My Hennessy preamp

[suzyj]

Hi guys,

Just thought I'd post up a couple of pics of my PGA2310 based preamp thus far - a shameless copy of Mark Hennessy's one (see http://www.mhennessy.f9.co.uk/preamp/index.htm but for stereo only, and with SMD parts.





It's able to select one of eight stereo inputs with relays, and uses a PGA2310 volume control, buffered with a OP2134 opamp. The control board is based on a PIC16F877A, with IR receiver, rotary encoder for volume control, and a graphical VFD.

At the moment I'm writing the firmware for the PIC, using Hi-Tech PICC-lite.

More design details can be found at http://www.atnf.csiro.au/people/sjackson/preamp/

Cheers,

Suzy

[Nisbeth]

Very nice work!


/U.

[anatech]

Hi Suzy,
I'm impressed. Very clean work indeed!

Let us know how it sounds when you are done. Good luck on your PhD!

-Chris

[Original Burnedfingers]

Very fine work. A work of art. I can't say enough good things about it. I know it will perform and sound great.

[Leolabs]

Nice looking PCB.

[suzyj]

Hi guys,

I had a good night last night, and got much of the code working. I snapped a few photos of the control board doing what a control board does:







What can I say... The display looks really nice, and the Spectrol rotary encoder, even without a knob, is beautifully smooth and lovely to use.

More details are on the project's new home, at:

http://www.littlefishbicycles.com/preamp/

Cheers,

Suzy

[suzyj]

Hi all,

I've put up the source code as it stands so far on http://www.littlefishbicycles.com/preamp/. It's about three quarters done.

Stuff that works:

• Power pushbutton
• Display
• Rotary encoder
• source select pushbuttons
• PGA2310 volume control
• source select relays

There's a bug on the front panel board that has to be fixed to get the source select relays to work. The 74HC374 octal flip-flop that drives the relay driver has it's output enable connected to VCC . It should be grounded instead. D'oh!

There's still some work to do on the code. I need to add:

• IR decoder routines
• Clean stuff up.

In order to use the code, you'll need Hitech's free PIC C compiler, as well as MPLAB (all free). I used a PIC ICD2 cable to debug and program the micro.

Anyway, I hope people are finding this useful.

Cheers,

Suzy

[davi_C]

Hi Suzy,
I'am following your project and all i can say it's: WOW!! You've got talent. Actually i'am looking at your work and i wonder if you can post the schematic for this preamp. I only get the front panel and the main input on your website. I will appreciate because i don't have sufficient skill to design all that.
Thanks

David

[jethari]

Originally Posted by suzyj

Hi all,

I've put up the source code as it stands so far on A HiFi Preamp. It's about three quarters done.

Stuff that works:

• Power pushbutton
• Display
• Rotary encoder
• source select pushbuttons
• PGA2310 volume control
• source select relays

There's a bug on the front panel board that has to be fixed to get the source select relays to work. The 74HC374 octal flip-flop that drives the relay driver has it's output enable connected to VCC . It should be grounded instead. D'oh!

There's still some work to do on the code. I need to add:

• IR decoder routines
• Clean stuff up.

In order to use the code, you'll need Hitech's free PIC C compiler, as well as MPLAB (all free). I used a PIC ICD2 cable to debug and program the micro.

Anyway, I hope people are finding this useful.

Cheers,

Suzy

Hi Suzy

Never knew you were on diyaudio. I bumped into your site a while back and was mighty impressed with your preamp. In fact, now its my turn to shamelessly copy your design. I've made a few changes though, instead of using the dB values, I'm using a bargraph for volume, bass, treble and balance(i've added the tone and balance controls as well). Where I'm stuck now is the IR routines. I'm desperately looking for some usable IR routines in C. I'm no good at modifying asm files. I wonder if you have made any progress with your IR routines. Please do let me know.
Thanks
Hari

[currentflow]

Hi jethari,

You might be able to modify the code in this link for your needs:
mikroElektronika View topic - Philips IR RC5 protocol
Note: TIMER0 prescaler needs to be set to 16 for a 4MHz crystal.

Regards,
currentflow