Burning Amplifier BA-2

[Nelson Pass]

There would be no reason why you couldn't invert the polarity
of the front end, using N channel inputs and a P channel VAS.

If you do so, you will want to find some P channel Mosfets
which don't have the "IR P channel distortion" for best results.

[bakpaosiomay]

Originally Posted by Nelson Pass

There would be no reason why you couldn't invert the polarity
of the front end, using N channel inputs and a P channel VAS.

If you do so, you will want to find some P channel Mosfets
which don't have the "IR P channel distortion" for best results.

it is possible to use 2sk246 and 2sj103 for the front end?
tqu

[Jason]

The output stage diagram has been updated. The PDF revision has been updated to Rev 2.0.

[Zero Cool]

Ok so who is working on a group buy for PCB boards? anybody worked out the layout yet?


Zc

[Variac]

cviller is working on it again. He has some preliminary designs that he will post very soon, but the concept has changed, which made it more reasonable to wait for hthe BA-2 to be revealed. The idea is to have the gain stage board separate so that it will work for BA-1 and BA-2 with additional different small bias boards for the two types of amps That way, with one board we can make both types of amps and/or have an external gain stage. It will be posted here in a few days. Nelson intended this to be a fundraiser for diyAudio so we want to be the only ones making the boards, but we realize that a responsibility goes with that- moving ahead!

Shortly we will have a design for your comments and input, then a Group Buy listed in the wiki and the GB areas..

Of course the hope is that many more people make these amps than the few that got amp chassis at BAF

Mark
-Variac

[chinsettawong]

If a group buy for PCBs will be available, I think it will be a good idea to also make a group buy for matched Mosfets and Jfets as well.

Wachara C.

[Zero Cool]

Oh good i was hoping the front end would be a separate board!

A group buy for the jfets would be nice!

[cviller]

Originally Posted by Variac

cviller is working on it again. He has some preliminary designs that he will post very soon, but the concept has changed, which made it more reasonable to wait for hthe BA-2 to be revealed. The idea is to have the gain stage board separate so that it will work for BA-1 and BA-2 with additional different small bias boards for the two types of amps That way, with one board we can make both types of amps and/or have an external gain stage. It will be posted here in a few days. Nelson intended this to be a fundraiser for diyAudio so we want to be the only ones making the boards, but we realize that a responsibility goes with that- moving ahead!

Shortly we will have a design for your comments and input, then a Group Buy listed in the wiki and the GB areas..

Of course the hope is that many more people make these amps than the few that got amp chassis at BAF

Mark
-Variac

I just did a quick layout of the frontend for you guys to comment on. The silk screen is still a bit messy and a few components will be aligned more nicely later. But I would like to get some feedback.

I have attached a blue/red version, where blue is bottom and red is component layer.
The green version gives a better impression of how the boards will look like when produced.

[tms0425]

Any chance the large connection pads could be a little bit further apart?

I will use Keystone turret terminals instead of soldering to the board thru hole directly, since they're going to get taken apart and put back together a lot. The larger ones like #1503 have a collar on the top of that is 0.187" (4.8mm) so they get VERY close on the F5 power supply boards I have now.

Tom

[cviller]

Originally Posted by tms0425

Any chance the large connection pads could be a little bit further apart?

I will use Keystone turret terminals instead of soldering to the board thru hole directly, since they're going to get taken apart and put back together a lot. The larger ones like #1503 have a collar on the top of that is 0.187" (4.8mm) so they get VERY close on the F5 power supply boards I have now.

Tom

Hmm.. I have to think about that. The reason for the distance (~5mm) I have chosen is that it fits with many standard terminals. If you can point me to some reasonably priced easy to get terminals of a different spacing than 5mm, I might change it.

BTW: The board is 2.7x5.4 in inches.