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xtrmaniac

Diy Subwoofer

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Hello,

 

First of all I'm amazed about what is discussing here, especially on "The Low Frequency Content Thread". That is solid work and thanks everybody for their contribution to this (much appreciate it). It's another perspective to look for movies and listen to them and without your involvement, none of this work could exist.

Still reading the "The Low Frequency Content" thread and I'm really impressed. Needless to say that it's inspiring and never found something similar. Thank you again for your commitment!

 

Since I'm reading the thread the only thing that comes to my mind is if I'am choosing the right subwoofer. I want to buy SVS PC-12NSD which based on the reviews it seems to be a good acquisition, however I'm still building the sound system where the floorstanding will have a range between 35-20kHz and I didn't quite decide if the subwoofer will be the right one. The floorstanding and the central speakers are ported, only the rear ones are sealed but with same drivers.

 

I read that some of you are building speakers also. May I know the project name and a weblink if it's possible for more inspiration?

 

What am I expecting from the subwoofer? The same experience that everybody is talking when they have a good subwoofer, however now I'm on a budget and I just want to know if I can meet the financial resources if I will choose to build one or two comparing with the SVS product mentioned above.

 

If it will be better by building it and I’m pretty sure that is the conclusion, if you don't mind, could you please guide me to certain diy subwoofer projects that deserve attention since the internet is full of them and it's very hard to decide.

 

If it matters, at home I have the following configuration:

Emotiva XPA-5

Anthem MRX-500

Oppo BDP-103

 

Have a great day,

xtrmaniac

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If you can build, do so.  It is hard to beat the value of building something that will fit your exact needs than something that 'will do alright'.

 

You need to provide more info.  Start with the room.  How big?  Open to where?  Where will the seats/speakers be?  You mention some pretty beefy mains.  Have they been built yet?  Extension to 35Hz in mains is not needed and can be counterproductive in some smaller spaces, as the positioning for mains/center surrounds is much less negotiable than for subwoofers.

 

Good beginning reading:

 

http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/LoudspeakersandRoomsPt1.pdf

 

http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/LoudspeakersandRoomsPt2.pdf

 

http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/LoudspeakersandRoomsPt3.pdf

 

You will hear this said over and over.  The room is the final and almost the most important part of the equation.  $100k speakers in a crap room = crap sound.

 

So lets hear about this room and mains/surrounds....

 

JSS

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I've designed and built a few subs. Most of the designs I have shared are over at AVS, I use the same user name there. The sub in my avatar pic is a couple generations old, but still not "done", I need to build and measure the replacement one of these days.

 

maxmercy hit the nail on the head though. Need to know a few more things to make suggestions. The room is a fundamental. Second is the budget. Third is the combination of SPL and extension, because to get one, it either costs the other, or more $$. No free lunches here. 

 

Subs are, to be blunt, the easy part. With the current crop of drivers and amps out there, you have a LOT of good options. A couple of proper sealed 18s and a couple kilowatts to each is a great start,and won't take up the whole room. Not enough? Add another sealed 18 and a couple more kilowatts, repeat until grinning.

 

Sure - I chose another path. I do this stuff for fun, and I know how to measure my junk. Without the ability to correctly take and interpret measurements, sealed subs are a safe investment of time and money. Ported subs are a bit more risky, but still pretty safe. In comparison, the horns and tapped horns I mess with are trainwrecks waiting to happen when I get it wrong. Been there, done that, and I have plenty of pix to prove it. 

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Start with this information...

 

1.) budget?

2.) How big of a subwoofer are you willing to deal with?

3.) Can you use multiple subwoofers?

4.) Listening habits and background? (What music do you listen to, how loud do you listen, do you have a background in car or pro audio, or are you mainly a 2ch home audio guy?) What bass systems have you heard and owned?

5.) How big is your room and what is it's construction? (Dimensions...Brick walls, or drywall with framing? Floor concrete in a basement or 2nd floor of the house and wood?)

6.) What is the rest of your basic audio system composed of?

