2. amps-preamps
  3. 1112986739

OP AMP Capabilities in Supporting 24 bit bandwidth

Hello Everybody

Iam in the market in search of a Minimalist Preamp and got pulled towards Morrison ELAD, I saw this piece of message in Don Morrison Website:
(The most important thing about it is that its circuitry is designed around the Analog Devices AD797, a highly advanced op-amp made with a fully complementary IC process. This complex device, consisting of 60 transistors, settles to a full 16-bit resolution in under a microsecond, has a noise spec equivalent to a 50-ohm resistor from 10 Hz to 1MHz, and achieves lower THD + N levels than any discrete audio circuit that has come our way. The preamp consists of two AD797's with associated circuitry - including separate volume controls for each channel)

Looks like it can handle 16 bit resolution at ease, but, how about handling higher bandwidth signals at 24 bit resolution?

Any advice is highly appreciated.

Thank you

sivamayam
eldartford
4,262 posts
 
The dean of the mechanical engineering school where I went told us that the final exam would be to design a ten ton crane hook, and stand under it as full load was applied.

For most things, worst case analysis is not conservative enough...a "safety factor" is added. However, sometimes you must go with something less than worst case, so that a failure is not impossible. The best example of this that I know is the plumbing of a multifloor apartment house. You simply cannot design for the situation where every toilet in the building is flushed at the same moment. Few airplanes have the structural strength to withstand aerodynamic forces that the pilot can easily cause by manipulation of the controls. (And I fly to Arazona tomorrow).
eldartford
4,262 posts
 
Sean...And to lower the tone a bit further, consider the design of residential sewage disposal fields. For ages everyone designed for "worst case" and then made it larger for "good measure".

Turns out that an oversized field is a bad idea. Parts of it will dry out, and the microbes that break down the sewage will die.

In audio (remember that) I once thought to improve a regulated power supply by adding capacitance. Bad idea. The regulator became unstable.

So I guess that every situation must be understood and accomodated in the design.
,
sean
6,229 posts
 
I agree that everything has to be factored in. Then again, if EVERYTHING is built "gonzo", nothing is left to go wrong : )

As to regulation circuits, most are piss poor. This is why there is a lack of dynamic headroom in regulated amps. That's because the regulation circuit is both too small and too slow to pass the necessary amount of current that the circuit requires on a dynamic basis.

Since the entire amp would be pulling juice through the regulation circuit, the regulation circuit itself should be sturdier with more capacity than both channels of the driver and output stages combined. I've never seen a regulated amp built to anywhere near this level, let alone heard anyone ever discuss such things. Sean
>
e3po
2 posts
 

If you are not happy with AD797 opamps, try LME49990.

ref:

http://www.analog.com/static/imported-files/data_sheets/AD797.pdf

http://www.ti.com/lit/ds/symlink/lme49990.pdf
e3po
2 posts
 


FYI:

http://www.eetimes.com/document.asp?doc_id=1278805&page_number=4
More to discover