Hello all,
I'm wanting to build my first sub. Due to WAF and room constraints, I'm needing to put it under a couch which is against a wall. There is a total of 11" of height with a butt in the seat, and the bottom is a trapezoidal shape of sorts, see the attached diagram. My receiver has Audyssey XT32 which I'll use for DSP.
I have a budget of $500ish for driver + amp. I don't have either purchased and will gladly buy used equipment.
What are a few drivers I should consider?
Which is a better design in this application, a down-firing 10" or 12", or side/front firing 10"?
If side/front firing, I'd put on a metal grill to avoid the accidental kick.
Thanks for the advice!
I'm wanting to build my first sub. Due to WAF and room constraints, I'm needing to put it under a couch which is against a wall. There is a total of 11" of height with a butt in the seat, and the bottom is a trapezoidal shape of sorts, see the attached diagram. My receiver has Audyssey XT32 which I'll use for DSP.
I have a budget of $500ish for driver + amp. I don't have either purchased and will gladly buy used equipment.
What are a few drivers I should consider?
Which is a better design in this application, a down-firing 10" or 12", or side/front firing 10"?
If side/front firing, I'd put on a metal grill to avoid the accidental kick.
Thanks for the advice!
Dual or even quad 8" has been the most popular, so look to TB W8-670C or similar in a folded pipe (TL).
Well you want to give the sun a few inches above the ground, so your 11 inches goes down pretty quick. Why are you talking about side firing? Do you have space?
you can try porting depending on the woofer you want to use.
you can try porting depending on the woofer you want to use.
I have more space than I thought. I put spacers under the couch legs and can fit an old sealed 12" car sub box with the driver side firing. This particular box is about 1 ft3 internal volume and is an easy fit.
Given I have more like 13" height to work with, I have a box of 1 ft3 already or I could make a new one around ~ 2cuft, what are some drivers to consider?
Given I have more like 13" height to work with, I have a box of 1 ft3 already or I could make a new one around ~ 2cuft, what are some drivers to consider?
Dayton audio 265ho4? Low/mid 20s. If you have ~105cm you could make a pair of them in dual opposed TLs with drivers tucked in mouth /rear chamber area and protected. Maybe shorter with some aggressive csa reduction?
Blue or green, whatever works .
Blue or green, whatever works .
Attachments
Given the form factor of the available space, the answer depends on what your x-over point to your mains is
- if < 80 Hz, build a tapped horn or reverse tapered TH (T-TQWP) that would be smaller but less efficient . Use some 8" drivers
- if > 80 Hz, build a TL (as GM recommended) . Here's an example - https://audioxpress.com/article/hideaway-tl-sub-revisited
- you could maybe build a sealed / ported sub but run the risk of boomy bass if your room doesn't co-operate. More tuneability with a TL
Mains I planned to cross no higher than 80Hz, seems I need to learn more about horns and TL!
Given you have 13" in height, and around 4 cubic feet to work with, if you slot load the drivers, you could consider dual 10" or 12", single 15" or 18" sealed or ported.
The slot exit height need not be over 3" (75mm) or so, and could be left open on the bottom to make loading the driver(s) simple, and reduce the volume occupied by the "V" shaped slot.
Agreed. With more than the 11" the OP initially spec'd, .. PPSL with dual 10s or similar is a viable option (no need for a more complex design with gain - as would be the case with smaller drivers)
Lots of intriguing options, many more than I originally considered. Thanks for all the input.
Of all the potential designs, which is simplest in terms of woodworking? My experience is limited, but I am looking to improve.
Of all the potential designs, which is simplest in terms of woodworking? My experience is limited, but I am looking to improve.
"Simplest", in terms of 90 degree cuts and the least parts (6, not including bracing) would be sealed, cutting circular holes for vertically mounted drivers on one or more sides.
A port adds a minimum of cutting one more circular tube holes, or adding a minimum of one wall part, the side, top and bottom of the cabinet forming the rectangular or square exit.
A slot adds either two or three 90 degree parts, or one or two angled parts.
"Tapped horns" (TH) or "transmission lines" (TQWP etc.) can add a lot more parts, with or without angles.
A port adds a minimum of cutting one more circular tube holes, or adding a minimum of one wall part, the side, top and bottom of the cabinet forming the rectangular or square exit.
A slot adds either two or three 90 degree parts, or one or two angled parts.
"Tapped horns" (TH) or "transmission lines" (TQWP etc.) can add a lot more parts, with or without angles.
A sealed box with the driver(s) vertically mounted will be a quicker and easier build. Being hidden under the couch is great. You wont need to address cosmetics. Try and find some used scrap plywood.
Under the couch means the sub is closer to a near field so less concerns with room nodes for better bass.
With 13" height think about 12" woofers. They often have an internal diameter of 11" so with easy external mounting thay should slide in nicely.
Consider two 12" horizontally opposed for vibration cancelling eg https://www.parts-express.com/pedocs/specs/295-534--dayton-audio-DSA315-8-specifications.pdf
Wire them in parallel for low impedance with a Class D amp
Makes sense.
My next question is, what are the tradeoffs between, say sealed vs the slot loaded vs tapped horn?
