Proximity Effect and related issues

[Chris F]

OK, I've reread THE BIG THREAD, and checked out the FAQ, and have also done a search - this last turned up little more than members bitching about who's a troll and who isn't. After all of that, I'd still like to learn a lot more about how to handle proximity effects of LDC's.

Here's my setup: A variety of cheap LDC's (B1, V67, Superlux, etc - none offer Fig 8 or Omni, which may well be the problem) into a Soundcraft M12, going into a MOTU 1224, then into a G4 running DP4. I'm a jazz bassist with a fantastic axe (see pics on the photo page of my site). When I record in the studio, the engineer is usually able to get a great sound on my bass (see "Fifth Business" on the soundclips page if interested). At home, I can get a good strong sound, but it always seems to have a low end rumble that is disturbing when the volume comes up even a little. Once I've recorded it that way, if I try to EQ it out, I lose too much body of the sound in the process.

My first thought is that I've got the mic too close to the table of the bass - about 12" is normal. If I get further away than that, the sound gets too thin for my liking, and picks up a lot of room noise that makes it "weaker" sounding. So with what I have my options seem to be:

1) Moving the mic away and just dealing with the room noise.

2) Keeping the mic close, but using the 100hz rolloff on the M12 - I fear this may rob too much fundamental on the low notes, but...

3) Building a few Rock Wool partitions to block room noise, then backing the mic away from the bass and later compressing it to get that "up close" sound

4) Doing the above, but purchasing a LDC that offers fig 8 and/or omni.

Any thoughts/suggestions? I'd love to get a comfortable bass recording setup that produces a basic sound I'm happy with, as I record a lot as part of my practice regimen. All non-flaming input welcome!

 

[guinsu]

I'm a recording novice, but I was just doing some recording this morning and my experinece might help. I was having a similar problem, too much low end but if I cut it the bass lost body and was lost in the mix. I ended up boosting the mids, somewhere between 1k-3k. I was just screwing around so the eq was set pretty wide, if you mess with it you might find the right frequencies to boost. Then I cut just a tad bit of bass and I was good to go. This was a Gibson Ripper though an Ampeg B-15.

Oh, another thing that helped was turning up the amp a bit louder, I got a sharper attack, more mids and a fuller sound.

 

[Wireneck]

2) Keeping the mic close, but using the 100hz rolloff on the M12 - I fear this may rob too much fundamental on the low notes, but...

Why do you have to roll off at 100hz? I don't know the exact freq but thats where alot of the Bass "body" is in my experience. Why not wait untill you get the track on your mac. Then use a more precise Eq to sweep and see where you can cut without killing the bass track. I would start at 50hz and move up from there.

 

[crazydoc]

My choice would be option 3, and maybe leaving the mic up fairly close. I don't know that 12" will give a problematic proximity effect, so this may not be your problem. You may be getting standing wave or other acoustic problems because of the room configuration and the instrument/mic locations. I assume you've tried moving things around, but putting in some sort of bass traps and other acoustic modifiers may help.

An omni mic would be an option too - ECM8000?

Thanks for starting "the big thread", by the way. Maybe Harvey can chime in here with a few hundred useful posts again.

 

[Harvey Gerst]

Ok, here's a wild ass thought that may just work:

Since you're dealing with proximity build-up, try putting a cardioid right next to your main mic (or even closer to the source), invert the polarity, and low pass the sucker to just let everything below 400Hz come thru. Run that to a second channel, so you can dial in (or out) the amount of proximity effect you want.

 

[mshilarious]

Is there any difference other than the mic/recording chain when you're in a pro studio? I'm guessing it's not the distance but the position that might be the issue. Try moving the mic around, not back & forth.

 

[cprieb]

At home, I can get a good strong sound, but it always seems to have a low end rumble that is disturbing when the volume comes up even a little.

From someone who never recorded a double bass...
Apart from room related issues, have you tried to cover the f-holes (total or partially) with a cloth or something? Partially covering the sound hole of "bassy" guitars sometimes helps (at least for me) to get rid of the excessive boominess.
César

 

[AGCurry]

You've received a number of great suggestions. As you may have noticed, many of the suggestions have nothing to do with EQ and a lot to do with mic placement and miking technique. If it's a good bass and sounds good in the room, then it really should be possible to record a good sound without a lot of signal processing.

