Compressing signal before writing to wav file

Pre-processing signals

Hello,

I think this might have already been answered but I cannot find the thread. I’m trying to do the DSP before it get’s written to the wav file. For example, I want to be enable the compressor effect and be able to record the compressed signal to the wav file. From what I’ve been able to do (and from the signal path chart on the web site) it doesn’t look like it can do it that way. All I’ve been able to do is record the dry track.

I think I read somewhere that you can do that by enabling the effect on the master channel. My problem with that is all the tracks gets processed in the playback monitor during overdub. And that is annoying especially if you’re using a guitar amp simulator that you want to use only for the guitar overdub track.

Is this beyond N-Tracks abilities?

I’m not sure why you’d want to do it that way. Perhaps you can enlighten me.

Afterall, if you have the dry track and the effect you can still re-create the effected track but have the benefit of being able to alter and adjust the effect. Once it’s written to wav you are committed. If CPU is an issue then do a partial mixdown/Freeze.

Of course specific guitar effects (eg an amp’s distortion) or gentle vocal compression are a different matter.

But basically I don’t think you can do what you want with n-track on it’s own. A plugin may help. I seem to remember something called “Tape It” which sits in a track an writes the processed track to a wav file. You’d then have to import the resultant track into n-track.


Mark

I agree with Mark.

A) n-Track won’t do it
B) you don’t want to do it
C) you can always do it later: “Freeze”, or else solo and mixdown to render to wave.

The reason you don’t want to do it is what’s so totally way cool – really just about the neatest thing – about using software amp/cab emulation. Listen closely, because here’s a secret. We ALWAYS adjust all FX and EQ while listening to the whole mix. Because that’s the ONLY thing that counts: how the track sounds in the mix. Of course, this means that we need to readjust as we change the mix. The good news is it’s easy.

Here’s the connection: the guitar amp & speaker tone is now just an effect, so you can tweak the tone after all the tracks are in the can. WAY COOL. Really.

Of course, you dial up the sound you want when you record. Also, if you can, you play it out nice big speakers so you get acoustic feedback (the way electric guitar should be played anyway). Unless the baby’s sleeping, and then you use headphones and live without the real feel of an electric guitar (and that’s the 2nd best thing about amp/cab modelers). You want that great tone because you PLAY it, it affects how you play.

But you can change it later. If it was a great track with the sound you dialled up, it’ll still be a great track with a slightly different tone. If there are two guitars, so much the better: instead of just using EQ to carve them out their own nitches to avoid stomping on each other, you can adjust the amp/cab, heck even the pickup style (e.g., single-coil emulation, such as it is).

Learn how cool it is and you’ll be happy you did. Meanwhile, just freeze the track to bake in the amp tone until you have more tracks and are ready to tweak. Be prepared to smile a lot.

Cheers
Jeff

I agree with Jeff and would expand slightly on it. I recently did some live recording where we used a Line 6 POD to do guitar-amp emulation. This was necessary for the monitors in order to give the player a sense of what it would sound like. Unfortunately, for the recording I simply recorded the stereo output of the POD and while it was OK, we were not too happy with the sound and weren’t able to change it significantly after the fact.

The next time I do it I will still use the POD and probably still record the stereo output but I will place a direct box in front of it and record the direct sound as well. This will let me use a plug-in or “re-amp” the track using the POD or an actual amp after the fact. Recording the stereo output saves a lot of effort if it happens to work and I can record up to 16 simultaneous tracks so I usually can get away with it. If I was short of channels I would use only the direct track and depend on the POD for monitors only.

If you are not familiar with “re-amping” it refers to playing back the track into the input of a guitar amp which is then mic’ed and rerecorded to another track. This lets you play with the sound to your hearts content without have to repeat the performance. Obviously I could also use the POD to re-amp and could fiddle with the sound in that way. The ability to use volume envelopes, gates and stuff between the track output and the amp make this an even more powerful technique.

I do have a question though. While I can work out the details of re-amping (adjusting for the delay etc.), it would be much simpler to just use a plug-in. Does anyone have any recommendations? I would be willing to consider buying even an expensive plug but I do have a natural “gag-reflex” at paying more for a plug-in than a hardware emulator such as the POD (which is useful for live playing as well as recording). I am not a serious guitarist so I am more interested in the occassional project than regular use.

Jim

Oh I totally understand the benefits of post-production effects processing. My problem is that I’m not getting the same results that I would expect.

Here’s the scenario. I like to use a light setting on a hardware vocal compressor to “pre-amp” the mic, so to speak. Afterwards, at mixdown, I’ll run the vocal track through N-Track’s compressor plug in and I get a good, strong and even dynamic range, with very little volume envelope manipulating involved.

