I mean... I intend to drive the low end section with a TPA3255 so I think I'm covered on that front lol
Not necessarily. The dayton can go down to 30Hz so I would say with some good design you could probably push it down to at least 20. The key here is I just want to do the best I can in a small design. You can only do so much to fight physics.
Kind of , , , when your neighbour's car gets 100x better gas mileage than yours - don't complain. When the engine needs to be replaced every few months because you are constantly thrashing the **** out of it - don't complain.
Can it? Without research I'll guess at 20-30hz the Dayton is probably - 20dB. Like a said, 100x more power to equalize with 100hz.
Multiple smaller drivers give you better bass (faster)... when we bought my son a bass cab, we decided to get him the dual 10" driver with the big amps... instead of the one with the single big 12 inch. The dual driver cab sounded really good, specially when he started to experiment with the string materials and then got the 5 string jazz bass guitar. You could really hear his picking mode...
Phil Jones seems to have carried this to an extreme... for a commercial product.
https://pjbworld.com/cms/index.php/products-cabinets/
With the likes of a Purifi, NCore or Hypex module, power for a bass driver is not an issue.
Why would a properly designed driver like the Dayton need to be replaced?
Compared to what? Few drivers will be naturally flat to 20Hz in a bookshelf. Of course the Dayton will require plenty of EQ if sealed, but that's pretty much what it's built for. And with a PR in a 10 liter box you can get an F6 around 26Hz, it seems.
That is for one self to decide. For me its just one of many reasons to go 10-18 inches.
Cheers
Like I said, I wouldn't mind adding another bass driver. The passive doesn't seem like a bad idea either.
I've actually been looking into MFB for that. @weltersys has been over there helping me work through it. The concensus though is I definitely need to spend more time on the enclosure.
I had not looked at the specs of the KEF SP1632 co-axial carefully, and the scale of the measurement, -5dB at 200Hz from 600 Hz. Probably not enough excursion to handle a 100Hz crossover, so the separate cabinet idea for the E150HE-44 won't cut it.
A sub you can place near you or tactile transducer in the seat is going to get you the "feel" of the LF with less transmission to the neighbors.
All three isobaric configurations, cone-to-cone, cone-to-magnet push-pull, or magnet to cone, still have only one cone open to the outside, so displacement is limited to one (little..) cone.
The isobaric cabinet can be half the size, but uses double the drivers and power to achieve the same output as one in the larger cabinet.
A very small cabinet using a low tuning requires a very long port which may occupy more cabinet volume than the back chamber.
A passive radiator can save that space, and also largely eliminates the upper port tube resonance.
Xmax and Xlim are the same on a passive radiator.
The E150HE-44's Vd is 139.7 cm3, don't go less than 280 cm3 Vd for the passive radiator or it may "clunk" at Fb.
Low tuned passive radiators have a lot of moving weight, using horizontal opposition of a pair will reduce cabinet shake without having to add a lot of mass to it.
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Ok so one enclosure then? Alright I can live with that. So then how many radiators would I need to offset? Just one?
Funny you should say that. A while ago I found a neat one that can go super low. I was intending to use it, but the move didn't happen before.
A pair of passive radiators in horizontal opposition would be one on each side of the cabinet.
The coax and E150HE-44 would be on the front side as closely spaced as possible, the cabinet elevated to ear height at your primary listening location.
The coax and E150HE-44 would be on the front side as closely spaced as possible, the cabinet elevated to ear height at your primary listening location.
If your going for a single box solution Id be more inclined to go for something like the Dayton RSS265HE-22 by PE's recommendations "Vented (home theater/music): 2.37 cubic ft. (gross internal, including driver and port) tuned to 23 Hz, with 1 4” diameter x 29” long flared vent, for an f3 of 21 Hz"
I like that. In theory that should be fairly small enclosure then. That was the goal so I like it 🙂
Ok so single enclosure, speakers close together, and 2 passive radiators. Sounds good to me!
It is the nature of all things mechanical, the greater the stress, the greater the likelihood of failure. This why a low-revving truck engine can manage a million miles but an F1 engine needs replacing after 24hrs.
Interesting, the Epique E150HE-PR 5-1/2” lists Xmech at 19mm (no Xmax on the spec sheet), while most passive radiators still use "Xmax" for what is actually Xmech/Xlim.
Does it say that in documentation somewhere? Or is it just better practice?
With the way they're trying to market it I'm not surprised. They're definitely going all in on the Xmax
BKrOn,
Yes, better practice to use double (or more) Vd for the passive radiator(s) than the driver(s) have.
Says in the overview:
"Epique E150HE-PR 5-1/2" Carbon Fiber Cone Passive Radiator...
Tip: As a general rule, the passive radiator(s) should have at least double the displacement of air (Vd) as the active woofer(s)/subwoofer(s) in the system. To calculate Vd=Xmax ∗ Sd"
The E150HE-44's Vd is 139.7 cm3. The E150HE-PR 5-1/2" Vd is 180 cm3, x2 = 360 cm3, should handle the driver's excursion a bit past Xmax.
The E180HE-PR 7” VD is 258.9 cm3, not quite double 139.7, so a bit on the marginal side, as well as the lack of force cancellation two opposing PRs offer.
The E150HE-44 spec sheet lists Xmax at 14.7mm, but does not list Xmech/Xlim.
The surround and spider don't look capable of one way excursion much past 14.7mm.
Have you pushed the driver by hand or with sine waves to measure what it's Xmech is, and what limits it first, surround, spider or coil contact with back plate?
Yes, better practice to use double (or more) Vd for the passive radiator(s) than the driver(s) have.
Says in the overview:
"Epique E150HE-PR 5-1/2" Carbon Fiber Cone Passive Radiator...
Tip: As a general rule, the passive radiator(s) should have at least double the displacement of air (Vd) as the active woofer(s)/subwoofer(s) in the system. To calculate Vd=Xmax ∗ Sd"
The E150HE-44's Vd is 139.7 cm3. The E150HE-PR 5-1/2" Vd is 180 cm3, x2 = 360 cm3, should handle the driver's excursion a bit past Xmax.
The E180HE-PR 7” VD is 258.9 cm3, not quite double 139.7, so a bit on the marginal side, as well as the lack of force cancellation two opposing PRs offer.
The E150HE-44 spec sheet lists Xmax at 14.7mm, but does not list Xmech/Xlim.
The surround and spider don't look capable of one way excursion much past 14.7mm.
Have you pushed the driver by hand or with sine waves to measure what it's Xmech is, and what limits it first, surround, spider or coil contact with back plate?
I was actually thinking two of the 7" PRs only because the epique is going to be sharing a space with another speaker. Yay or nay?
Funny you should mention that. I've been looking around lately at USB o-scope/sig gens. I know it's not going to be nearly as powerful as the stuff I used to use when I worked on radar (definitely don't need an RF spec an for audio) but I think for an audio project it should have enough resolution to get the job done.
Judging by Voice Coil Test Bench tests, the E180HE seems to have a more nonlinear suspension. Not sure how significant that is in a PR and how the difference plays out if you account for lower excursion requirements, though.
The tests also show that the E150HE can take excursion mechanically up to 19mm at least
The tests also show that the E150HE can take excursion mechanically up to 19mm at least