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Discussion in 'Amps and Cabs [BG]' started by bgavin, Jul 30, 2002.
Eden players: have you ever "creased" a speaker?
If so, was it an XLT, XST, older model, or Never?
At the risk of exposing myself as the idiot that I am...
What do you mean by "creasing" a speaker?
Creasing is a result of over driving the speaker. It shows up as a ridge of cone material that typically runs concentric to the dust cap.
Evidently the voice coil moves forward with sufficient force to buckle (crease) the cone. I suspect it probably happens at the cabinet tuning frequency, as this is the time when the cone has the greatest acoustic loading, and the most resistance to movement.
Eden drivers are the ones I see reported the most. I suspect it is a design flaw in the XLT cone, and I want to know if anybody has the problem with the newer XST type drivers.
I creased my underpants once.
"Wear my khakis with a cuff and a crease."
- Dr. Dre
Nope, never happened to me and my XLT.
I creased a speaker in my '76 SVT cab which sounded like ass anyway, which is why all 8 are at WeberVST getting reconed...
I'm arranging a D410XLT purchase for my daughter's bassist, but all four drivers are new Eden 1060XL types. The others were blown.
Now I'll get a chance to put a D410XLT on the bench and see what it's made of...
I creased all four 10's in my Aguilar cab when I overpowered it one night (power amp was bridged by a sound guy without my knowledge).
Visual creasing, but not sonically noticeable.
I arranged a purchase of a used Eden D410XLT for my daughter's bassist. The seller picked it up in a pawn shop where it had four blown Radio Shack speakers installed. He replaced these with four new Eden drivers and sold it to me. When it arrived, I had a little time to get it on to the test bench and run an impedance plot.
This D410XLT is tuned at 44 Hz. The lower impedance peak is at 21 hz, and the more important upper peak is at 83 Hz. The loudness increase is very significant at this upper peak, and is probably the Eden "bark" that everybody refers to.
Output from the vents at resonance is significant. Total vent area on this cabinet is 66 square inches, or equivalent to a 9.17" diameter round port. The top and bottom porting adds another benefit to this cabinet: reinforcement from buzzing. The vents have two reinforcing dividers that act as effective bracing to the inner cabinet walls and prevent them from vibrating. The driver cabinet is essentially a cabinet within a port cabinet.
Testing the D410XLT at 31 Hz confirms it is not a good choice for a 5-string bass. The driver excursion is quite large at this frequency, because it is well below the tuning frequency. The loudness falls off very rapidly below low E, and is about zilch at low B.
As for damage to this cabinet, I suspect creasing probably occurs around low E or F (41 ~ 44 Hz) due to the very high amount of damping applied to the cones at resonance. The large vent volume keeps the cones motionless at resonance. Below resonance, damage is mostly likely from bottoming or over excursion caused by the lowest notes of a 5-string bass.
I think I would go with the XST.
Thanks for researching and posting some tech info on the Eden cab - it is *always* interesting to hear some real numbers on commercial cabs, and makes a good point of comparison to DIY versions.
Me too, but this was a used deal for my daughter's bassist. She's strictly a 4-banger, so it will be great for her.
I suspect the new XST is the complete replacement line for the older XLT types. I'd like to get an XST on the bench, and I bet it is tuned lower.
I took off the grill on my Bergantino 2x10 to clean it, and what do you know both speakers are creased. Are there any major effects of creased speakers?
I thought I blew a speaker in one of my 410XLT's the other night. Took the grill off, and what do you know, all four drivers are creased big time. What's odd though is that the speakers in the bottom cab are fine. I suppose this explains why the other cab sounded so much better! So I guess I send them back to Eden for a recone?
Also, we tune to C. Maybe these cabs don't like to go that low...
Another also, I just picked up an EV-loaded roadready Mesa 2x15, and this cab seriously ROCKS. I might just sell the edens anyway and get more Mesa cabs.
Hu...funny that you say it's a bad cab for Bs, gavin. I used it for A and G below B, and it handled just fine, even at the hyper manic speed of death metal, with slap interludes. Never had a single problem with low end reproduction.
Care to explain this? I'm not being snide, I seriously want to know, if you happen to know the acoustics or psycho acoustics behind this...
