Op amp replacement
BOB URZ
find any (YET) in the US, and the That Semi replacement seems to
be month away from availability. Any ideas? Any other subs that
might work?
BOB
Phil Allison
"BOB URZ" <so...@inetnebr.com> wrote in message
news:3CA92422...@inetnebr.com...
** This IC has been obsolete for some time and there is no similar
replacement AFAIK. It is not a normal op-amp but a low noise differential
input preamp for microphones etc.
Regards, Phil
rid
search them on the web I don't have the address but we often get stuff from
them through a uk company called farnell you could try them
http://www.applegate.co.uk/engineering/company/ct_6249.htm
that should get you to them good luck
rid
"BOB URZ" <so...@inetnebr.com> wrote in message
news:3CA92422...@inetnebr.com...
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.343 / Virus Database: 190 - Release Date: 22/03/02
Mike Diack
>"BOB URZ" <so...@inetnebr.com> wrote in message
>news:3CA92422...@inetnebr.com...
>> Does anyone know a source for SSM 2017 op amps? I cannot seem to
>> find any (YET) in the US, and the That Semi replacement seems to
>> be month away from availability. Any ideas? Any other subs that
>> might work?
Analog Devices unceremoniously ditched the SSM2017 over a year ago,
thus putting numerous audio mauufacturers squarely up shit creek in a
barbed wire canoe. Nobody at the AD stand at the LA AES could come up
with even a lame excuse as to why they did it.
That wonderfully named company THAT (try doing a web search on THAT-
almost as bad as the LCD module manufacturer AND !!) has been
promising a pin for pin replacement next month for 3 years now.
Dont hold your breath.....
BTW the SSM2017 is (oops was) not a simple opamp - it was an
instrumentation amp ie 3 opamps in a block.
There is a Burr Brown part, INA103 which looks good on paper, but is
not pin for pin compatible.
M
BOB URZ
search.
I have downloaded spec sheets on the old beast, but have not had a chance
to study them yet. What i might have to study is the possibility of using
something like a 5532
or 4558 to replace it. Since these chips are already used for single chip
differential
mike pre amps in many units, it seems like there might be a mod to make
it happen.
Granted, the specs may not be as good, but I just need to get this beast
to work now.
Its no sophisticated 40 channel console, but a 100 watt Bogen PA amp in a
old nuns home. It does not have to be concert quality, it just has to
work. I did email That, and they told me about 3 months on the 1710
replacement samples.
BOB
GK
> Thanks to all that responded. I knew this was not going to be an easy
> search.
I'll take a look around our shop today and see if I can turn up something
from the junkpile.
GK
Phil Allison
> Thanks to all that responded. I knew this was not going to be an easy
> search.
> I have downloaded spec sheets on the old beast, but have not had a chance
> to study them yet. What i might have to study is the possibility of using
> something like a 5532
> or 4558 to replace it. Since these chips are already used for single chip
> differential
> mike pre amps in many units, it seems like there might be a mod to make
> it happen.
> Granted, the specs may not be as good, but I just need to get this beast
> to work now.
> Its no sophisticated 40 channel console, but a 100 watt Bogen PA amp in a
> old nuns home. It does not have to be concert quality, it just has to
> work. I did email That, and they told me about 3 months on the 1710
> replacement samples.
>
> BOB
** You are labouring under a misconception, the SSM2017 is NOT an
op-amp so NO op-amp can be used to replace it. That is the whole problem
with the withdrawl of the device.
The two op-amps you mention are dual types BTW while the SSM is a
single circuit, variable gain pre-amp.
Regards, Phil
GK
"GK" <NOSPA...@rose.net> wrote in message
news:uajmt43...@corp.supernews.com...
Nope. I couldn't find anything.
GK
BOB URZ
all will
work out ok. But, it still should be possible to retrofit a op amp in place of
a SSM2017. Granted, it would not be drop in. And components would have to be
changed. But it should be possible (Maybe not too practical though).
The 2017 has a differential input. So do most op amp mike pre amps.
