Super Op Amp

[LoKi6922]

Man that sucks, this is widely accepted as the best opamp replacement:



Vacuum tube forevah!!! :lol:

holy cArp! that thing is fishin' enormous!

OMG post soundclips pleeeease!!

:lol:

of course, i keed... i keed.

:lol:

[puretube]

no clips, but schemo:

[lovekraft0]

Looks and the pungent scent of snake oil aside, wouldn't that unity gain bandwidth make it prone to RF oscillation in some layouts, making this somewhat less than optimal as a drop-in replacement?

[Sir H C]

I would guess it is a video op-amp.  Those are the ones that get the high slew rates like that.  Also they suck for audio since they have very low overall gain so you get very poor linearity.  Notice that is one spec that is not listed for the op-amp.  Also the slew rate doesn't match the unity gain bandwidth.  Another big issue is what is the supply that it can work on, most fast op-amps like these are in small geometry processes and don't work well with a +-15V rail some audio equipment might use.

I would think this op-amp would sound like crap in most applications, especially since it is a dual op-amp and if you really are going for max quality you would want separate ones to reduce crosstalk.

[LoKi6922]

no clips, but schemo:

is that thing for real? i actually thought it was a joke...  :?:  :shock:

[soggybag]

I think this super op amp is bogus. I have never heard of Burson audio. I googled and found nothing but the Ebay listing and some talk on a forum somewhere.

[H.Manback]

I would guess it is a video op-amp.  Those are the ones that get the high slew rates like that.  Also they suck for audio since they have very low overall gain so you get very poor linearity.  Notice that is one spec that is not listed for the op-amp.  Also the slew rate doesn't match the unity gain bandwidth.  Another big issue is what is the supply that it can work on, most fast op-amps like these are in small geometry processes and don't work well with a +-15V rail some audio equipment might use.

I would think this op-amp would sound like crap in most applications, especially since it is a dual op-amp and if you really are going for max quality you would want separate ones to reduce crosstalk.

Do bear in mind that the one I posted a picture of at least was before opamps were available in solid state electronics. Of course you don't really want to use that one :wink:, the picture just came to mind with this idiots super opamp. I mean if you want to go with mojo bullshit, why stick to an IC?

http://www.uoguelph.ca/~antoon/gadgets/741/741.html

At the left you see a picture of a K2-W tubes general purpose computing Op-Amp from George A. Philbrick Researches. This type was first introduced in 1952, more than a decade before the first transistorized version. The op-amp is shown with and without its bakelite shell. What a beauty! The first solid-state monolithic op-amp, designed by Bob Widlar, offered to the public in 1963 was the µA702 manufactured by Fairchild Semiconductors but it had very weird supply voltages such as +12 and -6 volts and had a tendency to burn out when it was temporarily shorted. Despite all these little shortcomings this device was the best in its day. It contained just nine transistors and sold for about $300.00 US which limited the sales to the Military and Aerospace consumers.

[Vsat]

There are other op amp parameters that are important to audio besides the few mentioned in his auction. Also, there  are schematics on the net for some very high-performance discrete or semi-discrete op amps. Maybe it is based on one of those. Epoxy-block hybrid op amps were commonly used up to the early 70's, when the available IC op amps didn't offer as good performance. Probably nothing new there at all. SMT would certainly make it easier to build a good discrete op amp in a small package.
Mike

[Peter Snowberg]

no clips, but schemo:

is that thing for real? i actually thought it was a joke...  :?:  :shock:

Even more real than real.


http://www.analog.com/library/analogDialogue/archives/philbrick/computing_amplifiers.html



the link in the lower right will download the whole 75 megs (!) of PDF.

Get the whole thing TODAY!

[Sir H C]

There are other op amp parameters that are important to audio besides the few mentioned in his auction. Also, there  are schematics on the net for some very high-performance discrete or semi-discrete op amps. Maybe it is based on one of those. Epoxy-block hybrid op amps were commonly used up to the early 70's, when the available IC op amps didn't offer as good performance. Probably nothing new there at all. SMT would certainly make it easier to build a good discrete op amp in a small package.
Mike

THe slew rate kills me.  That is why I can not imagine a discrete op-amp.  In general, discrete ones have larger parasitic capacitances.  To slew 2500 V/uS as this one does with a 10pF capacitance at a node, would be 25mA, quite a slame with such a small (for discrete) capacitance.  Go to Analog Devices, Maxim, and TI/Burr-Brown and see what they have similar.  For that slew rate, it is video amps.   I can not imagine Joe Blow designing this when these companies have not.

I have designed several IC op-amps over the years and can say that what they say about it suggests that they are hiding the major problems.  I would love to see someone delid this and see what is inside.

[moeburn]

Uh, guys, you can get TWICE that bandwidth and a better slew rate by adding a $6 buffer after your opamp.  

An OPA624 buffered by a BUF634 for $7 has the stats to beat this $100 opamp.

