FEMTOVERB /Wavefrontsemi/ PCB layout

[Andre]

I have finally finished my Femtoverb which I started to build about 2 years ago.

I also build a PIC controller with LCD to control it and show the chosen preset.

I made a little demo to show the different presets
http://www.youtube.com/watch?v=35whSVXIhn0
The mix pot is in center position.
It is rather noisy and the mix pot acts a little strange as if the wet signal is inverted.

[MetalGuy]

I have finally finished my Femtoverb which I started to build about 2 years ago.

Looks nice. I didn't get what was noisy. Mine isn't.
If you use it after some high gain pedal however you'll hear some high frequency artifacts (maybe due to the high sampling rate and resolution) but they can be removed with the help of a simple filter.

[Andre]

Looks nice. I didn't get what was noisy. Mine isn't.
If you use it after some high gain pedal however you'll hear some high frequency artifacts (maybe due to the high sampling rate and resolution) but they can be removed with the help of a simple filter.

Maybe not in the video I made, but I can hear the noise especially when notes are decaying and it stops when I cut the note.
I will try some extra filtering.
I think I will also change the circuit around the mixpot a little bit.
What I want to try is to let the dry signal pass to the output and replace the mixpot with an effect level pot.
This may not be the best solution for the chorus and flanger mode, but I think it will give more control over the reverb depth without changing the dry note's high
frequencies.
To me it looks like there's a treble cut when I mix in more reverb.

At first I was not too happy about the reverb sounds, but now I've played it with it a little bit more, I'm starting to like them.
I think my final version will be without display but with a six step rotary switch with only the 2 hall reverbs, 1 room reverb and all 3 plate reverbs.
Maybe I will still use a PIC processor to do the Gray codes otherwise I would need a lot of diodes to do so with the switch only.

[Marcvv]

Hey Andre,

Nice build and nice to see this with the LCD!!

Could it be that you have added some reverb to the sound of the Femtoverb build on the demo? On the rotary preset I hear a reverb wich is not in the preset of the AL3201 as far as I know.

Marc

[Andre]

Hey Andre,

Nice build and nice to see this with the LCD!!

Could it be that you have added some reverb to the sound of the Femtoverb build on the demo? On the rotary preset I hear a reverb wich is not in the preset of the AL3201 as far as I know.

Marc

Now that you mention it.... yes.
I first used another amp with reverb off, then for the demo I switched to my Peavey Deltablues and forgot to turn off the reverb.
So it's reverb with a bit of reverb. 
Maybe I will do another demo with no reverb on the amp.

[peterv999]

Hey Andre,

Nice build and nice to see this with the LCD!!

Could it be that you have added some reverb to the sound of the Femtoverb build on the demo? On the rotary preset I hear a reverb wich is not in the preset of the AL3201 as far as I know.

Marc

Now that you mention it.... yes.
I first used another amp with reverb off, then for the demo I switched to my Peavey Deltablues and forgot to turn off the reverb.
So it's reverb with a bit of reverb. 
Maybe I will do another demo with no reverb on the amp.

Andre, Very much impressed by your Femtoverb and the youtube "show-off""

Peter

[DIY Bass]

OK, I know I am resurrecting a very old thread, but I am probably the last person in the world to have a few sets of the Alesis chips available, and I am about to try and build a Femtoverb.  I am intending to change the PCB layout a bit, so if anybody happens to have an Eagle file for this I would love it so I don't have to redo the whole thing.  Anyone.....?  Please....?

[DIY Bass]

I have done a board for this, and it has been over a week since I last made any changes.  If there is anyone out there who can check it for me in case I have missed anything I would be grateful.  Going to send it out for manufacture soon-ish.

http://www.filehosting.org/file/details/724315/Femtoverb%20sch%20and%20brd.zip

[cabintech]

Since this old thread has been resurrected, it is worth noting that pin-for-pin compatible chips are now made by Coolaudio that should work in this project. Note however that Coolaudio has different default programs for the DSP and the max supply voltage is 3.3 instead of 5V. See this page for a complete comparison of the 16 program defaults and the other known differences:

https://cabintechglobal.com/?prod=V1000

--Mark

[DIY Bass]

Coolaudio also don't make the separate A/D and D/a converters - they make a combined CODEC instead.  It would be possible to modify the schematic and board to use that part instead.  As for my project, the boards are back from the manufacturer, and I have started soldering before getting distracted by a different project.  I'll get back to it soon hopefully.