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post #1 of 25 Old 10-26-2014, 04:04 PM - Thread Starter
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Smallest size vs maximum output? 115dB to 20Hz

Hey guys,
I love my Martycubes. (See my thread in my sig for pics of the room). However my lovely wife is struggling to like them and I hear about it often. (Maybe more because they are currently unpainted). Just one of the struggles with a living room HT I guess.

So, I have been WinISD'ing various models on other sub box designs (including multiples), that would be a realistic alternative to the cubes to still provide reference (or close enough) SPL down to 20Hz. Sub-sonic frequencies not a priority. To keep the box size down. I figure that the biggest I can go is a 15" driver in them. Or 18" with the drivers mounted on the side of a longer, narrow box. I rarely listen at reference, but for my own fun and demo's I would really like to be able to at least reach 115dB at 20Hz.

If the boxes are small enough, I may be able to have up to 4 smaller boxes in the room. Max box size about 17-18" cube (external). Alternatively 20"H x 16.5"W x 18"D external to fit beside TV unit comfortably. I would like to go ported if I can to make the most of my output possibilities down to 20Hz, but a high-excursion/sealed alignment may be the only option with the box sizes.

The room is about 4.7m x 3.7m x 2.6m H with the right hand side open to a dining room and kitchen, and a hallway behind the LP on the right. Around about 3000 cu ft or so including the open sections.

Amperage: I have a Behringer EP4000 currently running the cubes.

Budget: I am willing to pay what is needed to achieve the said goal.

Now don't get me wrong, this is not meant to be a thread about unrealistic expectations. The real question at hand is:
When space taken up in the room is the absolute priority, what would a solid solution be for 115dB to 20Hz?

Last edited by AudyoVidyo; 10-26-2014 at 04:13 PM.
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post #2 of 25 Old 10-26-2014, 04:31 PM
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Such a small enclosure I would shoot for sealed. Uber excursion driver like a 15" ZV4. They need about 1.8cuft. Your 20" x 16" x 18" dimensions with 1.5" walls will net you close to 1.7cuft after driver displacement also. SO add some E and a BIG amp and your cooking. Put a nice veneer on a curved cabinet and your wife will likely like the outcome.
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post #3 of 25 Old 10-26-2014, 04:37 PM
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Two of these sealed.
http://www.parts-express.com/re-audi...-ohm--268-8152

An EP4000 isn't gonna cut it though. Two EP4000 bridged would be the minimum I'd recommend.

You could do HST-18's instead which would save you $400, but they don't go as loud, but darn close.
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post #4 of 25 Old 10-26-2014, 05:12 PM - Thread Starter
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Thanks guys. I have modeled these both up in small enclosures in an SPL graph.

XXX v2 15" - Yellow line
6000W to Xmax
85L box
114dB at 20Hz

Zv4 15" - Blue line
4000W to Xmax
50L box
108dB at 20Hz

Add 6dB for 2 of them. At these prices 2 would be the most I could push it.



I have to keep in mind though, that getting these to Australia may be difficult or impossible. Parts express says 'Truck only' on the XXX.

Thoughts?
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post #5 of 25 Old 10-26-2014, 05:27 PM - Thread Starter
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Here is the HST-18 in 80L with 4000W to Xmax for comparison
112dB at 20Hz
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post #6 of 25 Old 10-26-2014, 05:37 PM
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Sundown wont be cheap but you can order from the dealer in NZ that has cheaper prices than ordering from PE. I think the X series 15" was about $640 and the Zv4 was $760 aud shipped to me in Adelaide from NZ. SO I thought good prices considering.
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post #7 of 25 Old 10-26-2014, 06:08 PM - Thread Starter
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Thanks chrapladm. I will look into that.

Any other alignment suggestions?
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post #8 of 25 Old 10-26-2014, 06:22 PM
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For you size constraints this is about the best you can do. If you had enough room to go much bigger than yes. I will most likely be building an to hide my subwoofer that will be about 7cuft tuned to roughly 16hz. Some drivers with very powerful amps and EQ can be used ported to shape the response in an enclosure that is way to small. But it takes a lot of EQ trial and error to get it right not impossible just a lot more work than sealed.

