"Eeyore" wrote in message
...
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.

YUK ! Pro ? That's a joke.

When were these designed ? At least drop some 4560s in.

Graham


Hi Graham,

I have A20's which I use in my home audio system and cannot fault them. I
have no issues with them that would make me say the IC's should be changed.

Some people say they are too forward, some have said they are too bright for
their liking. I am quite happy with them.

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

APR

APR wrote:

"Eeyore" wrote

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.

YUK ! Pro ? That's a joke.

When were these designed ? At least drop some 4560s in.

Hi Graham,

I have A20's which I use in my home audio system and cannot fault them. I
have no issues with them that would make me say the IC's should be changed.

Fair enough if you're happy but audio designers like me vomit at the mention of
4558s.


Some people say they are too forward, some have said they are too bright for
their liking. I am quite happy with them.

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

Less noise and less distortion for two. The NJM4560 is an 'improved' 4558 by an
arm and a leg or two. They're actually pretty repectable. I must have designed
in several million of them.

Graham

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

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.

Hnmm ... it doesn't have enough treble to actually distort, unlike the 741
that had too much, otoh it is not spitty, just plain boring. There are
plenty plug and play alternatives ... but whomsoever plays the opamp upgrade
game should unsolder what is there CAREFULLY, you may need that exact opamp
for the circuit to work, and put good sockets in to avoid having to solder
multiple times on the pcb.

Graham

Kind regards

Peter Larsen

In article , Peter Larsen
scribeth thus
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.

Hnmm ... it doesn't have enough treble to actually distort, unlike the 741
that had too much, otoh it is not spitty, just plain boring. There are
plenty plug and play alternatives ... but whomsoever plays the opamp upgrade
game should unsolder what is there CAREFULLY, you may need that exact opamp
for the circuit to work, and put good sockets in to avoid having to solder
multiple times on the pcb.

Graham

Kind regards

Peter Larsen



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

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.

Graham

"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.

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