The 2017 has split supplies. So do most op amp configurations. The 2017 sets
its gain though a single resistor between two pins. The op amp mike pre uses a
resistor ratio. So, if ones makes a daughter board or such to properly set up
the op amp, it should be possible. Essentially, your replacing one gain block
with another of a different type.
Differential inputs, single ended output. You don't have to use both sections
of a dual op amp. Or, you can just use the second one for a buffer if you wish.
I hope i don't have to find out if its possible.
BOB
Phil Allison
> Well, the end result is i found some and they are one there way so
hopefully
> all will
> work out ok. But, it still should be possible to retrofit a op amp in
place of
> a SSM2017. Granted, it would not be drop in. And components would have to
be
> changed. But it should be possible (Maybe not too practical though).
> The 2017 has a differential input. So do most op amp mike pre amps.
> The 2017 has split supplies. So do most op amp configurations. The 2017
sets
> its gain though a single resistor between two pins. The op amp mike pre
uses a
> resistor ratio. So, if ones makes a daughter board or such to properly set
up
> the op amp, it should be possible. Essentially, your replacing one gain
block
> with another of a different type.
> Differential inputs, single ended output. You don't have to use both
sections
> of a dual op amp. Or, you can just use the second one for a buffer if you
wish.
> I hope i don't have to find out if its possible.
>
> BOB
** No, it is not. The SSM2017 has variable gain with one resistor
which is usually a 10 kohm antilog pot acting as input trim. The mic
connects directly to the input transistors which gives it such low noise -
this is not possible with an op-amp which will require input series
resistors to operate in balanced mode.
Regards, Phil
CareyD
> <snip> But, it still should be possible to retrofit a op amp in place of
> a SSM2017. Granted, it would not be drop in. And components would have to be
> changed. But it should be possible (Maybe not too practical though).
>
Phil is right, it is not simply an opamp. The SSM2017 is a specialist
audio preamp device with similar architecture to the opamp based
circuit common on most consoles. It's not just a case of changing
components. You would also need to add several including a differetial
input pair of transistors to get anywhere near reasonable audio
performance from a high gain mic preamp stage. The best way to do this
is to build a new conventional preamp stage on a small circuit board
and piggyback this above the main board. You could wire it into the
signal path and to the dual supply voltages. Not an easy thing to do
unless you have good electronic skills.
Regards,
Carey
Phil Allison
"CareyD" <carey....@allen-heath.com> wrote in message
news:dbeb448c.0204...@posting.google.com...
** From your email address I take it you are with the Allen and Heath
company so ought to know a thing or two about mixer design. Thanks for the
back up here - I now feel less like the proverbial shag on a rock!
Regards, Phil
BOB URZ
amp.
I agree that a Op amp won't drop in as a direct replacement. But, i disagree
that you could not make circuit mods or a daughter board to make a OP amp work.
I don't know what planet you guys have been on, but i have seen differential
input single stage Op amp mike preamps for years in products. And most of the
mid level MI stuff i have seen does not have discreet differential transistor
pairs in front of the Mike op amp. Maybe a transformer in some cases. If you
treat the mike preamp as a black box circuit design, its a gain stage with
differential input and single ended output. Pick the gain by the amps stability
and resistor ratios in a differential configuration. You could do that with a
variety of circuit topologies. It could be a 2017, it could be a op amp, it
could be discreet. While some of the methods would not have the noise or
quality level of a 2017, there is no reason why they won't work. I also don't
see thousands of people throwing out their mid level MI gear just because they
use a Op amp for the Mike pre amp stages. While I agree the only highest level
solution is the original part. It might get to the point where there are no
original parts left and you either have to mod it or toss it. In my case, it
was a 70 volt output commercial sound amp. I am sure the customer would have
never noticed the difference between a 2017 and a op amp mike front end. If we
were talking about studio level devices or high end road mixers, I would think
a little differently about the performance level.
You guys do make good points on high end mixer front ends though.
