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Which drivers would you like to see being tested AND could chip in to make it happen?

  • Ascendant Audio Avalanche 18

    Votes: 8 18.6%
  • Sound Splinter RL-p15/18

    Votes: 27 62.8%
  • Fi Q15/18

    Votes: 13 30.2%
  • Mach5Audio IXL-18.4

    Votes: 9 20.9%
  • Dayton RSS390HF/HO

    Votes: 10 23.3%
  • Something else? (post it)

    Votes: 9 20.9%

  • Total voters
    43
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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.
 

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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... :devil:

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.
 

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Elite Shackster
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Discussion Starter #64
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. :yes: 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?
 

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Carlos and I have been working on the details, and at the moment it seems that the Acoupower 18" test will happen. :yes: 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
 

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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.
 

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Elite Shackster
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Discussion Starter #67
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.
 

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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
 

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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 :T. however tuning such a high FS driver
to 15hz seems a bit too low.
 

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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.:T
 

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Elite Shackster
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Discussion Starter #72
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.
 

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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.
 

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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.
 

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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
 

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Attached are the T/S parameters and Klippel data from the review. I'm not an expert in copyright law so if the mods need to take it down, I respect that.

The editorialize a bit, obviously with an 18.25 mm "underhang" and a long coil the driver has very linear BL and due to using a 6" diameter 2-layer coil and copper sleeve on the has very high power handling and good low Le, good Xmax etc.

I know that drivers like this and the LMS TC sounds stuff capture the imagination of DIYers but I think that people are missing the point a bit. With the research that has been done by Harman and others showing how multiple LF sources having a very positive impact in smoothing rooms modal responses, the question isn't who can build the best $1k woofer, unless you have a lot of money to build 4 of them. Instead, four $250 woofers would be a better bet for that $1k budget. As engineering is really the art of doing the most with the least (and furthermore fits within the demands of the application from all other factors therein) these brute force approaches are not that interesting to me personally.
 

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I know that drivers like this and the LMS TC sounds stuff capture the imagination of DIYers but I think that people are missing the point a bit. With the research that has been done by Harman and others showing how multiple LF sources having a very positive impact in smoothing rooms modal responses, the question isn't who can build the best $1k woofer, unless you have a lot of money to build 4 of them. Instead, four $250 woofers would be a better bet for that $1k budget. As engineering is really the art of doing the most with the least (and furthermore fits within the demands of the application from all other factors therein) these brute force approaches are not that interesting to me personally.
I completely agree with you on this one. Also, the Infinity Kappa Perfect/VQ series is a perfect high quality budget option for such a situation. Eventually I will have four of them in use for movies and two in stereo use for 2-channel listening.

The thing is raw power just seems so much cooler than a bunch of "little" subs.
 

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We're just evaluating the driver here, not a bass system. If you have $1000 to spend and your goal is value based, then Acoupower isn't the best bang for the buck. Four lower cost drivers would then make the most sense. I have 2 of these Acoupower 18" drivers which will be non co-located. I'm not really on a budget so, I'd have no problem getting 2 more if needed.

Chris, thanks for sharing that data. I was also expecting an article to go along with it. If there is one, could you include that?

Thanks!
Dr V
 

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There are many ways to energize a listening area with low frequency power. I'm among those who like to see it done with just a couple drivers in smaller boxes. To do that requires special build qualities and design techniques using special materials and a person with a unique personal drive to keep advancing the technology. Acoupower is one of those special drivers.
Sub drivers more than mid range or tweeters peak my interest, kinda like other things that fit formulas IE: 12 oz. Bud Light, Dbl quarter pounder w/cheese, 36-24-36, Corvette Z06, etc.
 
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