7.) DIY an option? (Are you interested in learning about how speaker systems work and building your own cabinets and sourcing components? Do you have wood working experience? Do you just want to buy something that is a finished "plug in" product?)

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Thank you for the replies and for the web-links. The information is very comprehensive compared with different bits and pieces gathered from internet and library.

 

I don't know how I missed that but the sound system will be installed in the basement in a 2 storey house. The basement dimensions are: 292" x 129" x 81.5". The rooms is not that big, but enough to make it in a cinema room. Please find enclosed the layout with all the details.

 

Perhaps this is relevant so I will write it anyway. There are 2 concrete walls with 1.5" wood frame and drywall. The wall where the sound system will be installed has a 2 layer of sound proofing insulation. The ceiling has 1 layer of sound proofing insulation, resilient channel and drywall.

 

The speakers are not ready yet. Still building the enclosures and hopefully this weekend, if it will not be any show stoppers, I will complete them. The tricky part will be to apply veneer on MDF. The crossovers are partially done and it's just a matter of time to put all the components together.

 

Below you will find the proven designs that I choose after searching through different sites and combine with what kind of drivers I could buy at this point.

 

Floorstanding speakers

http://diyaudioprojects.com/Speakers/Hi-Vi-3-Way-Tower/

 

Central speaker

http://diyaudioprojects.com/Speakers/HiVi-Center-Channel/

 

Rear Speakers

http://www.underfloorers.com/speakers/center/

 

Regards,

xtrmaniac

layout.pdf

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Hi Ricci:

 
1. I preferred to be reserved on the budget point. I previously mentioned that I'm on the budget but first I would like to know what options I have in the cinema room to know how much can I extend it. I have a feeling that it will not be something very expensive, for example the SVS product mentioned above can be sold at 4-500$. I can start from there to see how much will add up.
 
2. Not a problem to convince my wife :)  but seeing the cinema room layout, the dimensions and the space left, how big can it get? It's not that I'm underestimating the dimensions of the subwoofer, but it can have a reasonable size.
 
3. Depends of the size of the subwoofer I can go with 1 or 2 subwoofers if I'm going to split the pre-out cable from the Anthem receiver.
 
4. I like to listen an open and warm sound and sometimes it could get loud. I'm listening mainly of rock and electronic music. That doesn't mean I don't have CDs with classical music :). I started with Logitech Z5500, continued with Axiom sound system, now I want to build them.
 
5. The room is situated in the basement. 292" x 129" x 81.5". I agree that the room is not big but enough so far. I need to add that in the previous reply I said 2 concrete walls, actually there are 3 concrete walls, the third one is situated on the side of the stairs based on the layout attached (2 concrete walls have 129" and one has 292"). The concrete walls have a wood frame 1 1/2" with no insulation, with vapor barrier and 1/2" regular drywall.
The 4th wall, where the floorstanding and central speakers will be, has a wood frame with 2 layers of sound proofing insulation and 1/2" drywall.
The ceiling has 1 layer of sound proofing insulation, resilient channel and 1/2" drywall.
The floor is concrete, covered with pieces of vinyl and on top of that underlayment and 14mm laminate flooring.
 
6. Please let me know if you need more details.
 
7. DIY definitely an option. About wood experience, I've redone the main floor and the basement by myself. I'm not making cabinet doors but I can handle a saw or a router.
 
 
Regards,
xtrmaniac

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Thanks for the room layout.  Is the space to the left/right of the sofa and chairs available or taken?

 

Your sentence structure makes me think that English is not your first language.  Where are you from (just curious)?

 

Looking at your space, the first thing that screams at me is you need back wall absorption, behind the sofa especially, then to the front wall behind the speakers.  Your effective 'sidewalls' are pretty far away and may not need any treatment except diffusion on the left, and maybe some absorption on the right.  With a hard floor, a rug will help with floor reflections, esp from the center channel, and some absorption on the ceiling at the LCR 1st reflection points.  

 

If you can, space the side surrounds further away from the sofa, to avoid localization to one surround (spl drops at 6dB per doubling of distance).

