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Low B Question

M

Moxa13

Apr 14, 2003
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#1
Here is my gear one avatar 210 cabinet, and an avatar compact 115 with horn speaker cab. Both cabinets are 4 ohm cabinets. I am playing through a peavey 700watt fire bass head. With both cabs it is a 2 ohm load. Which the firebass head should be able to handle. My usual bass is an OLP stingray 5 string. I sometimes play my Ibanez 406sr.

I notice that on the open b, and up to the sixth fret. I get some distortion. It was my under standing. That lower notes need more power, or clipping occurs. I notice the distortion happens mostly at lower levels. Is this a cab question or amp and power question? What do I need to do to prevent this from occurring? Or am I completely missing something?
 
#3
Actually, yes. It does sound odd. At higher volumes it does not distort. It still is not the best sound though. The red light on my speaker protection at volume 3 lights up like a christmas tree. The amp pushes 700 watts at 2 ohms, the speaker cabs should be able to handle the wattage. I have read on reviews of the Firebass, that the speaker protection light is sensistive. So maybe that is it.

What am I doing wrong here?
 
#4
Wow. A puzzle, this is.

BUT - if the protection light is coming on, that should mean that the amp is at or near its power limits, which jibes with the B string notes being power hogs (especially if you have bass EQ boosted anywhere in the chain).

Only thing I can think of that might explain distortion that goes away at higher volume settings would be a dirty volume pot on your amp. Do you hear any noise or crackling when you change volume settings?
 
#5
I would suggest that you are hearing distortion from the speakers. I imagine that the difference in distortion you hear at different volumes is a function of how your ears work at different volumes, but I couldn't swear to it.

Speakers are not very happy below their resonant frequency (Fs) and below the tuning frequency of the cab (Fb). The Avatars (like most commercial cabinets) sacrifice a bit of distortion for a lot of volume.

You will probably notice the distortion is worse with a neck-thru bass than with a bolt-on, as the neck-thru will have more energy at the fundamental frequency.
 
#6
Moxa13 said:
Here is my gear one avatar 210 cabinet, and an avatar compact 115 with horn speaker cab. Both cabinets are 4 ohm cabinets. I am playing through a peavey 700watt fire bass head. With both cabs it is a 2 ohm load. Which the firebass head should be able to handle. My usual bass is an OLP stingray 5 string. I sometimes play my Ibanez 406sr.

I notice that on the open b, and up to the sixth fret. I get some distortion. It was my under standing. That lower notes need more power, or clipping occurs. I notice the distortion happens mostly at lower levels. Is this a cab question or amp and power question? What do I need to do to prevent this from occurring? Or am I completely missing something?
Click to expand...
Is your bass knob on your bass turned up high for a "bassy" sound? Instead of cranking up the bass knob for more low frequencies, back off the mids and highs and you will accomplish the same thing without the added signal gain. A dimed bass knob really kicks up the signal level and is a common amp farting cause.
 
#8
KMACLEISH: No, I do not hear any crackling when I turn the volume knobs.

ESP-LTD: I’ve never heard that about bolt on and neck thru basses. I’ll have to keep that in mind. I have heard from others, that sometimes the avatars have trouble with the b string. Like you said, they probably sacrifice to allow more volume.

BABA: As for my EQ. It is all turned to zero across the eq.

KDT: Yes, I have heard that too about The Firebass system. The thing I do not get is that the speakers should be able to hadle 350 watts a piece. Especially the two ten cab I have. I guess when the lower notes are played the power “spikes”. Is that a correct assumption?

Thanks for all the input. I should know more about this stuff by now. I appreciate your patience.
:)
 
#10
This is just thought, but...

Perhaps your 210's are distorted all the time...but at low volumes, the low B is not being sent through the 15 very much...mostly the two tens.

Then at higher volumes the 15 is being utilized more and drowns out the 210's (which are still distorted, but cannot be heard as much because of the 15).

Essentially the 210's are distorted...at low volumes you hear the 210's more...high volumes you hear the 15 more.

Have you tried each cab seperately to tell if it is just one or the other at any volume?
 
#11
Yep, I have tried them seperately, and the same thing still happens. They both distort at the lower volumes. I am thinking about just going back to the 4 string. I dig the lower register, but I want o have a good town to go with it.
 
#14
Have you tried different speaker cables?

It could be vibrations causing a bad cable or perhaps bad wiring in the cab(s) to move and cause the distortion. At higher volumes the volume of your bass is drowning out the distortion you hear at lower volumes.

Interesting problem.
 
#15
Neck-Thru vs Bolt-On Construction

Probably more on this over at the Luthier's board, but as I understand it a neck-thru instrument has more energy associated with the fundamental than a neck-thru instrument.

Taking for example the E string (40 hz) it will have a harmonic content:

40 hz fundamental "a"
80 hz 1st harmonic "b"
160hz 2nd harmonic "c"
320hz 3rd harmonic "d"

-where a-d represent different amplitudes; the sum total of all the audible harmonics is the timbre of the instrument. Perhaps the relationship is:

b= 50% of a
c= 25% of a
d= 10% of a

-and so on (numbers for the sake of discussion). A neck thru instrument has more energy associated with the fundamental while a bolt-on would have more energy associated with the first harmonic (and would possibly have a much different relationship in energy distribution among the harmonics).

I used to play a bolt-on's until I bought a neck-thru and discovered that my amp would no longer pull the freight; particularly below A on the E string (where it used to do just fine). I decided to stay with the neck-thru (and go to a 5 string) and then build an amp and speakers to carry it.

It's my understanding that the neck joint causes either losses or reflections of low frequency energy (such is the common thought) so that bolt-on's have a different tone.

I will search for some references on this and post any I find; until then consider the above my opinion only.
 
#16
Your distortion problem is probably stemming from the fact that neither one of your cabs can reproduce 31hz very well. I don't know of many comercial offerings that do and the Avatar cabs you have certainly aren't known for their ability to do so. The reason it "goes away" at higher volumes is because the harmonic of the low B (80hz?) is amplified louder, is more audible, and overpowers the distorted fundamental frequency (31hz).

There are some cabs that will do your low B justice; Eden XST, Acme Low B-2, Low B-4, and any number of assorted 18'' sub woofer enclosures.

Also, if you want that low B very loud you're going to need a lot of power. Lower frequencies eat up headroom like kids on candy. It's likely that the real root of your problem is not having enough power for the volume levels you're playing at. Hope this helps.
 
#17
Does it by any chance get better after you play for a while?

If so, Peaveys are notorious (IMO) for running at low bias and distorting at low volume as a result. At higher volume its better because it gets swamped out by volume. Since it creates high harmonics, it might be audible most on low strings. As it warms up the bias changes.....

I kinda doubt thats the issue, but it is worth mentioning.
 
#18
Thanks for all the replies!

I have tried two different speaker cables. One of them a monster cable, and it still occurs. As for the string and th fretboard causing the distortion, I have used my ibanez sixer, and it still occurs. I have not tried different cabinets though. I do not seem to remember this occuring with my ampeg 15 inch cab. I keep forgetting I have a crate 200 watt head and 15 inch cab in the garage! I will mix and match the guitars speakers, and pwoer supply and see what happens. I think it is going to come down to the fact. That the avatar cabs just can't handle the low frequency. We will find out tonight.
 
#19
Well......

The cabinets are working just fine with the low b now. No distortion. We have been having some crazy weather where I live. Could humidity and drastic temp chages have something to do with this? I keep my gear indoors, but turn down the heater to about 65 degrees when I got to work. The cabs work just fine on either bass. I also used the same speaker cables.

Bizarre.

Thanks for all the help.
 

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