[Scott Dorsey]

Arny Krueger wrote:
"Scott Dorsey" wrote in message
...
Arny Krueger wrote:

"Don Pearce" wrote in message

You haven't kept up Scott. You don't need a transformer to achieve
good CMRR - and neither do you need to configure a full
instrumentation amp with three op amps.

Scott seems to think that the THAT1510 is not the device that its
producers
claim it to be.

The manufacturers never claimed it was a single op-amp.

To quote you Scott, why do you put words in my mouth? I *never* said it was
a *single* op amp.

Don Pierce was talking about building a preamp based on a single op-amp.
That was the subject.

If you are going to use that configuration, you need to use a transformer
input to get good CMRR.

Please read the thread before you reply to them. This is not the first time
you have changed subjects in mid-stream.

In what part of outer space does being an instrumentation amplifier prevent
it from being an op amp? Is there an official definition of op amp that
necessarily eliminates everything more sophisticated than a LM301?

An instrumentation amplifier is not an op-amp, and is a completely different
topology. You can build an instrumentation amplifier using three op-amps
if you would like, or you can build one with a finite-gain amplifier.

There is, yes, an official definition of an op-amp, which includes having
very high open-loop gain, etc.

Interesting side note - DPA is apparently getting through reworking their
line of measurement mics to be transformerless. IOW, they used to have
transformers. They weren't all that bad! ;-)

DPA does not make measurement mikes.

Again Scott, you are calling a well-respected manufacturer a liar.

http://www.dpamicrophones.com/en/pro...g&category=188
describes a goodly number of products that are obviously designed for making
audio measurements.

http://www.dpamicrophones.com/en/pro...188&item=24009
describes the 4004 as, and I exactly quote: "measurement microphone". OK,
Scott explain that!

It doesn't even come close to making IEC specs. I don't think you can in
fact meet IEC specs with a transformer. Putting the word "measurement" on
a microphone does not make it a measurement microphone.

DPA in fact, broke away from B&K because B&K didn't want to make recording
microphones. They took all of the low-cost recording designs with them,
which were pretty good but weren't measurement microphones. The 4004 is
an attempt to take one of the low-cost capsules as used in the 4006, etc.
recording microphones and use it for measurement applications.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Peter Larsen[_3_]]

Don Pearce wrote:

You don't seem to have much luck in buying stuff that works. I promise
you that you can build yourself a single channel preamp that is a
match for anything at any price - maybe not for 10 dollars, but
certainly for 20. Most commercial preamps don't reach their optimum
noise performance because the makers don't want to shell out the cash
for multiple parallel discrete input transistors. You can do that.
Frequency response is as flat as you want it to be and you choose your
own headroom in power supply design.

I'd get the Phil Allison designed kit if in diy mood, my gamble would be
that it is worth buying unheard and unbuilt.

Kind regards

Peter Larsen

That is all there is - get those right and you have yourself an
acoustically transparent preamp. There is no added "magic ingredient"
that only appears when you tack a couple of noughts onto the price.

d

[Trevor]

"Scott Dorsey" wrote in message
...
Putting the word "measurement" on
a microphone does not make it a measurement microphone.

That's just plain silly. It may not be a really good one, but it can still
be called, and used as, a measurement mic. Calibration is the key to any
proper measurement. Perhaps you are confusing *all* measurements with
national standards laboratory grade, traceable and certified?
(Which would not prevent the use of a DPA in any case if it maintains the
required calibration for the necesssary period.)
A calibrated DPA is a better measurement mic than an uncalibrated B&K in
fact.


DPA in fact, broke away from B&K because B&K didn't want to make recording
microphones. They took all of the low-cost recording designs with them,
which were pretty good but weren't measurement microphones. The 4004 is
an attempt to take one of the low-cost capsules as used in the 4006, etc.
recording microphones and use it for measurement applications.

Quite possibly, and quite possibly all that many measurements may require.
Not ALL measurements must be traceable to the national standards after all.
Setting up live sound equipment being a good example. Software these days
automatically corrects for the calibration curve of the microphone, and has
for some time.

Trevor.

[Trevor]

"Peter Larsen" wrote in message
k...
I'd get the Phil Allison designed kit if in diy mood, my gamble would be
that it is worth buying unheard and unbuilt.

What on earth makes you think that? You just like to gamble? :-)

Trevor.

[Don Pearce[_3_]]

On 17 Dec 2011 22:50:32 -0500, (Scott Dorsey) wrote:

Don Pierce was talking about building a preamp based on a single op-amp.
That was the subject.

