DIY - Elektor Vocoder - General Build Thread

[zephyrin]

I have used the same spectrum analyser but i don't have a nice result

[zephyrin]

I have calibrate my sound card it's seems better .

[Fitchie]

Fitchie how do you check the signal? Do you used a scope probe ?

I use a Rigol (low budget) scope to adjust and measure everything.
What do you mean by 'scope probe' ?

Do you have made electronic hardware for protecting your sound card ?

No, the sound card has a build attenuator on the input channels.
I always make sure to turn it completely before I send a signal to it, to prevent any damage.


Example of voice & carrier:

Example of bias measurement:

[Fitchie]

I have calibrate my sound card it's seems better.

Cool !
Did you use white or pink noise ?

[Fitchie]

I have calibrate my sound card it's seems better.

I like your high pass filter coming in exactly in the right place.
Much better than the original one.

[Fitchie]

The documentation on the website is really fantastically done. Good overview and clear explications of how to do it right, looks and feels very professional.
Congratulation great work Fitchie.

Thanks for this nice feedback !
I have invested a lot of time in this website with the aim that everyone can successfully build the vocoder.

Soon I will release a completely revised version for the adjustment procedures. Here's a first preview:
http://vocoder.eu/filter-adjustment.html

[zephyrin]

i have used white noise.
I have make a new calibration and now the lower sound are around - 125 db

But the low pass filter are not linear , I will trying to change resistor and choose them with a better value.

I don't know why each higher filter give more sound (dbu ) than the filters under it.

I have try too change the TL084, but nothing change, I will trying to change resistor .

[Fitchie]

But the low pass filter are not linear , I will trying to change resistor and choose them with a better value.

For that reason I was asking what kind of noise you did use.
I'lll contact Boogie and ask him for feedback.

[zephyrin]

i m using white noise from TrueRTAx
Green : Pink Noise
Blue: White noise

[zephyrin]

New analyses with Pink Noise

[Fitchie]

New analyses with Pink Noise

That's it !!!


For your info:

Similar to the way white light contains all the wavelengths of the visible spectrum at equal intensity, white noise has equal power across all frequencies audible to the human ear.

Pink noise is white noise, but with reduced higher frequencies.

[zephyrin]

I have calibrate all board , the first test in basic mode is good (with my voice and JU-06A )
For calibration
In the step 2 the best value that I found is between 4.5 and 5.5 mv , it's seem to be ok for me if I don't under 5mv that is writing in magazine.
For step 3, I have also quickly read tension in the output of vocoder for all board for this I have put P4, P8 and P12 on the left for having the minus value.
I have take the max value of those , in my case around 30mv , after I have set all board with this value.

For CA3080 i have take it from Banzai
They are 2 type of CA3080 , Standard CA3080E and military quality CA3080AE.
I have a good surprised to received the CA3080AE instead of standard for the same price.

http://www.banzaimusic.com/search.php?m ... rch&page=1

Now I must test it with extended board , I know that the noise board is ok but not the other ...

[Fitchie]

In the step 2 the best value that I found is between 4.5 and 5.5 mv , it's seem to be ok for me if I don't under 5mv that is writing in magazine.
For step 3, I have also quickly read tension in the output of vocoder for all board for this I have put P4, P8 and P12 on the left for having the minus value.
I have take the max value of those , in my case around 30mv , after I have set all board with this value.

I'm rewriting the adjustment procedure as explained in step 2 and step 3. If things go well, it will be ready tomorrow or the day after at latest. As usual, the necessary scoped dumps will be included so that it is clear to everyone.

[zephyrin]

Do you have an idea why Elektor team made the high pass Filter like this (with the error) ?

[Fitchie]

Do you have an idea why Elektor team made the high pass Filter like this (with the error) ?

I think capacitors at that time weren't that accurate at all and especially in very specific values ​​hard to find and very expensive.

[EdBrock]

I am having problems calibrating the filter boards. I calibrated the I/O board and have carrier and voice signals on pins A & B. I adjusted the DC offset of the high pass filter board. I connected the wiring to the panel for the high pass filter, and proceeded to adjustment step 2 - Inverting input DC bias voltage of the OTA's. I applied a white noise signal to the speech/voice input jack on the panel with the knob fully clockwise. I observed the output from panel output on the scope (pot fully clockwise) and adjusted P2 but there was little or no change to the output. The high pass LED is on and the in and out knobs on the panel fully clockwise. I didn’t see any instructions for using the 5500Hz sinewave on the Filter adjustment web page, but I assumed it is to be input into the front panel carrier jack. The sinewave has a slight DC offset. I kept the white noise on the voice input unchanged. I adjusted P2 again while observing the output on the scope from the panel jack. There was little if any change when adjusting P2. Am I following the procedures correctly? What am I supposed to see on the scope. My signal looks like noise or a sinewave and white noise together. I am pretty sure the CA3080’s are OK since I bought them from a reputable source and also tested them in another circuit. I also tried a bandpass board and had similar results. Any help is appreciated.

[EdBrock]

Nobody ??? Help !