Having recently custom built a 1x15 bass cabinet, I was surprised to find that it seems to distort in a way that I'm not familiar with. Basically, It seems to create an odd, honky distortion in the midrange, when the midrange is boosted heavily. It's also most pronounced when playing a J bass with the bridge pickup soloed, due to the tonal balance this creates. I was wondering if this is in any way normal, since I have never really heard anything like it before, and if it is likely to damage the speaker. It happens using both a Vintage tube amplifier and a cheap solid state, so it's not the amplifier, and only happens at high volume, although not enough to exceed the thermal limits. Thanks.
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Bass cabinet midrange distortion?
- Thread starter dubhnight
- Start date
More info on the cab will help try and guide you in the right direction. What is the brand and model of the speaker? What are the enclosure dimensions? Vented, sealed, or other? What is the enclosure itself made of?
Without knowing any of that info it's hard to guess. Pics could help as well.
Without knowing any of that info it's hard to guess. Pics could help as well.
What driver?
It may have a response peak in that area, or that may just be how it sounds when driven past clean operation. Remember xmax is already 10% distortion and that will be reached before any thermal limits.
Also how much port area? You may have port noise at higher output, than can make weird sorts of sounds.
Make sure the driver seal and everything else on the cab is sealed tight, no air leaks anywhere.
It may have a response peak in that area, or that may just be how it sounds when driven past clean operation. Remember xmax is already 10% distortion and that will be reached before any thermal limits.
Also how much port area? You may have port noise at higher output, than can make weird sorts of sounds.
Make sure the driver seal and everything else on the cab is sealed tight, no air leaks anywhere.
It's an eminence Legend CA154 in a cabinet design suggested by eminence, vented with a volume of just about 3.7 cu.ft and 2 ports each with a diameter of 4" and a length of 6.5". It doesn't sound like Port noise, and I'd be surprised if the driver is farting out, like the distortion seems to be around 150-300Hz... although I'm not really an expert in this area. Like, there is no distortion of the fundamental, and the distortion happens even if the bass is turned down fully on the amp. The cabinet isn't very leaky, just a little bit going through the jack. One thing I should probably mention is that I used no stuffing inside, since it hasn't arrived yet. Would this make any difference? Here is a picture Link Removed
The lack of lining will hurt the sound but shouldn't really sound like distortion, more a boomy sound and unclear in the mids. Push on the cone to make sure you can't hear any rubbing/scraping voice coil. Another possibility is you may have a speaker wire hanging against the back of the cone, vibrating on it when you play.
It's a brand new speaker, so it's in perfect condition. The amplifiers I used were a 100w Marshall JMP100 and a 185w Behringer Ultrabass (Big difference I know haha.) One thing I would say is that I'm not necessarily interested in getting rid of this sound, it gives the tone a very ballsy sound that I quite like. I was more worried that I am damaging the speaker by letting it work like this.
The speaker will handle either of those amps full, clean output. Craig may be on to it. Also, if it's brand new, it isn't broken in yet. Over several hours of play time, the suspension will loosen a bit, mids will smooth out a little, lowend will fill in a little.
I'd just double check everything. If it all is good...just play.
I'd just double check everything. If it all is good...just play.
This is the Klippel definition of Xmax.
The more conservative definition is the area of linearity where an equal number of turns are present in the gap.
A short time ago, I had a conversation with Big Tony at Eminence over a datasheet error.
It appears Eminence is moving to all-Klippel analysis of their drivers, and updating the sheets as the test results come in.
This will make their drivers appear beefier.. same as the Music Power thing makes the watts look bigger.
This is great. It's Bigger cuz I say so...
That is pretty much what I wanted to hear. Everything inside looks fine, and I can imagine that it would be able to break in a lot more than it is now. Thanks.