If you are going to use that configuration, you need to use a transformer
input to get good CMRR.

Please read the thread before you reply to them. This is not the first time
you have changed subjects in mid-stream.

My circuit uses a single op-amp, plus four discrete transistors
configured as long-tailed pairs. When I look at the topology more
closely, yes it is a kind of instrumentation amp. I'll post a
schematic later - I'm using a new computer and I don't have my web
site software running right now.

d

[Arny Krueger[_4_]]

"Scott Dorsey" wrote in message
...
Arny Krueger wrote:
"Scott Dorsey" wrote in message
...
Arny Krueger wrote:

"Don Pearce" wrote in message

You haven't kept up Scott. You don't need a transformer to achieve
good CMRR - and neither do you need to configure a full
instrumentation amp with three op amps.

Scott seems to think that the THAT1510 is not the device that its
producers
claim it to be.

The manufacturers never claimed it was a single op-amp.

To quote you Scott, why do you put words in my mouth? I *never* said it
was
a *single* op amp.

Note that Scott can't let it go:

Don Pierce was talking about building a preamp based on a single op-amp.
That was the subject.

I see a hair being split for no good reason other than to claim that you're
right and everbody else is wrong, Scott.

99% of everybody technical I know would call a one-chip instrumentation amp
"An op amp". While the manufactuer's data sheet shows an array of op amps
few if any of us know whether or not that is a precise representation of
what's actually etched on the silicon. Scott, you come along and plug the
word "single" into other people's statements (both Don and I) then make a
big show of saying that we're wrong because its really 3 amplifiers on one
chip. Forget the fact that most of the inputs and outpufs of those amplfiers
are permanently connected and not acessible from the outside world. Forget
the fact that manufacturer block diagrams of chips are often more
figurative, and not exactly literal. Yet again Scott's right and everybody
else is wrong.

If you are going to use that configuration, you need to use a transformer
input to get good CMRR.

Wrong in the mainstream. You can get good CMRR out of a single op amp, but
you end up constrained in terms of input impedance. Of course the word
"good" is pretty vague. So you can say that anything less than 100 dB CMRR
from DC to light is not good enough for you. Play that game! Its less
deceptive than putting words in other people's mouth like you have. :-(

I'm done with your deceptions and misleading comments Scott. If you want to
ruin this season like this, you're on your own.

[Arny Krueger[_4_]]

"Trevor" wrote in message
...

"Scott Dorsey" wrote in message
...

Putting the word "measurement" on
a microphone does not make it a measurement microphone.

That's just plain silly.

It is also a little libelous. Scott is basically accusing no less than DPA
of false advertising.

It may not be a really good one,

Even the 4006 that Scott wants to totally dismiss can be a very useful
microphone for doing most common acoustic measurements. Been there, done
that and seen a ton of other people do the same.

Would Scott have a myocardial infarction if he saw professionals using ECM
8000's as measurement mics? It happens all the time. ECM 8000s are true POS
compared to the worst measruement mci that DPA makes but at 1/40 of the
price... Some of the people who use ECM 8000s have proven track records for
producing good-sounding highly sucessful electroacoustical products. The
laws of physics allow many things that the rule of ego will not!

but it can still be called, and used as, a measurement mic. Calibration
is the key to any proper measurement.

Thus, an ECM 8000 plus a good microphone calibrator can be just as reliable
in actual use as anything B&K makes at a fraction of the total cost.

[Les Cargill[_4_]]

Arny Krueger wrote:
wrote in message
...

"Scott wrote in message
...

Putting the word "measurement" on
a microphone does not make it a measurement microphone.

That's just plain silly.

It is also a little libelous. Scott is basically accusing no less than DPA
of false advertising.


LOL... WUT?

http://images.icanhascheezburger.com/completestore/2008/8/26/dudexanax128642391274241200.jpg
snip

--
Les Cargill

[Scott Dorsey]

Don Pearce wrote:

My circuit uses a single op-amp, plus four discrete transistors
configured as long-tailed pairs. When I look at the topology more
closely, yes it is a kind of instrumentation amp. I'll post a
schematic later - I'm using a new computer and I don't have my web
site software running right now.

If this is the same topology used in the Mackie mixers (and just about
every other all-solid-state preamp), you can dispense with the op-amp
completely and replace it with a second differential stage and a current
drive stage on the output.

In fact, if you can get the front end matched well enough, you can get
remarkably good CMRR just using a capactively-coupled gain stage off one
leg, with a follower on the output. Six transistors total, and the
performance is primarily limited by the front-end transistors.

