- Feb 12, 2006
- 61,051
- 5
- 221,018
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
That's all it takes is a wrinkle, which is caused by damage to the cone pulp fibers.
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Agedhorse could you elaborate some? This is a very valuable teaching moment for us novices?
Thanks,
D
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While waiting for Aged Horse:
A speaker/cab system is designed around the assumption of the cone having a certain stiffness and the surround and spider having certain amount of compliance and resistance to movement so that it moves just the right amount within the gap of the magnet structure. When the cone creases like this it becomes more flexible and that ratio of compliance and resistance goes out of whack causing further damage to the coil. Also when the cone stops being stiff you lose low note amplitude because the cone no longer moves as single piston but moves differently in different places introducing distortion (IM?). Think of a canoe paddle. Which moves water more efficiently, the whole, stiff one or the one with a crack allowing it to flex? The part that flexes is no longer pushing water in the same direction as the rest. In a boat, you get to camp a little later and more tired. In air, the lack of coherence in the wavefront causes farty, indistinct fundamentals.
Mugre
A speaker/cab system is designed around the assumption of the cone having a certain stiffness and the surround and spider having certain amount of compliance and resistance to movement so that it moves just the right amount within the gap of the magnet structure. When the cone creases like this it becomes more flexible and that ratio of compliance and resistance goes out of whack causing further damage to the coil. Also when the cone stops being stiff you lose low note amplitude because the cone no longer moves as single piston but moves differently in different places introducing distortion (IM?). Think of a canoe paddle. Which moves water more efficiently, the whole, stiff one or the one with a crack allowing it to flex? The part that flexes is no longer pushing water in the same direction as the rest. In a boat, you get to camp a little later and more tired. In air, the lack of coherence in the wavefront causes farty, indistinct fundamentals.
Mugre
Hi,
Dumb question, but in this context, I'm not quite grasping the finer points of the word "geometry".
Would you mind elaborating what distinguishes "old" style speaker edge geometry, from "modern"?
The OP says this cabinet is from 2015, so what has changed in speaker design in the last 2 years, and why?
I personally don't own any drivers newer than the early 90's, and several of my cabs (with original drivers) are from the 60's, and 70's.
Whilst I've never had, nor encountered any of these problems ; forewarned is forearmed, and it would be beneficial to be aware of what's changing in the industry, and why - especially with regards to educating the musicians of tomorrow, so they don't cause any damage when they get a taste for vintage gear.
Thanks!
I'm happy I can now see (in the OP's pictures) and understand what cone creasing is.
Looking around the cone at the edges of the stain, I saw a ridge, a slight bulge in the paper.
That's when agedhorse answer of, That's all it takes is a wrinkle caused by damage to cone pulp fibers, connected in my head.
I was expecting to see creasing like folded paper. I'm learning.
Looking around the cone at the edges of the stain, I saw a ridge, a slight bulge in the paper.
That's when agedhorse answer of, That's all it takes is a wrinkle caused by damage to cone pulp fibers, connected in my head.
I was expecting to see creasing like folded paper. I'm learning.
Last edited:
- Feb 12, 2006
- 61,051
- 5
- 221,018
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
Nicely said.
The cone edge geometry combined with the thickness(and material) of the cone itself is partly responsible for the mid voicing of the speaker.
There are 3 common cone edge geometries (I'm of course simplifying somewhat):
The oldest was where the bulk of the cone comes up at an angle and the cone itself makes an angle parallel to the mounting surface of the basket. In this geometry, the inside edge of the fabric surround is flat and glues to the cone parallel to the mounting surface of the basket. This was fine for low powered speakers, but as amps got larger, the fatigue where the cone itself makes the bend (change in direction from angled to flat) caused very high failure rates. This was made worse by the surround pulling and pushing on the cone edge under high excursion and eventually the weakened paper at the joint would collapse. These were typically of the accordion surround (also at one time called a C-66 surround, though I have no idea why)
The second oldest is similar, except that the angle is made in the fabric and not the cone itself. This is much more reliable, but suffers from the same cone pulling forces under high excursion conditions. Why not just make the cone thicker and stronger? Because the mid voicing will be greatly affected. The mid voicing, especially with overdrive effects, is easier to make nicer on an accordion surround, as it has a particular breakup effect but you better not overpower it. So this is a compromise between the older style and the newest style.
The newest is really based on what we learned in pro audio over maybe 30-35 years, but the MI industry is generally slower to adopt these improvements until absolutely necessary. In order to lineraize the surround motion, the M roll (and sometimes yo will see it as an inverted M) is used which helps to minimize the sideways forces on the cone edge. These are always (or I haven't seen examples otherwise) with the bend in the fabric matching the cone angle and the bond can be either on the top of bottom of the cone. Also, we are seeing examples of more advanced materials in cone construction which allow the cone to be stronger where needed (the farther out, especially with curvilinear cones, the greater this kind of stress) without getting heavier or negatively impacting tone.
All of the "super drivers" that I am familiar with use the newest construction technique, they tend to be better able to handle the mechanical stresses associated with the higher power and low frequency displacement. The improved linearity also help stabilize the VC in the gap under high displacement, and (typically) have lower distortion versus displacement, as well as improved damping and control of midrange reflections (appear as resonances) traveling through the cone and reflecting back off of the surround. Another advantage is greater excursion from a smaller diameter surround, allowing the Sd to increase somewhat.