BOB
T.Alan Kraus
Burr-Brown. Similar architecture and parameters. You'll need to kludge it...
cheers
T.Alan
Phil Allison
** Bob,
if your Bogen PA head uses the SSM2017 as a fixed gain input preamp
then an op-amp with at least four resistors could be made to do the same job
with a major penalty in terms of much higher noise and poorer CMRR.
I do a lot of repairs on low cost desks and see very few with op-amp
only mic inputs since the addition of a few cheap transistors makes a very
good mic input stage - almost all have this.
To replace the SSM2017 with op-amps in a variable gain mic circuit
requires at least three op-amps, two low noise ones like the NE5532 pair and
a standard one ( say TL071) to act as a balanced to unbalanced output
buffer. This would still have much higher noise than the SSM but be
compatible with a variable gain pot as mentioned earlier.
Hope this clears the matter up.
Regards, Phil
John Deans
is pin and functionall compatible, I cant remember thew number try their
website
BOB URZ wrote in message <3CA92422...@inetnebr.com>...
Phil Allison
"John Deans" <de...@patrol.i-way.co.uk> wrote in message
news:dF%q8.586$7L2.9...@newsr2.u-net.net...
> Analog devices reccomend one of their low noise insturmentation amps which
> is pin and functionall compatible, I cant remember thew number try their
> website
** The AMP-02 is the one I think - expensive and noisy for a mic
pre-amp.
Regards, Phil
John Phillips
You will need to build a Instrumentation Amplifier to "roll your own" - too
much work!
Analog devices suggests that you use their AMP02
http://www.analog.com/productSelection/pdf/amp02.pdf and it is available (in
stock) from http://www.newark.com/ but like DigiKey, there is a $5 adder for
orders for less than $25. You may also be able to order it from ADI. I
looked at the AMP02 quickly and it appears to be a pin for pin replacement.
I did not find data sheets for the SSM2017 so you must check to see if the
gain equations are the same for both parts and replace the Rg resistor if
required.
John
"BOB URZ" <so...@inetnebr.com> wrote in message
news:3CA9C8DE...@inetnebr.com...
David Shorter
> As already pointed out by another poster, the SSM2017 is a 3 opamp circuit.
> You will need to build a Instrumentation Amplifier to "roll your own" - too
> much work!
>
> Analog devices suggests that you use their AMP02
> http://www.analog.com/productSelection/pdf/amp02.pdf and it is available (in
> stock) from http://www.newark.com/ but like DigiKey, there is a $5 adder for
> orders for less than $25. You may also be able to order it from ADI. I
> looked at the AMP02 quickly and it appears to be a pin for pin replacement.
> I did not find data sheets for the SSM2017 so you must check to see if the
> gain equations are the same for both parts and replace the Rg resistor if
> required.
I've sent you an email with the SSM2017 pdf file attached.
As you will be able to see, the AMP02 isn't a direct replacement
although it is pin compatible. At gains above 10 the voltage noise
density performance falls of markedly when compared to the SSM2017.
The distortion levels are higher with no specs given for gains over
100. The gain equation is different. The list goes on. You can draw
your own conclusions.
The best alternative to the SSM2017 is a Burr-Brown INA103 which is
a 16 pin device.
--
Regards,
David Shorter
Oceania Audio
Auckland, New Zealand
Any errors in tact, fact or spelling
are entirely due to transmission error.
John Phillips
on their web site.
My suggestions were based on his comment that it was a Bogen PA amp and he
just wanted to get it working. In his application, I do not think that the
added noise is a problem. I would rather install the AMP02 and change a
resistor than to build a daughter card with an instrumentation amp. Unless
he uses expensive resistors for close matching, he could have a hum or
general input noise. I agree that if best quality mattered, I would use the
INA103.
John
"David Shorter" <dazz...@ihug.co.nz> wrote in message
news:3CB8F70D...@ihug.co.nz...
> John Phillips wrote:
>
> > As already pointed out by another poster, the SSM2017 is a 3 opamp
circuit.
> > You will need to build a Instrumentation Amplifier to "roll your own" -
too
> > much work!
> >
> > Analog devices suggests that you use their AMP02
> I've sent you an email with the SSM2017 pdf file attached.