Great River OpAmp

[pstamler]

[quote author="Dan Kennedy"]By the way, this preamp is essentially discontinued, if anybody is interested I could make gerbers of the board layout and parts list available.[/quote]

Yes, please do.

Peace,
Paul

 

[chrissugar]

Gerbers and parts list? That would be fantastic. :grin:

chrissugar

 

[Bauman]

Yes, this could be awesome!

:guinness: :guinness: :guinness:

 

[Rossi]

Wow, that would be more than generous!

 

[Flatpicker]

Yes Dan, gerbers and part info would be great to have. In fact, just send them to Fabio and we'll all have boards in less than a month! :wink: :green: (with your permission, of course)

BTW, why have you discontinued it?

 

[clintrubber]

BTW, why have you discontinued it?

As a reason for a next session of drinking, ehh, opamp-designing ? :wink:

But serious, could understand that it could have become expensive to make - so some ecomony-round was in order perhaps ?
I was surprised by the somewhere here mentioned US$200 figure :shock: of the 2*5*2*0 but given that, this GrRvr-opamp uses a lot more parts.

 

[Dan Kennedy]

I'm glad to see there's interest. I'll put a package together for everyone, including gain switch boards and power supplies.

The reason it's being discontinued is the huge amount of labor involved in building these things. A big part of it is my labor, and there just aren't enough hours in a day anymore for me to be stuck on a production bench or a drill press.

There isn't enough call to job shop it out either, so what's happening is a full revision with better performance and features as well as incorporating all I've learned about manufacturablility in the last few years.

Give me a little time, I'll need to convert a bunch of Protel schematics to .pdf's Now's the time to bend over for Adobe I guess...

 

[Carl_Huff]

Dan,

If this is the same gain block that you sold me 4 years ago from your mic preamp product, I agree with you. It does sound great! At the time you sold me a pair of circuit boards (and instructions) that I assembled into a mic preamp pair. Great design on your part.

Gerbers and parts list, YES PLEASE!

 

[chrissugar]

Dan, you are so generous.
Thank you again. :thumb:

chrissugar

 

[jrmintz]

incorporating all I've learned about manufacturablility in the last few years.

That certainly does seem like a black art.

Nice of you to share your designs.

:thumb: :thumb:

 

[edanderson]

i've wanted to build a great river for several years, but layout questions and the steep price of preferred jensen input transformers put me off. with an original pcb being offered, i may have to fork over the cash (or find a reasonable substitute) for those transformers sometime soon.

thanks dan!

ed

 

[Learner]

[quote author="Dan Kennedy"]I'm glad to see there's interest. I'll put a package together for everyone, including gain switch boards and power supplies.
[/quote]

Wow! :shock:

Thank you so much for your generosity Dan. :thumb: :thumb:

As a EE amature I can not imagine how much work you have devoted yourself into that thing, your willingness to share the fruit of your dedication is really one in a million. Can't scrape up enough respect to show my appreciation!

You are truely one of a kind!!! :shock: :thumb:

 

[CJ]

Dan, you rock!
:thumb:

 

[DrFrankencopter]

Yup, Dan rocks....and so do his designs. I've bought 4 MP boards from him (my first forray into DIY actually), and they sound incredible. He even sent me a couple of his proto transformerless boards...they're really good too.

I highly encourage folks to try out his design!

Cheers,

Kris

 

[Samuel Groner]

Hope I'm not annoying, but could someone shed some light on the function of Q12/Q13?

Thanks!
Samuel

 

[tk@halmi]

[quote author="Samuel Groner"]...shed some light on the function of Q12/Q13?[/quote]

I think that would be a fancy Vbe multiplier to bias the output stage.
You could use four silicon diodes, but that gives you no adjustability over the standing current. Dan's is an elegant design and includes both NPN and PNP devices for better compensation. I wonder if they were somehow thermally coupled to the Q16/Q17 in the production units.

 

[Dan Kennedy]

HI guys, sorry for the low visibility here, I've just been swamped. I did get a .pdf exporter, I'm thru a fair amount of the drawings.

The biasing circuit is a direct rip-off the the Dynaco Stereo 400.

It's coupled sorta close, but not really, since this amp won't self destruct if SOA is exceeded, or approached. It really can't. The driver and output bias drifts around a bit, but not much, maybe .5ma. Certainly nothing to get excited about.

How do I make a .zip file available here, once it's all done anyway?

 

[Flatpicker]

[quote author="Dan Kennedy"]HI guys, sorry for the low visibility here, I've just been swamped...How do I make a .zip file available here, once it's all done anyway?[/quote]No problem, Dan. I?m sure we all know what it's like to be ?swamped?. :wink:

When you get the zip file ready, just put it somewhere on your web site and post a link here.

 

[fum]

[quote author="Flatpicker"]
When you get the zip file ready, just put it somewhere on your web site and post a link here.[/quote]

That, or there's the group space for posting files:

http://groupdiy.twin-x.com/index.php

Regards

ju

 

[chrissugar]

As someone (Jakob or Ethan) mentioned it a few days ago the twin-x upload service is not working so the best idea is to send the files to a group member who can host it.

chrissugar