Subwoofer driver buy-in poll

[mike c]

Ilkka wrote:

If I find something that I like a lot, I keep it, but usually I will sell them.

I see. thanks for the info.

[Ricci]

Ilkka wrote:

I haven't read/heard much of those. Can you tell me more? How much are they?

The Acoupower's are pretty expensive. They only make a 15" driver and an 18".The 18 goes for 850$ i think. They also have very nice looking 7" and 10" flared ports(expensive!). I've been in contact with Carlos Beltran who runs the operation and I think he's also the guy who engineered the drivers. He might be willing to work with you on pricing if you approached him. You should check out the website for some info and there are some videos on there.

The drivers are claimed to have 3600w rms power handling, 100% BL linearity out to 18mm xmax and 40mm mechanical xmax. It looks like nearly everything about the drivers is proprietary. They have neodymium motors and 6" VC's. The spiders are 13.5". Distortion and power compression is claimed to be very low.

[noah katz]

Illka, it does look like the chances are pretty good that you'll test the Ava 18

Could you refresh my memory as to how much I promised to contribute toward it?

I'd also contibute more to see what the Acoupower can do.

Its spider is metal and Carlos went to great lengths to remove heat from the voice coil, so it's possible it will better the LMS5400 in power compression.

Depending on how the BL holds up after 18 mm, it may be a reasonable alternative to the LMS, certainly pricewise, if the LMS is even available anymore.

[ISLAND1000]

Ricci wrote:

I was wondering if anyone would be interested in chipping in to get an Acoupower 18 tested, if Illka would be willing? I would for sure. It would be really interesting to see if these are all they are claimed to be. Anybody interested????

I'd chip in $50.00 to see this one tested. The website is interesting. The "surround" design may give this driver an edge in large xmax excursions over an LMS-5400 resulting in less THD plus it has a 6inch voice coil !

[Ilkka]

noah katz wrote:

Illka, it does look like the chances are pretty good that you'll test the Ava 18

Could you refresh my memory as to how much I promised to contribute toward it?

noah katz wrote:

When you put it that way, it inspires me to offer $50 for an Avalanche 18.

I'd also contibute more to see what the Acoupower can do.

Its spider is metal and Carlos went to great lengths to remove heat from the voice coil, so it's possible it will better the LMS5400 in power compression.

Depending on how the BL holds up after 18 mm, it may be a reasonable alternative to the LMS, certainly pricewise, if the LMS is even available anymore.

I will send Carlos an e-mail asap.

[Ricci]

Sweet! I'm on the edge of ordering 1 for myself but I'd really like to see it tested by somebody first. Counting myself thats 3 contributers for the Acoupower. Anybody else???? C'mon!

[vinculum]

I'll pledge $15 minimum toward the Acoupower 18" driver.

I'm very curious how this driver will perform compared to the LMS driver. And for a very good reason...

Dr V

[Ilkka]

Carlos replied to my e-mail and we are working on the details as we speak. I'll let you know asap as we agree on something concrete.

[Ilkka]

Getting the the Exodus Tempest-X here is pretty much confirmed. And if the Maelstrom 18 (XJ-18) will be ready before my tests begin, it will also going to be tested.

[ISLAND1000]

Ilkka, you've got yourself an interesting setup for evaluating sub drivers. You currently have two enclosures that would be suitable for testing the 18s and I don't know about 12 or 15s. I guess you could easily fashion a front baffle to hold the smaller diameter drivers while mounted in/on the same enclosures. You could make the box's volume smaller by adding bricks on the inside. Plus you have a couple of the best amps to drive them with while testing.
Looks like you got yourself another round of very popular tests to accomplish.

[Ricci]

Ilkka wrote:

Carlos replied to my e-mail and we are working on the details as we speak. I'll let you know asap as we agree on something concrete.

Great!

[Ricci]

ISLAND1000 wrote:

Ilkka, you've got yourself an interesting setup for evaluating sub drivers. You currently have two enclosures that would be suitable for testing the 18s and I don't know about 12 or 15s. I guess you could easily fashion a front baffle to hold the smaller diameter drivers while mounted in/on the same enclosures. You could make the box's volume smaller by adding bricks on the inside. Plus you have a couple of the best amps to drive them with while testing.
Looks like you got yourself another round of very popular tests to accomplish.

What are the 2 enclosures for testing 18's? Not the LMS ones? I think that the other 18's will be far from happy in 100L sealed and 200L tuned to 16hz. The generic, possibly interchangeable testing enclosure is a good idea though. 200L sealed and 400L vented would be better for the other 18's.

[Itay]

vinculum wrote:

I'll pledge $15 minimum toward the Acoupower 18" driver.

I'm very curious how this driver will perform compared to the LMS driver. And for a very good reason...

Dr V

Same here. I'm willing to donate 25$ for the acoupower.

I have the rl-p18 but I'm still very interested to see those drivers performance.

[Ilkka]

Ilkka wrote:

Carlos replied to my e-mail and we are working on the details as we speak. I'll let you know asap as we agree on something concrete.