Dual apposed sounds very cool, especially since I'm not wanting to turn the couch into a vibrating couch 😉
I plan on buying a pro amp second hand that can do 400-500w. There are nice QSC units with RCA-in locally that can be had for relatively cheap.
My space is one big open concrete & tile clad rectangle, 15ft x 50ft (think row home). I don't need to shake things off the walls, but do want deeper extension for reggae, EDM and done movies.
My next question is, what are the tradeoffs between, say sealed vs the slot loaded vs tapped horn?
Dual apposed sounds very cool, especially since I'm not wanting to turn the couch into a vibrating couch 😉
I plan on buying a pro amp second hand that can do 400-500w. There are nice QSC units with RCA-in locally that can be had for relatively cheap.
My space is one big open concrete & tile clad rectangle, 15ft x 50ft (think row home). I don't need to shake things off the walls, but do want deeper extension for reggae, EDM and done movies.
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Re. simpicity, ... you are going to want to add bracing to your sub - a tapped horn based on your proposed form factor would be more or less naturally braced because of the pieces that define the pipe path. A slot loaded enclosure or bass reflex - somewhat less so - so you would need to add some bracing at the very least.
Just for clarification: dual opposed != slot loaded (PPSL) .
* Dual opposed means cone facing cone and cones moving towards / away from each other at the same time
*PPSL - push pull slot loaded means cone facing basket and cones moving towards / away from each other at the same time (need to wire one woofer out of phase electrically to achieve the described mechanical behavior) - thereby achieving even order harmonic cancellation
* the slot (as small as physically possible) - help to introduce a small bandpass gain
Lastly, regarding the sound - ... and I'm trying to make broad generalizations using layman language here
- The bass reflex will sound fatter
- The sealed sub will sound tight - and not as deep
- The tapped horn will sound tight, ... moderately deep, and go loud - at the expense of crossing no higher than about 80 Hz .
- A reverse tapered tapped horn will sound like a tapped horn, but smaller and not as loud, though possibly still louder than bass reflex. Pick your poison 🙂
* Dual opposed will have the same force cancellation benefits as the PPSL, ... but not the harmonic cancellation benefits - so it will sound closer to a bass reflex
disclaimer - Of all these alignments, .. the only that I haven't built for home use is the PPSL - mostly because of time / specific applications.
Lastly, the one thing I don't like about the tapped horns (at least those that I've built) is that they don't transition well into the midbass very well (unlike direct radiator subs and front loaded subs). As a result, genres like reggae can sound a bit off (deep bass present but lacking a bit of mid bass punch). I understand midbass should mostly be delegated to the mains - but integration / roll off does matter - and direct radiators / front loaded bass horns are easier to work with in this regard. OTOH, IF you mains have copious amounts of mid bass , .. this won't matter as much
Hope this hasn't confused you too much
Lastly, I realize lumber is expensive - but the best way to find what works for you is to make sawdust. If you're in the US - check the scrap pile and you can often find mdf or ply at a discount. You can also have the store cut most of the profile pieces to the same width to simplify your build . And lastly, .. don't overthink it - make a plan but cut the pieces as you go . For 8 years of my DIY "career", the only tools I had were a circular saw, a home made saw guide, a jig saw, a drill, plunge router with 3 bits and 4 clamps 🙂 .
Note that dual opposed might make a reduction in sound reaching the couch through the floor.
However if the sub is doing its job there will be plenty through the air 😉
However if the sub is doing its job there will be plenty through the air 😉
Thank you for such a detailed
Thanks for the excellent explanation!
My mains Polk LSi15 and are rated -3dB at 35Hz, so a crossover at 60 or 80Hz seems reasonable (my receiver only crosses in 20Hz increments). I'm powering them with an Adcom GFA5500, so they're getting adequate power 😎.
Given the relatively low crossover, blending with the mains for music with more bass content i's an important factor to me.
I'm leaning towards PPSL for the vibration cancellation aspect and depth. Within that design, I assume PPSL sealed would best fit my space constraints.
In PPSL, do the drivers need to be coaxial? Do they share the same internal air space?
I don't think the drivers need to strictly align .. if that's what you mean by coaxial . That said, .. aligning the drivers this allows the magnet of one driver to "spoon" into the area occupied by it's complementary drivers cone area .. there y reducing the slot width .. which is desirable .
Yes, the drivers can share the same airspace
I can see how PPSL would lower HD when applied to a ported design. Kind of like a balanced cable set up with cancellation of noise?
I cant see how it would work in a sealed PPSL design?
ppsl applies to the driver alignment .. physical orientation of the drivers with respect to each other .. and is independent of the bass alignment (sealed , ported , TL etc )
in other words both drivers are always "pushing or pulling" the air volume at the same time .. despite one being physically flipped (and electrically flipped too to compensate ) .
Try "unfolding" a PPSL in your mind it may make more sense .
A PPSL alignment achieves 3 things
1. force cancellation because the woofers are always moving towards or away from each other
2. even order harmonic cancellation because even though the woofers are always moving towards or away from each other at the same time , one of the voice coils would be moving into the magnetic field while the other woofers VC would be moving away from the magnetic field. As a result, the non linearities do not add up. The end effect is that even order harmonics are suppressed . A very similar analogy is class A single ended vs push pull amplifiers
3. Lastly, the slot offers some amount of bandpass boost