Your thoughts / caveats re ETK3699, HT8970 and other Reverb chips, please

[Vivek]

I need to make a Reverb.

Please help me by sharing your views and experiences with

ETH3699
HT8970



Are these just PT2399 with different manufacturer part numbers ?


Here are some pertinent links that I found on google

ETH3699


https://www.youtube.com/watch?v=fApOWzp_-eI

http://www.icstation.com/etk3699-digital-kara-surround-reverb-delay-microphone-amplifier-preamp-board-p-13602.html

http://www.datasheetcafe.com/etk3699-datasheet-digital-audio-processor/
https://www.datasheetq.com/ETK3699-doc-ETC


HT8970

https://datasheetspdf.com/pdf/170709/HoltekSemiconductorInc/HT8970/1

http://www.datasheet.hk/view_download.php?id=1080602&file=0025%5Cht8970_204430.pdf

http://berasi.blogspot.com/2009/07/digital-echo.html

https://www.twovolt.com/2018/08/24/voice-echo-generator-sound-to-echo-sound-converter-circuit/



I would value your comments comparing above chips versus the usual suspects.

Thank you !

[ElectricDruid]

I've never heard of either of them. From the pin-out they look like PT2399 clones. Is that right?

The only advantage in that case would be if they somehow had improved specs over the PT2399.

[Vivek]

They suspiciously look like PT2399 with different manufacturer part numbers

But I could not find confirmation that they are pin compatible replacements.


BTW, did you see the youtube of the microphone/guitar preamp with what looks like a delay and an echo from the same chip. Is that possible with PT2399 too ?  What are the disadvantages of this approach ?

https://www.youtube.com/watch?v=fApOWzp_-eI

[Rob Strand]

The Holtek HT8970 came out around early 2000's.  I've still got a few.
Stretching my memory back,
- I'm quite sure it's identical in structure to the PT2399
- I'm 90% sure for the same delay it's not as good as the PT2399.
  I can't remember why.  Maybe the number of stages was half.
  Something was half as good.

Actually flipping through the data it's 20k ram instead of 44k ram.

[ElectricDruid]

  I can't remember why.  Maybe the number of stages was half.
  Something was half as good.

Actually flipping through the data it's 20k ram instead of 44k ram.

Looks like you were right. Half the RAM would do it!

[anotherjim]

Less RAM could actually be better for chorus since half the delay for the same clock speed. 8970 is spec'd down to 30ms. Shame they are so rare now.

[Ripthorn]

Less RAM could actually be better for chorus since half the delay for the same clock speed. 8970 is spec'd down to 30ms. Shame they are so rare now.

Pt2399 will do 30 ms just fine.

I've done several projects now with the ES56033 and it does down to 14 ms. I've done a double tracker, a chorus/ vibrato, and a delay with them. Delay times up to about 1.5s, though with some degradation. I also have done a reverb with 4 pt2399's that sounds really good, but takes up a fair amount of space.