I need a JRC4558 Op Amp chip
John Gottstein
Does anyone know where I can get a JRC4558 Op Amp Integrated Circuit?
They aren't made anymore, but are an important component in a few guitar
effects pedals. I can't use the NJM455, since they don't work as well
for this purpose.
I live in central New Jersey, but am also looking for mail order
sources. I only need one, but wouldn't mind having a few on hand.
Thanks a lot,
John gott...@erols.com
--
"Leave the gun... take the cannoli."
* Clemenza in "The Godfather"
Michael Black
On Sat, 6 Mar 1999, John Gottstein wrote:
> Hi,
> Does anyone know where I can get a JRC4558 Op Amp Integrated Circuit?
> They aren't made anymore, but are an important component in a few guitar
> effects pedals. I can't use the NJM455, since they don't work as well
> for this purpose.
>
> I live in central New Jersey, but am also looking for mail order
> sources. I only need one, but wouldn't mind having a few on hand.
>
> Thanks a lot,
> John gott...@erols.com
There is nothing special about the 4558. It's a standard pinout dual
opamp in an 8pin package. It's probably nothing better than a dual 741,
though if you look through the old data books plenty of op-amps will be
described as "better" but which have really very little improvement over
a standard 741.
Any dual op-amp in the same package should work, and anything made more
recently will undoubtedly be better.
Michael
John Woodgate
inimitably wrote:
>Does anyone know where I can get a JRC4558 Op Amp Integrated Circuit?
Isn't it just a dual 741-type device? If so, your problem is which of
the hundreds of possible replacements to choose. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
Phone +44 (0)1268 747839 Fax +44 (0)1268 777124.
Did you hear about the hungry genetic engineer who made a pig of himself?
Magliaro
John Gottstein wrote:
> Hi,
> Does anyone know where I can get a JRC4558 Op Amp Integrated Circuit?
> They aren't made anymore, but are an important component in a few guitar
> effects pedals. I can't use the NJM455, since they don't work as well
> for this purpose.
>
> I live in central New Jersey, but am also looking for mail order
> sources. I only need one, but wouldn't mind having a few on hand.
>
> Thanks a lot,
> John gott...@erols.com
> --
> "Leave the gun... take the cannoli."
> * Clemenza in "The Godfather"
You can buy the RC4558N from Hosfelt Electronics for $0.69. Their number
is
614-264-6464. They are in Steubenville, OH. They have a toll-free number,
but I don't have it
handy. You can get it by calling 1-800-555-1212, however. I just happened
to have an old
shipping receipt handy that showed this part on it (from Mar, 1997). Most
likely, what I
got was an NTE equivalent for the 4558, but it works all the same.
The RC4558N is just a common dual op-amp. I used just such a chip for a
preamp pedal I built out of the
"Electronic Projects for Musicians" by Craig Anderton. This book was
published in 1975, and
therefore uses many parts that are not common anymore. However, the
circuits are still
very useful.
You are, no doubt, doing something in a similar vein. On a related note, I
have also used
an 8-pin dual op-amp you can get at Radio Shack (I know, "Ugh!"). They
call it a
"BI-FET" op-amp. It's really really quiet, does the job well (is probably
better than the
4558).
Jim Richards
> Hi,
> Does anyone know where I can get a JRC4558 Op Amp Integrated Circuit?
> They aren't made anymore, but are an important component in a few guitar
> effects pedals. I can't use the NJM455, since they don't work as well
> for this purpose.
>
> I live in central New Jersey, but am also looking for mail order
> sources. I only need one, but wouldn't mind having a few on hand.
>
> Thanks a lot,
> John gott...@erols.com
> --
> "Leave the gun... take the cannoli."
> * Clemenza in "The Godfather"
If you're looking for low noise and compatability, try TI's TL072. Same
pinout, but amp & pedal mfr's use these in droves. Very low Ib specs.
--
Latergator
JimboR
J M Noeding
<j...@jmwa.demon.co.uk> wrote:
><36E1B4...@erols.com>, John Gottstein <gott...@erols.com>
>inimitably wrote:
>>Does anyone know where I can get a JRC4558 Op Amp Integrated Circuit?