 

If you move the surrounds further away, you are left with some great spaces to put nearfield subwoofers next to the sofa and chairs, or use the subs as stands for the surrounds if you do not want nearfield subs. 

 

How low do you want to replicate?  How loud?  I think you will be SPL limited by your Mains, Center and Surrounds, and I do not think clean reference level will be possible as they appear to be lower sensitivity speakers.  The dual-tweeter center was a curious design choice.  With ~87dB sensitivity, and a ~3m listening distance, you are looking at around 95-100dB maximum at the listening positions from them before distortion becomes unbearable.  That means you have a -10dB to -5dB system.  I would lean to the -10dB end of the scale.  So you need around 115-120dB at the seats from your subs to match your LCRS.

 

That can be accomplished in many ways.

 

How loud do you plan to listen to films?

 

 

JSS 

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Hi maxmercy,

 

Thank you for your answer! I really appreciate it.

 

I regret the late reply but I was busy this weekend finishing all the basement little details before being functional for watching movies. It's useless if I'm building speakers and nowhere to place them. Nevertheless now I should have plenty of time to complete the speakers even on this weather. I will update tomorrow the thread with another cinema room layout based on your specifications.

 

I have room left to the left/right of the sofa and chairs. 1 rear can be placed at the bottom of stairs, the 2nd one can be place on the far left near the closet. That means it will be plenty of space for nearfield subwoofers. 

 

About your question how low I intend to replicate, I'm afraid I don't have a straight answer for this. As low as it gets without hurting the wallet.

I mean I put a lot of effort building and finishing the cinema room. I would like to think that it can stand having these speakers and subwoofers.

I think, in the end, it's not about how loud I want to hear it, because literally the LCR will be right in my face. Not much of a distance for 10ft between sofa and speakers. I'm lucky if I will turn the receiver knob up to 30% for listening music loud.

So I will lean towards a sound which will envelop the space between the tv and sofa and people watching a movie. I will lean to an experience felt during the movie, not for loudness. And again I don't want to shake the neighbors houses to the ground, only mine :) (just kidding)

 

Please let me know how should I go forward with this, or if you need more details. If all the details will be resolved, probably by Christmas I will have a present :).

 

Best wishes,

xtrmaniac

 

PS: My background is Romanian but I'm established in Canada.

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I think near field subs would be best, behind the chairs and flanking the sofa (in that area). Another choice would be 2 large horns acting as a riser for the sofa. Room treatment would def be needed on front wall and back wall, floor and ceiling.

 

JSS

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I agree with you about room treatment. However, I am intrigued if sound and safe insulation added in the ceiling and in the wall behind the TV stand plays any role in sound absorption? I thought/hoped the insulation will do the trick.
I am wondering if I should install absorption panels on the entire wall or should I focused on a certain areas. Could you please advise what is the best way to determine the panel size in my case?

 

I'm not a subwoofer connoisseur but I think I will go with near field subs. Last time you mentioned that I should have 115-120dB at the seats from subs to match the LCRS. How can I do that?
Can you please guide me to some DIY near field subs designs / schematics? I didn't do my homework about this and I would like to study what are the requirements in order to build such subs. My goal would be to go below 15Hz.

 

All the best,

xtrmaniac

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I can answer in more depth this weekend.  If I am hearing you right, you have Safe n Sound INSIDE the walls.  that will do OK for acoustic isolation, but not anything for the sound within the room hitting the reflective drywall.  Like I said, I'll reply more later.

 

To place absorptive panels at the first reflective points (the brief version), you need a helper and a mirror.  You sit at the main listening position, the helper moves the mirror on the wall to be treated and you look for the speakers.  Where you see a speaker, treat.  It is a first reflection point.  You could also add corner traps to help with bass modal ringing.  I plan to build some modular ones soon.

