Speaker farting.

[Lobster11]

Two more things to check are your bass' battery (when they get low, they cause the bass to distort) and if the preamp has a volume trim pot, turn that down.

A weak battery in an active bass can definitely cause a "farting" sound. I'd check that first, as it's cheapest and easiest fix if that happens to be the problem.

 

[moody]

If you do a 40hz HPF on a 5er, your strings will sound uneven because the B is getting only the second harmonic and higher whereas all the other strings are getthing their full range reproduced.

Realising that this is theoretical and real life can have a different effect. With a 60hz high pass, the E and A string (55hz) will sound uneven from the D. This seems like a no-win situation with only the best compromise possible. (sweepable high pass filter and settle on what sounds best for you without farting).

Given that when I play a 5 string I very rarely actually use the B as a B I would be quite happy with a 40hz filter. I use a 5 string for ease of getting notes (particularly the E, F, G on the B string). I sometimes use the D, but with a 40hz high pass there would still be a fair bit of that getting through unless it was a really really sharp slope.

 

[will33]

Your Acoustic speaker is a Guitar Center house brand and is generally low budget stuff, it's not the same Acoutic company as the great stuff made in the '70's. But, that said, don't let people talk you into thinking you need to spend $500-$1000 on new speakers when twisting a knob or two will fix your immediate problem.

It might not throw the "tone in your head", but if you can't at least get a workable sound out of it, within its volume/power limitations, it ain't the gear's fault.

 

[morgansterne]

I also highly recommend one of fdeck's hpf pre pedals. High pass filtering can protect your speakers even if you can't hear that it's doing anything.
I use one at band practice most of all because it seems to clean up the sound in the room nicely.

 

[will33]

OP, you may've realized by now that bassists can be almost as bad as guitarists as far as throwing money at problems and getting more gadgets to fix whatever needs gadgeting, or gadgeting whatever needs fixing, or some such.

Fdecks hpf is a wonderfully well thought out tool with many practical uses, but your immediate problem is straightening out the knobs on your bass.

First upgrade should probably be a better quality speaker, but again, that may not be the source of your immediate problem.

Lets start by turning some knobs...down. That's free.

 

[friendlybass]

Any updates on whether this stuff helped? I'm curious to see if it was your input or if the speaker rating was set by the marketing guys instead of the engineers.

 

[4-stringB]

Maybe I'm uninformed about active basses, but isn't it not a Best Practice to run actives into a passive input? Someone please enlighten me.

 

[will33]

Maybe I'm uninformed about active basses, but isn't it not a Best Practice to run actives into a passive input? Someone please enlighten me.

Labeling inputs passive and active is generally a marketing thing and has precious little to do with what's going on electrically.

One input is likely padded down (attenuated), likely labeled active, the other is not, generally labeled passive.

In truth, it just depends on how "hot" (strong) a signal your pickups are throwing at the amp. Some passive pickups can send a hotter signal than some active ones, just depends on their design.

I almost always use the "passive", or "non-padded/attenuated" input for every bass. Only exception would be if its signal is so hot you don't have much wiggle room in the gain knob between "quiet" and "too loud/distorted".

So far, that's never happened.

I think padded (active) inputs are mostly a gimmick. Might be of some use if you have a big pedal chain in front of the amp with gain stacked on top of gain stacked on top of more gain...or if for some reason you need to send a line level input in the front of the amp.

Mostly just gimmick, and for some reason (input impedance?), padded inputs seem to suck something out of the tone compared to using the passive input and just turning the gain knob down a bit if need be.

 

[ArtechnikA]

Maybe I'm uninformed about active basses, but isn't it not a Best Practice to run actives into a passive input? Someone please enlighten me.

Bit of a diversion but yes.
Run everything into the Passive input unless you have such a hot signal (also possible with some passive basses) that you are swamping the input stage.

 

[agedhorse]

Ok, so with the amp rated at 250 watts into 8 ohms and your cabinet being 8 ohms, the amp's 4 ohm rating doesn't matter. You have 250 watts available into a cabinet that's only moderatly efficient. You may not have enought rig for your needs based on what I see and what you have said.

