claims that the 990C is below 1nV although I haven't seen what John Hardy's specs say.
Soultek,
What are you using it for, since you need THAT low a noisespec from the opamp? More often than not, this spec is masked by the needed support components like resistors etc..
Jakob E.
What are you using it for, since you need THAT low a noisespec from the opamp? More often than not, this spec is masked by the needed support components like resistors etc..
Jakob E.
Samuel Groner
Well-known member
They (and Hardy) spec 0.8 nV for one transistor and 1.13 nV for the diff. pair. 'till today I thought that 1.13 nV is the figure that compares to the one found in IC datasheets; thinking over that I'm not sure anymore. Anyone can help?
Samuel
smallbutfine
Well-known member
TI / BB doesn't offer anything in *that* low noise range... :shock:
(Personally i love the sonic qualities of these, but even opa227 is three times your wanted spec, opa 627/637 even higher. But they are widely available.)
If noise is really the ultimate condition for your choice probably i can recommend the AD797.
What should this be used for???
Kind regards
Martin
(Personally i love the sonic qualities of these, but even opa227 is three times your wanted spec, opa 627/637 even higher. But they are widely available.)
If noise is really the ultimate condition for your choice probably i can recommend the AD797.
What should this be used for???
Kind regards
Martin
thanks for the replies. Actually I am designing a few different things. I wanted to listen to a few different opamps and see what I liked the sound of the best. I started with the Avedis API 2520, NE5532, TL072, BA4560, and a class A opamp I designed myself. So far the 2520 won. I recently purchased the JE990, and I have the AD797 and LT1115 parts on the way. I wanted to hear something super low noise to see if I can hear a difference.
The circuit I am working on now is a transformer coupled line amp with a gain of maybe 0-30dB. I know this doesn't justify super low noise parts, probably overkill, but i would still like to hear them. I believe it is the transient response of the amps that determines if I like them more than another.
The source impedance will be from 50-1800 ohms, the input transformer is 1:1.
I suppose I should have asked a different question: for this application, which opamps to people like the best sonically.
I've already given my answer, but I just started comparing things.
I supposed I should try one of the BB parts as well, aren't they JFET input parts?
The circuit I am working on now is a transformer coupled line amp with a gain of maybe 0-30dB. I know this doesn't justify super low noise parts, probably overkill, but i would still like to hear them. I believe it is the transient response of the amps that determines if I like them more than another.
The source impedance will be from 50-1800 ohms, the input transformer is 1:1.
I suppose I should have asked a different question: for this application, which opamps to people like the best sonically.
I've already given my answer, but I just started comparing things.
I supposed I should try one of the BB parts as well, aren't they JFET input parts?
thanks for the replies. Actually I am designing a few different things. I wanted to listen to a few different opamps and see what I liked the sound of the best. I started with the Avedis API 2520, NE5532, TL072, BA4560, and a class A opamp I designed myself. So far the 2520 won. I recently purchased the JE990, and I have the AD797 and LT1115 parts on the way. I wanted to hear something super low noise to see if I can hear a difference.
The circuit I am working on now is a transformer coupled line amp with a gain of maybe 0-30dB. I know this doesn't justify super low noise parts, probably overkill, but i would still like to hear them. I believe it is the transient response of the amps that determines if I like them more than another.
The source impedance will be from 50-1800 ohms, the input transformer is 1:1.
I suppose I should have asked a different question: for this application, which opamps to people like the best sonically.
I've already given my answer, but I just started comparing things.
I supposed I should try one of the BB parts as well.
The circuit I am working on now is a transformer coupled line amp with a gain of maybe 0-30dB. I know this doesn't justify super low noise parts, probably overkill, but i would still like to hear them. I believe it is the transient response of the amps that determines if I like them more than another.
The source impedance will be from 50-1800 ohms, the input transformer is 1:1.
I suppose I should have asked a different question: for this application, which opamps to people like the best sonically.
I've already given my answer, but I just started comparing things.
I supposed I should try one of the BB parts as well.
smallbutfine
Well-known member
My personal opamp choices of the moment for sonical character are MC33078 (like lm833, sounds great, thanks Jakob for this), OPA2227/2228, OPA 2134, OPA 627/637, OPA2604 and AD797 depending on the perfomance parameters for the circuit.
:grin:
:grin:
Samuel Groner
Well-known member
Anyone on the 0.8 nV vs. 1.13 nV?
Samuel
Samuel
peranders
Well-known member
Soultek, are you aware of that you can't take advantage of this very low noise unless certain conditions are met. When you know this fact you will have lot's of more good opamps to choose from.
What is your signal, MC, MM, mic, line level, what?
Don't get a hangup on this noise parameter until you can understand what it means in real life.
What is your signal, MC, MM, mic, line level, what?
Don't get a hangup on this noise parameter until you can understand what it means in real life.
Samuel Groner
Well-known member
Thanks, I think that's true.