[puretube]

no clips, but schemo:

is that thing for real? i actually thought it was a joke...  :?:  :shock:

http://www.electronicpeasant.com/circuits/circuits.html
scroll down to: "Data Sheets", to get the manual... (thanx, Jered)
(for those that don`t download Peter`s 75MB link - thanx, Peter: got it!)

IIRC, Z.Vex firstly introduced this opamp to the forum...

[puretube]

http://www.national.com/rap/vacuumtubes.html

[Sir H C]

Robert Pease who worked for Philbrick back in the day and was under Widlar who I think designed that op-amp talks about it regularly in his columns in EDN.

[puretube]

http://diystompboxes.com/sboxforum/viewtopic.php?t=35264...

[Mark Hammer]

At the risk of sounding like an apologist, let's dissect this a bit and try to disaggregate the various aspects.

1) Do all audio-related circuits benefit from component-level improvements the same way?  No.  Far too many here who are accustomed to the kinds of component swaps that make (or don't make) an audible difference when using single-source/low-bandwidth signals going into deliberately unresponsive speaker systems are too ready to pooh-pooh something intended for an entirely different application.  *Our* preferences for op-amps in pedals headed for 12" limited-bandwidth speakers are part of an entirely different universe than someone attempting to process very wide bandwidth acoustic jazz headed for an electrostatic array.  Application matters.  Even if one accepts that premise, though, at a certain point, one reaches a zone where it takes a huge investment to realize an audible improvement.  I strongly doubt that subbing this little can in place of the op-amps in my $100 DVD player is going to yield huge benefits when the sound finally hits those cheap little plastic speakers and bargain basement subwoofer.  In other words, the remainder of the signal path has to be of a sufficient quality to realize whatever advantage can be gained earlier in the signal chain.

2) Component selection requires an inventory whose cost must be defrayed.  Obviously the can and epoxy hide some sort of closely-guarded combination of components.  It may well be that the performance specs shown (and, in deference to Mike's point, perhaps some other specs of greater musical relevance which are NOT shown) require some sort of hand matching or selection of components, and the purchase of larger quantities of primary components for this hand matching.  Whether the time required, the instrumentation required to assure level of matching or quality control in selection, or the inventory required for "picking the best", it all yields cost to the manufacturer, and those costs have to be met before profit can be realized.  If it was the case that the entire process was automatized, the die was available, and one could sell tens of thousands, conceivably the price would be much cheaper, but while the whole thing is done by hand it is going to cost more.  And yeah, it IS entirely possible that the height of the can suggests some complement of components which isn't in there, and the whole thing is a scam, but I'll assume for the moment that the person is honest

3) Expensive and inexpensive components can be matched on a lot of things except for what "matters".  There is only so far you can go in explaining why recorded sound sounds "different" than live sound by appealing to the traditional measures.  Once you've exhausted all the known specs, you're still stuck with the fact that X sounds better or more realistic than Y, and you don't know why.  Again, to return to Mike's point.  It is entirely possible that, despite whatever else on the market can meet and better the specs shown for a fraction of the price, the things which are not shown, or perhaps not even agreed upon with respect to standardized measurement methods, are the source of any audible improvements.  So, yeah, there can be some absolutely incredible op-amps for under $10 out there, and yeah it is entirely possible that whomever designed or listened to the can op-amps up for auction is a little misled or seduced by the power of suggestion, and they really are no better than readily available high-end op-amps from the major production houses, but again, I will give the benefit of the doubt.

I'm the first guy to admit that audiophiles sometimes can be but mere inches away from being Nike-wearing, poison Kool-aid swallowing, cultists.  But I've seen weird stuff that I couldn't explain make a difference, and I've seen/heard huge advances in sound reproduction quality over the last 40 years, and remember only too well how exotic a term like "slew rate" was for the audio community in 1976.

Of course, all of that is separate from whether the vendor is asking a fair price for what they offer, but I'm open to the possibility that it is.  How the hell I'd fit those on a board that would slide under my pots in a 1590B is another matter, though..... :lol:

And, uh, in case it crossed your mind that the person selling them is also named Mark, it is definitely NOT me.

[moeburn]

Actually, mark, I found that the headphone-amp's opinions of various opamps apply to guitar-related circuits the same way.  IE: Most say to go for an OPA624 in a headphone amp for the best sound, and most guitarists say to use a 4558 in a screamer for the best sound.  Turns out a dual OPA624 sounds even better

[moeburn]

With these, you could build the tallest pedal in the world!

[puretube]

LM7372
120MHz
3000V/µs
50ns
+/12V outputswing @150mA
$1.98

[Paul Perry (Frostwave)]

I'll assume for the moment that the person is honest.

Generous as always... but, I'm afraid he's on the cable caper as well :roll:
Incidentally, he's from Melbourne Australia, same as me.. but, he ISN'T me!!
So far a specmanship is concerned, puretube has the last word.