 

[will33]

Ok, so with the amp rated at 250 watts into 8 ohms and your cabinet being 8 ohms, the amp's 4 ohm rating doesn't matter. You have 250 watts available into a cabinet that's only moderatly efficient. You may not have enought rig for your needs based on what I see and what you have said.

He has an active bass with the bass knob "cranked". In other words, some 12 to 18db of 40hz shelving hitting the input. Former guitar player (mostly passive tone cap stuff there).

 

[agedhorse]

It that's the tone he's after (maybe he doesn't realize how the controls on his active bass work), then definately he will need much more rig for the gig.

 

[cfsporn]

It that's the tone he's after (maybe he doesn't realize how the controls on his active bass work), then definately he will need much more rig for the gig.

I don't think that is the tone he was after. Most/all guitars have passive tone knobs and he was probably shooting for a wide open tone, not knowing he was getting a +12db boost at 40Hz, 500Hz, and 4kHz.

 

[will33]

Needs more disco.

 

[groovatron]

Judging by the info so far in this thread......my diagnoses is this......

1. You are overloading frequency boosts from your basses active preamp.
2. You are likely doing this to achieve a tone and volume that your rig is not currently capable of producing.
3. You plan on playing in a metal band with 2 loud guitarists and need to have room to compete

My recommendations?

1. Start by setting your basses active tone control to flat. See how much headroom that gives you. If this solves the "farting" problem, but still leaves you wanting more, proceed to step #2.

2. Get yourself some better gear. I would start with a speaker cab. You talked about getting a 212. I would ditch the Acoustic cab and hook up with a quality 4ohm 212 (Avatar, GK, and the list goes on) If you plan on two cabs, grab an 8ohm cab.......but I would only do this if you plan on upgrading to a higher powered head. If this doesn't work, proceed to step #3.

3. Buy a new head to go with your new cab. There are a plethora of good options today so it's all a matter of taste. If it were me, I'd grab a used GK MB500 or MB800 if you can afford it......but then again, that's just my opinion on what would likely work for you.

Good luck......the journey of gear is a never ending battle.......hopefully TB can help you skip a few baby steps

 

[Fingerpickingood]

Sorry for the delay, everyone. Flattening the EQ settings on both basses definitely helped to alleviate the farting. I do however plan on getting a better quality cabinet. And cfsporn is correct about my erroneous beliefs when it comes to EQ stemming from my time as a guitarist. So much to learn!!!

 

[cfsporn]

Sorry for the delay, everyone. Flattening the EQ settings on both basses definitely helped to alleviate the farting. I do however plan on getting a better quality cabinet. And cfsporn is correct about my erroneous beliefs when it comes to EQ stemming from my time as a guitarist. So much to learn!!!

You've come to the right place.


Welcome to the lovely low world of bass.

 

[C130AVN]

I dabble in pro sound (insert sound guy slam here). From my experience barring any mechanical failures with the driver, you may have reached the limit of the cone excursion (Xmax) of the driver. I would recommend rolling of the very bottom end. I'm not sure what your amp settings are but our ears attenuate both low and high frequencies at lower volume levels, and what sounds good at basement volumes becomes boomy and over sibilant at high volumes. Try running your EQ flat at high volumes and then adjust to taste, if that doesn't take care of the farting out then you may have to roll up the tone knob on your bass.

 

[CL400Peavey]

If adding more speakers is not an option, try high passing your signal at 40Hz if you play a 4 string and 60Hz if you play a 5 string.

Because the low B is pure hell on 80% of all drivers. Much better to get the second harmonic IMO.

If you do a 40hz HPF on a 5er, your strings will sound uneven because the B is getting only the second harmonic and higher whereas all the other strings are getthing their full range reproduced.

Pretty much all this discussion on HPF's is not correct.

and treble, mid, and bass, all cranked.

As you have found out, this is your issue. Set your EQ flat, and get the tone you want from your amp. Then make small changes on the bass. As a note, boosting the eq on your bass may require you to pull your gain back a tad.

 

[Ric5]

Speaker farting.

Quit feeding it beans ...

Open the window and let in fresh air ...