If you're on a severe budget, a large area switching-grade transistor
like the 2N4401 will work okay on the front end although you will need
to select them for noise and gain. Or you can get a commercial array
like the MAT-06 or some of the arrays that THAT makes.

I did it once with 2N3055 power transistors, figuring the large area of
the power transistor would provide better matching for lower gain, and
it was surprisingly quiet although there was some excess noise from
junction contamination.

It is a kind of instrumentation amp, and as such it relies a lot on
the matching of the two halves, and they need to track very well with
temperature changes as well. In general the higher idle current on the
front end, the lower the noise with a given transistor type.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Don Pearce wrote:

My circuit uses a single op-amp, plus four discrete transistors
configured as long-tailed pairs. When I look at the topology more
closely, yes it is a kind of instrumentation amp. I'll post a
schematic later - I'm using a new computer and I don't have my web
site software running right now.

If this is the same topology used in the Mackie mixers (and just about
every other all-solid-state preamp), you can dispense with the op-amp
completely and replace it with a second differential stage and a current
drive stage on the output.

In fact, if you can get the front end matched well enough, you can get
remarkably good CMRR just using a capactively-coupled gain stage off one
leg, with a follower on the output. Six transistors total, and the
performance is primarily limited by the front-end transistors.

If you're on a severe budget, a large area switching-grade transistor
like the 2N4401 will work okay on the front end although you will need
to select them for noise and gain. Or you can get a commercial array
like the MAT-06 or some of the arrays that THAT makes.

I did it once with 2N3055 power transistors, figuring the large area of
the power transistor would provide better matching for lower gain, and
it was surprisingly quiet although there was some excess noise from
junction contamination.

It is a kind of instrumentation amp, and as such it relies a lot on
the matching of the two halves, and they need to track very well with
temperature changes as well. In general the higher idle current on the
front end, the lower the noise with a given transistor type.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Peter Larsen[_3_]]

Trevor wrote:

"Peter Larsen" wrote in message
k...

I'd get the Phil Allison designed kit if in diy mood, my gamble
would be that it is worth buying unheard and unbuilt.

What on earth makes you think that? You just like to gamble? :-)

Well, erm, I like to win and electronics design is not a social skill and
the guys electronics skills appear to be in reasonable regarded. Read up on
the thing, there's some website downunder selling the pcb or kit, google
knows where.

Trevor

Kind regards

Peter Larsen

[mmm guitar]

On Dec 15, 12:34*pm, Mike Rivers wrote:
On 12/14/2011 5:33 AM, mmm guitar wrote:

I have a Neumann TLM 102 and trying to figure out a decent way to
preamp it and get it into my PC based DAW.

My requirements are a mid level home setup.
I record either acoustic guitar, mic'ed amp, piano, vocal
and things like congas, bongos. *I'm never going to require mic'ing up
something like drums or multiple instruments.
I'm thinking of the DAV BG1U, and use
that with my current card, but plan to buy something like an external
AD/DA unit like the RME ADI-2.

or

Buy a more integrated unit, I'm thinking the RME Fireface 400
or 800.
I'm swinging towards the first way as I really like simplicity, i.e. a
unit which his sole purpose in life is a preamp, or an AD/DA.
I really dont know is whether having an integrated preamp + ADDA is
"better" as all the sound processing is happening in 1 unit, I dont
think thats really an issue.

Without reading through the dozens of replies yet, here's my
take on this.

I think you have a realistic perspective - a "mid-level"
setup with decent microphones and some attention to the
recording environment. As an engineer, the "system" approach
(separate mic preamp and converters) appeals to me not
because of the simplicity of dedicated hardware for each
function, but for flexibility. If you think you might get
some improvement from a different preamp, you can try one
with your present converters and make your comparison based
on a single variable. Same if you want to try a different
converter. There's another piece that you could un-bundle,
too, and that's converters from the computer interface.

But . . . I'll tell you that when it comes to "mid-level,"
and that covers a pretty broad range of price with a smaller
range in "sound quality," the integrated
preamp-converter-interfaces on the market today are
remarkably good.

The RME Fireface series is kind of at the top end of that
range. But for less than half the price, I've recently had
the Focusrite Scarletts here for review and I currently have
a PreSonus 44VSL, both of which sound very good. There are a
number of other similar products on the market. TASCAM and
Steinberg/Yamaha are probably very likely similar in
function and performance. I haven't shot one out with the
other, or either out with a Fireface (I've never worked with
an RME) though I'm sure that differences could be heard. But
I can tell you that there's nothing I've heard about the
ones I've had here in the last few months that would stand
in my way of making a good recording, all things external
being equal.

