Hi all. Just want to say these drivers sound very good on OBs (just for break in) and I am still trying to figure out what cabinet type will give the best bass. In OB they need a sub that goes up high.
djn,
I'm a lover of both open baffle sound and full range speakers. If you like the open baffle sound of your new drivers, then you could use your new drivers on OB and place them over a cabinet with a vented or sealed sub (really a woofer with enough extension to blend with your near full range driver). An extension of this idea is to add a second sub to fire backward and run the subs in bipolar fashion which would create a speaker with near omni-directional coverage in your room.
The beauty of this idea is that you have the full range driver crossed high enough so that the OB baffle width could be relatively narrow and not imposing in a normal listening room.
I've designed several mass loaded transmission lines (MLTL) (albeit with smaller drivers than yours) as you can read if you search this forum. Recently, I did some work with the Dayton Audio RS225-8 in a 30 inch tall cabinet and it yielded excellent results (3 dB down in the mid 20 Hzs range). While not a true subwoofer kind of performance, it would provide very good coverage and sound good crossed over to your OB full ranger. With dual drivers it has potential of better than 105 dB spl levels near Xmax.
Lots of ways to go with excellent coverage from an OB driver with bass augmentation.
Jim
I'm a lover of both open baffle sound and full range speakers. If you like the open baffle sound of your new drivers, then you could use your new drivers on OB and place them over a cabinet with a vented or sealed sub (really a woofer with enough extension to blend with your near full range driver). An extension of this idea is to add a second sub to fire backward and run the subs in bipolar fashion which would create a speaker with near omni-directional coverage in your room.
The beauty of this idea is that you have the full range driver crossed high enough so that the OB baffle width could be relatively narrow and not imposing in a normal listening room.
I've designed several mass loaded transmission lines (MLTL) (albeit with smaller drivers than yours) as you can read if you search this forum. Recently, I did some work with the Dayton Audio RS225-8 in a 30 inch tall cabinet and it yielded excellent results (3 dB down in the mid 20 Hzs range). While not a true subwoofer kind of performance, it would provide very good coverage and sound good crossed over to your OB full ranger. With dual drivers it has potential of better than 105 dB spl levels near Xmax.
Lots of ways to go with excellent coverage from an OB driver with bass augmentation.
Jim
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At bass frequencies the woofer will be more or less omnidirectional no matter where you put the woofer in the box. Using a pair push-push does have huge advantages in terms of what the active vibration cancelation does.
Do note that a non-OB woofer may have issues near the XO as the “rear” of th eassembly will have a transition from out-of-phase (OB part) and in-phase where the woofer works.
Typically in an OB to improve bass (and mid-treble too) one adds 1 or 2 big *** woofers, biamp and EQ the bottom as necessary.
dave
Dave is correct on his comments about how woofers radiate as an omni-directional
source low frequencies. Assuming that djn is using his new field coil driver for this design, he has plenty of flexibility to position the crossover frequency as he chooses. Running the FC driver on open baffle mitigates any worry about conventional box design for it. The tradeoff is the width of the OB baffle accordingly for best sound to match with the woofer. He could cross at a lower frequency to mitigate any bipolar woofers wraparound transition mentioned by planet10 for example.
Another thought is to use a second woofer to increase the sensitivity of the woofers so that they more closely match to the FC unit sensitivity which is in the low 90s spl.
Jim
source low frequencies. Assuming that djn is using his new field coil driver for this design, he has plenty of flexibility to position the crossover frequency as he chooses. Running the FC driver on open baffle mitigates any worry about conventional box design for it. The tradeoff is the width of the OB baffle accordingly for best sound to match with the woofer. He could cross at a lower frequency to mitigate any bipolar woofers wraparound transition mentioned by planet10 for example.
Another thought is to use a second woofer to increase the sensitivity of the woofers so that they more closely match to the FC unit sensitivity which is in the low 90s spl.
Jim
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Yes, I really like the sound on OBs but I want to build they don't need low end support. I just picked up a pair of 4 cu ft diy cabs yesterday and I'd try them too. I know it wont be long before we sell this place for a smaller house will a smaller listening space. Them I won't have room for 4 subs.
Happy Holidaze and all that jive! 😀
Which model did you buy, version FC-4 [vented]? If so, then based on published specs a ~Vb = Vas, Fb = Fs T/S max flat alignment is the default, though once all external resistance
[ML] TLs will normally be tuned the same, but will require a greater net Vb to get adequate 1/4 WL TL vent damping whether mass loaded or not.
If the driver has variable damping [DF], then you can dial in a bunch of LF EQ [raise Qts'] to tonally balance it over a wider BW, better 'fit' it to the OB baffle/room.
GM
With a 37 Hz Fs, 1.8 mm Xmax, it will need some form of horn and to get it in a narrow cab/small room pretty much dictates a corner horn or at least a simple BIB pipe horn [single fold Voigt pipe]: https://www.diyaudio.com/forums/ful...aft-handbooks.html?highlight=terry+cain's+BIB
GM
Yes, that's historically the norm for FC drivers, but the way the published data is presented it isn't clear to me whether it's set at the factory or is it customer adjustable?
GM
GM
Yes, the four different T/S parameters are based on the power setting coming from the power supply.
And yes GM, I was a bit confused at first with this as well until I asked about it.
And yes GM, I was a bit confused at first with this as well until I asked about it.
😀 Cool! Set it on [1] then to flatten it out and make it do deeper 'knee bends' with music/pink noise/sine waves/whatever that makes it move below published Fs to as low as 0.707x Fs = ~26 Hz to shorten break-in time.GM
Right now I have it on 1 and playing 24 hour FM. Even though they are on OBs the low mids and bass is not really sounding low, but fuller if that makes sense. Unfortunately, FM does not go down to 26hz🙂
Yeah, FM is only ~50-15 kHz so must be boosted a bunch on both ends and played generally too loud to do a proper break in of low Fs drivers.
GM
GM
I picked up a pair of 5.5 cu ft cans for test beds. I installed the drivers today and they have a whole bunch of bass.
BiB - Half Wave Voigt
Also consider the Late Terry Cains BiB (Bigger is Better) Half wave Voigt based design. I believe Scottmoose and GM can help you there. I'm a planning to build a pair myself shortly based on the excellent Mark Audio CHS-70A's. I have a copy of the Mk2 excel spreadsheet if I can work out how to attach it again 🙂
Also consider the Late Terry Cains BiB (Bigger is Better) Half wave Voigt based design. I believe Scottmoose and GM can help you there. I'm a planning to build a pair myself shortly based on the excellent Mark Audio CHS-70A's. I have a copy of the Mk2 excel spreadsheet if I can work out how to attach it again 🙂
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I thought about the BIB but I don't like the open top. Can it be made with the opening on the bottom?