 

For 115-120dB, you can probably start with four 15" subwoofers flanking the sofa, drivers pointing either at the back wall or towards the couches or towards the chairs, or dual opposed like nube's build at AVS.  Play your cards right and you can make them look like end-tables for the sofa with granite tops like nube did,and then they are not subs, they are 'furniture'.  Look up his thread.  Drive them with something like an EP4000 and you should be good to go, to a certain extent.  To delve deeper into the Infrasonic range, you need more displacement, but you can just add subs later to do so.  With the subs in the nearfield, they will not need nearly as much power or EQ.

 

 

JSS

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Thank you maxmercy! I'm looking forward to receiving your reply.

 

When you will have a chance, could you recommend me a corner trap model? There are only 2 corners on the left wall, I don't know if I should install something at the bottom of stairs (behind the rear speaker) and on the corner under the stairs where is a closet door.

 

I found nube's thread on AVS forum and I'm really impressed, the enclosure looks very well-constructed. I just have to figure out if there are similar drivers that I could use for my project without affecting their performance, because I didn’t find SSD-15" drivers on parts-express or solen.ca.

 

Reading your last line, I just want to confirm with you if 1xEP4000 should be enough without needing an EQ for near field subwoofers in this setup.

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I would make the corner traps if I were you, the cost savings if you can cut plywood is vast.  Corner traps do not need to be solid rigid fiberglass, and 'pink fluffy' insulation will work.  Place corner traps where you can.  Having them on only one wall is better than none. 

 

For the 1st reflection points, here's a good pdf on how to make some (I also used poly batt between the fiberglass and the fabric to ensure no glass fibers get into the breathable air):

 

http://www.readyacoustics.com/DIY-BASS-TRAPS-MADE-EASY.pdf

 

Great read:

 

http://www.accucalhd.com/documents/audio/Acoustical%20Concepts%20For%20Home%20Theater.pdf

 

I personally use 2" of OC703 on the ceiling and 4" on the front and sidewalls.  They make a difference, but you won't truly notice it until you take them down, and you realize the difference is HUGE.  I am currently using 4" traps straddling the corners, but will make true corner traps soon, to free up the 4" traps for more front and back wall duty.

 

Not sure I would use any absorption for the surround 1st reflection points, but definitely for the mains and center.

 

For economy, I would probably use the SI 15" drivers, only 3% driver sag so good for vertical driver placement if you will try to make end-table subs like nube's.

 

An EP4000 gets you basically 2000W.  That is enough to drive four RefHF 15" to Xmax down around 10-15Hz with a Linkwitz Transform via MiniDSP or whatever signal shaping you will use (older Audyssey firmware added a ULF boost as an 'error' in their algorithm that they have since fixed).  I think that unless you plan on running your subs hot, 2000W should be enough.  You can always add more power if you see clip lights.  For every halving of frequency you want to reach with the same SPL, you need 4x the displacement (4x the amount of drivers each seeing the same amount of power).  There is a point of quickly diminishing returns, even with nearfield subs.  Driving four SI15" drivers to the limit will take a little more power.  But you always want to be well within your system's limits.  Ther is no point to running on the ragged edge.  When I finish the Audio Test BD, it will have tonebursts to test speakers with, with tonebursts as low as 3Hz.

 

If FOH and others want to chime in, please do.  I am only one viewpoint.

 

Lemme know if you have any questions.

 

 

JSS

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Thank you for all the details! At some point I would like to resume how to improve the room with corner traps and absorption panels since I'm a little bit confused. I still need to finish reading those 2 web-links sent. Definitely I will ask more questions as I progress with everything,

 

I regret the late answer but I was busy building the speakers and unfortunately our house was in the path of the Ice storm. We have already a power outage which is lasting for almost 2 days. Nothing major happened only couple of tree branches felt on the driveway.

 

Anyway we expect to have the power restored as soon as possible.

 

 

I have some question off-topic about building the speakers. How do you keep the damping material away from the drivers? I bought something like this: 

http://www.parts-express.com/acousta-stuf-polyfill-speaker-cabinet-damping-material-5-lb-bag--260-330

 

The tweeter speakers didn't come with a gasket. I didn't expect that. So I need to go to a store to buy something. Can I replace the rubber gasket with something else? What do you recommend me?