One thing that might make a difference in the way you work
is how much gain the mic preamp has. Most of the integrated
boxes are internally calibrated (and mostly you can't change
this) so that at maximum gain, all of them require about the
same input level for the same digital output level. This
gain structure tends to be a bit on the low side when you're
recording a quiet source resulting in the complaint of "I
have to turn the gain all the way up and my tracks are still
too quiet." In general, I don't consider this to be a
defect, but it's usually the first criticism you'll read on
the 'net.

One thing that you should be concerned about is how the
digital data gets into the computer. Firewire is in its
sunset years. Unless you have an old computer or are
assembling a tabletop computer from parts, you pretty much
can't get a Firewire port any more. There are hardly any
Windows laptops with a Firewire port or even a Cardbus slot
for a Firewire adapter for sale today, and only a few Mac
models still have Firewire. This is really an important
consideration with a Fireface. It might work with the
computer you have today, but it might not work with your
next computer (and there WILL be a next computer).

Hand in hand with this is how good the drivers are if you're
using Windows and how compliant the hardware is with the
Apple Core Audio system if you're using a Mac. RME happens
to have a stellar reputation here. Mackie's name is mud. To
make your system somewhat future-resistant, you might want
to focus your sights on a USB2 interface between the
converters and the computer regardless of what's on the
other side of the converters (an integrated box or an
outboard mic preamp).

You have the mic already and it sounds like you're on
speaking terms with a dealer. Why not get something modest
from him and give it a try in your studio. Look at things
like a workable gain range without excess noise and
something that works with your computer without a lot of
fussing around (if you're using Windows - go directly to the
manufacturer's web site and download the latest drivers,
don't even bother with what's on the disk in the box. See
how it sounds to you and how it works for you.

This stuff is pretty fluid if you have the right attitude
about it. For $350 or so, you can make some very good
recordings, and when you decide that it's time to upgrade in
a year or two, it's really not that big of a deal to sell it
for $200 and take the next step, And if you get an
integrated interface with digital as well as analog I/O (an
S/PDIF port is pretty common) you can keep the same computer
interface for as long as it's supported with your computer
software and upgrade the converters or preamp.

Think flexibility and don't think that you'll be buying the
system that you'll use for the next 20 years.

--
"Today's production equipment is IT based and cannot be
operated without a passing knowledge of computing, although
it seems that it can be operated without a passing knowledge
of audio." - John Watkinson

http://mikeriversaudio.wordpress.com- useful and
interesting audio stuff

That is a great help thanks. Yeah I've noticed firewire drop off the
standards ports being shipped with PC's but did quite realise its on
the way out. Never understood quite why it was required as there were
plenty of digital connections before. Gain is an interesting on for
me, although from my understanding and replies from Arny its something
I dont need alot of given my microphone at the moment but in the next
x year's I could quite see myself playing around with some different
types of mic's.

Awesome, I've actually now ordered the DAV BG1U and I'm going to see
how it runs over the next few months if I match the gain to my
soundcard. Probably will end up buying something like the RME ADI-2
primarily as I'm really dependent on my soundcard which has a PCI
interface to my PC, and they are pretty much dead now... plus it seems
a good bit of kit but as you say, to have a very flexible system
is definitely a good idea.

Thanks again!

[Don Pearce[_3_]]

On 18 Dec 2011 09:07:14 -0500, (Scott Dorsey) wrote:

Don Pearce wrote:

My circuit uses a single op-amp, plus four discrete transistors
configured as long-tailed pairs. When I look at the topology more
closely, yes it is a kind of instrumentation amp. I'll post a
schematic later - I'm using a new computer and I don't have my web
site software running right now.

If this is the same topology used in the Mackie mixers (and just about
every other all-solid-state preamp), you can dispense with the op-amp
completely and replace it with a second differential stage and a current
drive stage on the output.

In fact, if you can get the front end matched well enough, you can get
remarkably good CMRR just using a capactively-coupled gain stage off one
leg, with a follower on the output. Six transistors total, and the
performance is primarily limited by the front-end transistors.

If you're on a severe budget, a large area switching-grade transistor
like the 2N4401 will work okay on the front end although you will need
to select them for noise and gain. Or you can get a commercial array
like the MAT-06 or some of the arrays that THAT makes.

I did it once with 2N3055 power transistors, figuring the large area of
the power transistor would provide better matching for lower gain, and
it was surprisingly quiet although there was some excess noise from
junction contamination.

