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From: Leon on 27 Nov 2009 19:48
On Fri, 27 Nov 2009 16:26:27 +0100, Marc Amsterdam <reply(a)newsgroup.only> wrote:

>
>I was wondering if anyone had experience putting different brands
>opamps to use as they all seem to have the same specs but turn out to
>be quite different.
>

I can't tell you about 5532's but I can relate stories about other op amps...

One that comes to mind is the 739, which was used in mic and phono pre amps. One
type that I had was quite stable, but replacements from another company were
unstable in the same circuit, oscillated like crazy... Since I couldn't find the
original types, I scrapped the mixer. (I found out later there were internal end
external comp. types available.)

Another slightly different problem I had concerned TI op amps, I forget the
number but they were FET input, 8p DIPs... very popular in the late 70s or early
80s, and the ones from TI tended to BREAK into pieces when their leads were
flexed to fit into the sockets! I lost a whole bag of them that way! I ended up
using non-FET replacements from another company... s' weird...

So my conclusion is, NOT all op amps are the same, even if they have the same
part no. Just check out the spec sheet, most parameters have ranges, you hope
you get a center spread but you can be unlucky!

As far as your headroom problem, you must have a circuit with very tight
specs... you aren't meeting the drive requirements or something... can you get a
schematic? Did you check your power supply for any voltage droop? Maybe those
ops are drawing power, or even oscillating!

From: Phil Allison on 27 Nov 2009 20:14

<Leon(a)nospam.com>
" Marc Amsterdam "

> I can't tell you about 5532's but I can relate stories about other op
> amps...

** Here we go off into la la land.


> One that comes to mind is the 739, which was used in mic and phono pre
> amps.

** Back in the 1970s.


> One
> type that I had was quite stable, but replacements from another company
> were
> unstable in the same circuit, oscillated like crazy... Since I couldn't
> find the
> original types, I scrapped the mixer. (I found out later there were
> internal end
> external comp. types available.)

** Fairchild made the uA739 - which needed external R + C compensation.

Raytheon later made the RC4739 - which, while pin compatible with the
uA739, is of quite different design.

Pays to read the numbers and have a glance at the data sheets to.



> Another slightly different problem I had concerned TI op amps, I forget
> the
> number but they were FET input, 8p DIPs... very popular in the late 70s or
> early
> 80s, and the ones from TI tended to BREAK into pieces when their leads
> were
> flexed to fit into the sockets! I lost a whole bag of them that way! I
> ended up
> using non-FET replacements from another company... s' weird...

** Faulty metal - you should have returned them.


> So my conclusion is, NOT all op amps are the same, even if they have the
> same
> part no.

** Shame your examples do not even back that up.


> Just check out the spec sheet,

** Just like you did not.


> As far as your headroom problem,


** Marc has a headroom problem - alright.

His swollen head to too big for his hat.



..... Phil




From: Phildo on 28 Nov 2009 03:01

"George's Pro Sound Co." <bmoas(a)yahoo.com> wrote in message
news:oKmdndgLdcniTZLWnZ2dnUVZ_u2dnZ2d(a)earthlink.com...
>> what does like headroom mean?
>
> Headroom is the space between the steering wheel and my lap :-0
> ba da boom

Nah, it's what Arny has between his ears - lots of empty space.

Ba-da-boom *tish*

Phildo


From: Phildo on 28 Nov 2009 03:02

"Arny Krueger" <arnyk(a)hotpop.com> wrote in message
news:ZOWdnehAM7JJSZLWnZ2dnUVZ_v-dnZ2d(a)giganews.com...
> <relishing the fact that Marc being a good Phildoite probably has me
> killfiled and/or will grant me no credibilty, and thus will shoot himself
> in the foot by ignoring this really helpful post>

Being ignored by the vast majority of people on here, even on the rare
occasions you actually have something useful to say, is the price you pay
for being such an idiot. You bring it all on yourself but are too much of a
coward to accept any sort of responsibility so try to blame everything on
other people.

Phildo


From: Leon on 28 Nov 2009 13:20
On Sat, 28 Nov 2009 12:14:21 +1100, "Phil Allison" <phil_a(a)tpg.com.au> wrote:

>
><Leon(a)nospam.com>
> " Marc Amsterdam "
>
>> I can't tell you about 5532's but I can relate stories about other op
>> amps...
>
>** Here we go off into la la land.
>

Really? If you say so... but go by yourself, pal.

>> One that comes to mind is the 739, which was used in mic and phono pre
>> amps.
>
>** Back in the 1970s.

I said that... you snipped it...

>
>> One
>> type that I had was quite stable, but replacements from another company
>> were
>> unstable in the same circuit, oscillated like crazy... Since I couldn't
>> find the
>> original types, I scrapped the mixer. (I found out later there were
>> internal end
>> external comp. types available.)
>
>** Fairchild made the uA739 - which needed external R + C compensation.
>
>Raytheon later made the RC4739 - which, while pin compatible with the
>uA739, is of quite different design.
>
>Pays to read the numbers and have a glance at the data sheets to.
>

Didn't have spec sheets at the time, was given "739" chips by the boss. I found
out later, as I said.

>
>> Another slightly different problem I had concerned TI op amps, I forget
>> the
>> number but they were FET input, 8p DIPs... very popular in the late 70s or
>> early
>> 80s, and the ones from TI tended to BREAK into pieces when their leads
>> were
>> flexed to fit into the sockets! I lost a whole bag of them that way! I
>> ended up
>> using non-FET replacements from another company... s' weird...
>
>** Faulty metal - you should have returned them.

They were DIFFERENT!


>> So my conclusion is, NOT all op amps are the same, even if they have the
>> same
>> part no.
>
>** Shame your examples do not even back that up.

Learn to read... but it doesn't matter, op amps have a spread of parameters, you
just ignore it.

>> Just check out the spec sheet,
>
>** Just like you did not.

Not applicable, I checked the data later... perhaps the OP did the same...


>> As far as your headroom problem,
>
>
>** Marc has a headroom problem - alright.
>
> His swollen head to too big for his hat.
>

HA!!! You talk about swollen heads??!! The Koreans have to wait for you to lie
down before they shoot a missle over Oz!!!

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