[sdiy] Hardware convolution box?

[analogheaven at hushmail.com]

I keep coming back to this as processors get cheaper and faster. If I
was better at Linux scripts and the Linux enviroment, I think a
convolution system could be cobbled together pretty quickly with Jack,
JConvolver, a standard audio interface and some hardware controller. 
Until then, I am pretty happy with the Logidy EPSi:
http://www.logidy.com/
Crappy interface, but have used it with all sorts of IRs.

On 2/7/2017 at 10:30 AM, "Mikko Helin"  wrote:This XMOS board designed
(for stompbox use mostly) by an XMOS employee
might be a good alternative for DSP chips and better than generic
ARM's:

http://www.diystompboxes.com/smfforum/index.php?topic=114354.0
On Tue, Feb 7, 2017 at 8:12 AM,   wrote:
>
> On Feb 6, 2017, at 9:20 PM, cheater00 cheater00  wrote:
>> I understand FFT domain convolution introduces latency, which is
not wanted in hardware.
>
> There are a few considerations regarding latency:
>
> 1) Most convolution represents a reverberation, especially
convolutions of impulses that last a couple of seconds. In nearly all
cases, the reverb involves a pre-delay before the signal appears in
the impulse response. In such cases, the latency can be subtracted
from the pre-delay and then there won't be any perceived latency.
>
> 2) All 24-bit converters have hundreds of samples of delay. Or at
least it seems that all 24-bit converters are built on delta-sigma
technology with tons of digital filtering. Unless you're going to
based your design around a 16-bit or perhaps 20-bit codec, you won't
be able to remove all latency regardless of the convolution algorithm
used.
>
> 3) One of the responses mentioned overlap-add FFT. That technique
allows for significant reduction in latency, provided that the
processor has the power to calculate many more FFTs per the time
available.
>
> That said, I support all designs which strive to reduce latency in
hardware! It's just not as easy as you might think. You certainly want
to start with a DSP, though, for the best chances.
>
> Brian Willoughby
> Sound Consulting
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy

_______________________________________________
Synth-diy mailing list
Synth-diy at synth-diy.org
http://synth-diy.org/mailman/listinfo/synth-diy
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20170207/641040c1/attachment.htm>