It is a kind of instrumentation amp, and as such it relies a lot on
the matching of the two halves, and they need to track very well with
temperature changes as well. In general the higher idle current on the
front end, the lower the noise with a given transistor type.
--scott

I have a big box of MAT02 and MAT03 matched pair transistors. I know
they are obsolete now, but they really are superb at low noise. I
haven't seen the Mackie circuits, so I don't know how that is
arranged, but just about any highish speed op amp does the job, and
they are as cheap as anything, so why not use one? I have another
circuit that uses three of the four op amps in a quad, plus two of the
MAT02s as discrete front ends. That is a proper instrumentation amp.

I've never tried the 2N3055 as a low noise pre-amp, although I can see
how it would be a good choice - maybe just a little short of Hfe
though?

d

[Arny Krueger[_4_]]

"Paul Babiak" wrote in message
eb.com...

You might be able to copy this one for $50.00 in parts, but I recommend
seriously considering a purchase.

http://www.seventhcircleaudio.com/T1.../t15_about.htm

The schematic is provided on the website.

It has virtually every potentially useful bell and whistle that can be
reasonably be put into a mic preamp. $50 might be a reasonable estimate for
parts aside from a good professional-grade box (e.g. 1 RU ).

[bruce seifried]

In article , Arny
Krueger wrote:

"Scott Dorsey" wrote in message
...
Arny Krueger wrote:
"Scott Dorsey" wrote in message
...
Arny Krueger wrote:

"Don Pearce" wrote in message

You haven't kept up Scott. You don't need a transformer to achieve
good CMRR - and neither do you need to configure a full
instrumentation amp with three op amps.

Scott seems to think that the THAT1510 is not the device that its
producers
claim it to be.

The manufacturers never claimed it was a single op-amp.

To quote you Scott, why do you put words in my mouth? I *never* said it
was
a *single* op amp.

Note that Scott can't let it go:

Don Pierce was talking about building a preamp based on a single op-amp.
That was the subject.

I see a hair being split for no good reason other than to claim that you're
right and everbody else is wrong, Scott.

99% of everybody technical I know would call a one-chip instrumentation amp
"An op amp". While the manufactuer's data sheet shows an array of op amps
few if any of us know whether or not that is a precise representation of
what's actually etched on the silicon. Scott, you come along and plug the
word "single" into other people's statements (both Don and I) then make a
big show of saying that we're wrong because its really 3 amplifiers on one
chip. Forget the fact that most of the inputs and outpufs of those amplfiers
are permanently connected and not acessible from the outside world. Forget
the fact that manufacturer block diagrams of chips are often more
figurative, and not exactly literal. Yet again Scott's right and everybody
else is wrong.

If you are going to use that configuration, you need to use a transformer
input to get good CMRR.

Wrong in the mainstream. You can get good CMRR out of a single op amp, but
you end up constrained in terms of input impedance. Of course the word
"good" is pretty vague. So you can say that anything less than 100 dB CMRR
from DC to light is not good enough for you. Play that game! Its less
deceptive than putting words in other people's mouth like you have. :-(

I'm done with your deceptions and misleading comments Scott. If you want to
ruin this season like this, you're on your own.

I'd say you've managed that yourself, single handedly.

I generally don't bother reading what you have to say, since you appear
to posses thinner skin than my rabbits; any little nick splits you
right open. This is the same boorish behaviour that killed
rec.audio.tubes. Do the world a favour and stop turning evrything into
a personal affront. One Andre Jute in the world is enough.

99% of everybody technical I know would call a one-chip instrumentation amp
"An op amp".

Nonsense. An instrumentation amp is not an op amp, regardless of its
packaging.

-bruce seifried

[Bruce Seifried]

In article , Arny
Krueger wrote:

"Scott Dorsey" wrote in message
...
Arny Krueger wrote:
"Scott Dorsey" wrote in message
...
Arny Krueger wrote:

"Don Pearce" wrote in message

You haven't kept up Scott. You don't need a transformer to achieve
good CMRR - and neither do you need to configure a full
instrumentation amp with three op amps.

Scott seems to think that the THAT1510 is not the device that its
producers
claim it to be.

The manufacturers never claimed it was a single op-amp.

To quote you Scott, why do you put words in my mouth? I *never* said it
was
a *single* op amp.

Note that Scott can't let it go:

Don Pierce was talking about building a preamp based on a single op-amp.
That was the subject.

I see a hair being split for no good reason other than to claim that you're
right and everbody else is wrong, Scott.