Now, I would really like to eliminate the hardware compressor completely and use the plug-ins (since it’s there anyway). I tried chaining two compressors in the effects chain, since that’s basically what I’m doing. But, the results are not the same. I can’t figure out why.

So, I was hoping that maybe N-track would be able to stick the effect in front of the wav. The effects chain as such:

mic -> effect -> wav -> effect

Instead it seems that N-Track can only do it this way:

mic -> wav -> effect -> effect

I can only assume it’s like the way guitar effects are slightly different depending on the signal path. For example, sticking a flange in front a delay…delays the flange. In contrast, sticking a delay in front of a flange…flanges the delay. I don’t know if I’m making any sense. In any case, I’m not getting the same result that I have been happy getting when using my compressor as a mic pre-amp.

I have, however, been successful in eliminating my hardware compressor and getting same result when I used a Korg D1600 digital multitrack. That system allows you to stick the effect before the track as well. So, I was hoping N-Track would be able to do the same and help me free up some desk space.

Anyways…thanks for the quick responses. The user forum has been an awesome resource.

It has to be a matter of gain staging - the order difference you describe should not make a difference.

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I would really like to eliminate the hardware compressor completely

I’ve been very unhappy with any plug-in when trying get the sound I remember from some old trusty hardware compressors/limiters. It’s not that the plug-ins don’t work, or even do a good job. It’s that they don’t sound the same. I can’t put my finger on it though.

I know this isn’t want you want to hear, but I suggest using a real hardware compressor. This can be done after the fact if you have a good multi-IO soundcard (play the track(s) and send it to the compressor only, record the output of the compressor on another channel). Something I plan on doing so day is just that, but I haven’t yet done it since my old hardware is still boxed up after a move from about 10 year ago. I’ve just moved again so maybe now is the time. :)

Optimizing cascading compressors can be pretty complicated. Remember that you have at least 4 controls for each (slope, threshold, attack and release time) as well as invisible differences (such as the detector characteristics). If the compressor characteristics are different it will also matter which sequence they are in. There are a few words on the subject (pertaining to hardware chained compressors) at FMR Audio. The quick summary is that it takes a lot of time and care to get the most out of cascaded compressors. These guys make some decent low-cost preamps and their compressor is interesting in concept as well as quite good.

If I were trying to “reverse-engineer” your chained compressor setup I would start by trying to reproduce the sound of the hardware compressor with a plug-in remebering that all the timing markings on the hardware unit’s knobs are probably close to meaningless. I would record the same performance by splitting the input and recording one track with hardware compression and a second track without. Play with a plug-in on the “dry” track until you get your best match then save it as a preset. Then try adding another instance of whatever configuration you prefered previously to each track and see how close the dual-plug version comes to the hardware plus plug version.

Jim

That’s a great idea, jimbob, one of those obvious ideas that just didn’t occur to me when I was thinking about dhsc’s problem. Huh, I feel stu-pid. :)

In the end I’m with phoo, however, my little dbx 163A compressors with one slider just sound better than fancy-dancy plug ins.

The one thing about taking the wav file out into the analogue domain and back in again is that it does subtly change the sound from the conversions - at least I can hear it when I have tried it with my aardvark - something just a bit unpleasant about the resulting sound - could have been me, however. I’d love to get a good analogue thing for summing.

:)

About re-amping. I just bought the Line6 Pod XT Live. With this unit you can monitor the amp signal through the outputs of the unit while digitally recording the clean signal direct from the guitar. You can then digitally send the clean signal to the unit and digitally receive the effected guitar using any amp modelling you want. This is the ultimate re-amping processor. I think I saw it for about $399 on zZounds, but that might’ve been a scratch and dent.

The amp modelling is great, but I am a bit disappointed in the effects chains that you can achieve. I used to have a Digitech RP12. It had an awful distortion sound and the reverb was pretty much teh suxxorz, but the effects routing/patches were really wonderful.

Jimbob,

Native Instruments Guitar Rig is supposed to be the bee’s knees in guitar/cabinet modeling these days. $500, unfortunately (IIRC). I haven’t ever heard anyone who’s actually used it say they like any other software package better, and it generally gets much better reviews than Line 6 POD (which I think is pretty darn good for the price & what it is.)

dhsc19,

The reason is probably that your hardware compressor has its own sound and you’re not getting that same sound from any software compressor you’ve tried. It would not have anything to do with before/after wave file saving – you’re barking up the wrong tree there.

The other reason it might sound better is that your soundcard doesn’t handle extremes well. You’re feeding a more processed (“better behaved”) signal to the soundcard and getting a higher S/N ratio among other things. With a quality soundcard this shouldn’t be the issue, but it is a possibility.