Secret project (Svart AD/DA converters)

semi gloss adds depth but doesn't look plasticy ?

The operational maximum for the AD4898 is +/-16.5V.  I'm running them at +/-15V, for about 0.3dB difference in output.  Mainly you are looking to operate any opamp close to operational maximum, but not use 100% of the voltage swing, or else you risk losing headroom and slew during large signal excursions that would exceed the current of the part and cause voltage sag.

While decoupling will bolster the current up to the part, the part itself can only draw so much current into itself. It's much harder to quantify this amount, as the datasheet only specifies a steady-state amount, usually at a single frequency to boot.  Once you get multiple signals or a fast, modulated signal, this current measurement can change pretty drastically depending on the frequency.

In RF terms we call this IP2/OP2 and IP3/OP3, or 2nd and 3rd order intercepts.  This roughly translates as you put in two tones (sine waves of different frequencies) and jack their levels up until the amplifier starts to compress(saturate/distort) and you'll see harmonics(if you are looking at a spectrum analyzer) or squaring of signals (on o'scopes) due to the headroom of the amplifier being used up.  Of course, the higher the levels before the amp distorts, the better.  

This is why most RF amplifiers are current driven parts.  Almost all small gain blocks and LNAs are class A devices and run on a specified current.  Even at idle they draw the same amount of current!  This keeps crossover distortion from happening, but overall it specifies how much signal you can put into and out of an amplifier at any given moment in time.  The voltage on the input of these parts can vary as it's usually drawn through a series RL circuit to match impedance.

Voltage driven parts (like most opamps) have a steady voltage rather than a steady current, and the current can vary.  Voltage ratings can give you a view of the possible headroom, but don't give you a view of the useful power of the amp before clipping happens.  Thus, most designers who use opamps generally shoot for a max operational signal level a couple volts below maximum operating voltage, to ensure that even under the worst cases, you don't stress the part by demanding currents exceeding the opamp's ability.

If you wanted to test this, get two signal generators and set one for like 30hz, and another for like 15khz.  Combine both through a resistor combiner, and then increase both equally into an opamp while watching the opamp's output.  You'll eventually see the low frequency signal increase while the high frequency signal will either stop increasing, or start to decrease and harmonics will come out of the noise floor, showing that the opamp is now failing to draw more current and is starting to saturate.

it's interesting stuff, and there are whole branches of engineering that deal with these kinds of things, especially in any kind of transmission/reception and/or test and measurement fields. 

There's a drug for that.

Volatagra and Slewalis right? If you have a rectification lasting more than 4 hours, call all your friends and post a pick on the net 8)

Color leave it silver as your pics above and as someone else posted just put your logo on it, plus RGO speedwagon.

Great idea

cheers

Wiz

Yall mugs be trippin.

So some small updates..

I was out of town at a surprise funeral over last weekend and half of this week, so I'm behind a few days on the project.

I'm working on the finish work for the front panels (prep and paint).

I'm also waiting on the silkscreen stuff, which was supposed to be done a couple weeks ago, and is still not done.  I've been promised it would be done this week..  We'll see.

I'm working on the last 3 DAC boards for the build.

I've also decided to adjust the LPF on the input to the ADC slightly to gain slightly better flatness.

Okay so please forgive me if I missed it but I haven't seen it really answered anywhere in this thread and have been following it for a little while, and I'm in the market for higher quality adda and so:
Will you be making this available to purchase anytime in the near future?
If so do you plan on releasing this as custom one-offs or do you have plans to have them assembled somewhere?
And finally do you have an idea (around) how much?
It looks good Svart.