Speaker rant

[toecheese]

Why do drivers cost so much? Look at this: 18" driver

Now, my friends who do this type of stuff say that a speaker is very difficult to build. There are books on enclosures; horns, sono tubes, IB, etc. Furthermore, if you're going to have 2-3-4 way systems, you have to design a crossover that works in your box specificially- and with the parameters of your drivers. So a lot of testing, prototyping, designing circuits, etc.

But... not the driver.

A driver (the 'speaker' part of a speaker) is this:

• cone
• voice coil
• suspension/frame
• magnet
• surround

Wikipedia has a good description here but I'll summarize:

A cone is typically (even in the speaker above) paper. Sure, you can coat it with this and that, but it is still paper with something on it.

A voice coil is copper wire wrapped around a cardboard tube. Yes, really. The end of the tube is glued to the cone.

The coil and cone are suspended in the frame, centered by the surround (foam around the cone) and the spider (centers the VC) in the middle of the magnet.

How you can justify $800+ for a paper cone, a metal frame and big magnet is way beyond me.

[Exocer]

Ouch.

I totally agree but there is way more to a speaker than it's paper cone, actually, in most cases I wouldn't be suprised if the cone is at the very bottom of the list in cost of parts needed to build a driver. I personally wouldn't pay $800 for the driver you linked to, not because it has a paper cone but because it simply doesn't move enough air for HT use IMO, not at $800 a pop, not with drivers like the Rl-p 15 at under half the price, capable of moving WAY more air for the low frequencies. Its insanely sensative,but it doesn't seem well suited for a subwoofer that does it all on its own for HT use, with infrasonics in mind.

Some reasons drivers can be expensive, special attention to...
Motor/Design- not all are created equal
Voice coil design-same as above
Magnets used- Some magnets are more expensive than others. In some cases you will need a stronger magnet (particularly with a heavy low fs cones).

The list goes on.

[toecheese]

Okay, I'll bite- tell me about the 'motor'... I think that is marketing speak for a coil of wire around a cardboard tube.

[Exocer]

The wire wrapped around a "cardboard tube" isn't the entire motor, its a voice-coil. The voice-coil, and magnets work together to create a linear motor. Some motors are more linear than others. 1 major source of driver distortion comes from bl non-linearities. google "blx curve" or "dumax reports" for a closer look. Ideally we want a driver to move outward with the same exact amount of force as it moving inward throughout its excursion range to minimize bl non-linearities as a source of distortion. The other source is change in inductance. We ideally want the change in inductance to be linear as well, and "low" for the flattest response into the upper frequency ranges and lowest distortion from inductance.

There are MANY ways manufacturers try to get around the trade offs of these two sources of distortion. Linear motor topologies like TC-sound's LMT or Adire Audio's Xbl^2 come to mind.

The Driver you linked to just isn't a good value for HT use. IMO Doesn't mean all drivers aren't a good value.

[drf]

Although I have no experience with the driver you linked to I can say that a good drivers is as finely engineered as any precision tool/instrument. Because the way a speaker works, all of its components are compromises for the greater good, I.E cone material is a compromise between that which will give a flat FR and that which has lower cone breakup. Also because Subs have to move a lot of air to get usable SPL at low frequencies the motor has to remain as linear as possible whilst maintaining as much excursion as possible. For example, in Exocers' example, the non-linearities experienced in the motor are due to the voice coil leaving the permanent magnets flux, thus moving less distance for the same input power. This non-linearity means the driver requires a larger magnetic field and a voice coil that is precision designed to avoid not only this non-linearity but also to not introduce its own FR perculiarities. Both adding a larger magnet and precision when producing the former and voice coil will add to the end cost of the unit.

Another point where precision comes into the manufacture process is with the spider and surround, If these are too tight, giving good damping, you will end up with a driver that has a relatively flat FR but very little low frequency response. If the spider and surround are too loose you will end up with a driver that has no mechanical damping and will just flap itself to death. leaving you with terrible harmonic distortion and no high frequency clarity.

while there is a great deal of dispute between what makes a driver/speaker system good, I believe you can't underestimate the value of good engineering and manufacturing when it comes to relative quality/unit price.

As I always say: trust your ears, not your wallet.

Hope this makes some sense.

dr f

[toecheese]

So- don't me wrong- being an engineer, I know that a lot of work goes into getting the engineering right. As far as the gap and flux of different designs (wikipedia does a good job explaining that), there are advantages to each.

But when we're all done with our engineering, we've got $40 in parts. And speakers aren't a new technology, so we're not financing bleeding-edge technology.

To understand where I'm coming from, this rant is from my $250+ driver 'blowing' and looking at a replacement. Since they blow rather easily (IMHO)- and my vendor says they aren't repairable, I'm going to go cheap I think.

[Exocer]

Very sorry to hear about your loss

But, going cheaper will probably increase the chances of you damaging your subwoofer, especially if you choose a driver that isn't up to the task of the your system's design as a whole.

Do you mind telling us a little about your project?

What were the enclosure dimensions?

How much power?

Sealed or vented? If vented, what tuning frequency?

Did you have a highpass filter?

What kind of content were you listening to mostly?

What driver?

[Chrisbee]

Loudspeaker drivers are cheaper today than at any time in history.

Choosing the wrong one is costly.

