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Beechnut

DIY Subwoofer - lilmike's Cinema F-20 vs lilwrecker

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So in researching DIY HT subs, I've looked a lot at both of these lilmike designs. Here are some of the "vs" comparisons I've come up with. (Help me finish fleshing this out)

 

Frequency Extension:

- lilwrecker: tuned to 17Hz

- F-20: tuned to 22Hz

 

Dimensions:

- lilwrecker: 70" tall x 28 1/2" deep x 25 3/8" wide

- F-20: 60" tall x 20" deep x 29.375" wide

 

Material List:

- lilwrecker: 4 sheets of 3/4" plywood

- F-20: 2 and a quarter sheets of 3/4" plywood

 

DIY difficulty: (my w.a.g. from reading the threads)

- lilwrecker: 5 of 10

- F-20: 3 of 10

 

Divers: (Prices as of Sept 2015)

- lilwrecker:

----- Alpine SWS-15D2 - ($129.95) - Amazon link

----- Alpine SWS-15D4 - ($129.95)- Amazon Link

----- Kicker CVX152 - ($399.95) - Sonic Electronix Link

----- Kicker CVX154 - ($399.95) - Sonic Electronix Link

- F-20

----- Dayton Audio RSS390HF ($172.69) Parts-Express link

 

Amplifiers (suggested)

- lilwrecker

----- Berhinger iNUKE NU3000DSP - ($279.99) - Amazon link

- F-20

------ Not sure

Edited by Beechnut

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So I'm doing this as I'm trying to decide which DIY subwoofer to go after, as it applies to my lifestyle and restrictions. Leaning lilwrecker right now.

 

I'm going to build 2. My life can accommodate a large cabinet. Once all is said and done...I don't think cost will be that different between a TubaHT, THTLP, F-20, or lilwrecker.

 

Any of these DIYs will need a separate amp. I will have Audyssey XT32 so I don't think I HAVE to have DSP.

 

I'm a long ways from having a final house, so the will be moving with me and need to fit through doors =+) Gotta have a side that is 27" or smaller in my guess to be safe.

 

So again, leaning lilwrecker. (only recently ran into this build or I may have steered away from a THTLP)

 

The 1st post is to help flesh out the vs in the two build. Some more parameters to update would be:

 

Cost for wood

Cost for different driver options

Cost for recommended amplifiers

Estimated Build Time

Recommended tools listing etc.

 

More to follow. Appreciate your help and insight.

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Looking for lowest cost = THT.

 

Upside is lighter weight, lots of size options & driver options. Fully horn loaded + lowest distortion.

 

F-20 Heavier, bigger but easier to build. Fully horn loaded so also lowest distortion.

 

Both are super efficient thus only a small amp is needed saving even more cash.

 

Lil wrecker. Tapped horn. Higher distortion due to design but tuned slightly lower. Also huge and only one size as far as i know of.

 

I'm not super familiar with the specs but probably less efficient, how much ? You will need to look it up.

 

If pairing up with LaScala's or other shorter bass horn designs avoid tapped horns.

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Build the one you like the best.  All will have low enough distortion for it not to be a real consideration.  Ply wood and MDF are  reasonable cost wise.  I just did 4 and the MDF was $30 per sheet.  Go for the largest sub that you feel comfortable with in the room.  This way you won't have to look back and say what if I had that extra output, extension and headroom.  An I Nuke DSP 3000 amp is not that expensive and the DSP will come in handy post Auddysee.

 

Once you are more familiar with the amp, there are things you can do that Auddysee can't and won't do.  The extra DSP amp cost only a little more than the amp without it.

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If pairing up with LaScala's or other shorter bass horn designs avoid tapped horns.

Please explain why this is the case.

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Yes. I don't want to skimp if I'm jumping into a big DIY project like this. I can handle the larger cabinets with my setup (hidden behind the entertainment center that has to decorative nick-nack towers on the side).

 

Just want to layout the facts in case someone hast he same question I do. Certainly the F-20 is more budget conscious and has a smaller footprint.

 

What drivers are people recommending for the F-20 recently?