99% of everybody technical I know would call a one-chip instrumentation amp
"An op amp". While the manufactuer's data sheet shows an array of op amps
few if any of us know whether or not that is a precise representation of
what's actually etched on the silicon. Scott, you come along and plug the
word "single" into other people's statements (both Don and I) then make a
big show of saying that we're wrong because its really 3 amplifiers on one
chip. Forget the fact that most of the inputs and outpufs of those amplfiers
are permanently connected and not acessible from the outside world. Forget
the fact that manufacturer block diagrams of chips are often more
figurative, and not exactly literal. Yet again Scott's right and everybody
else is wrong.

If you are going to use that configuration, you need to use a transformer
input to get good CMRR.

Wrong in the mainstream. You can get good CMRR out of a single op amp, but
you end up constrained in terms of input impedance. Of course the word
"good" is pretty vague. So you can say that anything less than 100 dB CMRR
from DC to light is not good enough for you. Play that game! Its less
deceptive than putting words in other people's mouth like you have. :-(

I'm done with your deceptions and misleading comments Scott. If you want to
ruin this season like this, you're on your own.

I'd say you've managed that yourself, single handedly.

I generally don't bother reading what you have to say, since you appear
to posses thinner skin than my rabbits; any little nick splits you
right open. This is the same boorish behaviour that killed
rec.audio.tubes. Do the world a favour and stop turning evrything into
a personal affront. One Andre Jute in the world is enough.

99% of everybody technical I know would call a one-chip instrumentation amp
"An op amp".

Nonsense. An instrumentation amp is not an op amp, regardless of its
packaging.

-bruce seifried

[Trevor]

"Peter Larsen" wrote in message
k...
I'd get the Phil Allison designed kit if in diy mood, my gamble
would be that it is worth buying unheard and unbuilt.

What on earth makes you think that? You just like to gamble? :-)

Well, erm, I like to win and electronics design is not a social skill and
the guys electronics skills appear to be in reasonable regarded. Read up
on the thing, there's some website downunder selling the pcb or kit,
google knows where.

Phils reputation is well known on usenet. It wouldn't inspire me to gamble
when there are circuits designed by qualified engineers with real experience
readily available.

Trevor.

[hank alrich]

Bruce Seifried wrote:

In article , Arny
Krueger wrote:

"Scott Dorsey" wrote in message
...
Arny Krueger wrote:
"Scott Dorsey" wrote in message
...
Arny Krueger wrote:

"Don Pearce" wrote in message

You haven't kept up Scott. You don't need a transformer to achieve
good CMRR - and neither do you need to configure a full
instrumentation amp with three op amps.

Scott seems to think that the THAT1510 is not the device that its
producers
claim it to be.

The manufacturers never claimed it was a single op-amp.

To quote you Scott, why do you put words in my mouth? I *never* said it
was
a *single* op amp.

Note that Scott can't let it go:

Don Pierce was talking about building a preamp based on a single op-amp.
That was the subject.

I see a hair being split for no good reason other than to claim that you're
right and everbody else is wrong, Scott.

99% of everybody technical I know would call a one-chip instrumentation amp
"An op amp". While the manufactuer's data sheet shows an array of op amps
few if any of us know whether or not that is a precise representation of
what's actually etched on the silicon. Scott, you come along and plug the
word "single" into other people's statements (both Don and I) then make a
big show of saying that we're wrong because its really 3 amplifiers on one
chip. Forget the fact that most of the inputs and outpufs of those amplfiers
are permanently connected and not acessible from the outside world. Forget
the fact that manufacturer block diagrams of chips are often more
figurative, and not exactly literal. Yet again Scott's right and everybody
else is wrong.

If you are going to use that configuration, you need to use a transformer
input to get good CMRR.

Wrong in the mainstream. You can get good CMRR out of a single op amp, but
you end up constrained in terms of input impedance. Of course the word
"good" is pretty vague. So you can say that anything less than 100 dB CMRR
from DC to light is not good enough for you. Play that game! Its less
deceptive than putting words in other people's mouth like you have. :-(

I'm done with your deceptions and misleading comments Scott. If you want to
ruin this season like this, you're on your own.

I'd say you've managed that yourself, single handedly.

I generally don't bother reading what you have to say, since you appear
to posses thinner skin than my rabbits; any little nick splits you
right open. This is the same boorish behaviour that killed
rec.audio.tubes. Do the world a favour and stop turning evrything into
a personal affront. One Andre Jute in the world is enough.

99% of everybody technical I know would call a one-chip instrumentation amp
"An op amp".

Nonsense. An instrumentation amp is not an op amp, regardless of its
packaging.

-bruce seifried

Bruce! Most excellent to read you here.

