Battle of the Monsters

[Bob_99]

Could someone explain to me why aluminum would make a better enclosure? Is it because it is less flexible (assuming thick enough aluminum)?

Thanks

bob

[vinculum]

I was thinking mostly about the transfer of heat the driver produces when asked to dissipate a few kilowatts in a sealed box. The basket could transfer heat to the mounting area given a thermally conductive sealer, and the backwave could blow directly on the aluminum like a gigantic heatsink. This along with the Acoupower driver's efficient heat wicking pole vent and 5 cubic feat of heatsink around the basket would be a winner me thinks.

Dr V

[Ricci]

Plus it would just look cool.

Dr V.,
Did you ever decide what you are going to do with your Acoupower's? I'm guessing that maybe you are holding out for Illka's tests to help decide what to do?

[Bob_99]

Very interesting!

Thank you for the explanation.

Bob

[vinculum]

Ricci wrote:

Plus it would just look cool.

Dr V.,
Did you ever decide what you are going to do with your Acoupower's? I'm guessing that maybe you are holding out for Illka's tests to help decide what to do?

As soon as I think I have the alignment nailed down, I'm considering something else! I was working on the amplifier selection not long ago.

I'd like to see it test of course, but I think thats a long time away for Illka to get a driver. Last I heard communication between the two has been sparse.

I'm glad to hear Nathan's impression of the ACP as being "tight". This puts more weight on considering a reflex alignment. I definitely want a tight sound. Moreover I don't want to be underwhelmed with my upgrade.

I've got lots of other considerations as well that I won't get into just yet.

One of these days soon I'll jump in and start cutting...

Dr V

[TheEAR]

Most impressive ! The RE XXX 18" is a monster,it moves air like no other,I am impressed to the point of getting two of these sick drivers.

[Blaser]

funky_waves wrote:

I did a couple tests today on the Acoupower and LMS5400, for maximum output before audible distortion, I also measured the mechanical cone travel, on all three, up to the point where the suspension really starts to stiffen up/become non linear. The LMS5400 is 65mm p-p the Acoupower is 64mm p-p, and the REXXX is 82.5mm p-p.

WOW How did you measure that?

[Ricci]

TheEAR wrote:

Most impressive ! The RE XXX 18" is a monster,it moves air like no other,I am impressed to the point of getting two of these sick drivers.

Copycater! JK Arthur. Maybe a pair in 9ft sealed each with some Itech8000 voltage???

Monster is the right term for the XXX though. I'm still trying to get a good imagining of what 118.6db at 10hz sounds like. I've never heard bass like that. Maybe some solid high-output 16hz stuff but nothing that heavy at 10hz. I don't think my tired old Velodyne CT1500's will do that much output at 40hz. That's from 1 driver too.

[funky_waves]

Blaser wrote:

WOW How did you measure that?

Just a simple manual measurment with a straight edge and a ruler, just to see how the suspention travel compared for the three drivers, they do stretch 5-10mm more in each direction when under power, so they all seem to have there respective claimed mech travel.

[ISLAND1000]

Great work Nathan and very usable listening impressions.
It looks like the loss of the LMS doesn't mean the "ultimate DIY sub driver" is history.
The XXX and the ACP are just as adequate for what we need! Lets get busy and get these two amazing drivers some place to vibrate . . . . . Vinculum . . . . EAR?

[Ricci]

I don't know. There still isn't a big uber 18 for the small sealed boxes or PR'd enclosures. That was what the LMS did well and there is not really a replacement for that yet. The Acoupower is more suited to mid-sized alignments(for an 18) and the XXX for large enclosures. Neither are going to rock in 100L quite like the LMS will. The Acoupower would be better in 200L and the XXX in 300L, or thereabouts.

[ISLAND1000]

Using WinISD take a look at the performance of (2) XXXs in a 6 cu. ft. sealed box with a Linkwitz Transform with the Fo set @ 40 and the Fp set@ 15.
I know that's not a 100L but it's a manageable size.

[anidabi]

I have to say this that there is some really interesting stuff going on. Great work Nathan, since you have the skills and the equipment, can you take a nearfield measurements from the drivers at hand? It would be nice to see how low the Le in acoupower really is.

funky_waves wrote:

I have been pondering the results, and have a theory. At tuning there is some port noise, but with real world material I have never heard any port noise with either driver. But! At 15hz the amp is not clipping, the driver is not at max travel, and there is some port noise, so perhaps the limiting factor near tuning is port compression(the noise is low due to the large flares but compression still may be occurring) Why the Acoupower compresses the ports at a lower level is interesting, maybe it is a good thing(drives the ports harder as Carlos claims), maybe with larger ports it would benefit more. might just have to build another box to test theory.

funky_waves wrote:

I got it to try out, I have a couple ideas, one I realy want to do, but it would be heavy I will likely biuld a smallish sealed enclosure for it. 20"cube maybe.