Carlos and I have been working on the details, and at the moment it seems that the Acoupower 18" test will happen. We haven't agreed on the enclosure design though. Carlos is recommending a larg'ish sealed enclosure or a higher tuned (like around 30 Hz) ported box, but I said that it is probably not what most people want. I am suggesting something like around 400 liters tuned to 15 Hz with an 8" port. What do you think?

[vinculum]

Ilkka wrote:

Carlos and I have been working on the details, and at the moment it seems that the Acoupower 18" test will happen. We haven't agreed on the enclosure design though. Carlos is recommending a larg'ish sealed enclosure or a higher tuned (like around 30 Hz) ported box, but I said that it is probably not what most people want. I am suggesting something like around 400 liters tuned to 15 Hz with an 8" port. What do you think?

Excellent! Bump me up to $20 donation.

Check out my build thread, I have a graph over there with the FR of your combination.

Dr V

[Itay]

the problem with the acoupower 18 in a LLT is it's high Q and FS - more
suited for pro applications or Sealed box. the 15 is a lot more LLT friendly.

[Ilkka]

Itay wrote:

the problem with the acoupower 18 in a LLT is it's high Q and FS - more
suited for pro applications or Sealed box. the 15 is a lot more LLT friendly.

Is it really? For example 300 liters tuned to 15 Hz already starts to peak the tuning frequency area quite a bit.

When it comes to the 18", IMO its sweet spot would be around 400 liters tuned to 20 Hz using that monster 10" port. Around 115 dB from 20 Hz and up with only 1000 watts. Power compression should be extremely low.

[vinculum]

Itay is correct. The higher Fo of 28.2 Hz makes the porting favor an approx. 20 Hz tune. The 15 is a little lower at 24 Hz. But for the minimal difference in price, the extra displacement of the 18" vs. 4 Hz lower Fo of the 15" , I still vote to test the 18". Don't forget that 1000 watts is really nothing to throw at this driver. It will easily take double that and with a 20Hz tune still produce some great SPL at 16Hz. Maybe an 18Hz tune would be a great compromise. The EBP favors a sealed alignment. Sealed, you can really put the power to it. In that graph in my thread, the sealed excursion just barely breaks 22mm. Its about 12mm at tuning in the others.

Dr V

[Itay]

Ilkka wrote:

When it comes to the 18", IMO its sweet spot would be around 400 liters tuned to 20 Hz using that monster 10" port. Around 115 dB from 20 Hz and up with only 1000 watts. Power compression should be extremely low.

Although that's not a LLT it looks GR8 . however tuning such a high FS driver
to 15hz seems a bit too low.

[Ricci]

I think that 450L with 2 6" ports tuned to 17hz looks pretty good for the Acoupower 18".

Illka,
I'll send my donation when you put up the Paypal info.

[Scott S]

600 liters tuned to 15hz with a 10 inch port look great to me.

[Ilkka]

vinculum wrote:

Itay is correct. The higher Fo of 28.2 Hz makes the porting favor an approx. 20 Hz tune. The 15 is a little lower at 24 Hz.

Dr V

It's not just the Fs that dictates the best possible tuning frequency. You have to look the shape of the frequency response too. You don't want to create a recession just above the tuning or peak at the tuning.

[noah katz]

I'm more interested in seeing the 18" Acoupower tested in a sealed box than ported, or will you do both?

I also don't understand Carlos' not wanting to give the commonly xmax spec of 70% BL, or why it would be unKlippelable".

He could just give the value of 10% THD which is supposed to roughly correspond to 70% BL.

Or Ilkka could tell him when he measures them.

[Chris Brunhaver]

The Acoupower 15" was measured in Voice Coil magazine a while back including Klippel data. I can dig it up and post it (the Klippel data), if there is interest, or maybe Carlos has the reprint rights. In my experience, due to the statistical nature of the Klippel test and the limited number of data points at the extremes, the results need to be taken with a small grain of salt. At least the suspension and BL we well balanced (with neither being a huge limiting factor) and so the data is more "real" that it would be if that weren't the case.

IIRC, Xmax was in the 28 mm range with near perfect suspension symmetry and centering. This is particularly impressive because of the spider being a 6" ID and 12" OD.

[vinculum]

Chris Brunhaver wrote:

The Acoupower 15" was measured in Voice Coil magazine a while back including Klippel data. I can dig it up and post it 9the Klippel data), if there is interest, or maybe Carlos has the reprint rights. In my experience, due to the statistical nature of the Klippel test and the limited number of data points at the extremes, the results need to be taken with a small grain of salt. At least the suspension and BL we well balanced (with neither being a huge limiting factor) and so the data is more "real" that it would be if that we're the case.

IIRC, Xmax was in the 28 mm range with near perfect suspension symmetry and centering. This is particularly impressive because of the spider being a 6" ID and 12" OD.

Yes, We want a copy of that. If you can't post it here, I'll PM my email address!

Dr V