Re: op-amps with wide open-loop bandwidth ?

Dave Moore wrote:
"Kevin Aylward" <see_website@xxxxxxxxxxxxx> wrote in message
news:s5fTf.224999$YJ4.60901@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
Dave Moore wrote:
a slew insults to go along with the mistaken presumptions.

I read your other replies in this thread, so I didnt make any
assumptions. It appears that you belive that having an open loop BW
at least equal to the audio BW is nessesary/advantages to get a good
sound.


No, I don't believe that at all. I do believe however that in
spite of what some so-called experts may say and in spite of
(what are often flawed) studies that it *might* be a factor
that bears looking into. It does seem to me to be of interest
that out of all of the opamps I have on hand, the two that
I like the best (THS2052 & THS2022) just happen to
have open loop bandwidths in excess of 20KHz


My guess is that in AB blind tests, *you* cant tell the difference. Its
that old delusion bit. One lies to oneself. You have an agenda that you
want to purpetuate.

"A good scientist tries to find evidence to support his theory, a better
scientist tries to find evidence to contradict his theory" - R. Fynmann.


This is very unlikely. All the open loop
gain that is now thrown away at the lower frequencies, can now no
longer be used to reduce the distortion at those frequencies. It
always pays you (distortion wise) to have as much loop gain as
possible over the widest frequency range.

Of course, if the amp is slewing prior to the audio BW, then...


What you're saying is right in line with my observations about
the THS2052 and the THS2022. They both have the same
open loop corner of abot 50KHz but THS2022 is the better
sounding of the two

I dont belive you.

and it does indeed have a higher open
loop gain and higher gain bandwidth product.



And no, I am not making any assumptions about whether
all engineers are the *real* audiophools. I'm quite open minded.
And I ususally believe that people have valid reasons based
on their experiences for believing the things that they do.
One scientist looking at one set of data will draw one
conclusion whereas another studying the same phenomena
with a different but contradictory dataset may draw a
completely different conclusion. In the end perhaps a new
conclusion is reached due to the controversy and everyone is
happy as they were all proved to be right.

Sure, but this open loop BW thing is a no brainer. Its not rocket
science. By itself, the open loop BW is not relevant. Its not
debatable at all. Its all very well understood.

Let's just say that it's bvelieved by some to be very well understood.


No. It is indeed completely understood. Period.

Very few physicists argue with the
general theory of relativity, and damn less qualified EE's argue
about the properties of correctly designed feedback amplifiers.


I suppose that depends on ones definition of a "qualified EE"
When it comes to guitar amplifiers, IMO a qualified EE would
be one that isn't tone deaf.

I'm and EE, and not tone deaf, I play guitar, and furthermore I have
actually got pro audio designs out there.




For example, some
actually have extensive professional experience in analogue design
and pro audio, from both a technical point of view and as a
musician. Some of these, after such extensive study, indeed
conclude that it there is no reason to listen to an amplifier in
order to design a straight piece of wire with gain. Its purely a
technical issue based on gains, distortion, bandwidth, noise etc.

The fact that I'd rather prove this to myself doesn't mean that
I don't respect the opinions of others. However there's a bit more
to this story that might be of significance if anyone cared to find
out first before popping off a few rounds and asking questions
later.

The issue here, is that I have heard all this before from endless
numbers of people.

Where there's smoke there's usually fire.

Nonsense.

Like, tea leaf reading, UFOs, astrology, thor, pixies, scientology
...yeah, get real mate. Life is full of vapourware.

People usually have an axe to grind and therefore invent all sort of
nonsense.



You have said nothing new. Its already a dead
subject. You jsut are not aware of all the prio art on this matter.

I am aware however of my own experience which means more
to me than any "prior art". There was also at one point in time
plenty of prior art on the subject of why Solid State amps
were an improvement over tube amps. As it turned out,
those that weren't tone deaf weren't fooled.

Again, complete nonsense. Sure, *some* people used to design *** SS
amps, just like some still design *** tube amps.

Look, you out of your depth. I would like to say this without it
sounding like a personal insult, but I just don't know any way to say it
differently. You just know what you talking about.

I have been designing amps for 30+ years, been playing guitar 30+ years.
I



I'm working on more than one front at once. Besides design,
I also do repair and upgrades for a select handful of musicians.

With all due respect, what this tells me is that you are really a
hacker/tech, not a qualified EE. You dont know what you are really
dealing with.

With all due respect, you're response tells me that you are
a presumptuous arrogant snob.

I am someone who has been there. Sorry if it comes out as arrogant, as
noted, its just about impossible to tell someone that they are truly out
of their depth without sounding insulting. Its trivially clear that you
just don't have the technical background to understand why you are
actually wrong. I wish it were different, believe me.



