Burning Amplifier BA-1

[Zen Mod]

just go for it

amplifiers want to be made !

[AndrewT]

Originally Posted by timbarnes

I guess I'd need to run the transformer with primaries in series on the 100V taps: this should give me almost 22V peak to peak.

with the primaries properly wired up for the voltage supply you have the transformer is a 550VA.

If you wire the two 100Vac primaries in series and connect them to a 115Vac supply you reduce the transformer to ~300VA.

DON'T.

[timbarnes]

Originally Posted by AndrewT

with the primaries properly wired up for the voltage supply you have the transformer is a 550VA.

If you wire the two 100Vac primaries in series and connect them to a 115Vac supply you reduce the transformer to ~300VA.

DON'T.

Fair point. I was applying Nelson's advice to get the right voltage without thinking about the power capacity of the primary windings. I guess I could use it that way with fewer transistors per side...maybe three or four?

Perhaps an alternative would be to series regulate it down to the required voltage? It would require a pretty hefty series transistor, I guess.

[timbarnes]

I'm going to keep my BA-3 with its own power supply, so I'm only concerned about power to the output stage and bias boards.

I want to use my 27+27V transformer, which yields about 38V DC.

It seems that the extra voltage would not burn the power transistors, but I'm not so sure about the bias boards.

Any thoughts?

[Darry]

The output stage of BA1 works in pure single-ended.

With 0.58 A per MOSFET (6), the BA1 provides, with ± 32V, 50 watts into 8 ohms, 25 watts into 4 ohms but only 12 of 2 ohms, ...

Is there a "small" circuit that could push the output stage in class AB (in the style of the Aleph 0, 0s and 1), for at least 50 watts into 4 ohms and 2.

Regards

Darry

[noSmoking]

Hi Zen,
I am building a BA 1 I have the front end together and tested out ok,now I am confused at how to WIRE the output I got 2 identical boards for ba 1 output stage ,I don't know how to wire them up ,the diagram has 12 fets post#4 my boards have places for 6 so 1 board is N and the other is P correct so far ?can the outs from both boards be connected ? the way it looks they are jumper-ed over in the diagram ,maybe that's where I'm confused.
I would like a diagram or drawing of how to connect/wire them together,I am trying not to live up to my nick,lol Cheers!
Thanks,
No Smoking( a joke on burning up perfectly good parts.)

[tinitus]

Originally Posted by noSmoking

my boards have places for 6 so 1 board is N and the other is P correct so far ?

no no

its true for Nelson's original 'idea', and schematic
I reckon he had some very huge heatsink cooling in mind
meaning, any big ordinary stereo box with big double heatsinks could be used for a mono amp

but forum version in the store are designed differently
1 output board holds both N and P devices for a mono amp
a very practical solution for bridged setup where you need a complete stereo amp

looking at my own BA2 output boards from the store, outputs are clearly marked with either 'N' or 'P'

[noSmoking]

Hi T,
So how is the store boards populated with the fets?they are all 240's right?

I will check that out and see if that's where I went astray,thanks!

[tinitus]

Originally Posted by noSmoking

I got 2 identical boards for ba 1 output stage

1 board is N and the other is P correct so far ?

UPS !

BA1 have 'N' outputs only

or else I guess you would have BA2 boards

nosmoking, quit smoking, you are confusing me

[noSmoking]

Hi Tinitus,
All N boards but that should be right if it uses all 240's ,I will put one in place and wire it up and see how it does,LOL.