Just an idea for a reduced size OB, using
inexpensive bass drivers. The OB will be
floorstanding.
This is just a concept, exact positions
of drivers will have to be fine tuned.
XO for the 2 lower drivers <180 Hz
lowpass only.
XO for the 2 upper drivers dependent
on Tweeter (Fullrange ?) used,
typically 1Khz, lowpass only.
inexpensive bass drivers. The OB will be
floorstanding.
This is just a concept, exact positions
of drivers will have to be fine tuned.
XO for the 2 lower drivers <180 Hz
lowpass only.
XO for the 2 upper drivers dependent
on Tweeter (Fullrange ?) used,
typically 1Khz, lowpass only.
Attachments
Ok - I should have paid more attention to the driver choices when I said "should work"...
Do not build this.
If you want to use 6x9s, use ones with a higher Qts value for the bass. This may mean cheaper drivers too, which isn't necessarily a bad thing. Are you sure you want to spend 8 x $60 on unsuitable woofers?
These tang bands are sub woofer drivers and cannot be crossed over to a tweeter particularly well.
I recommend four cheap high Qts 6x9s per side and a nice tang band fullranger for everything above 200hz. Designed properly this may indeed be a very good sounding speaker.
Do not build this.
If you want to use 6x9s, use ones with a higher Qts value for the bass. This may mean cheaper drivers too, which isn't necessarily a bad thing. Are you sure you want to spend 8 x $60 on unsuitable woofers?
These tang bands are sub woofer drivers and cannot be crossed over to a tweeter particularly well.
I recommend four cheap high Qts 6x9s per side and a nice tang band fullranger for everything above 200hz. Designed properly this may indeed be a very good sounding speaker.
Concerning bass response bjorno showed,
that this works rather well.
http://www.diyaudio.com/forums/showthread.php?s=&postid=1536627#post1536627
Concerning XO 0.9 to 1 Khz i cannot see impossibilities.
Pic 4(5) of the mentioned thread shows a red dashed line,
which would be the response in an infinite baffle.
One can approximate that response by keeping the baffle
step far lower than the crossover frequency.
Maybe it is possible to reach -3 dB at 1Khz by doing
nothing (no crossover). Filter rollof has to be set above
1Khz. An "acoustical" filter has to be designed, which
integrates into the whole system.
that this works rather well.
http://www.diyaudio.com/forums/showthread.php?s=&postid=1536627#post1536627
Concerning XO 0.9 to 1 Khz i cannot see impossibilities.
Pic 4(5) of the mentioned thread shows a red dashed line,
which would be the response in an infinite baffle.
One can approximate that response by keeping the baffle
step far lower than the crossover frequency.
Maybe it is possible to reach -3 dB at 1Khz by doing
nothing (no crossover). Filter rollof has to be set above
1Khz. An "acoustical" filter has to be designed, which
integrates into the whole system.
Oliver,
I am sorry, but I think something is wrong with bjorno's simulation. I have calculated it myself with his adjustments and with this result for the bassresponse (1 TB-driver 10" above floor 1 watt input):
The input figures bjorno present is not consistent with the bafflefigure in the second picture
/Erling
I am sorry, but I think something is wrong with bjorno's simulation. I have calculated it myself with his adjustments and with this result for the bassresponse (1 TB-driver 10" above floor 1 watt input):
An externally hosted image should be here but it was not working when we last tested it.
The input figures bjorno present is not consistent with the bafflefigure in the second picture
/Erling
I have 4 Beta 15 I tried in OB with a subamp from yes 180 hz down, they would go down all the way to 60hz!!! They were never clean they sounded like they were out of phase all the time (of course I triple checked, they werent) I used cardboard "wings" to change the OB size and bends, the lowest I could go was with the wings attached to the back wall, thats when they hit 60hz, my room has a resonance at 50hz, they never got there.
I swaped them for Altec 416, much cleaner but they didnt go that much lower either...
I swaped them for Altec 416, much cleaner but they didnt go that much lower either...
I attached an "Edge" Simulation for the baffle response
only. Drivers are idealized.
The baffle/driver configuration has to be rotated by 90 degrees,
then the mirror baffle below simulates the effect of the floor.
(I hope this trick is kown ... i learned it from
www.dipolplus.de )
The idea is to compensate the baffle rolloff by low pass
filtering the bottom pair of drivers at say < 180 Hz.
In the "Edge" simulation shown there is no lowpass applied.
