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Very low noise SINGLE audio op-amp in DIL-8 ?

E

Eeyore

Jan 1, 1970
0
There are lots of really good op-amps suitable for or specifically designed for
low noise audio use but the most popular configuration is the dual package (for
many good reasons).

Having established that my client for the refurbished 'boutique' mic pre-amp
doesn't mind if it's non-original provided there's an improvement, does anyone
have any favourite candidates to replace the venerable NE5534 ? Bipolar or fet
input, I don't mind, the noise source impedance at the op-amp non-inverting
input is ~ 1200 ohms.

Graham
 
E

Eeyore

Jan 1, 1970
0
Spehro said:
Why not just use half of a dual you know and love?

It's retrofit into an existing socket.

The 5534's en is ~ 3.5 nV/sqrt Hz btw.

Graham
 
S

Spehro Pefhany

Jan 1, 1970
0
There are lots of really good op-amps suitable for or specifically designed for
low noise audio use but the most popular configuration is the dual package (for
many good reasons).

Having established that my client for the refurbished 'boutique' mic pre-amp
doesn't mind if it's non-original provided there's an improvement, does anyone
have any favourite candidates to replace the venerable NE5534 ? Bipolar or fet
input, I don't mind, the noise source impedance at the op-amp non-inverting
input is ~ 1200 ohms.

Graham

Why not just use half of a dual you know and love?


Best regards,
Spehro Pefhany
 
F

Fred Bartoli

Jan 1, 1970
0
Eeyore a écrit :
It's retrofit into an existing socket.

The 5534's en is ~ 3.5 nV/sqrt Hz btw.

Why not just keeping it?
At 0.4pA/rtHz, the 5534's current noise will be unnoticable.
And since 1200R is 4.5nV/rtHz, total noise will be 5.7 (for a 2dB NF).
Getting down to a total 5nV/rtHz will require a less than 2nV/rtHz
opamp, which you'll probably don't like (cost).
 
E

Eeyore

Jan 1, 1970
0
John said:
fet input, I don't mind, the noise source impedance at the op-amp >> > non-inverting
input is ~ 1200 ohms.


OP-27?

A blast from the past ! I must look at it again and there's the op-37 too IIRC.

The best I've found so far is National's LME49710 (I didn't realise they did a single
part) which boasts typical mid-band en of 2.5 nV/sqrt Hz and stupendous linearity and
wonderful DC figures too. I expect In will be better as well.

Graham
 
E

Eeyore

Jan 1, 1970
0
Eeyore said:
The best I've found so far is National's LME49710 (I didn't realise they did a single
part) which boasts typical mid-band en of 2.5 nV/sqrt Hz and stupendous linearity and
wonderful DC figures too. I expect In will be better as well.

Ok, I have some samples on order, Farnell doesn't stock them yet. This part actually
smacks of a deliberate intention to make a form-fit-function equivalent upgrade for 5534s
( and 5532s with the LME49720).

AD have better of course but it's a dual in SOIC. It's tempting to make a converter board
and 'throw away' the unused half !

http://www.analog.com/en/prod/0,2877,AD8599,00.html

1.15 nv/sqrt Hz op-amps ! -105dB THD @ 20kHz ! Yummmmm. And they're not actually insanely
priced.


Graham
 
Q

qrk

Jan 1, 1970
0
There are lots of really good op-amps suitable for or specifically designed for
low noise audio use but the most popular configuration is the dual package (for
many good reasons).

Having established that my client for the refurbished 'boutique' mic pre-amp
doesn't mind if it's non-original provided there's an improvement, does anyone
have any favourite candidates to replace the venerable NE5534 ? Bipolar or fet
input, I don't mind, the noise source impedance at the op-amp non-inverting
input is ~ 1200 ohms.

Graham

LT1028 is around 1nV/rtHz above 100Hz.
 
G

Gareth

Jan 1, 1970
0
Eeyore said:
Ok, I have some samples on order, Farnell doesn't stock them yet. This part actually
smacks of a deliberate intention to make a form-fit-function equivalent upgrade for 5534s
( and 5532s with the LME49720).

AD have better of course but it's a dual in SOIC. It's tempting to make a converter board
and 'throw away' the unused half !

http://www.analog.com/en/prod/0,2877,AD8599,00.html

1.15 nv/sqrt Hz op-amps ! -105dB THD @ 20kHz ! Yummmmm. And they're not actually insanely
priced.