>
>Isn't it just a dual 741-type device? If so, your problem is which of
>the hundreds of possible replacements to choose. (;-)
or LM358N, only problem is to paint it "JRC4558"
LA...@ONLINE.no
Ing. Franz Glaser
>
> Isn't it just a dual 741-type device? If so, your problem is which of
> the hundreds of possible replacements to choose. (;-)
It is somewhat special, permitting input voltage down to the negative
supply rail. And the outputs can sink a little amount of current
until down to the negative supply.
If this is not necessary in the particular circuit I would strongly
suggest to replace the component by a modern FET type dual opamp,
which have less noise and better frequency response.
--
Franz Glaser, Glasau 3, A-4191 Vorderweissenbach Austria ++43-7219-7035
Muehlviertler Elektronik Glaser. Industrial control and instrumentation
-----------------------------------------------------------------------
http://members.eunet.at/meg-glaser mailto:meg-g...@eunet.at
http://www.geocities.com/~franzglaser http://members.xoom.com/f_glaser
Spehro Pefhany
> or LM358N, only problem is to paint it "JRC4558"
IIRC, 4558 is a higher performance device than an LM358, both higher
frequency and *typically* lower drift (at least the JRC ones are). The
LM358 (Being half an LM324) is a single supply op-amp, which the 4558 is
not.
--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Spehro Pefhany "The Journey is the reward"
sp...@interlog.com
Fax:(905) 271-9838 (small micro system devt hw/sw + mfg)
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
No Spam! Lundgren
[snip]
Damn, I just got knocked out of Netscrape with a GPF, and I lost that
other followup when it was marked as read. Anyway, the only problem is
that for a fuzzbox or guitar effects box, the opamp may require that it
is not that good or has poor freq response or clips the signal at a low
voltage. So having a 'better opamp' in this case may not make it sound
better.
In any case, I remember that the 1458 may be an acceptable substitute in
some cases.
David DiGiacomo
>opamp in an 8pin package. It's probably nothing better than a dual 741,
>though if you look through the old data books plenty of op-amps will be
>described as "better" but which have really very little improvement over
>a standard 741.
A 4558 has at least 2X the slew rate and 3X the GBW of a 741. It is
(barely) fast enough for audio, while a 741 is not.
4558s are not hard to find (Mouser, TechAmerica, NTE, etc.), but a 5532 is
usually a good replacement/upgrade.
John Miles
>
> John Woodgate wrote:
> >
> > <36E1B4...@erols.com>, John Gottstein <gott...@erols.com>
> > >Does anyone know where I can get a JRC4558 Op Amp Integrated Circuit?
> >
> > Isn't it just a dual 741-type device? If so, your problem is which of
> > the hundreds of possible replacements to choose. (;-)
>
> It is somewhat special, permitting input voltage down to the negative
> supply rail. And the outputs can sink a little amount of current
> until down to the negative supply.
>
> If this is not necessary in the particular circuit I would strongly
> suggest to replace the component by a modern FET type dual opamp,
> which have less noise and better frequency response.
That is asking for oscillation in some marginally-designed circuits.
Best to replace with a device as close as possible to the specs of the
original. There is almost certainly an NTE, ECG, or SK replacement...
-- jm KE5FX
------------------------------------------------------
Note: My E-mail address has been altered to avoid spam
------------------------------------------------------
Daniel Lang
>On Sat, 6 Mar 1999 22:38:35 +0000, John Woodgate
>>>Does anyone know where I can get a JRC4558 Op Amp Integrated Circuit?
>>
>>Isn't it just a dual 741-type device? If so, your problem is which of
>>the hundreds of possible replacements to choose. (;-)
>
The LM358N is a very bad choice for a replacement for audio usage.
The TI RC4558P has a bandwidth of 3 MHz and a slew rate of 1.7 V/usec.
It also has a moderately low noise figure of 8 nV/sqrt(Hz).
The Motorola MC4558CP1 or MC4558ACP1 is also a suitable replacement.
For better noise & speed, you can use the TI NE5532, NE5532A,
or TLE2227CP.
