USSA-5 PCB GB

[fab]

Hi Stretchneck
Neither my USSA7 nor USSA8 have used the FQ3P but rather obsolete 2SK2013/2SJ313 and 2SD2081/2SB1259 (now more recently obsolete). They could probably be adapted to have the FQ3P but have in mind that both these versions are considered prototypes….
see https://quebecdiy.forumactif.com/t54-ussa-8-turbo-edition-semi-limitee-classe-ab for more info.

Fab

 

[stretchneck]

Any updates on the helper PCB’s and Turbo build manual?

 

[fab]

Your manual is well done. I had commented your manual a few weeks ago on my ipad…..but the file was not save with my comments for an unknown reason….I will have to include my comments again into the document….maybe I can simply provide them in a list by email….
Fab

 

[nfsgame]

Your manual is well done. I had commented your manual a few weeks ago on my ipad…..but the file was not save with my comments for an unknown reason….I will have to include my comments again into the document….maybe I can simply provide them in a list by email….
Fab

I'll put the manual as an editable file in the dropbox this afternoon. Maybe that's easier ...

 

[fab]

Helper boards Manual is now reviewed.
Fab

 

[stretchneck]

Helper boards Manual is now reviewed.
Fab

Cool!

 

[Vunce]

Will the Helper Board manual be linked in post #1 when your satisfied with it?

 

[fab]

Hi Vunce
indeed it makes sense to do so. But helper pcb must be available too…
Fab

 

[Vunce]

Hi Fab,
Makes perfect sense, I’ll be on the lookout for when they are available.

Thanks

 

[nfsgame]

After one or two verification builds I think it would be the easiest when I upload the gerber files in the thread so that everyone who wants to build a "big one" could order the helper boards by him/herself...

fab and I are exchanging about the documentation. I have to do some graphics to clear the interconnection between the different boards ("wiring diagram") and then it could go into the hot phase...

 

[Vunce]

Sounds good Fellas!

 

[stretchneck]

How's progress on the helper PCB?

 

[fab]

nfsgame is probably too busy to respond….

 

[nfsgame]

Hey guys, I'm in Italy till next monday evening for work. I hope I can finish the package after my return.

 

[pinnocchio]

Just saw this addon board, very good idea nfsgame!

@fab, what is that new 0.8Rev PCB? Never seen this one before. Looks great!

Do

 

[fab]

Hi Pinnocchio
v 0.8 USSA pcb is a mini version for lower power amplifier to integrate in a small chassis. I use this pcb in my portable all-in-one music server/amplifier. In that case it is for an USSA-4B version. See attached pictures. Useful when I want good sound in a remote location rental cabin in the woods….
Fab

 

[baggerbole]

And it can be used as a headphone amp?

 

[fab]

Sure it can be used as a headphone amp. But in that case I would not install the power ouput transistors and rely only on drivers since they operate at more than 50ma which is quite enough for any headphone in class A region….
For headphone you can also use USSPA pcb with jfet input.
See below this USSA v0.8 pcb used in a preamp with bjt input and only drivers as output. Note the input cap on pcb is bypassed with a wire. However I have used a speaker crossover cap to protect the TKD potentiometer….

Fab

 

[baggerbole]

Great advice, thanks Fab! My headphones are 16Ohm and not very sensitive...
Which DAC did you use in this built?

 

[fab]

Hi baggerbole
in the last shown preamp there is no DAC (it was a previous build several years ago).
in my all-in-one portable amplifier, because of space constraints, it is a raspberry pi hat DAC AK4493 bought on Ali Express.

Fab