Sure, when I was doing my degree I used to suplement my grant (UK) by
doing repairs for a music shop. However, like, I'm going to do
physical work with that sort of stuff for other people 25 years on?

You don't understand that a "handful of select musicians means
friends of mine? So you're in essence too full of yourself to help out
your friends ? Just as I thought, an arrogant snob.

Too busy. I have a life.



However... A few weeks ago I did purchase a Marshall AVT150 combo.
The bloody fools have an effects loop that is not inline. This means
a volume pedal, or even a phaser won't work correctly. So, I emailed
for the circuit diagram and modified the effects loop to work
correctly. It even had an irritation of having the clean channel
with significantly more gain then the distortion channel, making it
hard to get maximum volume from the distortion channels when
switching. So, sure, I fixed the gains. But this is all for me
personally.


Yup, a selfish *** that'll help himself but not a friend,

A friend in need... is a pest,.. get rid of him.

Fortunately, I don't have many friends, so I don't have much of a
problem in being selfish that way.

Oh... by the way you need to understand just what selfish
means...http://www.anasoft.co.uk/replicators/altruism.html



In some cases an upgrade might entail something as simple as
swapping out the opamps in a unit. Under these circumstances
there is indeed a quite noticeable difference in the sound from
one opamp to another.

Maybe for a 709 to an op-37, but in general, little chance of hearing
any difference. Been there mate.

Kevin, with all due respect, yer an idiot.

Oh...?

http://www.anasoft.co.uk/band/bio.htm



Also, in the years that I have been
doing this I have noticed (as well as the musicians themselves)
very definite characteristics that always follow one particular
opamp around regardless of which piece of gear it is plunked
into.

Anecdotal meanderings. AB blind tests invariable show that this is
all wishfull dreaming.

Better for me. As I said in another post, tis why I got the gig with
the celebs

Oh...an argument by apeal to authority just dont wash mate. "Celebs"
have no more value to to the truth then a street sweeper.

and tone deaf arrogant snobs such as yourself are
relegated to hyping their technical prowess in newsgroups

Yeah, well no ones perfect.



As I suggested, been playing guitar and messing with electronics
audio both since I was 11. I'm not deaf,

How would you know since apparently you've been
tone deaf from the get go

In other words, you can see invisable men.


yet, so If there was any truth to
this sort of stuff, trust me, I would have discovered it. I actually
used to believe this sort of drivel until I *really* looked into it,
in detail.

Which involves just what exactly? Actually experimenting
or reading about some possibly flawed studies?

Building up more audio bits and peices than you have had hot dinners.
Look, I got my first electronics kit at 11, the same age I started
playing guitar.

For example, one of the bull*** golden ears claims is the ability to
detect small static phase shifts. Yeah, so like I never built up all
pass filters to test this sort of nonsense?

Flawed studies? like rigorous double blind tests on amplifiers.
Yeah...I'm that daft.




Ok, so I suppose someone is going to say at this point, well
of course, because the opamps are being plunked into networks
designed for other opamps. Let me address this. Firstly, sometimes
it's not possible to get a schematic on a particular piece of gear.
Also, often there is a diminishing point of returns to attempt to
trace and draw out the schematic or reverse engineer the circuits
from the PCB's themselves. So, the 'plunk in' option proves to be
the viable alternative

Sure, some opamps might actually oscillate at VHF in the wrong
circuit.

I always check for oscillations. If the opamp is oscillating, I either
compenstae it properly or rule it out of the sonic signature
observation list.

Oh dear...my usuall quote.

"Those that use 'sonic' in their audio phrasing are usually pretentious
twats, using 'sonic transparency's removes all doubt.

Look mate, what's wrong with "audio signature"?

This entailed yanking the the NE5532 on the front end and
replacing it with a THS2052 and yanking the NE5532 on the tail
end and replacing it with an AD828. The result, (in guitar terms)
much more detail & clarity on the high notes and much improved
tightness and bounce on the low notes. OK, so now the A/B
test.

Quite frankly, I dont belive you.

You are obviously confusing me with someone that gives a rats ass


Then why reply to this post?


Put the NE5532's back in. Sure 'nuff. The sound is muddy
again and it's difficult to pull out the low notes whilst finger
picking.

I don't believe you. I have done these sort of tests ad-infinitum.

perhaps it's time to try them again with some of the opamps
I've listed and in the comapny of someone that isn't tone deaf.

Yeah, yeah, yeah....






So, next up, trying the unit with a number of different opamps with
'better spec's' than the NE5532's Result, all combinations produced
better sound than the original 5532's as well as imparting quite
predictably whatever flavor or characteristics I have observed
to follow each particular opamp as they have been plunked
into various units over the years.