Daniel Lang
John Woodgate
inimitably wrote:
>or LM358N, only problem is to paint it "JRC4558"
No, the 358 IS different, due to the output stage that needs bleed bias
to eliminate crossover distortion.
We Are As1
suggestions about 4558 alternatives. This guy wants the JRC4558 because that
is the exact brand and type of opamp that was used in the Ibanez Tube Screamer
distortion pedal, made from the late 70's to mid 80's. There is a huge cult of
brainwashed guitar players who, prompted by a couple of ill-informed articles
in guitar magazines and quotes from a few interviews with drug-addled rockstar
guitarists, think that the JRC4558 somehow sounds better than any other type of
4558. It must be a *JRC*4558, made by Japan Radio Corp. In what way does it
sound better, you ask? In the same way that a certain emporer's new clothing
looked better, of course. I guess "it goes to 11", if you know what I mean.
Wait a minute... I have a few JRC4558's laying around... Maybe they're for
sale! In which case, what I really meant to say was:
They are *absolutely* the best opamp for use in guitar distortion devices.
There is no better device, and never will be. Even vacuum tubes pale by
comparison. The mere act of soldering a JRC4558 into your Fuzz-o-rama 2000
will make certain that you will have hot relations with several hot bi babes
within a very short time of installation.
alk...@mcs.com
> Hi,
> effects pedals. I can't use the NJM455, since they don't work as well
> for this purpose.
> I live in central New Jersey, but am also looking for mail order
> sources. I only need one, but wouldn't mind having a few on hand.
> Thanks a lot,
> John gott...@erols.com
> --
> "Leave the gun... take the cannoli."
> * Clemenza in "The Godfather"
any cheap cassette deck or player usually has them for lineouts
they may not be JRC's but a 4558 just the same.
an OP275 would be a better replacement,cleaner and lower noise
and around $3 each
John Woodgate
inimitably wrote:
> It is
>(barely) fast enough for audio, while a 741 is not.
Here we go again. You can'tget maximum output swing at 20 kHz, but at
low signal levels and modest gains, a 741 is quite OK.
Tom MacIntyre
Are you not willing to allow that a musician may be able to hear
slight nuances in sound quality that others may not hear...???
Tom
Holger Bruns
<j...@jmwa.demon.co.uk> wrote:
>Here we go again. You can'tget maximum output swing at 20 kHz, but at
>low signal levels and modest gains, a 741 is quite OK.
I would never use a 741 for audio applications, because the output
signal is too noisy. Even at low signal levels this misfeature causes
a significant lack of performance.
Holger
Spehro Pefhany
> guitarists, think that the JRC4558 somehow sounds better than any other type of
> 4558. It must be a *JRC*4558, made by Japan Radio Corp. In what way does it
JRC is the New Japan Radio Corp (same company) BTW.
> comparison. The mere act of soldering a JRC4558 into your Fuzz-o-rama 2000
> will make certain that you will have hot relations with several hot bi babes
> within a very short time of installation.
Wow. Time to warm up your "iron". ;-)
It would not surprise me if the JRC units exceeded the specs set by the
original maker (Raytheon) by more margin than other manufacturers, as I
mentioned in another thread we found their drift to be superior to other
makes (in tests of tens of thousands of units), so other characteristics
might be better as well.
Spehro Pefhany
> any cheap cassette deck or player usually has them for lineouts
> they may not be JRC's but a 4558 just the same.
The 4558 is probably still the single most common linear chip in Japanese
designs.
> an OP275 would be a better replacement,cleaner and lower noise
> and around $3 each
Yes, and the $3 is why the 4558 is probably still the most common..
I think the 4558 (JRC or Samsung) is something like 10-15 cents in
quantity.
We Are As1
slight nuances in sound quality that others may not hear...??? >>
Yes, I am willing to allow that. I account it to the placebo effect. I own
two Ibanez Tube Screamers, both of them from the early 80's, both of them have
JRC4558's. I have tried several different types of dual opamps in them, and in
several other of my *many* distortion devices. The sonic differences, save for
increases and decreases of noise level and high frequency response, are nil.