Further idea is to enhance efficiency of the "sub-booster"
drivers near the bottom by attaching a rear mounted
short U-Frame of 15-20 cm depth. Depth of U-Frame should
not exceed a certain size to push lambda/4 resonance high
enough, so it is dropped sufficiently by the subwoofer's
low pass filter.
The H-Frame serves as a stand for the baffle, but should
be narrower than the baffle to maintain that flat
spouse friendly "baffle" look.
Of cause the 2 bass driver pairs (bass and bass mid)
could each be merged to a single driver and the basic
concept is maintained.
Even my idea to use Tangband W69 1042 with series
resistors seems not very welcome ... there may be better
alternatives. But i'd like to find a woofer with acceptable
behaviour up to 1Khz (and large Xmax).
I want to use my own ribbon dipole tweeter in that OB.
If someone wants to use e.g. a small fr driver for mid-high range
one does not need excellent midrange performance of the
woofers. Then the range of woofers to be used is wider.
Although i think the concept is more adapted to use a tweeter,
it may be turned into a FAST concept, using a very small fr-friver
with "higher than usual" crossover frequency (>300 Hz).
Kind regards
only. Drivers are idealized.
The baffle/driver configuration has to be rotated by 90 degrees,
then the mirror baffle below simulates the effect of the floor.
(I hope this trick is kown ... i learned it from
www.dipolplus.de )
The idea is to compensate the baffle rolloff by low pass
filtering the bottom pair of drivers at say < 180 Hz.
In the "Edge" simulation shown there is no lowpass applied.
Further idea is to enhance efficiency of the "sub-booster"
drivers near the bottom by attaching a rear mounted
short U-Frame of 15-20 cm depth. Depth of U-Frame should
not exceed a certain size to push lambda/4 resonance high
enough, so it is dropped sufficiently by the subwoofer's
low pass filter.
The H-Frame serves as a stand for the baffle, but should
be narrower than the baffle to maintain that flat
spouse friendly "baffle" look.
Of cause the 2 bass driver pairs (bass and bass mid)
could each be merged to a single driver and the basic
concept is maintained.
Even my idea to use Tangband W69 1042 with series
resistors seems not very welcome ... there may be better
alternatives. But i'd like to find a woofer with acceptable
behaviour up to 1Khz (and large Xmax).
I want to use my own ribbon dipole tweeter in that OB.
If someone wants to use e.g. a small fr driver for mid-high range
one does not need excellent midrange performance of the
woofers. Then the range of woofers to be used is wider.
Although i think the concept is more adapted to use a tweeter,
it may be turned into a FAST concept, using a very small fr-friver
with "higher than usual" crossover frequency (>300 Hz).
Kind regards
Attachments
A&D woofers have been recommended fore OB
http://www.traumboxen.de/index.htm
Fore an OB sub only I plan to use 8 x 15" (IB15 from AE Speakers) - fore less drivers and higher xo point they can deliver a Dipole15, but it cost more
http://www.traumboxen.de/index.htm
Fore an OB sub only I plan to use 8 x 15" (IB15 from AE Speakers) - fore less drivers and higher xo point they can deliver a Dipole15, but it cost more
I think for OB use, array of smaller light cone woofers is better than one large woofer.
Look at kinetic energy table
http://www.linkwitzlab.com/frontiers_2.htm#N
freely flopping heavy cone of a large woofer is unstoppable
Look at kinetic energy table
http://www.linkwitzlab.com/frontiers_2.htm#N
freely flopping heavy cone of a large woofer is unstoppable
There is a FAW, to use Rudolf's terminology, readily available to Germans described in this thread: http://www.audiocircle.com/circles/index.php?topic=46951.0 . You will be surprised by its performance.
/Erling
/Erling
bigwill said:
The eminence drivers are very interesting for OB use and
seem good value for money.
I would have thought on using a single delta 15 lfa or
two beta 12 cx (omitting the hf unit if possible).
These two drivers have low fr and Qts around 0.5.
But a single 15" driver would not fit into my concept.
Two of them just need too much space.
Using two 12" drivers instead, the displacement volume
does not reach four of the TangBands. Difference in cost
shrinks too ... concerning cone breakup above 500Hz
i have more confidence using the 6x9 drivers, maybe
this is a prejudice.
The backward U-Frame should be as tiny as possible.
Two 6x9" drivers lying aslant in the U-Frame make a nice
stand capable of housing the crossover.
I will check the midrange performance of my TangBands
- dismantling them out of my subs -
using a series resistor before burning money ...
Thanks to all for your critics, proposals and work.
If you like i will report on the project here ... it will
take some time, because my ribbon tweeter needs
some tweaking first.
Best regards
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