Yes, I sometimes do stuff some foam in the f-holes of my bass, as it can get pretty boomy. It helps.

Currently, my practice is to use one of my AEA R84s about 18" away, approximately even with the end of the fingerboard. Too much of the lower bout can emphasize boom.

And, as was mentioned, a cheap LDC may be the least desirable of mic choices, as their off-axis response can be problematic.

 

[Chris F]

Thanks for all the replies! I'll see if I can answer most of them in a few words or less:

BOOST THE MIDS: This tends to sound "nasal" on my tracks, and brings out an unattractive aspect of the tone of the bass.

100HZ CUT: That's the rolloff frequency for the pres on the M12.

STARTING THE BIG THREAD: Thanks, but I defer all thanks to Harvey. Any idiot can ask questions...the same can not be said of answers. I can only marvel at the amount of views that thread has gotten, and how many folks Harvey has taught by being kind enough to post all of that stuff. And speaking of Harvey...

OUT OF PHASE 2ND MIC: If I'm looking (as I understand the suggestion) for controlled phase rejection, should the second mic be a close match to the first (as in 2 LDC's of the same make) for this to work, or can a different type of mic work?

F-HOLE FOAM: Hmmm, I dunno. I'll try it, but...seems a waste to play a bass with such an insanely good acoustic sound and then put foam in the f-holes for recording. But hell, I'll try it!

DIFFERENCE IN THE STUDIO AND HOME: Mics (CAD/Shure/Neumann vs. SP B1), pres (Universal Audio 2 610 vs. Soundcraft M12), pro engineer who knows what the **** he's doing vs. little old me, controlled acoustic environment....nah, it's pretty much the same.

It may take a while to build the partitions with the busy schedule, but I have a feeling it will be well worth it. I'll try some of the other stuff this week.

 

[leddy]

Chris,

We've talked before (TB member); I record my double bass all the time and dealt with similar issues. I just could not get rid of the over-powering rumble without removing the essence of the instrument or burying it in the mix.

I think this will make it simple:

The best solution I found was to only roll off the lowest lows, usually about 60hz and below, maybe more or less depending on the sound you are going for. Handle the rest with multi-band compression. I use a Voxengo plug called Soniformer that works great. I use it after I've mixed down into Wavlab. I'd be happy to send you some before-and-after MP3's if you like. It took me a while to dial in the multi-band properly, but now I am getting good sounding bass that translates well to other systems, and sounds like a bass. I use longer attack times and add it to the mix rather than the track, like I mentioned. More like mastering compression than anything else, but it's working for me.

My mic techinque is more about isolation in a live setting. I use a small-diaphragm mic clipped on the bass about 4" away pointed between the f-hole and the bridge on the G-string side.

 

[mshilarious]

DIFFERENCE IN THE STUDIO AND HOME: Mics (CAD/Shure/Neumann vs. SP B1), pres (Universal Audio 2 610 vs. Soundcraft M12), pro engineer who knows what the **** he's doing vs. little old me, controlled acoustic environment....nah, it's pretty much the same.

I wouldn't sell yourself short: you already know a lot of what the pro did. I don't want to start another SP = Neumann thread, but your gear shouldn't hurt that much. If you were complaining about muddy rather than boomy I might worry about the gear. The only major shortcoming I think you might have is the room.

Try something crazy: record outside (OK wait for a nice day first). Don't worry about all the extraneous bird and traffic noises: this is just a test of your room. If it doesn't sound boomy outside, it's your room.

 

[Chris F]

Chris,

We've talked before (TB member); I record my double bass all the time and dealt with similar issues

What name do you go by on TB?

I think this will make it simple:

The best solution I found was to only roll off the lowest lows, usually about 60hz and below, maybe more or less depending on the sound you are going for. Handle the rest with multi-band compression. I use a Voxengo plug called Soniformer that works great. I use it after I've mixed down into Wavlab. I'd be happy to send you some before-and-after MP3's if you like.

That'd be great! The only multi band compression I've got is a DP plug that I don't fully understand, but it'd be worth a try. I might need help with tricking out the settings the first time or two. I already roll of at 60, so that's not really the problem freq.