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Build the one you like the best.  All will have low enough distortion for it not to be a real consideration.  Ply wood and MDF are  reasonable cost wise.  I just did 4 and the MDF was $30 per sheet.  Go for the largest sub that you feel comfortable with in the room.  This way you won't have to look back and say what if I had that extra output, extension and headroom.  An I Nuke DSP 3000 amp is not that expensive and the DSP will come in handy post Auddysee.

 

Once you are more familiar with the amp, there are things you can do that Auddysee can't and won't do.  The extra DSP amp cost only a little more than the amp without it.

 

One of these cabinets will be plenty for just about any size room, you won't be dissapointed with wanting more output. Even the 8" driver in the Table Tuba blows away most store bought or online dealer subs.

 

Some consider lowest distortion a priority including myself.

 

 

 

 

 

If pairing up with LaScala's or other shorter bass horn designs avoid tapped horns.

Please explain why this is the case.

 

 

Tapped horns do not play cleanly much over 60 Hz or so.

 

The LaScala is no longer horn loaded just over 100 Hz so for best performance your horn loaded subwoofer should be crossed over there.

Edited by jason str

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Things to ponder:

 

Tapped Horn 

3508220.jpg

Tapped horns are similar in design theory to the Front Loaded Horns.  However, rather than placing the driver in the sealed chamber at the rear of the horn, it is placed in the mouth  (no chamber), so that the output from both sides of the cone can be utilized. Tapped horns can typically achieve a much flatter frequency response in singles, but do not benefit from extended low frequency sensitivity in groups like FLH's do.  Generally, this leads to an overall smaller system footprint to get desired frequency response, with a slightly lower bandwidth,as tapped horns display massive peaks and dips just above the subwoofer passband where the rear and front waves of the driver start to negatively interact.  

Pros:

  • Tapped horns can achieve similar sensitivity vs a single horn enclosure out of slightly smaller box size, as output from the rear of the driver helps Low frequency response
  • Generally a tapped horn is much flatter than a single FLH in its passband.  This makes running them in singles worthwhile, and still achieves about 6 db of added sensitivity over that found in a vented enclosure (or equivalent output out of half the drivers). 
  • Due to the lack of rear chamber,  it is easier to fit large drivers (18" and 21") inside a tapped horn design, without blowing the size budget.  This can further increase performance when one compares a single tapped horn vs a single FLH, as added displacement aids in both peak output a and LF response.  
  • For equivalent driver size, Tapped horns end up smaller than FLHs with similar tuning and sensitivity.  


Cons:
  • Not only does excursion rise quickly below horn tuning,  there is also a very high excursion peak withing the passband of the horn. This means that even employing a hipass does not adequately protect you from driver overexcursion and the distortion/risk of failure that comes along with it, as the design will now reach peak excursion inside the frequency range it has been designed to reproduce.  
  • To combat the problem above,  most tapped horn designs require a driver with extreme Xmax (linear excursion) capabilities, otherwise they are very limited in the amount of power they can take before driver damage occurs.  Unless the designer opts for one of these "super drivers" (which can be quite expensive), the design may be limited in peak output at the same point as a dual vented design (although it will take far less amp power and half the drivers to reach that output)
  • Even a well designed tapped horn will display response "glitches" only slightly above the passband (between 100hz and 250hz).   The is marked by massive peaks and valleys where the rear and front waves interact poorly.  Although these fall above the horn passband,  extreme peaks may still require notch filters to keep them from coloring the crossover region.  
  • Tapped horns do not gain a lower corner frequency from being used in multiples.  While they do display a generally flat frequency response as a single unit, this is as good as it gets.  Doubling cabs produces a 6 db increase in output, just as we see with vented designs.  
  • Distortion is not filtered out as seen with Front loaded horns, as the rear wave is produced directly in the mouth and does not travel through any folded horn path.  Given that max excursion is seen within the passband, that means distortion can be very high when the cab is pushed to its limits.  
  • Just like with any horn design, they are harder than direct radiators to design and build.  That being said, they are slightly easier to build than FLH's, due to the lack of a rear chamber.

Additional DSP would be something I would like to have for one of these subs.  Most people will use this in an HT setting.  Driver damage is a major concern if one get's over zealous with the gain control or DSP.  6 db for output advantege over a slot port design.  The subwoofer world is full of trade-offs.