 

There is a space cut under the tweeter for polarity connections. How and with what should I fill that space?

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Anymore I just use cheap poly filled pillows for sealed enclosures. No worries with those. For vented cabs they can still work but you use them sparingly and have to be mindful of the ports. Lining is also effective.

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Thank you very much for your answers!

 

I got the power back, after 7 days, so everything that I postponed, I need to do it in the next couple of days.

 

I will have more questions soon but until then, have a great week and Happy New Year!

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For economy, I would probably use the SI 15" drivers, only 3% driver sag so good for vertical driver placement if you will try to make end-table subs like nube's.

 

 

JSS

Hey JSS :)

 

First post on this forum, I have been admiring the quality of the BD audio analysis thread for a long time - empirical data is good :)

 

 

I just wanted to ask about the driver sag you mention above - is it similar for the 18 version?  Did you calculate the figures yourself?

 

I am currently working on a PPSL design and there seems to be arguments for and against vertical and also horizontal mounting arrangements, driver sag and pole misalignment being seemingly unavoidable consequences depending on the option chosen - so I am finding it hard to decide!

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Hello,

 

I lost the track of time with the sound system project this winter. However in the meantime I had the chance to finish reading what JSS have share it and I can say that I'm little bit more educated. Definitely I would like to buy the book from Floyd E. Toole, because I'm sure that I will find more interesting details there.

 

To sum up, I just finished the 5.0 sound system and I took a day off just to hear the music, listen a SACD, watch a movie or two...actually I will watch at least half of the BDs that I have just to review the movie experience and I need to say that is unbelievable. The dialogue in the Inglorious Basterds movie is awesome, clean and clear, same as goes with the effects from Gangster Squad, How to train your dragon, The A-team, Losers, Knight and day, etc.

It's more than clean and clear sound, it's a whole new experience of everything. As advertised the high frequencies are crystal clear, open and warm middle ranges and accurate bass. This system will be doing great as it is for movies that are filtered at 30Hz. :)
 
And btw JSS, I never doubt it and you were right about "How low do you want to replicate?  How loud?  I think you will be SPL limited by your Mains, Center and Surrounds, and I do not think clean reference level will be possible as they appear to be lower sensitivity speakers.  The dual-tweeter center was a curious design choice.  With ~87dB sensitivity, and a ~3m listening distance, you are looking at around 95-100dB maximum at the listening positions from them before distortion becomes unbearable.  That means you have a -10dB to -5dB system."
 
Now I can answer this question and I can say that it's more than enough. Until it reaches the distortion it can get loud enough for my ears, even pass my expectations. Definitely will be better with subs but for now it will do it.
 

The room is not yet finished. It needs acoustic panels and corner traps. Regarding the corner traps, I would like to know if I should use them between the ceiling and the wall and how should be distributed? I've read a case study from Ryan O. Allen about Acoustical Concepts and he recommended to be used. Based on the room measurements I'm inclined to go only with corner traps at the wall corners and acoustical panels. I would like to receive your feedback about it.

 

In my quest of finding what is the best and appropriate subs for my Cinema Room I found that I'm still not decided which subwoofer will work there.

I had a discussion with nube and I was asking him for more details about his design and I would like to thank him for taking his time and patience to share his experience. He also recommended to use TC sound drivers since they use less cubic feet than FI SSD15" to have great performances.

 

The design of 2 dual opposed drivers is great but I'm not very sure if going with that will not be too much. The space available there is not that much as you have seen in the updated layout. Central is at the distance of 10-12 feet and the surround between 15-16 ft from the listening point. And I have between 2.5 and 3 cubic feet to spare between the sofa and the chair to be used as side tables no more higher than 24". And I have only 2 areas to use for that.

 

Also I could compensate at some point with "bass shakers" for the feeling below 15Hz :)

 

I agree that I need more space to develop a real home cinema, however in this case I need to work with what I have and I will appreciate your advice.

