Chronic Philharmonic wrote:

"Arny Krueger" wrote
"Eeyore" wrote in
Chronic Philharmonic wrote:
"Arny Krueger" wrote
"Marky P" wrote

LM741 (pretty sure this is an op amp)

Yup and a real oldie. Slow and noisy, not to mention
power hungry and a weak output for what it does.

This was arguably the "breakthrough" IC op-amp. It was
one of the first popular devices that was actually a
monolithic design, and not a hybrid like some of the
original Burr Brown modules. It was compensated for
unity gain, which made it much too slow for anything but
a buffer for audio work. It had a slew rate of 0.5
volts/microsecond. With a +/- 12 volt power supply, 6
kHz rail-to-rail was about it for non-slew rate limited
signals. You could get 20KHz through it if you were
content with about 4 volts peak.

I think it had more applications in analog computing,
integrators, low frequency function generators, servo
controls, etc.

True but it DID get used in audio. Its companion, the 748
was uncompensated internally (like the 5534 vs the 5532)
and always seemed less noisy to me, so I used quite a few
of those.

The on-chip compensation cap for the 741 was a well-known source of noise.

I'm curious, what mechanism caused this noise? I suspect it must have been
realized in silicon, a reverse-biased P/N junction or something. Does
anybody know?

Exactly and I'm sure it was leaky.

Graham

Chronic Philharmonic wrote:

"Eeyore" wrote
tony sayer wrote:

And a scope to see what its getting up to in the MHz region;!...

Too true. Circuits that may be stable with junk op-amps may respond
differently when given the chance.

Random thoughts... Could it be that the original designers were aware of the
device's limitations, and took care to stay within those parameters? If they
used them in low-gain, low-voltage applications, with minimal gain
downstream, I can see how they could comfortably stay within the product
design specifications. And the intrinsic stability might have been a bonus.

You'd have to be a truly **** designer to need a 4558 to keep your circuits
stable ! Hever mind their noise contribution.


I wonder what made them choose that part in the first place.

Because they had 100,000 in stock ?


Could it be cost? Or stability problems that went away by subbing a part
without the
need to rev the PCB?

In which case they're incompetent.

Graham

"Chronic Philharmonic" wrote in
message
"Eeyore" wrote
in message ...


tony sayer wrote:

And a scope to see what its getting up to in the MHz
region;!...

Too true. Circuits that may be stable with junk op-amps
may respond differently
when given the chance.

And a certain segment of the techno-snob market will *upgrade* op amps,
create poor stability from good stability, and relish the newfound
"sparkling highs", not knowing the damped sine waves that their *upgraded*
equipment is creating.

Random thoughts... Could it be that the original
designers were aware of the device's limitations, and
took care to stay within those parameters?

Absolutely.

If they used
them in low-gain, low-voltage applications, with minimal
gain downstream, I can see how they could comfortably
stay within the product design specifications. And the
intrinsic stability might have been a bonus.

Very many designers did exactly that.

If your market is *not* full of techno-snobs, then the least technology that
reliably gets the job done will only make you richer and make your life
easier.

I wonder what made them choose that part in the first
place.

At the worst, inverse snobbery.

Could it be cost?

In many cases, the difrerence was pennies. If the volume is extremely high,
then pennies can matter, but very little pro audio equipment is built in
that kind of volume.

Or stability problems that went
away by subbing a part without the need to rev the PCB?

In some cases using techno-snob parts can force you from a single-layer
board to a multi-layer board, and that involves more than just a few
pennies.

Arny Krueger wrote:

"Chronic Philharmonic" wrote

Could it be cost?

In many cases, the difrerence was pennies.

One OEM supplier upgraded us from 4560s to 4580s for free because then they
could get better bulk discounts. Never forget that !


If the volume is extremely high, then pennies can matter, but very little pro
audio equipment is built in that kind of volume.

Uh ? Depends what you call pro. This is 'semi-pro'.
http://cgi.ebay.co.uk/Studiomaster-C...QQcmdZViewItem

And used around 25-30 op-amps (4560s). It came in smaller sizes too and we sold
over 100,000 of them.

That must be getting on for 2 million 4560s taking the various channel sizes
into account.


Or stability problems that went
away by subbing a part without the need to rev the PCB?

In some cases using techno-snob parts can force you from a single-layer
board to a multi-layer board, and that involves more than just a few
pennies.

Not really with audio op-amps.

Graham

"Eeyore" wrote in message
...


Marky P wrote:

tony sayer wrote:

I Wonder how may pro recording bits of gear are around with
5532's..

Just about most of it in current use.

Are they at all similar to 5534's? Sure I used them in a phono
pre-amp in the 80's, copied out of a R. A. Penfold book.

Yes, they're the dual version and about 3dB noisier although not quite
sure why.

Just thought I'd chip in (pun intended) and mention that the 5532 is
internally compensated for 0dB gain, whilst the 5534 requires external
compensation if used below 10dB gain. So the 5534 has a better G-BW product
when used at high gain than the 5532.

