ultra low noise audio design

[ilClod]

I'm lookin for infos, bibliography, web sites, manuals etc. concerning
ultra low noise electronic design, particularly for audio frequency
devices.
Any suggestions?
TIA

 

[Eeyore]

I'm lookin for infos, bibliography, web sites, manuals etc. concerning
ultra low noise electronic design, particularly for audio frequency
devices.
Any suggestions?

Most of the classic stuff is a bit dated now.

There's National's classic 'audio handbook' which is still a handy
reference but hardly state of the art by along shot and TI's bifet maanual
is also useful. PMI's SSM division also did an Audio handbook which was a
bit more leading edge when it came out.

What especially do you want to know ?

Graham

 

[Stanislaw Flatto]

I'm lookin for infos, bibliography, web sites, manuals etc. concerning
ultra low noise electronic design, particularly for audio frequency
devices.
Any suggestions?
TIA

Marantz!
About 50 years ago (the time of high-fidelity craze, mono) they came out
with a preamplifier that was better than the sensitivity of testing
instruments in various laboratories.
So reports were coming out with stories but no numbers!

Have fun

Stanislaw.

 

[john jardine]

Most of the classic stuff is a bit dated now.

There's National's classic 'audio handbook' which is still a handy
reference but hardly state of the art by along shot and TI's bifet maanual
is also useful. PMI's SSM division also did an Audio handbook which was a
bit more leading edge when it came out.

What especially do you want to know ?

Graham

Yes, the National book was (is) a marvellous read.
I'd also add
http://www.dself.dsl.pipex.com/ampins/ampins.htm as a worthwhile reference
point.
john

 

[Homer J Simpson]

I'm lookin for infos, bibliography, web sites, manuals etc. concerning
ultra low noise electronic design, particularly for audio frequency
devices.

Elektor has done some designs which use multiple transistors in parallel for
low noise.

 

[Eeyore]

Elektor has done some designs which use multiple transistors in parallel for
low noise.

A 2SA1084 ( or its complement ) will beat that arrangement.

Graham

 

[martin griffith]

A 2SA1084 ( or its complement ) will beat that arrangement.

Graham

Have you played with the LM4562 yet?


martin

 

[Eeyore]

Have you played with the LM4562 yet?

Not yet. Looks cute though. The datasheet's currently on my desktop btw.

Graham

 

[martin griffith]

Not yet. Looks cute though. The datasheet's currently on my desktop btw.

Graham

Disgusting datasheet, all the apps are copied from 1975, I think they
used Tippex to change the part numbers - It might be good as the
front end for audio ADCs that run off 5Vanalogue

In todays Times (OT)

the EU Enterprise Commissioner, admitted on Monday last week that the
bureaucratic costs to business of complying with EU regulation, almost
all of which is to do with the SMP, is some €600 billion a year.



martin

 

[Eeyore]

Disgusting datasheet, all the apps are copied from 1975, I think they
used Tippex to change the part numbers - It might be good as the
front end for audio ADCs that run off 5Vanalogue

In todays Times (OT)

the EU Enterprise Commissioner, admitted on Monday last week that the
bureaucratic costs to business of complying with EU regulation, almost
all of which is to do with the SMP, is some €600 billion a year.

It's out of control. That's over 1000 Euro per head of population !

Graham

 

[Phil Allison]

"ilClod"

I'm lookin for infos, bibliography, web sites, manuals etc. concerning
ultra low noise electronic design, particularly for audio frequency
devices.
Any suggestions?

** Keep on lookin' - Mr I Clod the Dickwad.

Since the topic simply does not exist - neither do any publications.




.......... Phil

 

[Mikko S Kiviranta]

: Elektor has done some designs which use multiple transistors in parallel for
: low noise.

Parallel coupling does not affect the noise temperature, but I guess
the audio guys are groping for a low noise matching resistance i.e.
voltage noise. Similar characteristics are desirable in SQUID readout
amplifiers ( 1-ohm generator with an effective 10K noise temperature ).
The best low-frequency numbers AFAIK come from discrete bipolar transistors
such as the SSM2210. One example is the bipolar/JFET composite amplifier
presented by Drung et al in Superconductor Science and Technology vol 19
no 5 p S235. Their amplifier has dc-to-50MHz bandwidth, 0.33nV/rtHz voltage
noise above 1kHz and 0.8nV/rtHz at 0.1 Hz. I feel this is at the edge of
what is achievable with commonly available components.

An easier choice is the venerable LT1028, a number of which can be
paralleled as shown in the Linear Tech AN-21 application note. In the
SQUID amplifier folklore the LT1028's in a ceramic DIP have lower 1/f corner
than the plastic ones. The brand new AD8599 appears to perform equivalently
to the LT1028, with better low-frequency characteristics than the good old
AD797.

