Not if I can't see Dave's design, I'm not....
AK Design Collaborative - TCB Subwoofer
- Thread starter Zilch
- Start date
Dave eMailed me the parameters for his push-pull Tang Band 6W-1139SI design, and I loaded them in BB6P. It certainly gets down, I must say:
I doubled it up for a TCB (stereo) version, as well. It has similar performance, but is 3 dB more efficient with twice as many drivers (Red).
There are vent length issues in both designs, but they are manageable. Cursor's at F6 in both cases, and both versions will handle full power down to there, the TCB gaining an additional 3 dB at 280 W.
It would appear we have moved from "modest" into the realm of "Holy CRAPOLA" here.... :tongue:
I doubled it up for a TCB (stereo) version, as well. It has similar performance, but is 3 dB more efficient with twice as many drivers (Red).
There are vent length issues in both designs, but they are manageable. Cursor's at F6 in both cases, and both versions will handle full power down to there, the TCB gaining an additional 3 dB at 280 W.
It would appear we have moved from "modest" into the realm of "Holy CRAPOLA" here.... :tongue:
Attachments
dnewma04
The Healer
Zilch, I have been giving this some thought and by playing with the dims the other day, I managed to make an enclosure that could serve a couple of functions. First, I want to keep it so that it will fit under a desk, second, I want it to be able to serve as a stand for Indignias, Minimus 7s, SuperZeros, or any other small monitor type speaker.
I figure a lot of people have small speakers like those in their offices, so keeping the sub under the desk could be a great way to keep it inconspicuous. Lay it on it's side and it's a good foot rest.
I'll try attaching another version of it, with less exacting dimensions to give you an idea.
I figure a lot of people have small speakers like those in their offices, so keeping the sub under the desk could be a great way to keep it inconspicuous. Lay it on it's side and it's a good foot rest.
I'll try attaching another version of it, with less exacting dimensions to give you an idea.
So we're talking 4 drivers, 2 per side in a PP arrangement in a 6th order (all chambers ported to outside) BP box right?
What does the 2 driver/2 chamber look like at 100W? PE has a 100W plate amp on sale right now. I'm guessing plenty for an under-desk powered sub to compliment computer speakers.
Ray
What does the 2 driver/2 chamber look like at 100W? PE has a 100W plate amp on sale right now. I'm guessing plenty for an under-desk powered sub to compliment computer speakers.
Ray
I see it this time, Dave, aqua and black, with the HF chamber at the lower left, dimensionless. It's the configuration you're illustrating, and I assume the volumes remain as you earlier suggested?
Yes.
100W = 100.3 dB @ F6, 25.65 Hz.
I'm not seeing any excursion issues until it gets under 20 Hz.
Highpass at 25 Hz would be advisable.
Group delay peaks at 28.68 ms, 23.41 Hz.
Room gain will bump the very bottom up 12 dB/octave below 30 Hz.
The four-driver TCB version is the true ass-kicker, but multiples of the dual chamber implementation allow for distributed sub placement. You don't get the 3dB advantage of mutual coupling from that, though.
I'm kinda vague about it in the TCB, but its additional 3 dB efficiency is coming from somewhere. Both curves I've shown above are at 140W....
dnewma04
The Healer
There were excursion issues with the one in the drawing at the full 100w, but IIRC, they were still within suspension limits of the TB at 16mm. You'd be looking at realistically 102dB or so with a bit of compression built in. With typical room gain, you'd probably have 105dB from low 20s to up near 90hz. (with a single sub).
With a pair, and 100w per side, obviously add 5-6dB.
Because of the ability we have to use transfer function to our advantage, i may try to tweak for a upper bass peak with a shallow rolloff to gain some system efficiency.
Bandpass boxes like this in cars, with transfer functions starting at 100hz in some cases sound very nice with what would be a one note bass boom box in a house. The cabin gain reenforces the low end to such an extent that flat response throughout the bass range down to below 20hz is possible. Obviously, the much larger rooms we have in our homes can't gain that much, but it's not unsually to gain 3-6dB per octave under 50hz.
Thoughts? It could make ports easier to integrate with higher tuning freqs.
With a pair, and 100w per side, obviously add 5-6dB.
Because of the ability we have to use transfer function to our advantage, i may try to tweak for a upper bass peak with a shallow rolloff to gain some system efficiency.
Bandpass boxes like this in cars, with transfer functions starting at 100hz in some cases sound very nice with what would be a one note bass boom box in a house. The cabin gain reenforces the low end to such an extent that flat response throughout the bass range down to below 20hz is possible. Obviously, the much larger rooms we have in our homes can't gain that much, but it's not unsually to gain 3-6dB per octave under 50hz.