In fact, these aforementioned differences occur often between different
JRC4558's (I have a bunch of them).
Don't think for a second that my ears aren't as 'golden' as yours, or that I am
not able to hear subtle differences between distortion types. That would be a
mistake.
greg szekeres
>John Gottstein wrote:
>
>> Hi,
>> Does anyone know where I can get a JRC4558 Op Amp Integrated Circuit?
>> They aren't made anymore, but are an important component in a few guitar
>> effects pedals. I can't use the NJM455, since they don't work as well
>> for this purpose.
>>
>> I live in central New Jersey, but am also looking for mail order
>> sources. I only need one, but wouldn't mind having a few on hand.
>>
>> Thanks a lot,
>> John gott...@erols.com
>> --
>> "Leave the gun... take the cannoli."
>> * Clemenza in "The Godfather"
>
>pinout, but amp & pedal mfr's use these in droves. Very low Ib specs.
Yes, and the AD712 is a bit better in most respects. Jameco had a few left
for about $1.50 each. A bipolar might be better depending on the circuit.
Try a LM833 and see or hear what works best. THe 4558 is basically a
dual version of a 4136, which is a better 741 with aa slew of at least 1.5.
greg
John Woodgate
inimitably wrote:
>I would never use a 741 for audio applications, because the output
>signal is too noisy. Even at low signal levels this misfeature causes
>a significant lack of performance.
Your comment contains a technical error which shows that your opinion is
worth what you have charged for it.
Jim Richards
> Hi,
> Does anyone know where I can get a JRC4558 Op Amp Integrated Circuit?
> They aren't made anymore, but are an important component in a few guitar
> effects pedals. I can't use the NJM455, since they don't work as well
> for this purpose.
>
> I live in central New Jersey, but am also looking for mail order
> sources. I only need one, but wouldn't mind having a few on hand.
>
> Thanks a lot,
> John gott...@erols.com
> --
> "Leave the gun... take the cannoli."
> * Clemenza in "The Godfather"
Good lord, John. You SURE know how to start a discussion!
--
Latergator
JimboR
qwerty
What a response! The key factor here is that there is a whole mythology
surrounding the JRC4558. A couple of very highly regarded guitar players
are known to have used a specific battery-powered overdrive pedal that
utilized the JRC4558. Later models used a different 4558 and as such are
not considered desireable. Some swear they can tell a difference. And of
course it has to be the IC, not the different circuit that the later
models also had. You guys can recommend a 5532, TL072, or any of the
dozens of drop in replacements, but be sure, none but the JRC4558 will
suffice.
If some old roadie for Jimi Hendrix came out and said that Jimi shoved a
potato up his ass before every performance, you can bet guitar players
everywhere would be debating whether russets or red spuds are the key to
better playing.
Welcome to the the mind of a musician.
Holger Bruns
<j...@jmwa.demon.co.uk> wrote:
>>I would never use a 741 for audio applications, because the output
>>signal is too noisy. Even at low signal levels this misfeature causes
>>a significant lack of performance.
>
>Your comment contains a technical error which shows that your opinion is
>worth what you have charged for it.
You are entitled to use the old 741 for any purpose you like. Years
ago I designed an audio amplifier for the playback function of a tape
machine. I checked out several versions, including one with the 741
and one with the 5532A, which can be treated as a low noise version of
the 4558. The noise level was significant higher with a 741. That's
why I would never use a 741 for audio applications.
For other applications a 741 may be a suitable choice. Later I created
a PLL circuit with the LM301. It's not a 741, but it's rather similar
to it. This PLL works fine. This is my personal opinion. You may
accept it or not. But I have no reason to change my opinion due to my
experiences with operational amplifiers.
Holger
Holger Bruns
<keyb...@mediaone.net> wrote:
>John Gottstein wrote:
>
>> Hi,
>> Does anyone know where I can get a JRC4558 Op Amp Integrated Circuit?
>> They aren't made anymore, but are an important component in a few guitar
>> effects pedals. I can't use the NJM455, since they don't work as well
>> for this purpose.