--
shut up and play your guitar * http://hankalrich.com/
http://www.youtube.com/walkinaymusic
http://www.sonicbids.com/HankandShaidri

[Steve King]

"hank alrich" wrote in message
...
Bruce Seifried wrote:

In article , Arny
Krueger wrote:

"Scott Dorsey" wrote in message
...
Arny Krueger wrote:
"Scott Dorsey" wrote in message
...
Arny Krueger wrote:

"Don Pearce" wrote in message

You haven't kept up Scott. You don't need a transformer to
achieve
good CMRR - and neither do you need to configure a full
instrumentation amp with three op amps.

Scott seems to think that the THAT1510 is not the device that its
producers
claim it to be.

The manufacturers never claimed it was a single op-amp.

To quote you Scott, why do you put words in my mouth? I *never* said
it
was
a *single* op amp.

Note that Scott can't let it go:

Don Pierce was talking about building a preamp based on a single
op-amp.
That was the subject.

I see a hair being split for no good reason other than to claim that
you're
right and everbody else is wrong, Scott.

99% of everybody technical I know would call a one-chip instrumentation
amp
"An op amp". While the manufactuer's data sheet shows an array of op
amps
few if any of us know whether or not that is a precise representation
of
what's actually etched on the silicon. Scott, you come along and plug
the
word "single" into other people's statements (both Don and I) then make
a
big show of saying that we're wrong because its really 3 amplifiers on
one
chip. Forget the fact that most of the inputs and outpufs of those
amplfiers
are permanently connected and not acessible from the outside world.
Forget
the fact that manufacturer block diagrams of chips are often more
figurative, and not exactly literal. Yet again Scott's right and
everybody
else is wrong.

If you are going to use that configuration, you need to use a
transformer
input to get good CMRR.

Wrong in the mainstream. You can get good CMRR out of a single op amp,
but
you end up constrained in terms of input impedance. Of course the word
"good" is pretty vague. So you can say that anything less than 100 dB
CMRR
from DC to light is not good enough for you. Play that game! Its less
deceptive than putting words in other people's mouth like you have. :-(

I'm done with your deceptions and misleading comments Scott. If you
want to
ruin this season like this, you're on your own.

I'd say you've managed that yourself, single handedly.

I generally don't bother reading what you have to say, since you appear
to posses thinner skin than my rabbits; any little nick splits you
right open. This is the same boorish behaviour that killed
rec.audio.tubes. Do the world a favour and stop turning evrything into
a personal affront. One Andre Jute in the world is enough.

99% of everybody technical I know would call a one-chip instrumentation
amp
"An op amp".

Nonsense. An instrumentation amp is not an op amp, regardless of its
packaging.

-bruce seifried

Bruce! Most excellent to read you here.

Ditto!

Steve King

[Scott Dorsey]

Don Pearce wrote:

I have a big box of MAT02 and MAT03 matched pair transistors. I know
they are obsolete now, but they really are superb at low noise.

The data sheet for either the MAT-02 or MAT-03 has a really cute mike
preamp circuit. Four transistor front end, op-amp out, constant current
source with a 2N3904 or something for the front end. It's basically the
same as the Mackie front end.... however as I recall the schematic on the
datasheet is missing a feedback network for the output op-amp so look out.

haven't seen the Mackie circuits, so I don't know how that is
arranged, but just about any highish speed op amp does the job, and
they are as cheap as anything, so why not use one?

No reason not to, especially if you can move as much gain as possible to
the front end. In fact, Sennheiser made some consoles using the four
transistor topology with a 301 as a driver stage, but the 301 was running
a gain of maybe ten. It sounded better than anything with a 301 had any
right to sound.

I have another
circuit that uses three of the four op amps in a quad, plus two of the
MAT02s as discrete front ends. That is a proper instrumentation amp.

In practice this can give you better CMRR because the MAT-02 doesn't have
infinite gain. These days, though, you can get higher beta large area
transistors than the MAT02, which helps a lot.

I've never tried the 2N3055 as a low noise pre-amp, although I can see
how it would be a good choice - maybe just a little short of Hfe
though?

Yes, precisely. When I tried that, the MAT-03 was expensive and rare
exotica. These days you can order a THAT 300-series array from Mouser
for a couple bucks.

Now, getting a quiet 2N5088, that's hard...
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

On 2011-12-19 said:
I'd get the Phil Allison designed kit if in diy mood, my gamble
would be that it is worth buying unheard and unbuilt.
What on earth makes you think that? You just like to gamble? :-)
Well, erm, I like to win and electronics design is not a social
skill and the guys electronics skills appear to be in reasonable
regarded. Read up on the thing, there's some website downunder
selling the pcb or kit, google knows where.
Phils reputation is well known on usenet. It wouldn't inspire me to
gamble when there are circuits designed by qualified engineers with
real experience readily available.
This is true, i might not buy the kit from him, but if I
were in the mood, had facilities to diy, or just
breadboardthe thing possibly and try out his design just for
grins.


