"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.

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.

I wonder what made them choose that part in the first place. Could it be
cost? Or stability problems that went away by subbing a part without the
need to rev the PCB?

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