Re: For all the group

I already added you to the "good guys" column ;-)

I'm sure it's noise related, and thus depends on the configuration... resistors; type: charge redistribution, current-steering, etc.; device types: BJT or MOS....

...Jim Thompson

If you want to be a tight-ass (or smart-ass) about terminology, there's no limit to _resolution_ -- how many useless bits do you want, though?

The limit to the useful number of bits in current-day converters seems to be noise dependent.

Monolithic 16-bit converters that sample at 100ksps have about 1-2 counts of RMS noise -- this means that your output number will routinely vary by four to eight counts from nominal. This can be leveraged, however; if you have the processing power you can sample up to the speed limits of the converter then average down to your desired 'actual' sample rate you get a nice anti-aliasing filter for closed-loop control, and considerably more precision (if not accuracy) than 16 bits.

Ditto for 14-bit monolithic converters sampling at 40MHz, with perhaps more LSB's of RMS noise.

I suspect that you could do better with a hybrid converter, but I'm not Jim, so I don't know how much better, or how far you'd have to move heaven and earth to keep the critter in production if you did.

If your process is slow you can get 24-bit sigma-delta A/D converters that sample out at 60Hz. I suspect the same (or perhaps only slightly better) noise spectral density as the above converters, but I've never done the math (it'd be interesting to do so).

Yes, I mixed resolution and accuracy :-(

And I agree with "how many useless bits do you want?" But I'm sure the Monster Cable crowd can "hear" the difference ;-)

Once upon a time, there was a plane called the L1011 (IIRC). They thought they needed a 16-bit DAC for the seat audio system. I demonstrated an 8-bit resolution plus 8-bit "gain-rider" that sounded great and was CHEAP, but they opted to spend a lot of money.

Marketing people have no brains ;-)

...Jim Thompson

No. You're a goddamned aioe retard.

YOU of all people should be complaining the most about the bullshit the admins at your selected service provider pulls.

The 1011 is a very nice airplane.

I married one with brain :-)

I wish they'd invest the savings in better headphones. Just came back across the ocean on American Airlines and their new "stick-in-the-ear" thingies are horrible. THD was about 90% on both long-haul flights, you had to crank it to max volume to hear anything. Terrible.

I made up an adapter to allow me to plug in my over-the-ear phones ;-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

Thus reducing the number in the workforce with brains by one.

Gee, THANKS A LOT, Joerg!

:-)

On a sunny day (Tue, 18 Mar 2008 10:45:37 -0700) it happened Joerg wrote in :

I stole a little adapter plug, and the seats work on my own headphones.

Yeah, I am going to buy a pair. Right now I only have the monstrous pilot's version with mike and all that, plus a Sennheiser HD480 but the foam pads on that one have crumpled away :-(

I guess the drivers in the airplane arm rests would be able to drive the usual lowish impedance. What is nice is the monitor in the seat and the selection nowadays. They had five movies and two of them were really good. The food on the return trip was quite good, the departure food wasn't.

It was my very first contact into marketing after I had my degree. She had to test our design and I could not concentrate on taking notes ...

Resulted in marriage and we are still married ;-)

It looked like normal 3.5mm stereo plugs to me. Heck, they even had a removeable remote in the seat and if you turned it around it became an in-flight telephone with credit card slot. It was a Boeing 777.

A few hundred rapidly shrinking greenbacks will get you a nice pair of Bose noise-cancelling 'phones. Best regards, Spehro Pefhany

On a sunny day (Tue, 18 Mar 2008 11:14:30 -0700) it happened Joerg wrote in :

I just found it again, it is actually 2 mono 3.5 mm at about 12.5 mm apart, with on the other side a stero 3.5 mm that your normal haedphone fits into. You could make one from 2 mone male and one stereo female. This is for the 747.

They offered noise-cancelling ones for $65 from their duty-free but probably not Bose. Hmm, maybe the horrible "ear pieces" do foster duty-free sales ...

That was the really old style, right after those PVC-tubing concoctions. Probably so people would not take the headphones home. Now they are

That's what I did... stole the cheapy in-ear headset, and made an adapter out of it ;-) Mine can do single or dual-plug seat jacks.

...Jim Thompson

FWIW, Sony has some out now that work pretty well and aren't nearly as expensive as the Bose. They come with plug adapters for airlines, too. Needed to get a set for the office, working around some noisy gear.

Easy to buy for < $10 in a single molded unit. Included with most noise-cancelling phones I think. Best regards, Spehro Pefhany

Do you know the type and who carries them?