The time limit for the impulse responses should be at least ten-folded to allow for at least 200ms IRs to include some room response.
Currently the maximum cab IR length is 21 ms, according to documentation. This is surpassed by Logidy EPSi (an almost 10 years old product running a very simple chip) easily running 500 ms and by Strymon Iridium handles 500ms, Boss IR200 handles 500ms, Axe FX handles 170ms, as well as probably other higher end units.
While it can be argued that 20ms is enough to replicate the cabinet, the room reflections within 200ms time frame or more add considerably to the realism and amp-in-the-room feeling. 200ms and 500ms has become somewhat of a standard for quality IR sellers.
To me it looks like 200ms should be sufficient - ibhave rarely seen any commercial IR’s having information in more than 200ms.
5 Likes
I wonder if this is why I cant see/use my Celestion IR’s? QC downloaded them but they dont show up in the CAB section. I think they are 200ms. When I got them there is a 200ms and 500ms option. Shame if I can’t use them.
You “should” be able to use them! The QC use the first 1024 samples odf the IR and truncates the rest. Same goes with the sample rate - it’s “plays back” at 48 kHz whatever the IT sample rate is. If they don’t show up (as a microphone alternative, not as a “cab”), are there any odd characters in the file name?
1 Like
Aha! Thank you! I didnt realize they are under the mic settings and nit cabs. They are there, thank you and now to try them.
The issue is though that at 21 ms all the info from the room, in which thr microphones were placed, is cut out and in turn the IR does not sound as realistic.
If one would wish to cut out the room reflections, it would be easy to just shorten the IR files, but if one wishes more realism when using the Cortex as a standalone unit with headphones, then this makes big difference.
For direct captures or if you feed the audio into your daw, where you can add any IR file you wish, this does not make a difference.
I feel this is an important point, as the Cortex is a close to perfect contender to be independent from a PC for studio quality tones.
2 Likes
I was actually surprised and disappointed this was not an option on such a device as the QC.
Increased IR length to 200ms is something I hope we will see soon.
I guess 200ms IRs require more processor power – maybe two new dedicated IR blocks would be a good solution. One for 21ms that uses less resources for people who prefer the tighter sound of 21ms and and one that can run 200ms.
Being able to preview the IRs in list view would be nice too.
1 Like
I agree.
Qc must be independent from pc or external ir loaders.
170/200ms today are the minimum quality standard.
And eventually the options on CABS (that i love) with the choice between 21 and 200
1 Like
We have to insist on this topic :slight_smile
Two silent years
And due the fact that plugins have longer irs (reply from support).
Longer stock cabs of QC would be plus valor
(And really compatible quality as plugin)
2048 samples are more than enough for cab block I think. But also 1024 are just fine.
With redwirez (mixir) the difference Is noticeable, when we have longer ir and we set 21 or 200
NOBODY says that 1024 sounds bad
But the point Is another : a professional unit can’t be limited to 21ms…!
1 Like
Longer IR files could possibly be used as convolution reverbs and not just cabinet emulations, could be very useful for creating custom reverbs/ambiences
Keep in mind the QC isn’t just for guitar…
1 Like
Right !!
Returning to guitars:
acoustic guitar irs are really limited at 21ms and in this case BAD…sadly.
2 Likes
I hadn’t thought about it before, but I wonder if that’s why I prefer captures of IRs to just IRs loaded into the cab or IR Loader block. I wonder if longer IRs translate differently into captures than short ones.
Might be worth experimenting with a DAW and IR loader to be captured on the QC
Can you provide with some audio samples?
Capturing in this case introduces distortion if i make up then the gain knob (from qc capture parameters)?
Already done in The past, posted here in discussion.
I don’t Remember the topic. It was 20 and 200 on circa 120ms of originalr ir, with mixir from redwirez.
It was ownhammer ir.
The same Neural DSP plugins uses longer irs as QC. A more organic response from cabinet.
This from ndsp support on my ask.
I had the sensation , that plugins cabinet, with the same external Guitar head, had Better sound overall as QC cab (That i love, to be clear)
Then emailed ndsp, i had received the reported reply.
Sorry for my english…i don’t use translate…and this Is my limit 
2 Likes
I tried capturing the same IRs of different lengths, and the results were indistinguishable so I guess the capture process pares them down like the IR importing process does- to where there’s really no difference in the final files.
Back to wishing/begging for longer IR import capability
2 Likes
So the Ir for QC is 20 ms 48hz?
I can’t see a reason why the QC is limited to 1024 when even the HX products support double the length. I believe the TMP supports up to 4096 or something. This should really be brought up to modern standards. You can still give the choice of using shorter IRs if for some reason you would run out of DSP.