Summer Project - Replication of MBL loudspeaker 101mkII

[Magnasanti]

Originally Posted by bear

I would have thought that a spider is mandatory for this driver, no?

How else will it not rock and become un-centered in the gap, and rub??

Usually dome mid-ranges do not utilize a spider. I would guess because the voice coil and dome are one piece, the dome's surround acts on part of the spider. Anyone correct me if i am wrong.

[bear]

not the stock dome midrange unit, the MBL unit, it requires a spider, or are you going to just glue to the dome or dome edge??

[Magnasanti]

Originally Posted by bear

not the stock dome midrange unit, the MBL unit, it requires a spider, or are you going to just glue to the dome or dome edge??

Sorry i thought you meant the Dayton. Well the plan is to dismantle the Dayton. This would require taking out both the dome/surround and the voice-coil. I will install a new coil and glue my carbon fiber lamellas to the coil. I think i know what you are thinking, but i believe the support rods are there to essentially suspend the sphere in the gap. The lamella group/coil isn’t dropped into the gap. Also mbl uses ferro-fluid in the gap and if used correctly can be used to center the voice-coil.

[bear]

Yes the dayton - but the MBL clone is a different matter.

I do not think that the support rods will play any role in placing the VC in the gap keeping it parallel and centered, unless the construction is very precise.

I'd personally prefer to use a spider to maintain the centering.

If you can manage to produce a melon that is very stable and symmetrical, then perhaps a VC only construction will work, but I find that to be really problematic, and very difficult to do.

Also why use the dayton? I'd want the max flux in the gap, which would require a lot more magnet and motor... although for just proof of concept that doesn't matter.

_-_-bear

[Magnasanti]

Originally Posted by bear

Yes the dayton - but the MBL clone is a different matter.

I do not think that the support rods will play any role in placing the VC in the gap keeping it parallel and centered, unless the construction is very precise.

I'd personally prefer to use a spider to maintain the centering.

If you can manage to produce a melon that is very stable and symmetrical, then perhaps a VC only construction will work, but I find that to be really problematic, and very difficult to do.

Also why use the dayton? I'd want the max flux in the gap, which would require a lot more magnet and motor... although for just proof of concept that doesn't matter.

_-_-bear

Right this is merely a proof of concept as well as testing different variables,as discussed previously. What i meant to say was that the rods suspend the group in the gap and also might help with centering. I believe the whole assembled unit has to be pretty precise. Also I believe mbl uses the centering force of the ferro-fluid to further help. Producing a "melon that is very stable and symmetrical" is part of the reason, to practice for the real thing.

[bear]

make ur life easy, use a spider?

think about how to keep the walls of the VC parallel to the inner pole piece?

very little is needed to move the vc out of parallel or out of center...

_-_-bear

[Magnasanti]

Originally Posted by bear

make ur life easy, use a spider?

think about how to keep the walls of the VC parallel to the inner pole piece?

very little is needed to move the vc out of parallel or out of center...

_-_-bear

I will definitely experiment with one.

[AVWERK]

Because of the total weight of the petals and the low frequency filter I don,t see how it will work without a spider.
Those domes aren,t made to function at 80hz or 100hz with any kind of serious travel probably needed to "flex" these big petals. Ferrofluid isn't going to keep it from rubbing at a low frequency
I don,t know what frequency MBL uses but looking at the dual port bandpass design, it can,t be very high.
Do you know what frequency MBL uses and the order? 2nd ,3rd ? for its midrange?

What do think is the reason MBL did not use carbon fiber for this specific driver? Could it be a combination of poor sensitivity and the need for cooling the aluminum petals would provide because of it? It would seem carbon fiber would be a natural here... And yet they didn,t go that direction.. Just speculation on my part.
Maybe a disimilar material connection will be a bad idea resulting in a smoked coil?
Your low frequency and slope will be extremely important if the petals are not capable of disipating any kind of heat.

[Magnasanti]

Originally Posted by AVWERK

Because of the total weight of the petals and the low frequency filter I don,t see how it will work without a spider.
Those domes aren,t made to function at 80hz or 100hz with any kind of serious travel probably needed to "flex" these big petals. Ferrofluid isn't going to keep it from rubbing at a low frequency
I don,t know what frequency MBL uses but looking at the dual port bandpass design, it can,t be very high.
Do you know what frequency MBL uses and the order? 2nd ,3rd ? for its midrange?

What do think is the reason MBL did not use carbon fiber for this specific driver? Could it be a combination of poor sensitivity and the need for cooling the aluminum petals would provide because of it? It would seem carbon fiber would be a natural here... And yet they didn,t go that direction.. Just speculation on my part.
Maybe a disimilar material connection will be a bad idea resulting in a smoked coil?
Your low frequency and slope will be extremely important if the petals are not capable of disipating any kind of heat.

I think you have it all wrong. I am not trying to experiment with the "Melon". The big aluminum group. I am using the Dayton for the upper-mid range. This mid-range group operates at 600hz to 3.5khz. All the specifications can be found on post #1.
specifications:

Crossover frequencies: 105Hz, 600Hz, 3.5kHz (Linkwitz-Riley, fourth-order). Acoustic center: 45" (1140mm) from floor. Frequency range: 24Hz–40kHz. Sensitivity: 81dB/2.83V/m. Nominal impedance: 4 ohms. Power handling: 320–500W continuous, 2.2kW peak

[el`Ol]

Originally Posted by bear

I would have thought that a spider is mandatory for this driver, no?

How else will it not rock and become un-centered in the gap, and rub??

The DC gold drivers are designed to rub, teflon on teflon is like ice on ice.