Graham

What about AD797 or AD829?

Or LT1028

http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1009,C1026,P1234,D3480

--
 
J

John Devereux

Jan 1, 1970
0
Eeyore said:
Ok, I have some samples on order, Farnell doesn't stock them yet. This part actually
smacks of a deliberate intention to make a form-fit-function equivalent upgrade for 5534s
( and 5532s with the LME49720).

AD have better of course but it's a dual in SOIC. It's tempting to make a converter board
and 'throw away' the unused half !

http://www.analog.com/en/prod/0,2877,AD8599,00.html

1.15 nv/sqrt Hz op-amps ! -105dB THD @ 20kHz ! Yummmmm. And they're not actually insanely
priced.

Isn't the AD797 supposed to be the "ultimate" audio opamp from AD?
 
J

John Larkin

Jan 1, 1970
0

LT1028 is a fabulous amp *if* your signal is very low impedance. We
use them as current-shunt amps with ppm precision. The feedback
resistor current is so high that we put another, cheap opamp in the
loop just to drive the feedback, so we don't heat up the 1028 and
spoil its beautiful offsets.

Current noise is high.

Maxim did a MAX1028 for a while, but I think LTC stopped them somehow.

John
 
P

Phil Hobbs

Jan 1, 1970
0
John said:
LT1028 is a fabulous amp *if* your signal is very low impedance. We
use them as current-shunt amps with ppm precision. The feedback
resistor current is so high that we put another, cheap opamp in the
loop just to drive the feedback, so we don't heat up the 1028 and
spoil its beautiful offsets.

Current noise is high.

Maxim did a MAX1028 for a while, but I think LTC stopped them somehow.

John
Probably by ordering some, which always causes Maxim to discontinue parts...

Cheers,

Phil Hobbs
 
M

martin griffith

Jan 1, 1970
0
Isn't the AD797 supposed to be the "ultimate" audio opamp from AD?
ISTR reading that it tends to go quite unstable,( layout, gravity,
leylines, Hubble const. 440Hz, etc,) but I havent checked it out on
Snopes


martin
 
ISTR reading that it tends to go quite unstable,( layout, gravity,
leylines, Hubble const. 440Hz, etc,) but I havent checked it out on
Snopes

I've never used that AD797, but I suggested it once as a possible
alternative to the LT1028, and the guys that tried it were very happy.
The output stage of the LT1028 can be a bit cranky with some loads,
and the AD797 is apparently rather nicer.

It is a relatively fast op amp, good for 20V/usec output slew rate and
the data sheet does emphasise the need for good decoupling and careful
layout, so there are people around who could find it unstable.

http://www.analog.com/en/prod/0,2877,AD797,00.html
 
C

Carl Ijames

Jan 1, 1970
0
I've used the Analog Devices AD829 as the second stage in a preamp and
it worked well. Specced at 1.7 nV/rtHz. They also have the AD797 at
0.9 nV/rtHz if it's fast enough for you. You can sort their op amp list
by noise if you haven't already found that magic button.
 
B

Boris Mohar

Jan 1, 1970
0
There are lots of really good op-amps suitable for or specifically designed for
low noise audio use but the most popular configuration is the dual package (for
many good reasons).

Having established that my client for the refurbished 'boutique' mic pre-amp
doesn't mind if it's non-original provided there's an improvement, does anyone
have any favourite candidates to replace the venerable NE5534 ? Bipolar or fet
input, I don't mind, the noise source impedance at the op-amp non-inverting
input is ~ 1200 ohms.

Graham

If you can live with +/-5 V try MAX412
 
M

MooseFET

Jan 1, 1970
0
On May 15, 4:10 pm, [email protected] wrote:
[....]
I've never used that AD797, but I suggested it once as a possible
alternative to the LT1028, and the guys that tried it were very happy.
The output stage of the LT1028 can be a bit cranky with some loads,
and the AD797 is apparently rather nicer.

The LT1028 can be tricky near unity gain. They really hate being
smacked into the rails and don't like hitting slew rate limit. Other
than these things they are actually not too bad to work with.


Since this is high end audio, you may want to look at parts like the
LT6230-10. These give better highs.
 
R

Robert Latest

Jan 1, 1970
0
["Followup-To:" header set to sci.electronics.design.]
Phil said:
Probably by ordering some, which always causes Maxim to discontinue parts...

Thanks, Phil, you made my day.

robert
 
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