Newbee build: PA03 amp (LM4780)

[loafimus]

For me, it's not always chasing the next best thing, but having a project to work on. The PA03 convinced me that I needed to build new speakers. Next is going to be a preamp of some sort.

After that I'm thinking either a DAC upgrade or a class D amp.

 

[clog]

Wow, that is funny. Glad to hear it's all working now!

Also, top notch Clog. You are the official PA03 tech support guy from now on!

Loafimus, You are flattering me Just once in a while (every ten years or so) I have a smart moment. This was the one for this decade.

 

[snake69fast]

Hi
Any replacement for
Mouser Part #:
511-4020
Manufacturer Part #:
HCF4020BEY
Manufacturer:
STMicroelectronics
Description:
Counter Shift Registers 14-Stage Binary Cntr?

Maybe
HCF4060YM013TR?


Thank you!

 

[kcdonahue]

Try 595-CD4020BE

 

[clog]

Try 595-CD4020BE

That's the one I am using in my finished and nice working PA03.

 

[snake69fast]

Try 595-CD4020BE

That's the one I am using in my finished and nice working PA03.

Thank you!

 

[loafimus]

Same one I used also.

 

[daanm]

Loafimus, You are flattering me Just once in a while (every ten years or so) I have a smart moment. This was the one for this decade.

Hi Clog. Thanks that you have spent this very rare moment on me . Otherwise this new hobby of mine would have died quickly. Btw.... ordered a first one amplifier. Looking forward to the 'battle'.

 

[snake69fast]

Hi

I've found in a local store CD4040BE. Is it OK to use it? For 595-CD4020BE I'll have to wait the next Mouser order...

 

[loafimus]

Have any of you guys tried any different opamps for the PA03 yet? Do you think there would be any advantage by replacing the OPA134 with something different?

 

[peranders]

You can possibly get some improvement with replacing the opamps but I have info of successful change. The application is not very critical so feel free to test.

 

[loafimus]

You can possibly get some improvement with replacing the opamps but I have info of successful change. The application is not very critical so feel free to test.

Thanks. I ordered some AD843s to give it a try.

 

[clog]

Loafimus, I have to confess I'm a bit sceptic about opamp rolling. Nevertheless I'm very interested in your opinion about the AD843 in this role.

 

[loafimus]

Trust me, I am too. I'm just bored and in between projects though, need something to entertain me, lol.

 

[loafimus]

Well, I just got the new opamps in. I can't say that I can hear a noticeable difference, but they do work! If anything, I will repurposed them for a future project where they will make a larger impact.

 

[peranders]

Loafimus, I have to confess I'm a bit sceptic about opamp rolling. Nevertheless I'm very interested in your opinion about the AD843 in this role.

Try a pair of uA741, then you should hear a difference!

 

[kallel123]

resistor configuration

ok people i'm baffled i have one board populated tested not working, my fault for bad solder on lm4780 chip. While soldering i accidentally soldered pins 26,24,and 22 together .Wanted to start on a new board, but then i noticed, in pics from other completed pcb's everyone's resistors are orientated different from then one on the site sjostrom's .i thought the resistors went on the pcb the way its silk screened .yet everone's pcb's are working but mine lmao,again my fault. Any help would be greatly appreciated regarding correct orientation
​

 

[peranders]

Do you follow the documentation? Can you show us with a picture so I understand what you mean?

 

[clog]

@kallel123
If a board is finished it's imperative that you check the board thoroughly for correct soldering and correct placement of components. Orientation of resistors is of no consequence (of course values have to be correct). Use a magnifying glass. Carefully read the documentation. Look at posted pictures from other builders. First time start with variac or dim bulb tester. Then check rail voltages and voltages on testpoints TP1 and TP2.
This little amp is amazing and worth your time and money.

As peranders mentioned a set of (hi-res) pictures would be useful.

 

[clog]

Try a pair of uA741, then you should hear a difference!

What to expect here, soundwise ?