Hi,
This is a 2 part question. I have a SB20FRPC30-8 full range driver and 2 SB20PFCR-00 passive radiators.
My plan is to build (will do calculations) a box which is slim (depth), but it could be made pretty large regarding height/width.
Because of the aesthetics, I want to do PR - FR - PR next to each other, vertically.
And also because of the depth there is no way to mount them on the sides.
Question 1: Are there cancelation problems if I mount these 3 in the positions I mentioned?
Question 2: Let's say in the future I hook (multiple of) these up to a 5.1 amplifier and cross them over at 80hz or 100hz, will the PRs still have their function or should I just go for sealed then?
Btw, I'm an absolute beginner. Know my way around making the cabinets with MDF but have not done anything more advanced regarding crossovers etc.
Thanks for your time!
This is a 2 part question. I have a SB20FRPC30-8 full range driver and 2 SB20PFCR-00 passive radiators.
My plan is to build (will do calculations) a box which is slim (depth), but it could be made pretty large regarding height/width.
Because of the aesthetics, I want to do PR - FR - PR next to each other, vertically.
And also because of the depth there is no way to mount them on the sides.
Question 1: Are there cancelation problems if I mount these 3 in the positions I mentioned?
Question 2: Let's say in the future I hook (multiple of) these up to a 5.1 amplifier and cross them over at 80hz or 100hz, will the PRs still have their function or should I just go for sealed then?
Btw, I'm an absolute beginner. Know my way around making the cabinets with MDF but have not done anything more advanced regarding crossovers etc.
Thanks for your time!
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1. no
2. crossed over at 80 the bass reflex action will not be needed as they probably is tuned 30-50 Hz or so an octave below crossover.
However, phase and frequency response around 80 Hz might still be different between such a design and a (small) closed box. This would affect the behaviour at the crossover somewhat.
2. crossed over at 80 the bass reflex action will not be needed as they probably is tuned 30-50 Hz or so an octave below crossover.
However, phase and frequency response around 80 Hz might still be different between such a design and a (small) closed box. This would affect the behaviour at the crossover somewhat.
So I can’t see any benefit to the design you propose for any reason. A wide but shallow enclosure for a fullrange driver is a really bad idea…..you’re going to have high amplitude reflections coming right back through the cone in the upper FR where clarity from the driver is at a premium……you can’t afford to mess that up
Those PR’s ain’t cheap….no financial benefit either…..two inexpensive 8” woofers crossed over at 250hz or so would produce far better and more efficient results given the cost. Run the active SB driver OB with a sealed pair of the 8’s or port it out the sides
Those PR’s ain’t cheap….no financial benefit either…..two inexpensive 8” woofers crossed over at 250hz or so would produce far better and more efficient results given the cost. Run the active SB driver OB with a sealed pair of the 8’s or port it out the sides
yes, right, shallow ( whatever what that means ) box is not good for the reason exposed. Better to let extinguish the back wave without interfering with the motion of the cone. I used to see very deep boxes lately ( ahem, 20 years ago) in commercial stereos ( all-in-one with external boxes, from Yamaha, denon etc.) and with minimal baffle; it's the trend nowadays, isn't It?The OB guarantees that the reflection from the back panel ( or all the six panels if it's a parallelepipedum, since inside there's pressure) is not present, but if not well 'screened' the backwave, which Is anti phase of the useful signal, Is a problem for the environment;
1950-1990 wide boxes with 8" drivers as small 10-12" as large and 15" as really large.
1990-present Floor speakers with as small drivers as 5" but usually two 6.5" driver with really narrow fronts.
They look smaller straight on and diffractions is less spread out in time domian.
However, the transition from spherical to half spherical radiaton (ie baffle step) occur at a higher frequency this makes a difference in the upper bass lower midrange. For better or worse? That depend on who you ask...
So my take is all designs are compromises and wider-shallower vs narrower-deeper simply is two different compromises neither one is intrincally "better" than the other.
1990-present Floor speakers with as small drivers as 5" but usually two 6.5" driver with really narrow fronts.
They look smaller straight on and diffractions is less spread out in time domian.
However, the transition from spherical to half spherical radiaton (ie baffle step) occur at a higher frequency this makes a difference in the upper bass lower midrange. For better or worse? That depend on who you ask...
So my take is all designs are compromises and wider-shallower vs narrower-deeper simply is two different compromises neither one is intrincally "better" than the other.
What I have for now is a box with a depth of 20 cm internally, working with 22mm MDF so if I flush mount the driver this would leave a space of 13.5cm from the back of the magnet to the back of the box. So maybe this isn't as shallow as I thought?
This project has a box which is more shallow with the same speaker: https://www.audiosciencereview.com/...b20frpc30-8-based-rear-speaker-project.41687/
I'm not really getting the point about substituting the PRs with activate woofers. 1 PR is €28 which is quite cheap I think? Also I cannot find a (suitable/acceptable) 8 inch woofer which is cheaper than this, plus I'll have to do a crossover (which I've never done before) and will need to buy crossover components which will also add to the cost. That does not mean that I don't think you're right with that idea, 2 active woofers with a crossover is definitely better, but also more complicated.
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Nothing but tons of smeared stored energy from that design…..a combination of internal reflections, resonances, etc
If you want to do a wide band driver design, the ‘simplicity’ of it can’t boil down to a driver in a box……the delicacy of the light weight thin cone that ALLOWS these drivers to play over such a wide frequency must be respected.