Burning Amplifier BA-1

[Variac]

This is the place to discuss the latest Pass amplifier, the BA-1, which is documented in the article here:

Burning Amplifier BA-1

As most of you are aware, Nelson "Papa" Pass distributed a bunch of almost complete amps at the second Burning Amp Festival, lacking only the gain stage. You can read all about it here:

Burning Amps

Nelson will be publishing a series of articles right here on diyAudio documenting designs for the various chassis that were distributed. They have different output stages so there will be at least an article for each of these configurations. That's good for us as we will have a multitude of great new designs! We will produce boards so that even people without the head start of the generous "gift of amps" will be able to make them. Nelson mentioned that these designs are to be a fundraiser for diyAudio, so the boards should only be available from here.

[cviller]

Great article! Thanks Nelson!


Variac asked me to make a layout for the frontend and here it is. It is version 0.9, which suggests I'll pick up suggestions from you guys before diyAudio puts it into production. Any profit will go towards the forum upgrade.

The board is 3" x 3.5", and one of the primary design constraints is that it must be able to fit into the cabinets given out at the Burning Amp festival.
I have made one change in respect to the original schematics, which is the addition of footprints for 2sj74 as an alternative to the 2sj109.

[Zen Mod]

as always .......

BA1 front :

[Zen Mod]

BA1 output

[Zen Mod]

BA1 PS

[PSz.]

I haven't read the whole thing yet, but I would like to add my to the layout. Actually just the mounting of the front end board. I see a few good options.

First would be a relatively large board mounted on the psu caps. My chassis happens to have four of the big cans, but doing it this way would allow those with two cap chassis to conveniently add capacitance as suggested.

best regards,
psz.

[PSz.]

Second would be a large board mounted on the caps with psu parts hard mounted to it and swappable front end modules.

Another good option I see is to set the mounting holes on the front end boards to 1.5" by 4" so they can be mounted on standoffs and use the existing holes/hardware that hold the heatsink parts on.

best regards,
psz.

[Variac]

Nelson warned us not to have the board close to the first pair of caps in the pi filter, so we won't be covering the top of the 4 caps. A pair the size we have is designed fit vertically beind the front panel... but any ideas will be of great interest... I personally have been tempted by separate front end modules because the front end will be the same for all the amps, its only the biasing components (which are onthese boards) that will vary... . But 2 different boards would be more expensive..



Mark

[PSz.]

Originally posted by Variac
Nelson warned us not to have the board close to the first pair of caps in the pi filter, so we won't be covering the top of the 4 caps.

That's easy to solve. Just use the more remote caps as the first stage in the pi filter. That is how NP did it on the amp in my first attachment.

best regards,
psz.

[Nelson Pass]

Always a pleasure when not all the mistakes are mine.

Prepare for BA#2, which uses the complementary output stages.