The quietest audio op-amp with ultra-low THD

Speaking of dirty... I'm waiting for the marketing types to sell some super-expensive cans of compressed air to clean out heat sink dust.

Improve heat transfer! Make your heat sinks sparkling clean with AudioPhool(tm) Compressed Air! Crisper highs! Tighter Bass! Make your power transistors happy! Give your electrons a bath! We blow away the competition! (in cubic feet per minute that is)

Michael

I've just done a deal with the LHC at Cern, I'm buying the stripped off electrons from the ultra fast protons that they use in round thing.

How should I package them?

martin

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Dave Dearden, that name rings a bell. I jumped ship to Brit Row around

1. It was mental at Midas then, bank holding the purse strings, full order book but no cash flow. Pro40 was crazy, so much more electronics crammed into the same old Pro4 frame, Geoff just wouldn't contemplate having a larger frame. They got seriously hot.

les...

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Dave Dearden... Many Confused Individuals (MCI consoles). them where the days, when SMPTE timecode was new

martin

Those need to be transported in a humidor :-)

Ever time I hear the word "Humidor" I think of a Belgium dude, Hercules Parrot, and over-acting, and an authoress who had a hangover and went missing for a couple of days, and made the UK "Daily Mail" headlines( maybe)

martin

When we did a re-furbishment at my local venue last year we blew them out with compressed CO2 that they normally use for pressure delivery of the beers. Did a fantastic job. Make a few people quite dusty though.

Graham

there ?

That's the feedback resistor value in an inverting summing amp thay may be fed from up to 32 sources simultaneously, giving an Rin of 400 ohms approx.

Just done the sums. Does anyone want to slap me round the face with a wet fish ?

I make 400 ohms 2.6nV/sqrt Hz ! I wasn't expecting it to be that noisy. I didn't mess up did I ?

Graham

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Tech Director then of DDA that had just merged with Klark Teknik. Now in the same poition at Audient. He was with Soundcraft previously. I worked alongside him for a while in design.

Weren't XL's being shipped then ? That's where it seems it all went wrong.

I can recall seeing a heatsink drawn on one schematic of theirs !

Graham

You know I interviewed for a post at Midas once. Would have been around 1980.

I don't recall the names now but would Geoff have been the tech bod ?

I took down some of my work to show him including a pcb layout and an actual pcb IIRC. Do you know what he said ? He said I should start up my own business !

I simply wasn't financially in that position, having lost my parents at age 14 and 18 and gained a truly evil (wanted to be a black witch) stepmother. Had my father still been around I have no doubt he would have backed me. He was that kind of guy. It's so sad both my parents had to die so young, both from cancer.

So there you go. Maybe if Geoff had taken me on. I'd be running Midas (at least as tech Dir) now !

Graham

Martin Griffith wrote:.

Maybe Dave was with MCI before Soundcraft ?

Taling of SMPTE etc, do you remember Audio Kinetics and their synchroniser / locators ? I worked for them for a while too as a summer holiday job when I was at college.

Graham

locators ? I

Yep DD was with MCI with another guy called bernie. Qlock , strange company, badly organised. Lot of systems, walked out of the backdoor, as spares. Opposite side of the road from FWO Bauch in Boringwood, where I did some time, a year and a day I think, fixing Studers. Do you remember Werner?

martin

there

No, but it's a comparison between two components at the same circuit point, so the power ratio is the square of the voltage ratio.

Cheers,

Phil Hobbs

noise

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monitoring

"That depends how many inputs are assigned. As these are going only to be monitoring desks, the number of inputs will be 24 or 36 typically. So the suming node will see ~ 400-600 ohms. Current noise shouldn't be a problem here,"

Ahh I see it's one big summing junction. But what is the feedback resistor? (I know nothing about high end audio stuff.)

Georgw

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NE5534

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Its value, correcting for the gain structure mess-up of the original design will be 7k5, i.e a voltage gain of around -18x , but must be stable with nothing routed which equates to a stable gain of -0.5x. I don't see a problem with the stability issues, I thought it out on the walk back from the supermarket.

Graham

locators ? I

That's after my time. Audio Kinetics was in beautiful converted church in St Albans when I worked for them. Must have been 77 ish.

I personally wire-wrapped some of the very first Q-locks. We used Ampex ATR 100 series as test machines. Woo-hoo - were they something else !

Graham

there ?

from

That's about right. So the summing resistors are about 400*32 = 12.8K each. Each input has a gain to the output of a bit over 1. Noise gain is close to 40.

I wonder if multi-group summing would be any better.

John

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didn't

That would be ideal and is a method implemented in some more modern products. In this case we're stuck with what we have i.e. a single mix bus.

Graham

locators ? I

That must be it as I was with Soundcraft before Midas. :)

les...