a problem with bass guitar signal

[trispectrum]

Hi all,

I have been trying to record my bass using my computer but I've found that after recording a take there is a problem with the bass guitar's waveform. The signal seems to "favor" the bottom half of the full dynamic range. It's a little tricky to describe but imagine a pure sine wave centered about -inf dB but the bottom peaks of the wave have a greater amplitude than the top peaks. I don't think this is a DC offset problem as the signal rests at -inf dB when nothing is played. It's as though the waveform is skewed, or warped, or weighted in one direction, obviously decreasing it's overall loudness.

I also recorded a guitar track alongside the bass but it didn't suffer the same problem. I've run into this problem before when recording vocals. This has been bugging me a lot and I'd really like to know what's going on here so I can correct the problem and get a better signal. Is it my bass? is it somehow related to the position of the pickups on my bass? If it matters I'm playing a 1981 rickenbacker 4001. I recorded a clean signal - no effects, compression or eq. I'm really hoping there is someone here who knows what's up. Thanks for reading!

 

[Rokket]

It sounds like maybe you need something in your signal chain to boost it. I DI my bass into a Fostex MR-8, and when I transfer the files to my pc, the wave forms look the same as the others. How are you hooking up to your pc? Your soundcard might not be able to properly record the low end freq's of the bass.

 

[trispectrum]

I forgot to mention. The chain is as follows:

bass guitar -> direct box/preamp -> small mixing desk -> soundcard

 

[Rokket]

I forgot to mention. The chain is as follows:

bass guitar -> direct box/preamp -> small mixing desk -> soundcard

Is it a stock soundcard? You may want to look into getting one that is made for recording. It sounds like what I said earlier, that your soundcard isn't made to handle the low end of your bass....

 

[trispectrum]

Actually the soundcard is fairly high quality. It's an M-Audio Delta 66 card.

 

[EVT]

Hi trispectrum,
When you put your bass through an amp does it sound ok? I doubt it's the amp. Is it maybe a setting that you have to adjust for routing onto a different track? Have you tried testing the bass through the same input that you went through with the guitar that worked ok?

I think the ric is a passive instrument so, you need to put it through a preamp to power it. What preamp are you using? Also what kind of mic are you using? Does it need phantom power?

evt

 

[trispectrum]

Hi trispectrum,
When you put your bass through an amp does it sound ok? I doubt it's the amp. Is it maybe a setting that you have to adjust for routing onto a different track? Have you tried testing the bass through the same input that you went through with the guitar that worked ok?

I think the ric is a passive instrument so, you need to put it through a preamp to power it. What preamp are you using? Also what kind of mic are you using? Does it need phantom power?

evt

Thanks for the reply EVT,

The preamp I am using is a midiman audio buddy and the Rick is indeed a passive bass guitar. Strangely, the problem seems specific to the bass, other guitars don't seem to suffer the problem when using the same recording chain. This led me to suspect it may have something to do with the bass guitar itself. The problem is still very much a problem, but I can't find a fix. It's not that the bass sounds bad, it's simply that the problem prevents me from getting a loud, balanced signal out of the guitar something that can be easily seen in a wave editor but can't necessarily be heard. Everything is fine tonally, it's more of a loudness issue.

 

[EVT]

trispectrum,
adding compression may help. You can raise the volume by raising output level on the compressor. What guitar are you recording with? Is it active or passive? Maybe you have a low frequency cut setting that's set on or something? Does the bass sound ok when playing it, or only when listening to it back on the recording does it sound low?
evt

 

[rapedbyape]

something that can be easily seen in a wave editor but can't necessarily be heard.

If it sounds alright, why does it matter?

 

[AGCurry]

My first thought was DC offset, but it sure sounds like the problem's in the bass. I'm thinking that it has to be a problem with the pickup(s) or perhaps a faulty capacitor on a tone pot. It's the kind of thing that *might* sound okay playing through an amp (imagine the speaker excursing more one way than the other) but could definitely cause problems in digital recording.

 

[Todzilla]

Why do you have the mixer in the signal path? If you're going into a preamp, the resulting line output should be ready to go right into your sound card.

I always favor as direct a signal path as possible.

 

[Farview]

Some instruments are just like that. It could be the way you are playing that makes the string warble more in one direction. I normally see this when something is compressed with the attack set too fast.
20 years ago, you wouldn't have been able to see what the sound looked like. You had to rely on your ears. If it doesn't sound bad, it really doesn't matter what it looks like.