DIYHiFi.org

I haven't tried PCM1704 but I have tried AD844 as a common base stage for AD1865 and had good results, but not much different sounding than the already present discrete IV I had been using.

Sorry to hear that. I saw the writing on the wall in 1970 and took up computer programming. Getting in the door was hard because I didn’t have a degree but once inside I rode the wave and retired twenty years later. Because you are younger and smarter than me, you shouldn’t have any trouble making the switch.

Ulas,

I use to be Chief Engineer at one of the top 10 hardware/software companies in the world and hated every minute of it. Computers suck the life out of people. I would not go back to that industry for anything. I was making the company myself well like tons of cash and what would I get out of it. Nothin... My bosses all have places in the Hamptons and 5000 sq foot grand rooms and what did I get out of it... I have a set of leather luggage I got for 15 years in.

As for making a living in Audio, I do ok... no not as good as above, but then again I have little stress.

It's not hard to make money in any industry. But you have to work for it. If no one knows your out there then nobodies going to know you selling something they may want.

Thanks
Gordon

_________________
Gordon
Chief Scientist
Wavelength Audio

Who are you calling younger?

Jocko

Jocko,

They say it's all in the mind :)

Who are they anyways?
Gordon

_________________
Gordon
Chief Scientist
Wavelength Audio

I dunno.........!

Jocko

I agree.
I arrive at home at the end of the day almost dead. Turn on the soldering iron.
Then a couple of hours later I forget all the problems and stress during the day, and the problems to solve next day.
I started working with computers when a diskette drive for an IBM PC cost more than 500€.
You were payed big money to replace a 10Mb hard disk and reinstall MS-DOS 2.1.
Installing SCO Unix was almost a full day feeding more than 30 diskettes to the deam server.
Then software programming, you arrive at the end of the day with your head almost blowing.
But the daily challenge to find solutions, to simplify, to speed up the code execution is usefull for most everythings in life.
You learn to think SIMPLE, and to write the solution in 3 lines of code, while others made it in more than 50. This is rewarding, challenges the logic every day, makes you think, use your head.
The company cashes millions, and you don't see anything. That's the hard part.

_________________
Carlos Filipe

"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius - and a lot of courage - to move in the opposite direction." Albert Einstein

Carlos,

In college I did only analog stuff. But they suggested I do a computer thing so I made this little Z80 single board computer with HEX keypad and 16 digit display. I entered my first program into EPROM with toggle switches. Actually got something to work on the second try. The school then invested in a EPROM programmer and we interfaced it too the VAX 11/780.

My first computer job was a PID controller used to regulate axial compressors mainly used in Oil Pipelines. My first development system was a Zilog ZDS system with wire wapped back plain and something like S100 bus but proabably Zilog. It had 32K of memory and the controller I designed had 3 Z80 processors (one for analog I/O and digital filtering, one for serial communications and the host cpu for I/O).

I remember we got one of the first IBM PC's with dual floppies. We also made a PLC, well back then called Programmable Controllers or PC but then they changed the name to PLC or Programmable Logic Controllers. We were going to use the PC as a programing terminal. Instead we designed our own based on CPM.

Oh the good old days when we did so much with so little. Heck now I can get a microcontroller dev system for $100 bucks and an ARM processor in an 24 pin package that is 4x more powerful than my first development system.

Gordon

_________________
Gordon
Chief Scientist
Wavelength Audio

In 1986 I had one at home.
With mono green display and a hercules mono graphics video card.
640k memory (part of this memory was on an ISA card!), 10Mb HDD and 360k 5 1/4" floppy.
Luxury.

Btw those IBM keyboards were almost undestructible.

Gordon, you started earlier, I'm younger, but I have still worked at a time where one could make money in that business. Hardware or software.
Companies needed software and there was never one commercially available that made what they wanted. Everything had to be made from scratch.
PCs were very expensive, but if you sold them, you could have at least 50% margin, minimum.
Repairs were expensive and lucrative.
Later came the chinese and started to make cheap PCs. That business was no more. That's for the young kids now, starting their carreer. It's much easier now.
They will never know what is it to configure the HDD parameters with jumpers on the controller, and format it at low level with the MS-DOS debugger.

_________________
Carlos Filipe

"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius - and a lot of courage - to move in the opposite direction." Albert Einstein

Gordon, what are you complaining about? You accepted compensation you received and chose to work for the same company for 15 years. After I established my reputation in the industry, I only took jobs that were challenging and offered compensation commensurate with my contribution. In ’91, when it appeared most technology companies were being run by marketing weenies and producing ‘me too’ products I decided to chuck it all. My wife and I sold our Menlo Park house for 5-times what we paid for it, converted our stock holdings into a charitable remainder trust, and retired to a house we built in the country. I haven’t worked for anybody since and I don’t regret it.

I hope this doesn't irritate anybody by getting back on topic...

As has been said a lot of times, current output DACs, audio or not (back to my day job) produce minimum distortion when used into very low impedance loads. Ideally a virtual ground. That's because the current sources used within aren't perfectly linear - they're designed to be monotonically accurate and fast.

Probably 99.985% of every current output DAC implementation used in commercial products for audio has used an opamp as an I/V converter. Why? Because it appears to be the right thing - it says so right there in the data sheet - and they are cheap and repeatable. (So is bad ethnic food...) The problem is that the virtual grounds supposedly found in inverting opamp stages really are only inverting grounds at audio frequencies. Unfortunately, the switching currents at the DAC output are much higher in frequency than that. So much for the virtual ground. If you want to read more about that, Google the name Barrie Gilbert and read what he has to say on the subject. If he isn't qualified enough on the subject for you, you're certainly wasting your time here.

Common base circuits can be made very, very linear and easily enough. Yeah, you can make an opamp work in the circuit, but you have to go to great lengths and use an expensive part. Even then, it may well not sound as good.

Better you should build a simple I/V converter and spend your time and money on improving the power supply and regulation - a whole other topic.

Good points.

Jocko

If you're referring to Menlo Park, CA, then we were almost neighbors at one point in time. Although I was a high school student in Atherton in '91. And if you're talking about Menlo Park, NJ, then I guess I understand better why you left.

_________________
He's not hi-fi, he's my stereo.
DIY projects:
http://www.ezdiyaudio.com

Hi all,
I hope I'm not being disrespectful here but my 2 cents is that if everyone is keeping it close to their chest then no I/V stage is going to come out of this place.As knowledgable or "expert" the people here, maybe the vision is a bit narrow but there is a greater force in play.Think metaphysics, each one must find his own path but the "reality" is with all the negativity here all the positive ideas will be repelled or resisted with answers like:

It will not work.
Been there,done that.
No free lunch.
Someone will steal my idea and I don't even get a mention.
I get no satisfaction,no money,no honey.Life sucks.
They are all the same,ripoffs.
Good points.( I'm not telling)
Trying to tap my brains.

Your thoughts are powerful.What do you wish this place to be?

Hey, lots of good advice has come out of this thread. What's so bad about that? Do we have to do all the work for you? This is "DIY", not "CIY" (copy it yourself). Seriously, the opinions and advice given so far should be enough to steer anyone in a good direction, or at least to avoid some common pitfalls.

Typically, if someone has a schematic, they'll start a new thread and we take it from there.

jh