Thoughts? It could make ports easier to integrate with higher tuning freqs.
dnewma04
The Healer
Yes, i believe the dimensions are detailed to enough of an extent in an earlier post.
you know the port dimensions, and i was designing with a 7" interior dimension in mind to keep it as thin as possible while still allowing the driver to fit. The overall dimentions can be adjusted in terms of height and depth.
you know the port dimensions, and i was designing with a 7" interior dimension in mind to keep it as thin as possible while still allowing the driver to fit. The overall dimentions can be adjusted in terms of height and depth.
dnewma04
The Healer
26.75 x 21.75 x 8.5 (outside dimensions)
The walls are 3/4". With the 13.1" port length, that gives us a small enclosure with internal dims of 7.125 x 7 x 12.25.
I'll finalize some dims in a bit. I'd like to make the 26.75" height into 25.5 to allow someone to just by 2x4' 'handy panels' rather than toting around 4x8 sheets of MDF.
The walls are 3/4". With the 13.1" port length, that gives us a small enclosure with internal dims of 7.125 x 7 x 12.25.
I'll finalize some dims in a bit. I'd like to make the 26.75" height into 25.5 to allow someone to just by 2x4' 'handy panels' rather than toting around 4x8 sheets of MDF.
You might be able to make a general guess...maybe around 50Hz or so? That would put you in the right neighborhood (~20' longest dimension in the room) and you'd start gaining below that. It would really depend on the room it's in so I wouldn't get too caught up in the minutiae or we'll have to change the design for each room it goes into. BB6 does have a "room gain" calc built into it but you have to come up with the basic transfer function yourself and it just implements it.
Ray
Dave, one thing to remember, is that you need to provide driver access, for both drivers, somewhere. Having the driver be stuck in the box could be bad, if there ever is a problem with a driver!
The easiest thing, with the drawing as you have it, would be to have side of the box comprising the longer of the two sides of the small chamber (i.e, the left side of the drawing as oriented in the picture above), be removable... that would allow both drivers to be removed, easily...
What kind of dimensions are we looking at? Looks like maybe around 16x16 by something? EDIT: I see the dimensions... duh. That's kind of large... almost 27 x 22?
Keeping an eye on this... I just discovered I HAVE a pair of '1139s, here, new in the box! I was going to do something similar in my truck, for bass... but wound up using the space behind the seats too much, so I gave up on that...
Regards,
Gordon.
The easiest thing, with the drawing as you have it, would be to have side of the box comprising the longer of the two sides of the small chamber (i.e, the left side of the drawing as oriented in the picture above), be removable... that would allow both drivers to be removed, easily...
What kind of dimensions are we looking at? Looks like maybe around 16x16 by something? EDIT: I see the dimensions... duh. That's kind of large... almost 27 x 22?
Keeping an eye on this... I just discovered I HAVE a pair of '1139s, here, new in the box! I was going to do something similar in my truck, for bass... but wound up using the space behind the seats too much, so I gave up on that...
Regards,
Gordon.
IME, if it's really shallow (less than 6 dB/oct), then 45 Hz or so would be pretty good to start with, as a "knee" for the tilt to start (as you go down in frequency). 50 Hz might work, in a small room...
If it's more sharp (steeper rolloff, approaching between 6 and 12dB/oct)... you might want it to start at 40 Hz or so...
Regards,
Gordon.
dnewma04
The Healer
dnewma04
The Healer
The latest version that I sent to Zilch did have a very shallow rolloff built in, but just a matter of a db or two from it's peak. I have 3" ports on hand right now, so i'm sticking with those, but it would be possible to split these into two smaller enclsoures, one driver per sub, and possibly use some rectangular ports and keep the dimensions manageable.
The drivers are only on sale for another week or so.
Not sure about the amp. No highpass, apparently:
http://www.parts-express.com/pe/pshowdetl.cfm?Partnumber=300-802
Not sure about the amp. No highpass, apparently:
http://www.parts-express.com/pe/pshowdetl.cfm?Partnumber=300-802
Attachments
skywave-rider
Slumming in Akihabara
Is this the TCB driver?
http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=264-832&vReviewShow=1&vReviewRand=9389009
If this design turns out to be studio apt. small, and easy to build in those confines -- using a jigsaw -- I'm intrigued.
http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=264-832&vReviewShow=1&vReviewRand=9389009
If this design turns out to be studio apt. small, and easy to build in those confines -- using a jigsaw -- I'm intrigued.
Yeah, that's the driver. And with a straight edge guide you could do it with a jigsaw. Wouldn't want to try cutting a straight line that long freehand. A hole saw to do cutouts for ports would probably be a good investment too. Those are tough with a jigsaw.
Ray
Ray