- Nov 24, 2008
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- Owner & designer, AudioKinesis; Auth. mfg, Big E (Home Audio only)
My guess is either an internal resonance or a panel resonance is the culprit. The solutions are acoustic damping material inside the cabinet (like foam glued to the walls but kept clear of the ports), and aggressive internal bracing, respectively. You can glue & screw "1 x 2" pine strips edge-wise inside on the panels inside the box to significantly stiffen them. You'd want to concentrate on stiffening the parts that are likely to flex the most - centers of panels, and in between cut-outs.
Or if you kinda like the way it sounds, don't worry about it; unless I'm seriously mistaken about the cause, what you're hearing is not going to damage anything.
Bingo.
RTA analysis shows a huge amount of ragged baloney when doing a full range sweep of an unlined cab.
It really is quite harsh.
This is the Klippel definition of Xmax.
The more conservative definition is the area of linearity where an equal number of turns are present in the gap.
A short time ago, I had a conversation with Big Tony at Eminence over a datasheet error.
It appears Eminence is moving to all-Klippel analysis of their drivers, and updating the sheets as the test results come in.
This will make their drivers appear beefier.. same as the Music Power thing makes the watts look bigger.
This is great. It's Bigger cuz I say so...
Haha....nice.
Some stuff I'd read, can't remember where, about the dist.% way and the physical measurement/dimension didn't seem to come out very far off from each other. I guess there'd be other factors in play? Meaning equal turns of coil is equal turns of coil, while other aspects of the driver could affect what % distortion that physical spot would result in?
I hear unlined boxes as boomy and sort of "smeared" in the mids. Guess I was thinking " distortion" as more of a sound effect than just being something different coming out than what's going in.
Klippel analysis is valid, and very expensive.
I've read the mathematical analysis of the process... it is typical high-end German engineering.
Considering the market for electric bass gear, the vast number of users can't hear the difference between zero and 10%. Or more.
G*itar players are worse... they WANT that distortion.
In the end, Klippel strikes me as a legit and expensive way to make the products numbers bigger.
As long as Eminence provides coil and gap dimensions, the old dinosaurs can calculate physical Xmax and stay within those boundaries.
My take: want more noise, add more speakers.
I've read the mathematical analysis of the process... it is typical high-end German engineering.
Considering the market for electric bass gear, the vast number of users can't hear the difference between zero and 10%. Or more.
G*itar players are worse... they WANT that distortion.
In the end, Klippel strikes me as a legit and expensive way to make the products numbers bigger.
As long as Eminence provides coil and gap dimensions, the old dinosaurs can calculate physical Xmax and stay within those boundaries.
My take: want more noise, add more speakers.
It sounds odd, kinda trombone like almost, in a way. The sound isn't particularly muddy at all, actually. The first time I heard it, I assumed it was down the the Marshall head, and I thought that it sounded good, but since it makes exactly the same sound with the behringer head as well, I guess it must be the the cabinet. It doesn't sound particularly boomy or muddy at all actually, surprisingly.
maybe try matress eggcrate foam on the rear inner wall of the cab? then stuff it? just an idea. . .
Hi.
That would be my guess as well.
I wouldn't call an unlined cabs behaviour distortion-like either, not in the traditional sense anyway.
It is distortion though, anything that's not the same shape as the input signal -just with greater amplitude- is distortion by definition.
If You're interested in finding the cause easier, you can download a signal generator and run that signal through your rig.
That way it's easy to isolate the freqency and the cause.
Regards
Sam
That would be my guess as well.
I wouldn't call an unlined cabs behaviour distortion-like either, not in the traditional sense anyway.
It is distortion though, anything that's not the same shape as the input signal -just with greater amplitude- is distortion by definition.
If You're interested in finding the cause easier, you can download a signal generator and run that signal through your rig.
That way it's easy to isolate the freqency and the cause.
Regards
Sam
Could it be hardware or lumber buzzing in sympathy?
I'm wondering about a grille or handles (or a loose glue joint) that resonate somewhere in the midrange...
I'm wondering about a grille or handles (or a loose glue joint) that resonate somewhere in the midrange...
