Introducing The new CSS EL70

[chrisb]

Originally posted by CSS/XBL
Hi,

The EL70 does not use XBL though Mark and I have talked about using it on future product. The main differences with the FR125SR is the higher sensitivity of the EL which was a very specific goal. Since both use paper cones there will be similarities in the overall sound. The technology employed in forming the EL70 cone is new and bodes well for further cone development. With a slightly higher Xmax and larger voice coil the FR will handle a little more power but that is so often enclosure loading dependent.

Given the large number of enclosure designs that will be released in the next weeks it is clear that the EL parameters support a very wide range of designs. The manufacturing track record evident in all Mark Audio productions also means the driver to driver consistency will be higher with the EL70.

We expect to be doing some extensive listening comparisons in a couple of weeks at the Vancouver Island DIY event at Dave's so look forward to those results and impressions.

Bob

yes, Bob - too many designs for us to possibly build all of them - but I think it's fair to say there's probably something for just about everyone, and I do love what I've been able to hear so far


edit:

Have you or Mark had a chance to measure these yet? At the very least, I think the @80dB figure for sensitivity is low.

[markaudio]

Here's the EL70's T/S data and graphs

Revc= 3.600 Ohm
Fo= 64 Hz
Sd= 50.2 Cm/2
Vas= 6.1 Ltr
Cms= 1.702m M/N
Mmd= 3.62 g
Mms= 3.82 g
BL= 2.85 T·M
Qms= 3.23
Qes= 0.66
Qts= 0.55
Levc= 0.25 mH
No= 0.216 %
SPLo= 86 dB
Xmax= 4.5mm (1 way)
Pwr = 20 W (cont)

[noodle]

Have any box plans posted yet?

[CSS/XBL]

Originally posted by noodle
Have any box plans posted yet?

They're coming, perhaps later today.

The kits listed above basically work in .5 cu ft (14 litres) for one driver and .75 - 1.0 cu ft (21-28 litres) for a pair.

Bob

[planet10]

Here is the 1st one:



Plans

dave

[speakrsrfun]

Hmmm I wonder if this Desktop TL will work with the CHR-70? looking for a desktop TL for a system I'm putting together for my mother, could be an interesting design. Anywho I could always try and see even though specs are quite different from ther EL70.

[speakrsrfun]

Just to clarify I don't mean "WILL THIS CABINET DESIGN" work with the CHR-70 more along the lines of how well a TL will work with the CHR-70 as I'm still trying to find a design I'm happy with...

[planet10]

I think Henkjan may have also done one for CHR ... he is on holiday right now so hard to ask...

dave

[markaudio]

Hi Guys,

Bob has asked me to point out some features on the EL70. Much of the following info also applies to my other designs.

Please take a look at the picture as I've numbered the features.

1 - Surround: there's various grades of material available. Cheaper drivers will use single or dual mix butyl. The EL70 uses a tri-mix Ei grade, a type mostly found on more expensive units. We test each cone/surround sub-assembly to be within +/- 3(Fo-Hz) of its design rating. This is very close tolerance for a lower cost driver.

2 - Bonds: single bond glues cost less. On the EL70, an A/B mixed bond is used to get the solid connection needed to make the cap acoustically efficient.

3 - Cones: there's a lot of talk about paper cones. The EL70's cone paper is sourced from Japan, the source for most of the best papers. The material is important but also must be accurately moulded. Our new Multiform process give us micro-control over the complete surface of the cone, making all production cones precise at the micro level.

4 - Frame: is a mixed polymer. it's rigid, strong and acts as a resonance damping component. I make no apologies to those who love metal frames, many ring like a bell sending stray resonance's into the cabinet. We could have cut costs by using an "off the shelf" frame, instead the EL70 uses the same Markaudio custom frame found on the CHR-70.

5 - Connector: this humble part is custom sized. So many drivers come with this component straight from the parts bin, not the case for the EL70. Most cheap drivers have this part riveted to the frame. On the EL70, its glued and screwed.

6 - Coil to cone: the fit tolerance on many cheaper drivers is up to 0/+0.5mm. On the EL70, its 0/+0.1mm. We use less glue because the fit is more accurate. Less glue means less mass and less variation in the moving mass of the power-train.

7 - Spiders: cheaper drivers (and many expensive units) use Conex and similar grade materials. These grades of material are mostly fine depending on the weave selection for a given load. The factory standard tolerance is +/-0.15 on the specified stiffness rating. Typically, a spider can vary by as much as 35% of the mean stiffness within a batch. This can result in a wide range of variance in the resonance frequencies within a batch of drivers. This is not the case with the EL70. Each spider is individually checked to a working tolerance of +/-0.1, much tighter than most other driver production.

8 - Power-train layout: This section of a driver design is critical. I design the layout to make sure there is no spider damage during the soldering process. One small undetected nick in the spider will reduce the life of the driver and results in an un-even distribution of the stiffness compliance. The flying leads are accurately positioned with enough room to remain clear of other driver parts while under LF loads.

These are some of the features, there's much more but I'll leave them for another time.

Some of you know my approach to building drivers. For those who are new to these drivers, I "engineer" these units in order to gain consistent high performance and reliable service life.

Cheers,

Mark.

[noodle]

Whats the advantage of having two el70 in an enclosure?
How would you hook them together?
Any box plan for that?