Oh, and the 5534 was originally called the TDA1034 and came in a TO99 metal
can.

David.

"Arny Krueger" wrote in message
...


LM741 (pretty sure this is an op amp)

Yup and a real oldie. Slow and noisy, not to mention power hungry and a
weak output for what it does.


Yeah, but it was *stable*, unlike those sodding 709s which howled like a
banshee regardless of what external compensation you attached!

David.

David Looser wrote:

"Eeyore" wrote
Marky P wrote:
tony sayer wrote:

I Wonder how may pro recording bits of gear are around with
5532's..

Just about most of it in current use.

Are they at all similar to 5534's? Sure I used them in a phono
pre-amp in the 80's, copied out of a R. A. Penfold book.

Yes, they're the dual version and about 3dB noisier although not quite
sure why.

Just thought I'd chip in (pun intended) and mention that the 5532 is
internally compensated for 0dB gain, whilst the 5534 requires external
compensation if used below 10dB gain. So the 5534 has a better G-BW product
when used at high gain than the 5532.

Oh, and the 5534 was originally called the TDA1034 and came in a TO99 metal
can.

I think I may even have a couple.

Graham

In article , "Arny Krueger" wrote:
"GregS" wrote in message

In article ,
(GregS) wrote:
In article
, "Arny
Krueger" wrote:
"Eeyore" wrote
in
message
Chronic Philharmonic wrote:

"Arny Krueger" wrote
"Marky P" wrote


LM741 (pretty sure this is an op amp)

Yup and a real oldie. Slow and noisy, not to mention
power hungry and a weak output for what it does.

This was arguably the "breakthrough" IC op-amp. It was
one of the first popular devices that was actually a
monolithic design, and not a hybrid like some of the
original Burr Brown modules. It was compensated for
unity gain, which made it much too slow for anything
but a buffer for audio work. It had a slew rate of 0.5
volts/microsecond. With a +/- 12 volt power supply, 6
kHz rail-to-rail was about it for non-slew rate
limited signals. You could get 20KHz through it if
you were content with about 4 volts peak.

I think it had more applications in analog computing,
integrators, low frequency function generators, servo
controls, etc.

True but it DID get used in audio. Its companion, the
748 was uncompensated internally (like the 5534 vs the
5532) and always seemed less noisy to me, so I used
quite a few of those.

The on-chip compensation cap for the 741 was a
well-known source of noise.

LM301s were another alternative once the market matured
some more.

I believe that the integrated preamp/crossover for the
original Infinity Servo-Static system used 741s.

As others have pointed out, their slew-rate limitations
were not that bad if you were running them at usual
consumer levels like 1.5 volts RMS.

The more recent NHT pro monitors used RC4136's in the
active stages.

I was talking about the Ken Kantor pro speakers.

I have the schemtics for the A10 and A20 amplifier-equalizers here before
me. They are loaded with 4558s, no 4136s in sight. I looked inside my A10
and found that they were indeed 4558s.

I guess my menory was bad. Those are even worse.

greg

In article , Eeyore wrote:


GregS wrote:

Eeyore wrote:
Chronic Philharmonic wrote:
"Arny Krueger" wrote
"Marky P" wrote

LM741 (pretty sure this is an op amp)

Yup and a real oldie. Slow and noisy, not to mention power hungry and a
weak output for what it does.

This was arguably the "breakthrough" IC op-amp. It was one of the first
popular devices that was actually a monolithic design, and not a hybrid
like
some of the original Burr Brown modules. It was compensated for unity
gain,
which made it much too slow for anything but a buffer for audio work. It
had
a slew rate of 0.5 volts/microsecond. With a +/- 12 volt power supply, 6
kHz
rail-to-rail was about it for non-slew rate limited signals. You could get
20KHz through it if you were content with about 4 volts peak.

I think it had more applications in analog computing, integrators, low
frequency function generators, servo controls, etc.

True but it DID get used in audio. Its companion, the 748 was uncompensated
internally (like the 5534 vs the 5532) and always seemed less noisy to me,
so I
used quite a few of those.

The RC4136 was used in a lot of stuff. It had a faster slew rate, and I
measured
up to 1.8 v/us, and was called a quad 741. Weird pins too.

I know the one. Avoided it like the plague if only for the pinout !

Didn't TI make a TL075 with the same pinout ?

Graham


Right, and I always wanted to use them in my old Soundcraftmen equalizer, then I could not get them.
I was set up to make conversion boards but never finished. I still have that equalizer but I don't use it.

greg

In article , Eeyore wrote:


APR wrote:

What difference would you expect a different IC to make over the 4558's?

Just to put this into perspective, the 4558 is little better than the rightly
maligned (today) 741 op-amp.

4558s are most commonly found in low-rent DJ gear.

Graham


I was redoing some cheap DJ stuff. One time I put in some National
chips, one of the newer designs at the time, and I found one chip
with popcorn noise. First time I ever heard that.

greg