[Tracy_L]

Bang for buck hands down, IMHO, are these 18" from Mach 5 Audio.
I've got 2 in an IB with an EP1500 (1200 watts bridged) at about 60% gain, and it is just outrageous the amount of bass these put out.

With shipping, they were right a $100 apiece, coming from Canada. Untill I saw these, I was in a wait and hold pattern for some decently priced 15"s to come out for the new IB.

Tracy

[Chrisbee]

Tracy

You're right that these represent incredible value for money. If I lived right next door I'd probably have 16 just to be on the safe side!

Others might argue that research into extending the excursion and improving other parameters needs to be paid for by someone. (preferably the customer)

It will be fascinating to see what the new, long-throw driver sells for. This will be a better indicator of what competitive drivers cost to manufacture.

I note that Acoupower's website has not been available for some time. Is this an indicator that stretching the price envelope doesn't sell product even when it represents considerable investment in R&D?

[Sonnie]

Tracy, I upgraded your account so you can post links now.

I note that Acoupower's website has not been available for some time. Is this an indicator that stretching the price envelope doesn't sell product even when it represents considerable investment in R&D?

Hmmm... didn't even realize their site was no longer working. I see the Bully sub site still works, but that is a much cheaper sub too. I wondered how many of those $900 subs Carlos would have ever sold anyway...

[drf]

toecheese wrote:

So- don't me wrong- being an engineer, I know that a lot of work goes into getting the engineering right. As far as the gap and flux of different designs (wikipedia does a good job explaining that), there are advantages to each.

But when we're all done with our engineering, we've got $40 in parts. And speakers aren't a new technology, so we're not financing bleeding-edge technology.

To understand where I'm coming from, this rant is from my $250+ driver 'blowing' and looking at a replacement. Since they blow rather easily (IMHO)- and my vendor says they aren't repairable, I'm going to go cheap I think.

sorry, your right about the total cost of parts, but I figure its the same as any tool manufacture, why does a 100 piece set of undustrial quality spanners cost $200 when the raw materials only cost $30? I guess its all in the precision of manufacture and materials process tolerances. E.G if the process that dopes the cones doesn't get an even mix of chemicals or spread, then what would be the end result?
For example what if the 1000+ turns on the voice coil was spread un-evenly due to poor or cheap machinery, then the speaker would have more throw in one direction causing a sine wave to look more like a saw tooth wave which would give your music more of a brassy edge.

To get back to where your coming from though, to me it doesn't sound like the quality of the driver is the issue, it sounds like there is an issue in your system in which your driver is not suited. Basically more along the lines as exocer said. How does it sound before they blow? is there any discernable distortion?

[toecheese]

Here's where I reported the issue. http://www.hometheatershack.com/foru...ses-my-ib.html

But, I'm just ranting about overpriced paper, magnet and wire assemblies. I do not believe that the driver I reference earlier is worth anything near $800.

My setup was two Adire Tempest 15s, powered by an EP2500 (not bridged). They were installed as an IB. The EP2500 is on the output side of my BFD with a house curve and a fair amount of boost for the lower frequencies. I had the levels tuned to what REW and the various guides recommended and had been running it this way for six months or so. They were used for movies and it wasn't (this sounds stupid) until I watched Clerks II that I noticed one of them making the unpleasant noise. I'm angry that the vendor of this product doesn't do repairs for it, but has no problem selling me new units.

As a result of information from this thread, I'm probably going the Mach5 route.

Thanks,

[Exocer]

Yeah, if it had no problem working right for 6 months theres no reason it should suddenly start to make weird sounds...unless one of your drivers is faulty. Again, sorry about your loss and going the Mach 5 route sounds like a great idea IMO.

Good luck with the rest of your project...keep us up to date

[bossobass]

toecheese wrote:

Here's where I reported the issue. http://www.hometheatershack.com/foru...ses-my-ib.html

But, I'm just ranting about overpriced paper, magnet and wire assemblies. I do not believe that the driver I reference earlier is worth anything near $800.

My setup was two Adire Tempest 15s, powered by an EP2500 (not bridged). They were installed as an IB. The EP2500 is on the output side of my BFD with a house curve and a fair amount of boost for the lower frequencies. I had the levels tuned to what REW and the various guides recommended and had been running it this way for six months or so. They were used for movies and it wasn't (this sounds stupid) until I watched Clerks II that I noticed one of them making the unpleasant noise. I'm angry that the vendor of this product doesn't do repairs for it, but has no problem selling me new units.

As a result of information from this thread, I'm probably going the Mach5 route.

Thanks,

I assume that the problem with the driver is a frayed coil from over excursion. Otherwise, the driver should be under warranty, but...

My question really is whether or not it has been determined if there was a manufacturing defect (like an assembly that was out of alignment beyond tolerance, bad glue, etc.) or the cause of the problem was considered abuse (did the upstream hardware send a severely clipped signal at VLF, etc.)?

I've never frayed (vs fried) a coil except by use of extreme prejudice in order to find the point at which a particular driver has had enough so I would be much more inquisitive with the vendor than ranting in a forum, until I was satisfied with the cause of death.

It's a mystery that Carlos pulled the Acoupower site with no word at all, but I suspect that most of his sales had nothing to do with the internet, where he seemed to be treated rather harshly in many car audio and pro sound forums, IMHO. But, to be on topic, I feel safe to say that the OP would not have had the same problem with a pair of Acoupower 15s...ever. Just an opinion based on years of using bargain drivers vs uber drivers.

Bosso