Adire Extremis 6.8 - help with bizarre experience...

[ptwining]

Recently got a pair of Adire Extremis 6.8 midwoofers. Decided to build a proto cabinet based on the D'app MTM Seas Odin design. Okay, fair enough.

I'm driving them with a pair of UCD180's (which drive my 4 foot floorstanding MTMWW's big time) and these Adires are WEAK.

Their range and SPL is extremely disappointing - quiet and thin. I'd heard these things would rattle your teeth out.

Not.

What's the deal here? Is this a break-in issue? Do they want 900 watts or something? They're rated at 100w (300 peak). Curves looked sweet w/ average SPL of 86db all the way up to 4Kh.

Wired in parallel at the moment but I've had 'em in series to bring them to 4 ohms and same deal.

They are not XO'd yet (except the Dayton silky on a Dayton PE 3-way @ 5600) and the box isn't ported yet as I simply knocked the box together to audition the drivers

Any ideas or experience w/ these drivers?

Regards,
Tom

[ruerose]

Double check your polarity, I know it seems obvious.

[ptwining]

Wired them six-ways-to sunday - no dice. I'm thinking I'll give them twenty hours of breakin - port the box - and them put 'em on a shelf somewhere if they stay boring. Maybe make a pair for my kids computer with 'em.

With all the hype I thought I'd give them a try.

Give me a pair of Dayton 10" reference every time. Makes Yo Yo Ma sound like, well... Yo Yo Ma.

Maybe my box is off - D'apps measurements tho. Must examine my process (I do screw up now and then ).

A port will gain a few initial db faster but the curve is the curve.

I'm gonna cut a few holes and jam a tube in this puppy (which is a bummer because I like sealed bass).

Humph...

Regards,
Tom

[Geenius]

My experience with the Extremis 6.8 is that it is very inefficient (I currently have them in a 2-way system: 82dB! ) and it lacks upper bass / lower midrange dynamics. Give me a Seas L18RNX/P anyday.

[bear]

Never laid eyes on these drivers...

but parallel connection of 8 ohm drivers will give you 4 ohms, AND an effective boost of 6dB in the reference sensitivity. So, if these speakers are actually 82dB/1w/1m/8ohms, then in parallel with a solid state amp driving them, you should measure 88dB/with the same voltage applied to the terminals.

Otoh, the series connection of 8 ohm drivers will give you 16 ohms, and the series connection of 4 ohm drivers will give you 8 ohms. The parallel connection of 4 ohms drivers will give you 2 ohms and is probably not a good idea for most amplifiers.

You want the parallel connection, unless you have 4 ohm drivers.

As far as the midbass being "lean" consider floor bounce?
That will put a big notch in the response in the lower midbass region.

_-_-bear

[ptwining]

Wow. I'm amazed that the hype surrounding these things is so deep. They are okay, but no great shakes.

I'll position them a bit and see where they get better but I really shouldn't have to. (if they were actually "all that").

They are wired parallel for the 4 ohm total - however I've had to implement a series/parallel to add the tweet @ 8 ohms

8---------8 (for 4)
| |
| |
|----8----| (sums to 5.33 ish)

Look right?

Regards,
Tom

[sreten]

Originally posted by ptwining
d to implement a series/parallel to add the tweet @ 8 ohms

8---------8 (for 4)
| |
| |
|----8----| (sums to 5.33 ish)

Look right?

Regards,
Tom

Hi,

No it doesn't at all. They all should be in parallel for a parallel
crossover. MTM's without baffle step compensation sound terrible.

Impedance does not sum to 5.3 ohms at all.

/sreten.

[Cal Weldon]

Tom,

I too am struggling with mine. I have two in a box with a PR and am not getting the results I hoped for. I think my cabinet was too big so I tried filling it with some scrap 2X4's and that has helped. It started around 60 litres and with stuffing and bracing is around 50 now.

What is the volume of your closed box?

Do the woofers flop around a lot but not seem to make enough noise?

This is what I'm dealing with so the next thing I will do is to actually cut the box down. I think I will try it at 40 litres and see if that helps control the movement. I think I might even seal the box as well. These don't seem well suited to a PR system anyway.

It may just be that the Q is too low for the acoustic suspension of a larger box. Who knows. Let us know what you come up with.

[ptwining]

According to this impedence calculator http://colomar.com/Shavano/impedance_proc.php the series/parallel arrangement I described sums to 5.33 ohms.

Put two 8ohms in the top series row and a single 8 in the second.

The extremis are wired in series in parallel with the 8 ohm tweeter.

The tweeter is XO'd at 5600 and (for now because I'm just auditioning them) the extremis are running full-range.

I am building an XO for them but even full-range they should not suck so much...

I don't think I've got a wiring problem.

The box is currently 36.8 liters (9.5w x 24h x 14d = 1.3cf) based on D'apps Seas Odin design. I made my box larger than his because he admits he arbitrarily down-sized the box for aesthetic reasons. Still it's to small to port legit but I'm buzzing a hole as we speak. I may stuff the box w/ poly fill to increase the apparent volume to accomodate the port.

The extremis do not move much - they aren't thrashing but they can eat full welly from my UCD180 and remain thin and quiet.

I'll let you know.


[later edit]

Oh oh...

sreten is onto something here and I think I'm wrong but I'm not sure just how yet.

Thank you - you've got me thinking now...

Regards,
Tom

[kevinkr]

I'm really just a bit confused by your description...

How many extremas do you have in series parallel? Integer numbers only or if not you need to add a resistor value equal to the VC impedance in parallel with the odd one - this will at least ensure something like a similar distribution of power across all of the actual drivers.

The other thing if I understood you correctly is that you are using a series x-over? (Ignore this if you are using a conventional parallel type network.) Normally this would be implemented with the woofer and tweeter in series, the woofer shunted with a cap, the tweeter shunted with an inductor - anything else won't work well. And this generally works best if the woofer(s) and tweeter are the same impedance and sensitivity.

Edit for clarity