>>
>> I live in central New Jersey, but am also looking for mail order
>> sources. I only need one, but wouldn't mind having a few on hand.
You can use a RC4558ND, manufactured by Raytheon, as a direct
replacement. A german retailer (Conrad Elektronik) sells it for only
1,35 DM (less than $1,00) per device. If you can't get it, you may
look for a NE5532N. This device is compatible to the 4558, but it has
better performance data.
>Good lord, John. You SURE know how to start a discussion!
This is Usenet.
Regards, Holger
Tom MacIntyre
><36e3bb4...@news.bremen.pop.de>, Holger Bruns <hbr...@gmx.de>
>inimitably wrote:
>>I would never use a 741 for audio applications, because the output
>>signal is too noisy. Even at low signal levels this misfeature causes
>>a significant lack of performance.
>
>Your comment contains a technical error which shows that your opinion is
>worth what you have charged for it.
>--
>Regards, John Woodgate, OOO - Own Opinions Only.
>Phone +44 (0)1268 747839 Fax +44 (0)1268 777124.
>Did you hear about the hungry genetic engineer who made a pig of himself?
Nice catch, John!!
Tom
Tom MacIntyre
...
>If some old roadie for Jimi Hendrix came out and said that Jimi shoved a
>potato up his ass before every performance, you can bet guitar players
>everywhere would be debating whether russets or red spuds are the key to
>better playing.
>
>Welcome to the the mind of a musician.
That may be, but...as a musician in my 1st year of a 2-year
electronics course a number of years ago, I was involved in a
discussion with the top student in the senior year...he was ADAMANT
that solid state devices were far superior to tubes in every way, were
capable of duplicating EVERY waveform/sound that a tube could, and no
mere musician who was only in 1st year could tell him
otherwise...stubbornness/arrogance/lemmingness isn't limited to
musicians...isn't using one's own senses to come to a conclusion
better than believing something simply because it has found its way
into a book?
Tom
Holger Bruns
tmac...@highlander.cbnet.ns.ca (Tom MacIntyre) wrote:
>Nice catch, John!!
I learned from usenet, multiple exclamation marks are a sure sign of a
poor mind. As far as I understand, you are a great lover of tube amps.
In your opinion, tubes are much better than solid state devices, and
old solid state based amplifiers are much better than the more recent
ones? Besides, the sound of a tube can be easily produced with a
digital signal processor.
The 741 op amp is really not a good choice for audio purposes. You may
read data books. Compare the diagrams for the input noise voltage as a
function of the frequency. You will see, that a 741 is up to ten times
more noisy than a 4558. That's why I discourage to use a 741.
Holger
PS: I gave up the hope, that you along with your british friend
understand, what I mean.
greg szekeres
>On Mon, 8 Mar 1999 19:00:16 +0000, John Woodgate
>
>>>I would never use a 741 for audio applications, because the output
>>>signal is too noisy. Even at low signal levels this misfeature causes
>>>a significant lack of performance.
>>
>>Your comment contains a technical error which shows that your opinion is
>>worth what you have charged for it.
>
>ago I designed an audio amplifier for the playback function of a tape
>machine. I checked out several versions, including one with the 741
>and one with the 5532A, which can be treated as a low noise version of
>the 4558. The noise level was significant higher with a 741. That's
Could also be just a bad one. I suppose it does have higher noise, but not as
much as using a bifet in a low Z stage. Ever get an op-amp with the dreded
popcorn noise?
greg
greg szekeres
>
>
>What a response! The key factor here is that there is a whole mythology
>surrounding the JRC4558. A couple of very highly regarded guitar players
>are known to have used a specific battery-powered overdrive pedal that
>utilized the JRC4558. Later models used a different 4558 and as such are
>not considered desireable. Some swear they can tell a difference. And of
>course it has to be the IC, not the different circuit that the later
>models also had. You guys can recommend a 5532, TL072, or any of the
>dozens of drop in replacements, but be sure, none but the JRC4558 will
>suffice.
>
>potato up his ass before every performance, you can bet guitar players
>everywhere would be debating whether russets or red spuds are the key to
>better playing.