I guess that you have quite a lot work going on already, but bigger port effect and small sealed enclosure performance would be nice to see.

[Ricci]

Anidabi,
Back on the first page Nate posted this from the WFT3 for the Acoupower
Published:
Fs: 28.2hz
Re: 6.2
Qms: 8.9
Qes: 0.62
Vas: 174L
Le: 1.2mH

Measured
Fs: 24.9hz
Re: 6.16ohm
Qms: 4.18
Qes: 0.59
Vas: 177L
Le: 0.72mH

0.72mh LE

ISLAND1000,
I still have another XXX 18 that I will be going sealed with at some point. Were you saying 6ft for 2 of them? I'm thinking that I will do around 8ft sealed for my one. The problem is that the main claim to fame of the XXX is the HUGE displacement ability and it's almost impossible to get enough power to use most of it in a small sealed box. How much did you model it with in 6ft?

[anidabi]

Hi Ricci! I saw that, but I was refering to proper graph where you can see it clearly. Like this:



and this:


http://www.hometheatershack.com/foru...html#post51571



The numerical Le doesn't tell you in wich impedance model they have been measured(praxis, MLSSA, klippel). TC Sounds drivers have been measurured with praxis method and I believe that Exodus audio with klippel. Acoupower method I don't know. Unibox models with LR-2 method(don't know this stuff, just heared from Ilkka) and winISD does only a rough impedance modeling. So LMS Le parameter doesn't model right with unibox and in winISD Le is useless because it produces wrong FR. It's a bit messed up situation with different measuring methods and modeling programs. That's why I would like to see picture over some random number.

[Ricci]

Nathan,
Are the Acoupower and the LMS the same mounting pattern and size? If so, maybe run the LMS in the 130L sealed box to compare against the Acoupower?

Sidenote:I watched Finding Nemo last night with the XXX sub and the Darla tapping on the tank scene was ! My girl was holding a glass of red wine and it was shaking in her hand. I love this sub man! Thank you!

[ISLAND1000]

I was just experimenting with that driver to see what box size and possible multiples of drivers would produce a similar power and FR similar to a LMS 5400 18".

[Owen Bartley]

It's so nice to see that there are still some killer big drivers out there (not that I'll have the need for one any time soon). Having a few options at this level is going to lead to some really impressive projects, and I can't wait to see them as they roll in. Nathan, thanks for stepping up and comparing these monsters.

[SteveCallas]

Ricci wrote:

It appears as though it works as suggested eh? 11hz tune check

Hmm, if that's an 11hz tune, the enclosure is pretty undersized, as there is ~14db rolloff below 18hz.

Funkywaves, can you take a close mic measurement of the XXX sub?

[funky_waves]

Steve,

I no longer have the XXX sub, so I can't take any more measurements, I was going to get a ground plane before it shipped but I ran out of time.

Take a look at these graphs comparing the FW18.1 ground plane and same enclosure in the same location as the XXX sub was in. If you look at 20hz and 10hz. There is a 16db differential from ground plane to in room, if you factor that in to the XXX sub it is down 17db at 10hz from 20hz, so in actual fact it is only down 1db at 10hz, this might be off a few db, Simulations predict around 4db down at 10hz, it is probably closer to that, but it gives an idea what is going on there anyway.
My room has a very large resonance at 20hz that is causing that.

[SteveCallas]

Ricci, can you take a close mic FR?

[Ricci]

Steve,
I'm getting to it soon. I just got back from a business trip to HK last night and I have a lot of loose ends I need to tie up. I still need to give a review of the SDX subwoofer! I just fired up my new notebook today actually and I'm getting ready to download REW. Apparently someone lifted my Turtle Beach SC I ordered while I was gone, so I've got to iron that out too. I'll get to it hopefully within the next week or 2. Nathan had one of my XXX's. As he has noted the 25ft cab was tuned to 11hz roughly and this was confirmed with an impedence measurement and also through test tones. It should be around 3 to 6db down at 10hz and this seems to be the case, but I will definitly try to confirm concretely with measurements when I can.

[Ricci]

Once I get REW running I'll take some FR measurements on the XXX enclosure. Here is the impedence curve that Nathan took with the WFT3. I also measured this and got a nearly identical reading.

ReXXXbox impeadance.pdf

[Ricci]

Here is a raw FR of the XXX at one of the primary listening spots.



here is a close mic of the driver...




How do I go about getting a good close mic response of the system? It's in room and the port and driver are separated. Do I just put the mic half way between the 2? What level?

[Itay]

your suppose to measure each separately (close mic) and then "sum" both (in a nutshell)