The only thing that makes me doubt is the fact that this would (for the 990) imply an OSI of 800 ohm; however if you look at the engineering report, fig. 3, it looks more like the 1k13 that the 1.13 nV number would indicate.
Samuel
[quote author="peranders"]Soultek, are you aware of that you can't take advantage of this very low noise unless certain conditions are met. When you know this fact you will have lot's of more good opamps to choose from.
What is your signal, MC, MM, mic, line level, what?
Don't get a hangup on this noise parameter until you can understand what it means in real life.[/quote]
For this particular project, it is line level. I know the noise spec is overkill. If you'll look at my above post, you'll see that I revised my thread to opamps that people like the sound of for the application I mentioned. It would be very hard for me to listen to every opamp I could use, I need to narrow my scope somehow.
I am aware of how to design opamp circuits to maximize their noise spec. Unless you know something I don't, which is quite possible.
What is your signal, MC, MM, mic, line level, what?
Don't get a hangup on this noise parameter until you can understand what it means in real life.[/quote]
For this particular project, it is line level. I know the noise spec is overkill. If you'll look at my above post, you'll see that I revised my thread to opamps that people like the sound of for the application I mentioned. It would be very hard for me to listen to every opamp I could use, I need to narrow my scope somehow.
I am aware of how to design opamp circuits to maximize their noise spec. Unless you know something I don't, which is quite possible.
DrFrankencopter
Well-known member
Well, for one, whike the AD797 can have an extremely low noise it wants a low source impedance (like 1k or less) to get this performance. This can have a big impact on what you actually get out of the IC. It may not be the best peice to use as a line input buffer (usually 10kOhm+), but might be good as an intermediate stage, or mic input.
Cheers,
Kris
Cheers,
Kris
I was about to say the same but Dr Frankencopter beat me to it!
Yes, the AD797 is not particularly useful unless the impedances are low.
In my designs I use MC33078 where impedances are medium in the signal path; it has very good 1/f noise and has a class A output topology which seems to help the sound. (I have not seen the circuit diagram of the MC33078; I'm writing from hearsay, so pls dont take that as gospel). Certainly I prefer it to the 5532, even for driving funny loads.... visible lower 3rd order distortion at low level.
But unless you are looking for 20dB gain plus, most modern ICs are quiet enough to be masked by surrounding components.
Ted Fletcher
www.tfpro.com
Yes, the AD797 is not particularly useful unless the impedances are low.
In my designs I use MC33078 where impedances are medium in the signal path; it has very good 1/f noise and has a class A output topology which seems to help the sound. (I have not seen the circuit diagram of the MC33078; I'm writing from hearsay, so pls dont take that as gospel). Certainly I prefer it to the 5532, even for driving funny loads.... visible lower 3rd order distortion at low level.
But unless you are looking for 20dB gain plus, most modern ICs are quiet enough to be masked by surrounding components.
Ted Fletcher
www.tfpro.com
Kev
Well-known member
Hi Ted
yep when the gains are relatively low to unity many of the op-amps perform fine
20db is enough to get most EQ and buffer jobs happening
Don't over load your op-amps with either voltage OR current
For those that want to run High rail voltages the choice of op-amp does get smaller
I tend rely heavily on the LM833 for general use.
yep when the gains are relatively low to unity many of the op-amps perform fine
20db is enough to get most EQ and buffer jobs happening
Don't over load your op-amps with either voltage OR current
For those that want to run High rail voltages the choice of op-amp does get smaller
I tend rely heavily on the LM833 for general use.
bcarso
Well-known member
I like the LM833 too although again the optimal Z's are pretty low given the 100's of nA of input bias current. This is also the part as I mentioned earlier that measurably improves with some loading of the output to the negative rail, and some say sounds better as well.
dasbin
Well-known member
As far as sonics go, OPA 627 is the winner in my books in many applications (though not all).
It has just a wee bit of character to it, giving things an overall "rounded/pleasant" sound, but is exceptionally detailed.
I haven't tried every opamp listed here though. I just know it beats out (by FAR) 5534, TL072, many NJM/JRC, OPA 2304, OPA 604, and some others. Not really fair to compare it to discrete opamps which usually have a very distinctive character. It is more detailed than many though, including API (but then it doesn't have that API sound).
It is a little more tricky than the more "general purpose" IC's to use... high power requirements, sometimes oscillates, may want to bias to Class A... and you probably don't want to be driving really high impedance with it.
It has just a wee bit of character to it, giving things an overall "rounded/pleasant" sound, but is exceptionally detailed.
I haven't tried every opamp listed here though. I just know it beats out (by FAR) 5534, TL072, many NJM/JRC, OPA 2304, OPA 604, and some others. Not really fair to compare it to discrete opamps which usually have a very distinctive character. It is more detailed than many though, including API (but then it doesn't have that API sound).
It is a little more tricky than the more "general purpose" IC's to use... high power requirements, sometimes oscillates, may want to bias to Class A... and you probably don't want to be driving really high impedance with it.
