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MLTL for dual Jordan Eikona Drivers
MLTL for dual Jordan Eikona Drivers
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Old 3rd December 2017, 07:22 PM   #11
GM is offline GM  United States
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??? you're also doubling the stuffing, so it will wind up at the same distance from the top; the fact that the drivers now have created a ~ rectangular single driver has no audible bearing on how its damped.

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Old 3rd December 2017, 07:35 PM   #12
colmo is offline colmo  United Kingdom
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Originally Posted by GM View Post
??? you're also doubling the stuffing, so it will wind up at the same distance from the top; the fact that the drivers now have created a ~ rectangular single driver has no audible bearing on how its damped.

GM
More than double as one driver is below the other.
Instead of csa 56 ins and stuffing down to 10 ins from the top it is 112 ins csa and stuffing down to about 15 ins which is half way.Will this overdamp or should I reduce the density to compensate.
I am assuming that it is best to have one driver below the other.
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Old 3rd December 2017, 08:07 PM   #13
planet10 is offline planet10  Canada
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MLTL for dual Jordan Eikona Drivers
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I am assuming that it is best to have one driver below the other.
Yes. With one driver just above, and one just below the Zd for a line with 1 driver. Ignore the slot vrs circulsr restricted terminus

Click the image to open in full size.

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Old 3rd December 2017, 08:36 PM   #14
Scottmoose is offline Scottmoose  United Kingdom
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Originally Posted by colmo View Post
More than double as one driver is below the other.
Instead of csa 56 ins and stuffing down to 10 ins from the top it is 112 ins csa and stuffing down to about 15 ins which is half way.Will this overdamp or should I reduce the density to compensate.
You're damping the pipe & its modes. The nominal Zd becomes the centreline point between the closely spaced driver pair. The volume quantity & position of the stuffing remains unaltered: it's relative to the pipe, not the drivers.

There are certain caveats to that, but those are primarily related to internal reflections, which are a separate matter to the longitudinal standing wave & its harmonics. For 'normal' QW pipes, where Vb is relatively modest for a given tuning I think GM & I both tend to favour lagging the internal surfaces with 1in acoustic fiberglass, SAE F10 felt or similar, rather than stuffing it. How many surfaces depends on how acoustically efficient the box is. A good starting point for boxes like this would be top, back & one sidewall. Possibly you might get a few more harmonics coming through, but you can always add more, & as a rule although people claim they want absolute accuracy, a bit of euphonic distortion tends to be preferred in practice.
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Old 3rd December 2017, 09:30 PM   #15
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More than double as one driver is below the other.
Instead of csa 56 ins and stuffing down to 10 ins from the top it is 112 ins csa and stuffing down to about 15 ins which is half way.Will this overdamp or should I reduce the density to compensate.
I am assuming that it is best to have one driver below the other.
No, it's not. Example: if a 1 ft^3 box needs 1 lb^3 of polyfil, then it needs 1 lb, ergo if the box is 2 ft^3 it takes 2 lbs.

If this box instead requires lining with [4] pcs of 1" thick OC 703 [my preference] 12" x 12", then use the equivalent area of [8] pcs for 2 ft^3, though of course they will need to be cut to fit the new wall sizes.

For 'FR' drivers, yes.

GM
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Old 3rd December 2017, 10:07 PM   #16
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Originally Posted by Scottmoose View Post
There are certain caveats to that, but those are primarily related to internal reflections, which are a separate matter to the longitudinal standing wave & its harmonics.

For 'normal' QW pipes, where Vb is relatively modest for a given tuning I think GM & I both tend to favour lagging the internal surfaces with 1in acoustic fiberglass, SAE F10 felt or similar, rather than stuffing it.

How many surfaces depends on how acoustically efficient the box is. A good starting point for boxes like this would be top, back & one sidewall.

Possibly you might get a few more harmonics coming through, but you can always add more, & as a rule although people claim they want absolute accuracy, a bit of euphonic distortion tends to be preferred in practice.
Yeah, the larger dims lowers the cab's internal eigenmodes, but the damping required to quell its 1/4 W pipe resonances does a sufficient job on even the huge Altec cabs folks have built when using ~19 mm no void plywood and plenty of bracing to the point where one Italian gentleman not only didn't like the relatively light damping MJK's model predicted, but ultimately none at all.

Indeed, just about all the designs using his software that I got feedback on said they wound up pulling half or more out, so switched to only recommending "damp to 'taste'".

Right, the pioneers did little damping and only starting using more as marketing forced ever smaller cabs, cheaper made components, cabs.

I asked one of the Altec distributor's in-house system designers why the newer [late '70s] A7 VoTT were so flimsy, 'loose' to the point of kind of 'wheezing', which he referred to as 'breathing'; he of course said cost, but it was also a way of dealing with the then rapid increase in amp power, EQ folks were hooking up to these once high power, but now 'low' power speakers and since then as now, SPL levels are often set based on audible distortion, the cab leaks away acoustic efficiency when over driven plus raises the cab's tuning to help offset the mid-bass loss due to thermal power compression. 'Dumb like foxes', these pros of yesteryear didn't miss a trick!

GM
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Old 3rd December 2017, 10:09 PM   #17
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MLTL for dual Jordan Eikona Drivers
I would love to hear a pair of Eikona 2’s to see what Jordan drivers are all about but at $475/pair not including shipping and duties is just prohibitive. Seriously, for 4in class drivers? Aluminum cone - I am wondering if a Fountek FR135EX might be something to consider for a lot less?

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Old 3rd December 2017, 10:12 PM   #18
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Cheapskate. Mine sound very good thank you. Is that really a lot of money? You only have to buy them once you know, they last a long time
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Old 3rd December 2017, 10:22 PM   #19
xrk971 is offline xrk971  United States
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How are you handling the +7.5dB 10kHz peak? I think an impulse response would show a clear ringing response with a 10kHz (100usec period) oscillation. A tizzy sound perhaps? But maybe that’s why they are angled 90deg with a deflector plate as shown on website.

I have about 40 pairs of full range drivers. The most expensive ones are the ScanSpeak 10F, Visaton B80, and PRV 5MR450NDY. All in the $100 range. The others are $15 to $50 range but I have many. So maybe one only has to buy 1 set, but hard to justify for a cheapskate like me.
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Old 3rd December 2017, 10:26 PM   #20
scottjoplin is offline scottjoplin  Wales
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You are looking at the aurora, no idea what that's all about. I listen off axis, I did a lot of experimenting, they are definitely best that way, have heard it said they are designed specifically to be listened to that way. Eikona Order Info — Ars Harmonia
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