Or just lurk and see if I hear anybody talking about it.



Richard webb,

replace anything before at with elspider

[Peter Larsen[_3_]]

wrote:

On 2011-12-19 said:

Phils reputation is well known on usenet. It wouldn't inspire me to
gamble when there are circuits designed by qualified engineers with
real experience readily available.

This is true, i might not buy the kit from him, but if I
were in the mood, had facilities to diy, or just
breadboardthe thing possibly and try out his design just for
grins.

Phils reputation is that his electronics skills are better than his
patience. And yes, I don't mind checking.

Or just lurk and see if I hear anybody talking about it.

http://sound.westhost.com/project66.htm

To my unskilled eye it is exactly as a mic pre should be as per Scotts
description.

Richard webb,

Kind regards

Peter Larsen

[Trevor]

"Peter Larsen" wrote in message
k...
Phils reputation is that his electronics skills are better than his
patience.

That's not saying much. Now if they were anywhere near the level of personal
abuse he hands out, he'd be a leading authority rather than a uni drop out.

And yes, I don't mind checking.

Most people kill file him so they don't have to see his rants, not go
looking for it!

Trevor.

[Arny Krueger[_4_]]

"Trevor" wrote in message
...

"Peter Larsen" wrote in message
k...
I'd get the Phil Allison designed kit if in diy mood, my gamble
would be that it is worth buying unheard and unbuilt.

What on earth makes you think that? You just like to gamble? :-)

Well, erm, I like to win and electronics design is not a social skill and
the guys electronics skills appear to be in reasonable regarded. Read up
on the thing, there's some website downunder selling the pcb or kit,
google knows where.

Phils reputation is well known on usenet. It wouldn't inspire me to gamble
when there are circuits designed by qualified engineers with real
experience readily available.


Phil's technical work is IME generally very good. His affect problems are
legendary, partially because of the excellent technical work. His personal
situation should be apparent to anybody who follows him for long. If you are
familiar with that malady, his excellent technical performance on good days
should be no surprise.

The good thing about the so-called "Phil Allison Mic Preamp" is that there's
a reliable buffer in place called Elliot Sound Products. The biggest
problem I see with the http://sound.westhost.com/project66.htm mic preamp
project is the absence of phantom power. That makes it impractical for use
with the mics that have been mentioned on this thread and the majority of
mics that it is likely to be used with.

The other mic preamp kit that has been mentioned on this thread looks very
practical, in contrast.

[Phil W[_3_]]

Arny Krueger:

The good thing about the so-called "Phil Allison Mic Preamp" is that
there's a reliable buffer in place called Elliot Sound Products. The
biggest problem I see with the http://sound.westhost.com/project66.htm mic
preamp project is the absence of phantom power. That makes it impractical
for use with the mics that have been mentioned on this thread and the
majority of mics that it is likely to be used with.

Well, there are still in-line phantom power supplies for such situations.
Never having needed (and consequently used) one yet, I can´t comment on
possible effects on the sound or introduced noise. I only know, these things
exist.

Anyway, there are enough recording situations, where a dynamic mic is a good
choice. Besides that, there are condensor mics, that take batteries and
don´t need external phantom power... or tube mics, that have a dedicated
power supply anyway. ;-)

[Les Cargill[_4_]]

Phil W wrote:
Arny Krueger:

The good thing about the so-called "Phil Allison Mic Preamp" is that
there's a reliable buffer in place called Elliot Sound Products. The
biggest problem I see with the http://sound.westhost.com/project66.htm
mic preamp project is the absence of phantom power. That makes it
impractical for use with the mics that have been mentioned on this
thread and the majority of mics that it is likely to be used with.

Well, there are still in-line phantom power supplies for such
situations. Never having needed (and consequently used) one yet, I can´t
comment on possible effects on the sound or introduced noise. I only
know, these things exist.


I cannot imagine them being anything but 100% transparent. Don't know if
this is typical, but it's 3 to 3, 2 to 2 and 1 to 1.... just add DC.

http://www.new-line.nl/?i=61

Anyway, there are enough recording situations, where a dynamic mic is a
good choice. Besides that, there are condensor mics, that take batteries
and don´t need external phantom power... or tube mics, that have a
dedicated power supply anyway. ;-)




--
Les Cargill