Aleph P - microcontroller

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Hello fellows,

I´m now planning to build an Aleph P 1.7., since my Aleph 4 monos are working excellent and waiting for an adequate source...

The analog part of the Aleph P circuit is quite easy to be build - but the "digital part" for the full comfort function controlling is maybe a no-go because of the processor.

One question about this heart of the Aleph P digi-part, the micro controller U201 87C752 software. Is this part a flashed controller (at the Pass plant) or is it a special developed ROM mask processor individually produced for Pass labs?

If it was a ROM, can it be bought at Pass as a spare part? I guess, this question could just be answered by the master himself... Wondering, if Nelson could agree if someone would really copy the Aleph P even with the special features and not "just" the amp part.

Curious about the answers!


PS: backup is the Aleph P 1.0 volume control with motor-poti remote control.
Hello Klaus!

I think an easy way to modify a little bit the schematic and use a single and easy-to-make PIC application.
I recommend to use an PIC16Fxx. The price even lower, than the 87C52 (or comparable)

With the PIC you can easily drive an LCD display too, and on the web you can find application for it also. The LCD can be 1x8, 2x8, 1x16 or 2x16 characters or whatever (Hitachi displays).
Good Luck!

Again, i'm 'promoting' my preamp. You might have seen it before and maybe are getting tired of me mentioning it again. But my aim is to help other people, not to 'show off'.

So check out the website, i am using a PIC16F84 for preamp control. Only the RC5 code is presented (for decoding a remote), but other stuff (?) is available through mail. But you need to be able to do some assembly programming, it is not a 'kit'.

Maybe i could simplify the thing (no kenwood control, no positioning of the volume) if there is demand for it. Only had a few questions about it, so at the moment there doesn't seem to be much need.

I put the micro into sleep if there's no need for it to be running.
That's why there is no LC display. They have there own processor and clock, and there is no 'sleep mode'...

BTW, working on a DAC with two TDA1541's now, one for left and one for the right channel (both left/right channel of the dac used). With a choice of one of the channels being inverted. Using some shift-registers and a GAL. I don't have much time (new house), but maybe i'll get there (if it works..).


is getting complicated...


thank for your hints, should be easy for digi-freaks. I am a poor analog-freak, and I think replacing controllers, feeding software into them and this stuff is a bit of to much for me. I need plug&play divices.

So, after the stuff I read, it becomes more and more the easiest way to buy a remote controll set, a motor drive for a poti and build Aleph P 1.7. One LED in the volume button will do me "the hyper display". I love the discreet way... Mute relays for instand shut down of volume and input selection is not that hard to realize.

Joined 2002
Paid Member
Aleph microcontroller

The Aleph P used either an 87C752 or an 87C750/751.
These parts are discontinued now and we have only a few left for repair. A counter would work or a pot feeding an ADC with parrallel output port would work. The National ADC 08 would work.
Klaus, I understand you but if you are not an expert in microcontroler but you want use it, you will find your good fortune here :
The price include generaly the board + some component.
I hope that can help you.

:att'n: It's nothing wtih this but if you are intresting to see my last loudspeaker I think you never see something like that before (sphere in full carbone)


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The Little PIC That Could

Nelson you slay us all.....

I'm building what you're talking about right now. I bought
a PicKit1 from Mouser, it's $35.

If you want an adventure you can buy that and it has all you
need to get started with programming.

Or you can wait for me to do the heavy lifting.

I'm using the PIC16F684 from the kit, I've got just under
1000 instructions so far and there are several functions it
performs. I'm designing for encoders as the input devices, and
will use a few shift register latches daisy-chained together so
it looks like the PIC has 32 outputs. One day I plan to add 4 more
shift registers to drive LED displays too. Very sexy.

1) initialize PIC
2) read current encoder state
3) set volume to bleed output caps to ground, mute is active
4) wait 3s
5) connect last used input and set to low volume level
6) wait 100 ms
7) release mute
8) respond to inputs: vol, bal, input select
9) fast mute and input disconnect when power supply dies

Sorry I can't promise a time to be finished but I will make the
source code and the board designs available. Its a hobby.

No matter what you decide, I think a PIC is a good way to go.

ahhhh that's the stuff

OK guys, if you want to see what a PIC assembly program
looks like, here she is.

DO NOT USE THIS FILE !!!!!!!!!!!!!!!!!!!

I've just started simulating it - but it operates as I wanted
to the first order. Meaning the volume, balance, and select
and mute control SEEM to work under the few scenarios I
have simulated. Note that the delay is really short for my testing
all I have to do is change the comments to get the correct

Here are the assumptions:
Port A 0/1 volume encoder inputs
Port A 2/3 balance encoder inputs
Port A 4/5 selector encoder inputs
Port B 0 output data
Port B 1 output clock
Port B 2 output parallel shift instruction
Port B 3 output reset

Might be a good starting point for someone to modify code.
I think it's pretty well commented and you should be able to
follow it. THere are a lot of subroutines so it's nice and
hierarchical. I think there's about 700 instructions or so.

I'll make the final version available.

You'll note there is shut-down code but no entry into that

I also want to add a display driver so I can have some
sexy blue LEDs on my amp front panel.

Have fun.

Oh ya, to look at this code and simulate it, go to the
Microchip website and download the free MPLAB IDE.
You'll need to change the filetype to ".asm" before reading
into MPLAB, I can't post an asm file so I changed the filetype
to ".txt" so I could post.

If anyone finds any bugs please email me or post....



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rsbay said:
Hello Klaus,

have a look at my homepage

I have a microcontroller based Aleph P. If you are interested in
my design I can share it with you.


Hi Ralph,

thanks for your hints and offer! The tread is very old - my P1.7 plays almost two years now with 7bit vol setting like P1.0. A motorpoti with simple IR remote control offers volume setting, one switching relay changes gain to 0dB from -20dB. Also phase inversion (a cross-change of the branches behind the input cap) and mute is on board. No remote for input selection. I am happy.

But I will check your good homepage and write you a mail the other day...


Hi I am anxiously awaiting a final version of Waynes pic code and a schematic!
I am going to study the 700 plus lines of code and try to figure out how the code uses the register latches to create so many outputs.
I am in the process of putting together an Aleph p 1.7 and I would like to use the pic and programmer which I already have however I would like to add a remote control and Display (for basic input and volume display and gain levels if possible) in addition to what Wayne described. My problem is I have no clue how to do this with encoder inputs, I would either have to duplicate encoder signals OR somehow play with the code to accept another input just for the remote control signals. However knowing this and being able to do it are two different things and I don't know how long it might take for me to figure out! Please help me!
What are some recommended encoders for this??

P.S. This would make a nice christmas present for my uncle! As I am building one for him as well!
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