Limited on budget and space the best thing is usually sealed with the biggest driver you can fit.
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post #9 of 25 Old 10-26-2014, 07:08 PM
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Quote:
Originally Posted by AudyoVidyo View Post
Any other alignment suggestions?
Sealed using a Linkwitz transform is the only way to get really low with a small box. But Hoffman's Iron Law being made of iron you need lots of excursion and mucho watts to get high level output.
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post #10 of 25 Old 10-26-2014, 07:30 PM
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Make your current cabinets look great and problems are greatly reduced ;-)
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post #11 of 25 Old 10-26-2014, 10:01 PM - Thread Starter
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Quote:
Originally Posted by Bill Fitzmaurice View Post
Sealed using a Linkwitz transform is the only way to get really low with a small box. But Hoffman's Iron Law being made of iron you need lots of excursion and mucho watts to get high level output.
Thanks Bill. Your LT suggestion is great. I forgot about that. Here is the XXX and Zv4 with a LT on both. Both in 50L (1.8 cu.ft) boxes. I would run the LT with the miniDSP I already have.



The XXX will take 1400W to get it to Xmax with an added 1st order HPF at 13Hz.
The Zv4 will only take 600W to get to Xmax with a 1st order HPF at 20Hz.
Am I missing something here? I thought I would need more power? Or is the extra power given throught the miniDSP in electronic EQ somehow? I'm confused on that one.
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post #12 of 25 Old 10-26-2014, 10:54 PM
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each 3db that you add in the eq requires twice the amp to produce.


so if your linkwitz transform added 12db to the bottom end, it would require 12/3 = 4 doublings of power, which is 2, 4, 8, 16...16 times the power on your input tab in winisd. this will show up on the va tab.

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post #13 of 25 Old 10-27-2014, 05:30 AM
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each 3db that you add in the eq requires twice the amp to produce.
That, and each 6dB of boost doubles the driver excursion. Another factor is that as excursion rises so does THD.

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Last edited by Bill Fitzmaurice; 10-27-2014 at 06:25 AM.
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post #14 of 25 Old 10-27-2014, 06:07 AM
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Did someone say Sundown @Mfusick maybe its time for a GROUP BUY!
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post #15 of 25 Old 10-27-2014, 06:11 AM
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Sundown is a nice option for small and still output .

-

"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
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post #16 of 25 Old 10-27-2014, 06:25 AM
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Quote:
Originally Posted by AudyoVidyo View Post
The XXX will take 1400W to get it to Xmax with an added 1st order HPF at 13Hz.
The Zv4 will only take 600W to get to Xmax with a 1st order HPF at 20Hz.
Am I missing something here? I thought I would need more power? Or is the extra power given throught the miniDSP in electronic EQ somehow? I'm confused on that one.
I'm guessing that 1400w and 600w are your input power values, right? Switch to the Amplifier Apparent Load screen. It shows you the actual amount of power required to produce the response your graph is showing. So it will take into account the LT you've added and will be much much higher than 1400w and 600w as you get down to 20hz where your eq is doing the most work.
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I'm surprised no one mentioned this, but why no love for passive radiators? They seem to be perfect to get ported cabinet output in a tiny box, at the expense of cost. Look at data-bass. A 12'' TC-Sounds driver is legitimately producing 115dB at 20Hz, 1 meter outdoors, with a 19x15x20.5'' box, which could be made much smaller if 12'' passive radiators were used instead of 15'' (and Ricci said the 15'' PR's were never close to their limits).

A Zv4 15'' with 2 or 3 15'' PR's might fit in a 18'' cube, and shouldn't be more than a few dB behind the output of a martycube.

Last edited by LowerFE; 10-27-2014 at 07:02 AM.
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post #18 of 25 Old 10-27-2014, 02:07 PM
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Quote:
Originally Posted by audiovideoholic View Post
Make your current cabinets look great and problems are greatly reduced ;-)
Just furthering this (and is somewhat the pot calling the kettle black). Have you considered cleaning up (i.e., filling in the screws) and priming/painting the cabinets white like just like the furniture/console the electronics sit on, then putting grills on the front of the woofers and use white speaker cloth to cover it? At least in the short term?

 

My DIY Subs ... http://www.avsforum.com/avs-vb/showthread.php?t=1233892

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post #19 of 25 Old 10-27-2014, 03:40 PM - Thread Starter
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Quote:
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I'm guessing that 1400w and 600w are your input power values, right? Switch to the Amplifier Apparent Load screen. It shows you the actual amount of power required to produce the response your graph is showing. So it will take into account the LT you've added and will be much much higher than 1400w and 600w as you get down to 20hz where your eq is doing the most work.
Ah that makes sense. I just looked at that tab and I can see that I can only really run 470W input power to the XXX to hit a max of 4000W (max power of my EP4000 bridged) at around 13Hz and that nets me about 108dB at 20Hz but only gets me to 31mm Xmax. Got another 23mm to go! That doesn't really run this driver well enough to justify it then.