Edited by derrickdj1
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F-20: tuned to 20Hz

 

22 I believe.  The "20" in F-20 is cubic feet of the box not tune frequency.

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- F-20 ----- Not sure what driver is recommended currently

 

It's a Dayton.. I'd need to look up the model number but it's not too pricey.

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It's a tough call. First DIY project is always filled with "eureka" moments - I had quite a few on my THT build. I would recommend the THT or THTLP. The THT will require 1/2 BB, so the ply will cost you a little more. But the 15" driver (DA RSS390HF) is a great driver; combined with the efficient THT it just won't distort. I've pushed it as hard as I feel comfortable with, and it just chugs along. I want to build two more, but, I'll probably just build one; thinking a 30" version for behind my seating area. I'm not sure if anymore than two is necessary right now, or ever lol. I can't recommend the THT enough, just so impressed with its incredible output.

Edited by Rowan611
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It's a tough call. First DIY project is always filled with "eureka" moments - I had quite a few on my THT build. I would recommend the THT or THTLP. The THT will require 1/2 BB, so the ply will cost you a little more. But the 15" driver (DA RSS390HF) is a great driver; combined with the efficient THT it just won't distort. I've pushed it as hard as I feel comfortable with, and it just chugs along. I want to build two more, but, I'll probably just build one; thinking a 30" version for behind my seating area. I'm not sure if anymore than two is necessary right now, or ever lol. I can't recommend the THT enough, just so impressed with its incredible output.

 

Baltic Birch is not required.

 

Any quality 4+ ply plywood with no thin veneer or voids may be used.

 

Quality particleboard is another option, not OSB (oriented strand board).

 

Lots of other driver options besides the Dayton too.

 

Drivers with higher Fs work best in smaller width cabinets and lower Fs best in wider models, normally anything within 10% of the T/S parameters is fine.

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It's a tough call. First DIY project is always filled with "eureka" moments - I had quite a few on my THT build. I would recommend the THT or THTLP. The THT will require 1/2 BB, so the ply will cost you a little more. But the 15" driver (DA RSS390HF) is a great driver; combined with the efficient THT it just won't distort. I've pushed it as hard as I feel comfortable with, and it just chugs along. I want to build two more, but, I'll probably just build one; thinking a 30" version for behind my seating area. I'm not sure if anymore than two is necessary right now, or ever lol. I can't recommend the THT enough, just so impressed with its incredible output.

Baltic Birch is not required.

Any quality 4+ ply plywood with no thin veneer or voids may be used.

Quality particleboard is another option, not OSB (oriented strand board).

Lots of other driver options besides the Dayton too.

Drivers with higher Fs work best in smaller width cabinets and lower Fs best in wider models, normally anything within 10% of the T/S parameters is fine.

My bad, I should have said recommend not required. When I got the plans from Bill there were only two driver options, both DA. I'm sure others work, but I didn't want to risk it. The DA driver I listed was the best of the two options in the plans.

Sent from my HTC One_M8 using Tapatalk

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The recommended drivers in the plans are just the easiest to find here in the USA, If every possible driver that could be used were in the plans there would be no room for the plans itself.

 

The recommended Dayton & Eminence are fine drivers.

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The recommended drivers in the plans are just the easiest to find here in the USA, If every possible driver that could be used were in the plans there would be no room for the plans itself.

 

The recommended Dayton & Eminence are fine drivers.

Lol, in my ignorance I didn't even think about outside this country. Ops!!

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The recommended drivers in the plans are just the easiest to find here in the USA, If every possible driver that could be used were in the plans there would be no room for the plans itself.

 

The recommended Dayton & Eminence are fine drivers.

Lol, in my ignorance I didn't even think about outside this country. Ops!!

 

 

No big deal, just like others to keep their options open.

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Sooo if I end up keeping my La Scala II's what would be a good match for them? I'm not a master wood worker and have only built the Anarchy tapped horns so the easier the better. Mind you my listening room is 12x10 with a cathedral ceiling.

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were your Anarchy's any help with you LS II's bottom end?

Oh heck yes they sound great to me but when I crank the peach to 10 o'clock position the tapped horns cant keep up.

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The easiest horn sub I've built is the F-20.  It will do everything you need it to.

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