Anytime a driver uses an accordion surround, care should be used to avoid mechanical damage under high excursion applications. This is one example where thermal power handling can often exceed mechanical power handling and why.
JBL was an early adopter of M roll geometry in low frequency drivers, but the bigger drivers by Faital, Eminence, B&C, 18 sound, RCF and others have migrated to the newest geometries.
@agedhorse ,
Thanks so much for that insightful response ; I realised I was very familiar with the first two, older type geometries, but have to admit that I was completely oblivious of the newer variant.
To try and get a better idea of what you were describing looked like, I just googled M roll speakers ; of course the first result that showed up was a repair kit.
Industry strives to make things idiot proof, but the world keeps producing better idiots
I can't say that I've noticed this type of speaker in any backline, but I feel I've seen it in some studio monitors, and domestic Hi-Fi.
Thanks for the great info!
Thanks so much for that insightful response ; I realised I was very familiar with the first two, older type geometries, but have to admit that I was completely oblivious of the newer variant.
To try and get a better idea of what you were describing looked like, I just googled M roll speakers ; of course the first result that showed up was a repair kit.
Industry strives to make things idiot proof, but the world keeps producing better idiots
I can't say that I've noticed this type of speaker in any backline, but I feel I've seen it in some studio monitors, and domestic Hi-Fi.
Thanks for the great info!
A classic example of where more power doesn't result in more loudness / SPL. I was just thinking that a typical 4x10 is around the 105db/w/m mark. Which is usually quite loud with very little power. 4x10's are notorious for stage dead spots, so i'm wondering if that's what's happened. The owner wasn't hearing much on stage and cranked up the amp to hear more. Just moving the cab to a better or different spot on stage would probably been a better option.
Exactly. I am aware of this problem so tend to always avoid getting tempted. Apparently you can't trust people to do so as well.
Anyways, I wrote an email to aguilar tech support today hoping to hear their opinion on this matter.
The DB210 case has been filed as a dispute via paypal so now we patiently wait.
Moving the cab might make a difference in the lows, but that's not where the 4x10 design is flawed, it's in the mids and highs. Even if you ignore the high frequency comb filtering and poor horizontal midrange dispersion of the 4x10 the main problem is that it sits too low, so the directional mids and highs pass by you too far below ear level. Tilting it back or lifting it up can help, but not nearly as much as using two 2x10s stacked vertical. That puts the mids and highs close enough to ear level to hear them, and as a bonus eliminates comb filtering in the highs and more than doubles the horizontal dispersion in the mids.
This is exactly why I was planning to make a db410 and db210 stack, where the db410 would sit at the bottom and then the db210 either vertically or horizontally stacked.
It is pure coincidence that I discovered this issue at all by the way. I don't usually open cabs just for fun but it was different this time. Me and my friend who is an electric engineer wanted to install a dpdt switch to change the db210 impedance from 4 ohms to 16ohm or vice versa so that the stack would work together nicely. Well, instead of a switch I have a load of shock on my back at the moment :/
Ur F'd. If you're very lucky pay pal may reimburse you. All they are going to do to the shifty seller is ban his account. "no response so far": means he knew what he was doing when he sold you that garbage. I always buy used locally, so I can see and test what I'm buying. Or from Guitar Center and ask them send it to the local local store so I can do the same thing. Even buying new products online from reputable sellers can be hit and miss. It's a good lesson for you, I hope you get your money back.
Thanks. I have phoned paypal and they assured me I have provided them with plenty of information and I have also quoted agedhorses initial response (Agedhorse I hope this is ok with you!) and now I am in the waiting mode. They are now waiting for the seller to respond (edit grammar) till novemeber 10th. Then they will start resolving this.
You really think that this is going to be a tough one? I sure hope not. :/
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I think you're in a tough situation. If you don't get your money back, you may have to move on to option 3: buying a new speaker to replace the bad one. It may cost you some more but may save you from trying to just dump the cab in it's current state.
Yes well this is also very possible and I might just end up doing that at least for the DB410. The only thing I have to reconsider is whether I want to stick with these cabs forever or not. Buying complete new replacement speakers and selling it after would be a complete waste of resources IMHO.
Yeah, that's always gonna be the Big Question in these situations: Is it cost effective to replace with new or a used in good condition, or start over?..
How much can I get for the cab the way it is? Can I even find a speaker replacement? How does it sound now, and how will it sound with my gear when fixed? Do I wanna be stuck with it? What would I be able to sell it for if I fixed it? I doubt that seller is going to want to pay for shipping his own garbage back to himself. I think I would plan for worst case scenario. Good Luck! It's just a waiting game now to see if you get paid. Cheers
How much can I get for the cab the way it is? Can I even find a speaker replacement? How does it sound now, and how will it sound with my gear when fixed? Do I wanna be stuck with it? What would I be able to sell it for if I fixed it? I doubt that seller is going to want to pay for shipping his own garbage back to himself. I think I would plan for worst case scenario. Good Luck! It's just a waiting game now to see if you get paid. Cheers