All anecdotal meanderings. I have done the same, and it is in stark
contrast to your claims. What's more, pro double blind tests on these
*type* of tests *always* show no differences.

Well, the guy who happens to own this equipment has perfect pitch

Physics impossible.

and was voted by his guitar playing peers in New Orleans
to be New Orleans best guitar player which is no small feat
considering that New Orleans is somewhat of a Mecca for
exceptional guitar players.

Oh dear....your serious?


I've have given him on numerous
occasions the option to choose his own opamps and capacitors.
I never make any suggestions in advance.
He invariably makes the same choices that I do. It's to the
point now where he usually just says " go ahead and make
the choices yourself, I trust your judgement"

As far as I'm concerned, your so-called pro double blind
tests are anecdotal.

Your doing yourself a disservice.

I'l go with what I can hold tangibly in my
hand thankyou very much.

So, you're wanker, whats new?




In the end I settled for the
two opamps that I predicted would probably best complement
the unit being that of the opamps I currently have on hand, they did
just that, they best complemenbted the unit. So riddle me this. Hoiw
did I know in advance that those two opamps were probably going to
win the contest.

I suppose you also believe in fairies, palm reading, thor, tea cup
reading, astrology?

No, I believe in the responses I get from the small handful of
exceptionally gifted ( non-tone deaf) professional musicians that
I deal with and tangible empirical results that I can prove for myself

Yeah...




I've also sat down with various musicians and let them decide
which opamps they best like when plunked into their gear.
9 times out of ten they choose the same ones that would have
chosen.

I dont belive you.

again, better for me


And this is without any pre-suggestion on my part.

So, as you can see, under these circumstances I have very
legitimate reasons for wanting as large of a pool of spec-varied
opamps that I can get my hands on and taking notes on just
what sonic characteristics tend to follow them as they're
plunked into one pice of gear after another.

I think you are simple deluding yourself. A shame really. You sound
as if you could be more objective.

You say that you don't believe me and I'm speaking the truth
so as far as I'm concerned, you're the one that's not being objective.

No, your deluding yourself. You don't have the background to understand
just how and why you are obtaining erroneous results. Again, I wish it
were different, but it aint.


So let me ask you this, would being objective entail discarding
all of the tangible and empirical results that I've accrued

Yes. The reason is that your "empirical" results disagree with credible
pro test results. Your lying to yourself, yet don't realise it.





Sure to design a tube distortion
circuit does require listening to it, but thats irrelevant to the
design of the actual amplifier circuits.

I agree. When I design, I start with as clean of an amp as I can
and dirty it up from there. And when it come to designing a "clean
amp" I truly do respect the skills of the more advanced engineers.
But even here, since there is in reality no such thing as an ideal
opamp, the issue becomes just how far which spec's need to go to
dissappear coloration.

As far as an audibly a straight piece of wire with gain, many op-amps
are indeed ideal. You have probably been listening to 741s running
at a closed loop gain of 100, where sure, that may well be a
problem. Modern op amps are audible perfect. Thats just the way it
is despite all this golden ears nonsense.


Try
THS2013
THS2062
THS2032
THS2052
THS2022
AD826
AD828
AD829
AD843
LM6172
LM318
OPA2228
OPA2604
OPA2134
OPA275
LT1208
LT1363

running at closed loop gain of 12
and at small enough signal levels where
slewing shouldn't be a factor and also in inverting
mode where differential input errors are reduced




And this opens up another debate about how
sensitive the ear is to coloration. My conclusion is that the
coloration threshold is probably different for different people.
Most of the more accomplished and talented musicians that I've
worked with seem to have an extraordinary ability to hear subtle
nuances.

They certainly claim they do, but in actual tests it all disappears.

Not in the actual tests that I have done.
And none of my musician friends have made any such claims.
They're quite humble about their abilities.
But I have noticed these abilities in them and it's probably
the reason that they've gone pro whereas the more tone-deaf
such as yourself have opted for careers in electronics.

Get bloody real mate. You just show how out of touch with reality you
are. Success in the music busines has f'all to do with musical ability.
This is trivially obvious. There are like 100,000s applicatnt for every
music "position". Clever peaple take life options that give them the
best chance of success, rather then bask in pathetic dreams... I can
tell you I make way, way more money in my day job as an analogue i.c.
design engineer then millions of wanna be guitarists.

How you can claim what you do above is beyond belief. I no longer have
any more time for your delusions.

{snip unread stuff}

Kevin Aylward B.Sc.
431infoEXTRACT@xxxxxxxxxxxxx
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

"There are none more ignorant and useless,than they that seek answers
on their knees, with their eyes closed"


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