Regards,
Mikko

 

[Mikko S Kiviranta]

: no 5 p S235. Their amplifier has dc-to-50MHz bandwidth, 0.33nV/rtHz voltage
: noise above 1kHz and 0.8nV/rtHz at 0.1 Hz. I feel this is at the edge of
: what is achievable with commonly available components.

I should have said "...*close* to the edge of what is achievable.." before
someone points out that the 1/f corner can perhaps be pushed with chopper
stabilization, or you can couple even more SSM2210's in parallel, or
suggest using ac modulation with a matching transformer (like Koch et
al in Rev Sci Inst vol 67 p 2968 - perhaps even that approach can be
tweaked into audio use by some quirck)...

But now that I think of it I suppose Drung could make more money by
selling his amplifiers to audiophiles as turntable moving-coil preamps
than selling them to the SQUID community. Surely everyone initiated
can hear a clear difference between a 20MHz and 50MHz roll-off.

Regards,
Mikko

 

[Eeyore]

: Elektor has done some designs which use multiple transistors in parallel for
: low noise.

Parallel coupling does not affect the noise temperature, but I guess
the audio guys are groping for a low noise matching resistance i.e.
voltage noise. Similar characteristics are desirable in SQUID readout
amplifiers ( 1-ohm generator with an effective 10K noise temperature ).
The best low-frequency numbers AFAIK come from discrete bipolar transistors
such as the SSM2210. One example is the bipolar/JFET composite amplifier
presented by Drung et al in Superconductor Science and Technology vol 19
no 5 p S235. Their amplifier has dc-to-50MHz bandwidth, 0.33nV/rtHz voltage
noise above 1kHz and 0.8nV/rtHz at 0.1 Hz. I feel this is at the edge of
what is achievable with commonly available components.

An easier choice is the venerable LT1028, a number of which can be
paralleled as shown in the Linear Tech AN-21 application note. In the
SQUID amplifier folklore the LT1028's in a ceramic DIP have lower 1/f corner
than the plastic ones. The brand new AD8599 appears to perform equivalently
to the LT1028, with better low-frequency characteristics than the good old
AD797.

You don't have to spend that much to make quiet audio.

Graham

 

[Homer J Simpson]

It's out of control. That's over 1000 Euro per head of population !

And there's no point to most of these regulations.

 

[ilClod]

Wed, 18 Oct 2006 01:31:02 +0100:

There's National's classic 'audio handbook' which is still a handy
reference but hardly state of the art by along shot and TI's bifet maanual
is also useful. PMI's SSM division also did an Audio handbook which was a
bit more leading edge when it came out.

Are those ebooks? Are they free and downloadable?
Anything more recent?
If only in paper form are there online bookstores having'em?

What especially do you want to know ?

Maybe i'm a little bit pretentious, but my aim is to design and build
audio devices as quiet as possible. Obviously keepin'in mind which
kind of devices I'm using and what results can I get using (as an
example) cheap components connected in particular configurations.

Hope i was clear enough.

Thanks again

 

[xray]

It's out of control. That's over 1000 Euro per head of population !

I'm not very informed on EU issues. What's SMP? A google came up with
this:
"Butter and skim milk powder (SMP)"

Can that be what you are referring to?

 

[martin griffith]

I'm not very informed on EU issues. What's SMP? A google came up with
this:
"Butter and skim milk powder (SMP)"

Can that be what you are referring to?

single market programme from
http://www.timesonline.co.uk/article/0,,3284-2408875,00.html
but the Times is slightly non left wing


martin

 

[PeteS]

Mikko S Kiviranta wrote:




You don't have to spend that much to make quiet audio.

Graham

No indeed. A simple switch will make the audio as quiet as one desires

Cheers

PeteS

 

[Eeyore]

Are those ebooks? Are they free and downloadable?

They're *real* books and cost a bit - but not expensive. I got mine for free
fwiw - that's how support was traditionally done. The National one actually went
out of print but has now been reprinted so strong was the demand.

Anything more recent?
If only in paper form are there online bookstores having'em?

It's a bit of a niche and not such a big issue these days so little catered for.
I expect TI have some decent app notes. Quality audio was once more of a big
seller. Now, the averge quality of audio has progressed to the point where most
ppl are happy with run-of-the -mill stuff and / or standards have fallen ( e.g.
mp3 ).

Maybe i'm a little bit pretentious, but my aim is to design and build
audio devices as quiet as possible. Obviously keepin'in mind which
kind of devices I'm using and what results can I get using (as an
example) cheap components connected in particular configurations.

That's the kind of thing I do. I strongly suggest you read up on discrete design
for really quiet ( and relatively inexpensive ) operation.

Graham