 

[Chris F]

MS - Thanks, but this engineer is not only a good musician and a pro, but he can also do one thing that I can't do: crawl around on the floor in the room he'll be recording me in while I'm playing to figure out exactly where to put the mics. I should try his upper mic technique as well - something Harvey suggested years ago and I couldn't figure out how to make it work! The other thing that's great about this guy is his willingness to share information - when we mix, he's really good about telling me exactly what he's doing so I can try to learn. I'm sure I'm a pain in his ass, but he's a real sport about it.

 

[leddy]

Chris, I'll send you an email with the MP3's. I don't know how or where to post them.

 

[leddy]

Why do you have to roll off at 100hz? I don't know the exact freq but thats where alot of the Bass "body" is in my experience. Why not wait untill you get the track on your mac. Then use a more precise Eq to sweep and see where you can cut without killing the bass track. I would start at 50hz and move up from there.

This is true for me as well. I find it best to roll off below around 60hz, leave everything in around 100hz, and notch out a bit around 200 where the muddy, boomy sound usually is. Then I add the mutli-band comp, which works well for this by not taking away the lows until they get out of control. I set it to begin very gently working around 400 and progressively more down to the bottom. Long attack times keep it natural sounding.

 

[4-Man Takedown]

I believe Figure 8 mics have the most amount of proximity effect so I wouldn't neccesarily use one of those. Omni has the least so that may help. But I'm sure most mics you would conisder would have variable patterns.

 

[chessparov]

How about the lo-tech solution that Chess Records used?

Use an EV 635a on stand-up bass or electric.

Just like they did on Willie Dixon.
Seems to have worked "pretty good".

Chris

 

[Harvey Gerst]

Ok, let's go back to basics: What is a cardioid pattern?

It's a construction of omni (pressure) with an equal mixture of figure 8 (velocity). When the mixture is 50/50, you get cardioid. But, when you get too close, the velocity component swamps the omni part and you get the proximity build-up, typical of all pressure gradient patterns.

How do you fix it? Well, by moving back a little, out of the circle where the velocity part swamps the pressure part. That's one way. My suggestion was to correct the velocity buildup by using a reversed proximity effect only (on another channel) to dial in just the amount of desired proximity effect. It should work in theory, but I don't know that for certain.

Rotating the mic slightly might reduce the proximity effect, since velocity (and its resultant proximity effect) would be diminished from off-axis sources. You risk changing the high frequency response, but that may only need some mild, more benign EQ.

A wide cardioid has less proximity effect, so that might be another choice. Or playing a little more with mic positioning. EQ and multiband compression might work, but I'd be concerned about adding unwanted artifacts to the signal.

It's a problem in need of a good solution.

 

[Chris F]

Ok, let's go back to basics: What is a cardioid pattern?

It's a construction of omni (pressure) with an equal mixture of figure 8 (velocity). When the mixture is 50/50, you get cardioid. But, when you get too close, the velocity component swamps the omni part and you get the proximity build-up, typical of all pressure gradient patterns.

Gotcha.

How do you fix it? Well, by moving back a little, out of the circle where the velocity part swamps the pressure part. That's one way.

I just tried this, and the results were encouraging: Instead of 12" directly in front of the string afterlength (my usual spot), I moved the mic up to just over the bridge and backed the mic up to about 18" from the table. Also, based on an earlier suggestion, I also moved out into the center of the room in the hopes of diminishing any weird bass response I might be picking up from the walls (I've got bass traps, but...). Last, I dug out my old dusty B*******r preamp with a variable hi pass on it and set it for about 60hz. All of this together got me a cleaner signal for sure, although I haven't tried compressing or "normalizing" it yet.

My suggestion was to correct the velocity buildup by using a reversed proximity effect only (on another channel) to dial in just the amount of desired proximity effect. It should work in theory, but I don't know that for certain.

Right...I'm anxious to try this, but can you tell me if I need a matching mic to do this effectively? I've been using the SP B1 lately, but I only have one of them.

It's a problem in need of a good solution.

True! But I've been getting closer, and tonight I got closer still. I've already decided to hire the engineer to come help me set up my home rig when their schedule lightens up. He's into the idea, and so am I. But until then, you guys are helping just fine, thanks.

 

[Harvey Gerst]

Gotcha.

I'm anxious to try this, but can you tell me if I need a matching mic to do this effectively? I've been using the SP B1 lately, but I only have one of them.

It wouldn't hurt but since you're trying to just get the proximity effect out of the picture, any decent second cardioid mic should work fine (if the idea even works at all).