If the other RC4558's which are available do not sound the same, I'm sure
there are tons laying around from people replacing them with other parts.
greg
Daniel Haude
Holger Bruns <hbr...@gmx.de> wrote:
> The 741 op amp is really not a good choice for audio purposes. You may
> read data books. Compare the diagrams for the input noise voltage as a
^^^^^^^^^^^^^^^^^^^
Here we go allright. That's better. It may be that you just confused
"input" and "output" and "high" and "low" in your previous posting by
accident.
> PS: I gave up the hope, that you along with your british friend
> understand, what I mean.
He understands perfectly well what you mean, and there are hardly any
people who would disagree with you when it comes to using 741's in audio
application. The problem is that you did not give the correct *reasons*
why the 741 shouldn't be used.
--Daniel
--
"The obvious mathematical breakthrough would be development of an easy
way to factor large prime numbers." -- Bill Gates, "The Road Ahead"
Gray Frierson Haertig
.
>
> If some old roadie for Jimi Hendrix came out and said that Jimi shoved a
> potato up his ass before every performance, you can bet guitar players
> everywhere would be debating whether russets or red spuds are the key to
> better playing.
>
Actually it was a Yukon Gold.
Gray
--
Telecommunications Engineering
Gray Frierson Haertig & Assoc.
820 North River Street, Suite 100
Portland, Oregon 97227
503-282-2989
503-282-3181 FAX
g...@haertig.com
Tom MacIntyre
>On Tue, 09 Mar 1999 10:48:10 GMT,
>tmac...@highlander.cbnet.ns.ca (Tom MacIntyre) wrote:
>
>>Nice catch, John!!
>
>I learned from usenet, multiple exclamation marks are a sure sign of a
>poor mind.
Really!!??!! Oh, my poor, poor mind!!!
>As far as I understand, you are a great lover of tube amps.
>In your opinion, tubes are much better than solid state devices, and
>old solid state based amplifiers are much better than the more recent
>ones? Besides, the sound of a tube can be easily produced with a
>digital signal processor.
You misunderstand...I was simply pointing out that there are
differences. I have heard solid state devices for electric guitar
which suited my purposes...the last 6 or so years that I played
semi-professionally, I used a solid state amp, with a solid state
effects unit. There isn't even any one particular "tube" sound, so how
can it be "easily" produced by solid state?
>
>The 741 op amp is really not a good choice for audio purposes. You may
>read data books. Compare the diagrams for the input noise voltage as a
>function of the frequency. You will see, that a 741 is up to ten times
>more noisy than a 4558. That's why I discourage to use a 741.
This depends upon your expectations/requirements for audio, with
regards to bandwidth and dynamic range...I was congratulating John on
having picked up on a nuance of the entire principle of noise which
was obviously misunderstood in another post...that noise is more of a
problem with low signal levels, and generally less with high signal
levels.
>
>Holger
>
>PS: I gave up the hope, that you along with your british friend
>understand, what I mean.
>
Here's hoping you understand.
Tom
John Woodgate
inimitably wrote:
>PS: I gave up the hope, that you along with your british friend
>understand, what I mean.
We know what you mean, but we don't agree. Along with many others, when
I say you can use a 741 for something, you point out that something else
is better. Sure, but the 'betterness' may not be necessary: in cases
where it is, I wouldn't advise anyone to use a 741.
For example, a 741 operating with 0 dBu input is not too noisy for sound
reinforcement applications (if it is, there's lots of bad product out
there!), but it's far too noisy to use at -80 dBu input.
Holger Bruns
g...@prophet.pharm.pitt.edu (greg szekeres) wrote:
>Ever get an op-amp with the dreded popcorn noise?
No. I never get a popcorn noise from an op amp. I suppose, the op amp
is either damaged or it works as an oscillator due to a feedback loop.
Holger
greg szekeres
Its not likely you would today. Its vertually nonexistant. I did
hear and see it on some 70's maybe 80's components.
