Burning Amp BA-3

[Tea-Bag]

I think it is D and G.

 

[generg]

across R13 seems good to me...

@tea-bag D could be after the cap.....

 

[NicMac]

Output stage for BBA3

I'm hammering up a BBA3 and I just realized that I do not have an output stage to mate it with
Really just an excuse for finding additional projects
Any suggestion anyone? I don't need much power and I don't think I have heat sinks for 300W dissipation.
Cheers,
Nic

 

[buzzforb]

Do single fet output version of BA output stages.

 

[Backbones]

Just a pair of mosfets?

 

[Backbones]

I'm hammering up a BBA3 and I just realized that I do not have an output stage to mate it with
Really just an excuse for finding additional projects
Any suggestion anyone? I don't need much power and I don't think I have heat sinks for 300W dissipation.
Cheers,
Nic

I think the 300W refers to the full six pairs of fets i.e., two output boards per channel. More manageable if you just use one output board per channel.
Chris

 

[Backbones]

across R13 seems good to me...

@tea-bag D could be after the cap.....

Thanks. Yes it's got to be before the cap.
Chris

 

[Backbones]

Generg,

Have you decided on a position of P3 which you prefer to listen to? If so why do you prefer it?
Chris

 

[buzzforb]

I think the 300W refers to the full six pairs of fets i.e., two output boards per channel. More manageable if you just use one output board per channel.
Chris

A single mosfet pair would mean two pairs or 4 fets per channel for a balanced setup. If you ran two mosfet pairs, that would be 8 per channel and you would need even more dissipation capability than standard BA output.

 

[Backbones]

A single mosfet pair would mean two pairs or 4 fets per channel for a balanced setup. If you ran two mosfet pairs, that would be 8 per channel and you would need even more dissipation capability than standard BA output.

So how many mosfet pairs are on one output board?

 

[buzzforb]

Standard BA-3 has 3 pairs or six fets per channel. If you look at the schematic for BA-3b, you now have to double that in order to have a complete amp if using standard output stage. Think of BA-3B as a pre-amp and the needed BA output as an F4 running as a mono-block instead of stereo output. Go back and read listing of BA-3B info and look at the output power compared to standard BA amp. That did not come from just different FE. It is a function of the FE and the doubling of the output transistors.

 

[Backbones]

So as long as I run the BA-3 as a single ended design I can still use the single output board is that right?
Just looked at the BA-3b design and I see what you mean.
Chris

 

[buzzforb]

Yep.

 

[tinitus]

Nelson Pass BA schematics show 6pair per mono channel

diy store boards were designed to use 3pairs

might be confusing

with the talk now about balanced BA amps, it makes sense

 

[Backbones]

Generg,
Did you see my earlier post? Just wanted your observations on how the BA3 sounded on various P3 settings (or anyone else for that matter).

 

[generg]

hi Backbones,


the problem is - the Mac software is on a desktop PC (hackintosh) and I put the amps besides it,

when I have in November the software on my laptop (windows software) i can measure and hear in my living room with the speakers, so I have to wait if I prefer more or less k2......

 

[Backbones]

I might beat you to it by just twiddling P3 one way and then the other--adjusting everything else along the way--and having a listen.
Now I've soldered everything in place can I measure the R value on P3 for different positions (thinks to himself); I'll go down to the garage and see.
Chris

 

[generg]

hit me please, hit me, hit me....wasn´t there a song like this 30 years ago?

why are you going to the garage? and was "measuring the R value of R3" a question?

I am very eager to hear if you can hear a difference!!!!!!!!!!!!

good luck!

 

[generg]

Ian Dury & The Blockheads, first released 23 November 1978

 

[Backbones]

Fantastic albums