I would like to investigate the passive radiator suggestion that was made. I read that test on the TC Sounds sub with PR's and that thought crossed my mind also. Would using say 3x15" PR's for 1 15 should net some solidly deep bass without having to use an LT? My knowledge of the workings of a PR enclosure is very basic. Simply that the PR acts similar to a ported enclosure. Is this correct?

As for the cubes, I will be finishing them off soon, as this project will take a while to come to fruition, but the WAF problem is really the size of the cubes.
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post #20 of 25 Old 10-27-2014, 08:26 PM
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Quote:
Originally Posted by AudyoVidyo View Post
Ah that makes sense. I just looked at that tab and I can see that I can only really run 470W input power to the XXX to hit a max of 4000W (max power of my EP4000 bridged) at around 13Hz and that nets me about 108dB at 20Hz but only gets me to 31mm Xmax. Got another 23mm to go! That doesn't really run this driver well enough to justify it then.

I would like to investigate the passive radiator suggestion that was made. I read that test on the TC Sounds sub with PR's and that thought crossed my mind also. Would using say 3x15" PR's for 1 15 should net some solidly deep bass without having to use an LT? My knowledge of the workings of a PR enclosure is very basic. Simply that the PR acts similar to a ported enclosure. Is this correct?

As for the cubes, I will be finishing them off soon, as this project will take a while to come to fruition, but the WAF problem is really the size of the cubes.
Puss the cubes together and add a nice top. Granite or some pretty wood or something. Then get a nice wine rack or whatever else she is into and spend the difference on spirits / vino, etc....

Maybe she will learn to love them?
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post #21 of 25 Old 10-27-2014, 09:04 PM
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Smallest size vs maximum output? 115dB to 20Hz

I don't see a room layout photo but is there anyway you can use one of the marty cube drivers in a "Stonehenge" like format and place it behind the tv? It's roughly 30x30 but only 16" deep. Takes up little floorspace, doesn't require new drivers or amps- you could get creative and hide this somewhere, hell, place a potted plant or something in front of it- it would be like hiding an old radiator-type heater.


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post #22 of 25 Old 10-28-2014, 05:38 AM
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At these power levels, how big of a deal is thermal compression? My gut tells me that you are going to lose a few dbs at the bottom end because of it.
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post #23 of 25 Old 10-28-2014, 06:23 AM
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Smallest size vs maximum output? 115dB to 20Hz

How about this for a cheap option:

Your Martycubes are 24x24x25.5, 8.5 cuft gross, 4.75 cuft net, tuned to 20Hz or so.

Build two new sealed boxes, 22x22x22, 6.2 cuft gross, 4cuft net, and put in two opposed RS460HO-4 drivers in each box.

The box will be about 3/4 the total size of a Martycube, and if you match the height and white finish would probably fit in much better. Plus, you can use your existing amp, running each sub at 2ohms, though you would be pushing the amp (Behringer's rating is 2x 2000W at 2ohms). And the SPL performance is close or better across the board.

You could possibly split that into four single sealed boxes as well...

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Last edited by rhodesj; 10-28-2014 at 06:33 AM.
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post #24 of 25 Old 10-28-2014, 03:27 PM - Thread Starter
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Quote:
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How about this for a cheap option:

Your Martycubes are 24x24x25.5, 8.5 cuft gross, 4.75 cuft net, tuned to 20Hz or so.

Build two new sealed boxes, 22x22x22, 6.2 cuft gross, 4cuft net, and put in two opposed RS460HO-4 drivers in each box.

The box will be about 3/4 the total size of a Martycube, and if you match the height and white finish would probably fit in much better. Plus, you can use your existing amp, running each sub at 2ohms, though you would be pushing the amp (Behringer's rating is 2x 2000W at 2ohms). And the SPL performance is close or better across the board.

You could possibly split that into four single sealed boxes as well...

Attachment 336762
Thanks very much for that suggestion and the model. It sounds like it could work. I am unfamiliar with the dual opposed configuration. Do you have any info I could read up about it? And how would you model that up in WinISD?
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post #25 of 25 Old 10-28-2014, 06:41 PM
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Two speakers opposite each other in the same box. Here's a random thread inbound with a couple pictures.

Lab 12 Dual Opposed Sealed Sub

To model it, just pick two drivers, and adjust box size and power to match.
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