By the way, does anyone actually have a JRC spec sheet
I just wanted to compare against other 4558 brand spec sheets, as well
as the 4136.
greg
David DiGiacomo
greg szekeres <g...@prophet.pharm.pitt.edu> wrote:
>By the way, does anyone actually have a JRC spec sheet
>I just wanted to compare against other 4558 brand spec sheets, as well
>as the 4136.
http://sdremote1.njr.com/cdrom/index/ae/ae04049.pdf
I think the data sheet specs are actually worse than those of other vendors
(e.g. 1V/us slew rate).
Spehro Pefhany
> By the way, does anyone actually have a JRC spec sheet
> I just wanted to compare against other 4558 brand spec sheets, as well
> as the 4136.
Sure, check out: http://www.njr.com/products/ic/opamps.htm
I suspect you will find the guaranteed specs are the original (Raytheon?)
ones, but the typical characteristics may well be substantially better.
John Woodgate
inimitably wrote:
>On Tue, 09 Mar 1999 15:46:26 GMT,
>g...@prophet.pharm.pitt.edu (greg szekeres) wrote:
>
>>Ever get an op-amp with the dreded popcorn noise?
>
>No. I never get a popcorn noise from an op amp. I suppose, the op amp
>is either damaged or it works as an oscillator due to a feedback loop.
>
Somethimes this is called 'popcorn noise', but that term should really
be reserved for very low-frequency noise having occasional short pulses
of very high crest factor. When I were a lad it was attributed to
surface contamination of the die, and Toshiba made some transistors
which were free from contamination and with very few surface defects -
'Perfct Crystal Technology' - which were to a very high degree free of
the effect. Maybe the cause is better known now.
David DiGiacomo
John Woodgate <j...@jmwa.demon.co.uk> wrote:
><36e31...@news.spies.com>, David DiGiacomo <da...@slack.com>
>inimitably wrote:
>> It is (barely) fast enough for audio, while a 741 is not.
>
>Here we go again. You can'tget maximum output swing at 20 kHz, but at
>low signal levels and modest gains, a 741 is quite OK.
OK, the slew rate is tolerable for low signal levels, but what about the
GBW? The typical value is 1MHz, and haphazard study of various data sheets
suggests the minimum is half that. Is an open loop gain of 25 adequate
for even a modest closed loop gain?
To make things concrete, maybe you could give an example of a suitable audio
application for a 741 (the signal level and gain), and the THD+N performance
you would expect in that application.
We Are As1
application for a 741 (the signal level and gain), and the THD+N performance
you would expect in that application. >>
They work well in fuzzboxes. Typical gain factor: about 100 to 500. A couple
of oppositely-polarized crappy diodes placed in the feedback loop, or shunted
to ground after the output, depending on the desired flavor of grunge. The
diodes clip the wave peaks and add nasty to the sound. THD and Noise? Lots!!!
We know how you guys love to argue about opamps, but keep in mind that the
original poster of this thread wanted to use the opamp in a fuzzbox, not an
instrumentation amplifier. He's probably gonna run it off a single 9 volt
battery, fer chrissakes! In fact, some fuzzbox guys prefer to use half-drained
batteries, because it gives the starved-for-supply-current fuzzbox circuit a
compressor-like "sag" at the beginning of transients. You think these guys
care about THD and noise specs? It's very likely that this guy doesn't care
how noisy it is, and the more it distorts, the happier he'll be.
Tom MacIntyre
But, doesn't this depend upon whether the person wants "good"
distortion or "bad" distortion (he said with difficulty, because his
tongue was deeply buried in his cheek)? I still remember cranking my
old early 60's Fender Super 45W, 12AX7/7025 preamp and 6L6
output...everything sang...the output transformer saturated, even...I
hear a Barbara Streisand song coming on...
Tom
Spehro Pefhany
> hear a Barbara Streisand song coming on...
Barbra. She deliberately dropped the second 'a' in her name early in her
career.
I guess the good ol' 709, 741, 4558 etc. are really "The Way We Were"
John Woodgate
inimitably wrote:
>To make things concrete, maybe you could give an example of a suitable audio
>application for a 741 (the signal level and gain), and the THD+N performance
>you would expect in that application.
Well, I could give you actual measurements, but unfortunately I can't
spare the time at present. That is the real truth and not a cop-out.