 

Please find attached the frequency response on each speaker after calibrating with ARC from Anthem. I think they are pretty good.

The only thing that is concerning me are the surrounds. The volume is almost 0.7 cubic feet in a sealed enclosures. I attached the schematic. As per surround graphs the response is dropping dramatically after 6kHz. Hopefully I didn't mess with anything and that is everything that I could squeeze from them.

 

All the best,

 

 

 

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post-615-0-72702500-1392832957_thumb.jpg

post-615-0-23025400-1392833230_thumb.jpg

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Make sure the crossovers are wired correctly in the surrounds, and that no 'cinema processing' is taking place in hour AVR rolling off the top end on your surrounds.

 

Per your PM, you need -20dBRef capability (maybe a little more) down to 15 Hz, but you also want to minimize the volume taken up by the system, and you would like to use 12" drivers if possible, and not break the bank.

 

That is a tall order. A vented box alignment tuned to 15Hz would be less expensive, but take up more space. A pair of folded horns would be the least expensive option, but also be large. A sealed alignment would be the smallest, but likely the most expensive, but also most likely to dig to below 15Hz when called upon.

 

As far as acoustic treatment, definitely treat first reflection points on the ceiling, the wall behind the LP, and the frnt wall behind the speakers with lower priority to the sidewalls as they are so far away. Corner traps will reduce modal ringing, and can be used floor-to-ceiling, or wall-to-wall on the ceiling-wall junctions. Floor-to-ceiling will of course be easier to implement.

 

Using multiple sealed drivers in the nearfield (right behind the seats, firing into the seat-backs) may be a good option for you.

 

JSS

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Thank you for your reply JSS!

 

I don't recall to have cinema processing setting on Anthem, but I will take another look. The menu settings is pretty straight forward.

About checking now the x-overs, that it will be a little bit impossible. I tested them before installing them in the enclosures several times. Even when they were installed in the cabinet without gluing the last piece of the enclosure, they sounded ok as I could hear that x-over is working and they are wired correctly. This is my first diy sound system and I didn't want any surprises.

I did though boosted the surround with +3dB in the AVR and watching HTTYD, Kung Fu Panda, I was somehow surprised about the sound effects in the surround speakers at -20dBRef, but I still have a feeling that something is missing. Definitely, if there is a problem there I would like to check it out but now I'm a little bit confused.

 

Thank you for guiding me in choosing a design for the subwoofers. The 4x12" drivers will be my best option in the room and I will go with dual opposed design which will give me the best solution: space, going below 15Hz and used them as furniture as you said before.

But having multiple sealed drivers in the nearfield firing into the seat-backs is not bad at all. It's just bringing me a good feeling and a smile when I'm watching something like this:

 

I assume that a 12" driver has around 1 cubic feet volume in a sealed box that means the enclosure should have around 2-2.5 cubic feet volume with the driver displacement and bracing.

In this case could you please tell me if there is a good 12" driver which could meet my requirements without breaking the bank? :)

 

About acoustic treatment, I'm already working at this. Hopefully, soon I will finish this and do another calibration of the sound in the room.

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If you will fire them into the seatbacks in trapezoidal enclosures, the driver does not have to be pretty, and you could get away with the Infinity 1260W or 1262W, a very high-value driver. If the drivers have to look the part, TCSounds Epic, Dayton Reference HF, and Dayton Ultimax are all good $/Xmax values. Simulate them in enclosures with WinISD.

 

Looking over your room layout again, corner traps in the front corners would be easiest.

 

DO NOT expect 4 12" drivers to have anything close to what popalock's videos show. To do what he does, you need LOTS of displacement. 4 12's will not be in the same category. Far from it. If you think you will EVER want more, just buy it now, and go with 15s. For -20dB listening, and in the near field, 4 12's should do OK, and mate well with your speakers. Also, set your mains to small when you integrate subs and see if they measure well.

 

For the most economy, use the 1260W or 1262W in a folded horn, and build 2.

 

JSS

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