Here is a picture of the wave form...
http://stabilitynetwork.blob.core.windows.net/g-tunes/Screenshot%20(22).png

 
Solo'd it sounds like this...
http://stabilitynetwork.blob.core.windows.net/g-tunes/Slap.mp3
 
Frankly it sounds like clipping to my ear. I keep running it down to this track, wondering if the drummer hit a mic or something, but it's always the bassist.
 
The spectrum impacted by the slap spike is really large, so it's hard to just trim it out with EQ.
 
I've tried the Waves RBass plugs. Unfortunately, the slaps aren't really all that musical, so it isn't obviously intentional. It just sounds flawed.
 
Tips are welcome.
 
 It was recorded with a mic cable direct from the Bass Amp. The bass was an acoustic standup bass. I have no idea how the pickup in the bass was designed.
 
If you want to listen in context, try this...
http://stabilitynetwork.blob.core.windows.net/g-tunes/20131215_Vasi_07.mp3
Keep in mind with this track that I have done my level best to 'fix' all the slaps that sounded out of context.
 
Frankly, in some cases I've been splitting the bass track around the slap and just cutting it out all together.

That last one definitely looks like a clip. I couldn't really hear it though (just got my phone right now). I would split it like you've been doing. I know it can be time consuming, but if it's done right, no one will ever be able to tell that you messed with it. Groovy music, btw.

It could be a few things.
 
Sometimes the slap sends the string down onto the pickup cover or magnet and you get a little micro-phonic "pop". Sometimes it's just a nasty fret noise that ends up seeming like a metallic percussion hit. If it's an active pickup it could be a nasty electronic gasp in the on board pre amp.
 
Having just listened, it's hard to guess what that is... especially because the overall signal level seems fairly tame and the playing doesn't seem out of control.
 
Light strings and slack tuning???
 
1) In general, I'd try the easy thing first: Hard limit it down so that they are no louder than the other peaks. You can set the threshold so that it barely changes the character of the bass, and then you can use a compressor after the fact to work on the character if you want.
 
2) I doubt that is going to help and so, If that doesn't work, I'd open that track's audio file in a wave editor and work on the smallest number of samples you can to turn down the level of the offending "pops". This will work better than the hard limit as you can lower the volume of just the offensive stuff and leave all the rest untouched. It will seem like it takes forever, but if you start and dig in you will get through it and when it's done it's done.
 
It seems like it would be worth working with that bassist and finding out what is actually causing it as the ensemble seems to be playing some really cool stuff and it'd be a shame if you didn't get it figured out for the next gig.
 
Happy Holidays!
 
best regards,
mike

Slap bass is not the word I use to describe that instrument. Acoustic double bass is better. For me slap bass implies what electric players do and that also creates some similar issues.
 
I think you will find these sounds are intentional and usually will be in time with the groove. It is a percussive and rhythmical effect. It adds to the sound the acoustic bass player is creating.
 
This is when a separate editor (Adobe Audition etc) is still superior to everything else. You just open a track like this and target the very loud short sounds. Hard limiting is good to do here, eg you limit the top of that peak to match the rest of the track or perhaps be 2 or 3 dB louder. You do not reduce gain here to solve these issues, leave the bottom part of the transient alone just limit how far up it goes.
 
A little EQ can also go a long way on these snappy percussive bits.  I like to then limit the peaks of the whole track down to a more manageable level and add some rms to everything to bring up the level overall. You do all this prep before mixing starts. Save this with the word ED after the original title so you have the original track intact. Drag this into your session te replace the existing bass part. Sets up a nice bass sound right from outset.
 
By doing this prep work properly what you are doing is leaving the original bass track intact with all its dynamics and original life but now all those percussive transients are fixed and sit well with everything else on that track. That is what is excellent about the editor. It targets only very precise areas and leaves everything else alone. Something a processor over a whole track cannot achieve. It still has to be involved with everything even to only tame a few things here and there.
 
Now the only processors you need are gentle compression types to just clamp down the level a little further and add a hint of attitude. With this compressor too don't have the attack too fast either. Let it breath a little and let those transients through. (eg 10 ms or so) Low ratio like 2 or less to keep the sound big. Small ratio means big sound. By the time you get to this point in your mix the percussive sounds will still be present but much more blended with everything and sound good, aiding the music.
 
I assume you are using a mic to record acoustic bass. Despite any spill that may result it is still worth it by far. You are not over dubbing anything so it does not matter so much. This sound will always be emphasised in the DI signal too. If you are mixing DI and mic signals together here you can always drop out the DI hits from the mix at those points too. Do some fades either side of it etc..If you combine DI and mic sounds it is good to filter the DI sound after about 700 Hz or so and just use it to add sustain and a little depth to the acoustic sound.

you have to tame these peaks BEFORE they hit the convertors...
 
or
 
you have to greatly reduce your input gain, so that you never peak, then process it after the fact once it's in the daw.
 
i use a fairly quick acting outboard compressor for slap bass, set up for limiting

Could it be be a clip on mic with clip that isn't fully secure, or it could be a stand up bass getting knocked into a microphone?
 
 

On that little mp3 clip the first one sounds intentional after the bass line goes up higher (in time more so) but the second one after the low notes sounds more like a technical fault.
 
It sounds a little out of tune to me too but that could be me.

mike_mccue
Sometimes the slap sends the string down onto the pickup cover or magnet and you get a little micro-phonic "pop". Sometimes it's just a nasty fret noise that ends up seeming like a metallic percussion hit. If it's an active pickup it could be a nasty electronic gasp in the on board pre amp.

That's exactly what it sounds like to me, i.e. the string touching the pickup.  The instrument needs to be set up correctly so that this doesn't happen.
 
And slap bass is not the style used here.

Ok. Thanks for all the information from everyone. It's a standup fretless bass. I watched him perform it, obviously, and he seemed to slap the strings with his hand from time to time. During the performance, it was not as distracting as it is in the mix.
 
What I recorded is effectively a DI. In other words, his bass was plugged into an amp and there's a send on the back of his amp that I recorded from.
 
All of your information is really good. Mike and Jeff, special thanks for your detailed explanations.
 
I hadn't hard limited the track yet. I had applied some good EQ. It was when I listened in the car that I kept noticing sounds that seemed out of place in the mix. As I ran them down, they were always off the bass track.
 
Jeff, I think you're right that during the performance, the sound in the room was much tamer than what I captured on the recording.
 
I'll try the hard limiting. I mostly use limiting on a final mix. I don't have a lot of experience adjusting limiting song by song to reduce this kind of attack on the instrument.
 
There are no cases in the image I show in this post where the signal actually clips. I also agree with Jeff's assessment that in the mp3 clip that the first one is the more common sound I'm struggling with and the second was an unusual incidental that seemed unintentional.
 
Again, a loud thanks to everyone who responded!

again, i say, outboard compression.
 
i'm talking to myself here, i know.....