Author Topic: ADAU1701 stereo chorus  (Read 2325 times)

Vlad Koen

ADAU1701 stereo chorus
« on: March 20, 2018, 04:01:06 PM »
ADAU1701 dsp chip stereo chorus - flanger - exciter

Made in tee box.

soundcheck on
https://soundcloud.com/sun_sequence/tee-chorus-diy-box-test








Digital Larry

Re: ADAU1701 stereo chorus
« Reply #1 on: March 21, 2018, 12:22:05 PM »
That's pretty cool.  I wasn't too familiar with the ADAU1701, mostly having the Spin FV wrapped around my axle.  But this looks like it could be good for some things that are difficult on the Spin, especially opening up a more flexible set of input controls (4 pots, switches) and possibly getting better SNR.  Price wise it seems close to the FV-1.  Did you get a developer board to prototype this or are you just naturally brilliant?

Also wondering about the assembly, did you do it by hand?
Digital Larry
DSP tinkerer and former transistor twister

ElectricDruid

Re: ADAU1701 stereo chorus
« Reply #2 on: March 21, 2018, 02:53:02 PM »
+1 Agree, very cool.

My only "oh what a pity!" moment was the limited on-chip RAM. Otherwise that seems like a great chip.

I'm also not clear why these DSP chips tend to run from an external EEPROM rather than on-chip Flash memory like most uPs these days. Is there a technical reason for that? On-chip flash would be easier and save another chip...but these are questions for AD, not you.

Anyway, nice work.

Tom

free electron

Re: ADAU1701 stereo chorus
« Reply #3 on: March 22, 2018, 10:47:14 AM »
I'm also not clear why these DSP chips tend to run from an external EEPROM rather than on-chip Flash memory like most uPs these days. Is there a technical reason for that? On-chip flash would be easier and save another chip...but these are questions for AD, not you.
Tom

Flash read/write operations are often too slow to run dsp applications. Firmware is loaded into RAM and run from there. DSPs are usually accompanied by another "houskeeping" MCU, which may store the firmware and load it in to DSPs RAM at startup. Or just use an SPI/I2C bus and an external memory.
Here is an open source programmer for the AD's Sigma series of DSPs:
https://github.com/freeDSP/freeUSBi

Vlad Koen

Re: ADAU1701 stereo chorus
« Reply #4 on: March 22, 2018, 02:22:08 PM »
Hi !

It is nice to see all replays on my box.

I bought a processor in an online store, and a circuit board to it.




Vlad Koen

Re: ADAU1701 stereo chorus
« Reply #5 on: March 22, 2018, 02:35:35 PM »
Structure of chorus and flanger in Sigma studio:



Digital Larry

Re: ADAU1701 stereo chorus
« Reply #6 on: March 24, 2018, 12:03:19 PM »
I bought a processor in an online store, and a circuit board to it.

Do you mind tell me where you got those items?  I couldn't find anything comparable through a casual web search.
Digital Larry
DSP tinkerer and former transistor twister

Vlad Koen

Re: ADAU1701 stereo chorus
« Reply #7 on: March 25, 2018, 05:30:07 AM »
I bought this set on very special place, on russian website:
https://www.chipdip.ru/product/dsp-rdc2-0027v2

this is the electrical circuit:
https://static.chipdip.ru/lib/868/DOC002868482.pdf

But the same thing there is, and with sigmastudio USBi interface:
https://www.minidsp.com/products/minidspkits/2-x-in-4-x-out

But better to start with ADAU1452, because memory (to make simple reverb) is 40kB.
Jast now I looking for A DAY 1466, latest simple sigmastudio processor with 96 kB memory.
Unfortunately, AD don't sell it in 10-pic set.  Only do it at 1000 ))

Vlad Koen

Re: ADAU1701 stereo chorus
« Reply #8 on: March 27, 2018, 01:57:45 PM »
Now I have got improvement for my stombox.
First of all, it have been moved to steel box; plus  add input compressor , distortion, presens filter at 2500 hz , and headphones  amplifiers .

Now it is complete sound box for home guitar repetition.

I think about to add delay on external pt2399.




Vlad Koen

Re: ADAU1701 stereo chorus
« Reply #9 on: April 03, 2018, 01:48:46 PM »

Vlad Koen

Re: ADAU1701 stereo chorus
« Reply #10 on: April 09, 2018, 09:57:46 AM »
Adau1701 low sampling rate.

Today I was able to change the adau1701 to a low clock speed, about 11 kHz sampling.
To do this, I changed the quartz from 12 MHz to 3.5 MHz, and increased the resistance of the resistor in the ADC circuit (see PDF) from 18k to 100k.

After that, the delay line became about 200 ms.

At the AD forum it is said that it is impossible to change the ADAU1701 lower than 44kHz.

Digital Larry

Re: ADAU1701 stereo chorus
« Reply #11 on: April 09, 2018, 10:42:37 AM »
At the AD forum it is said that it is impossible to change the ADAU1701 lower than 44kHz.
Sometimes when vendors say something is "impossible" it simply means they haven't tested it, can't guarantee it, or for whatever reason don't want to support people trying to do things that way.  In this particular case I have no idea, but I can imagine people running at really low sampling rates and then complaining about how crappy it sounds.  Nyquist who?
Digital Larry
DSP tinkerer and former transistor twister