The D410XLT I had on my test bench was tuned at 44 Hz. Cone excursion at 31 Hz was significant using a sine wave and very modest input power. Vented boxes unload very rapidly below the tuning frequency. In English, this means they have no acoustic loading on the cones. They don't fare any better than a driver operating in an open back cabinet. If you don't push it too hard, it will not self-destruct.
Low G is 24.5 Hz. The 3rd harmonic of low G is 73.5 Hz, which is very close to the center of the big midbass hump that is present in the Eden. I'm not being snide either, when I say I seriously doubt you have actually heard low G, and not just the 2nd or 3rd harmonic. The D410XLT simply isn't capable of producing these low notes anywhere close to the loudness it can produce at 80 Hz.
Accurate production of sound is not the same as tone. You mentioned being entirely satisfied with your tone and low end reproduction. If you are satisfied, that is all that matters, other than over driving your rig and killing the drivers. As for creasing, I suspect it occurs at 44 Hz where the box is tuned. The resonant air load places an iron grip on the driver cones, hence the creasing under high power. Damage from over excursing the drivers is different from creasing.
Hook your Eden into your computer sound card and put a sine wave signal to it. Sweep down from 100 Hz to 44 Hz and watch the cone motion. It will appear to stand still at 44 Hz, and all the radiation will come from the ports. You can audibly discern the big boom at 80 Hz. Be careful of your power, and sweep down from 44 Hz to 24 Hz. You will get to low B and hear nothing, but you will see the cones moving in and out. Going down lower will accentuate the cone movement, so be sparing with the input power. You will hear almost nothing.
The D410XLT is a seriously loud cabinet (106 SPL). The laws of physics don't allow for loud, low, and small size in the same cabinet. One parameter has to give way. Since the Eden is indeed loud, and nowhere close to 20 or 30 cubic feet, then low frequency extension is the portion traded away.
Bruce, you say damage from overexcursion is different from creasing. What happens from overexcursion?
I wrote an email to Eden and this was their response:
Some where along the way they must have been pushed rather far past there mechanical limits. Perhaps a big power surge or an amp that acted up. The crease is from the voice coil being driven completely out of the gap and that causes the cone to go past it's mechanical limit as well.
But you say creasing occurs at the tuning frequency. I would think that if the damping at resonance is very high, this would rigidize the cone so much that it would be very hard to crease it. No?
It is my understanding that creasing occurs when the voice coil moves and the cone does not move. Something gives, so the cone folds (creases). At the tuning frequency, the cone has almost no movement because of the acoustic loading. But, the voice coil is still trying to move.
Over excursion is when the voice coil completely leaves the gap, and centering is lost. If it comes back, it grinds hell out of the coil, or rips the centering mechanism, etc.
I can also see the cone creasing after the voice coil leaves the gap, and the cone geometry is no longer true. Hard to say. Eden knows their product, and since so many Eden drivers wind up creased, they must have identified the problem cause by now. I wonder if the new drivers in the XST series will have the same creasing failure rate.
If over excursion is indeed the cause of the Eden problem, it is most likely the result of operating below the tuning frequency. In other words, pumping a 5-string bass at low B, at maximum power. This set of conditions is the most likely to cause over excursion.
Cone movement is minimal at the tuning frequency and rises to maximum peaks both below and above the tuning frequency. A rough guess is about a half-octave on either side. I doubt the 65 Hz (upper peak) is damaging the drivers, so it more likely the lower peak is the cause.
I wish someones Daddy whould arrange top-o-the-line purchase and bench test my gear for me.
Someone's Daddy did indeed arrange the purchase of the D410XLT... with a TB'er in Louisiana. The used cabinet came from a pawn shop with blown drivers, so the TB'er put all new Eden drivers into it, then sold it to me at a very fair (used) price.
Someone's Daddy also happens to be a bass player and felt the Eden would be a good match for Aroarah's 4-string bassist. The bench testing was a lucky opportunity to tinker with the Eden without having to own one.
The girls paid for the entire amp themselves. Regular gigging earnings and car washes generates the cash.
Someone Else's Daddy arranged for the complimentary Rush tickets Rush tickets and full-access back stage passes so the girls could meet Geddy and Alex, and get their pictures taken with Rush for the girls' web site.
Yeah, Someone's Daddy (two of us) puts time and energy into the girls' band. But, the girls have 16+ original tunes, and are going into the studio in November to record their 2nd CD. This Daddy has yet to record his first CD, let alone write all the original music.
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Where did this come from? Been a year since this thread was active...