Distortion when isolating frequency ranges

Firstly, I must say that I can see the potential of this plug in is huge! I received my license about 10 minutes ago , perhaps I’m not qualified to drive yet… so forgive me if I have missed the obvious.
I am running Spectro in Nuendo 4. I have attempted to isolate a band of frequencies on several sources. The result always sounds as if a digital clock has become unlocked with clicking and frying sounds being the result.
Thanks in advance!


Hi Ade. Thanks for registering!

Did you try increasing the fade setting (the lower knob on the edit box)? If what you’re hearing is the abruptness of the edit beginning and ending, a longer fade-in and fade-out will help.

Spectro does some fairly advanced processing in order to make edit transitions smooth and artifact-free. If you think you’re hearing actual distortion or audio processing errors, that would mean something’s wrong, so please report back.

Hi there and thanks for that fast response!
As I understand it, the Fade function takes care of transitions between audio entering and exiting the boxes.
What I am referring to is a persistent distortion which manifests itself throughout the duration of a box. I think it best that I use an attachment to demonstrate.
Trying to attach files. mp3 not permitted. zip failed as does doc, jpg and wav :confused:
Now providing links…

Thank you for going to the trouble to post the audio files, that was extremely helpful. I spectroed them myself to see what’s up.

The fade knob smooths time-domain transitions in and out of your edits (in the time domain) and also smooths frequency-domain transitions above and below the edits – you’ll see the fade box grow wider and taller as you turn the knob.

In your situation, applying edits at very low frequencies, I think you’re hitting the frequency resolution of Spectro, which is about 20 Hz @ 44.1k. That’s essentially the “pixel size” of the spectral edits you can apply. I think in this case you are hearing a bass harmonic tone alternating between being muted and unmuted (as it wavers above and below the muted band).

Cranking the fade knob will probably help, but once an edit gets low enough in frequency there’s just not enough resolution left to make things really smooth. This is a fundamental problem with FFT analysis, you have to try to find a sweet spot between frequency resolution and time resolution – if I make the frequency pixels smaller, I have to make the time pixels longer, so you start to lose transient information.

I hope that helps!

Thanks for that response!
So does it make sense to place a hpf before spectro?

I have persevered with this and I’m wondering how to deal with material which has low frequency content in an effective way.
If I solo a band of frequencies on a bass guitar which are well above the thresholds you set out above, I am still confronted by clicks.
I’ve tried placing a steep HPF before Spectro but that does appear to help.
Can you provide any suggestions?

Ade, here’s a special Spectro build just for you with a longer FFT window size. This version should allow you to edit lower frequencies, though you will also see less transient definition. If you compare this version with the regular version, you’ll literally see more frequency pixels and fewer time pixels (it will be visually sharper along the frequency axis, and blurrier along the time axis).

[link removed] … unzip and place in the same directory where Spectro is already installed, both versions can coexist (they will both read the same license file even). Because of the longer window size, that version will also have higher latency and CPU use, so I’d recommend using the special version only when needed.

I’d suggest being generous with the fade knob as well. Let me know if that helps!

I can’t believe I missed this!
Please forgive the tardy response. Thank you for doing this!
I assume that even with the May 22 09 release, this dedicated version is still the one to use in LF situations?
I notice that the link is no longer operational.
Are there any other functionality changes in the May 22 version that the special version would benefit from?