Latency jump when using Row 3 & 4

Quad Cortex Bug Reports
1

CorOS Version: 2.0.1

Describe your issue:
When I use Row 3 in conjunction with a Block (any Block or Splitter), I get an added 2.67ms of latency.

It is roughly the equivalent of 2 amp blocks + 3 cab blocks. (around 1ms per amp and cab combo, the amp block being a third of a millisecond).

Described here on the QC numbers report (latency, send levels, etc.) post

Steps to reproduce your issue:

  • Open a blank preset
  • measure your In to Out latency (should be around 1.75ms)
  • insert a Gain Block on Row 1
  • measure your In to Out latency (should be around 1.75ms)
  • Set your Row 1 output to Row 3
  • Drag the Gain Block to Row 3
  • measure your In to Out latency (should be around 4.42ms)

I expected this to happen:
I assumed Rows 3 & 4 did not add any latency to the global grid (preset), but it does.

I have tried the following things:
There seems to be no workaround other than not using Rows 3 & 4 or accepting the added latency.

3 Likes
2

I don’t work for Neural DSP, but I think I can make an educated guess on why we are observing this behavior.

It has been confirmed that Rows 3 & 4 are handled by a different DSP core. Based on your measurements, that second DSP is processing the output of the first DSP in buffers of 128 samples. Given the sample rate of 48 kHz, we’re getting:

128/48000 = 0.00266(6), which precisely matches the additional 2.67 ms of latency you’re measuring.

Some additional latency is inevitable whenever buffering is involved, but it is a mystery to me why that buffer has to be that large considering that Rows 1 & 2 clearly work with a smaller buffer (otherwise it wouldn’t be possible to get the 1.75 ms number you’re quoting, and what the other people have measured on simple presets utilizing only Rows 1 & 2).

1 Like
3

@Max ,

This looks like a solid chunk of deduction !

Maybe you could add/include this post in QC numbers report (latency, send levels, etc.) for reference.

It could enlighten people that have questions on the subject…
That was the aim of the “qc numbers topic” : finding explanations and putting words on what most of us are “feeling” while playing.

Thanks !

1 Like