Assuming you'll occasionally want to 'crank' it up and/or play some relatively dynamic recordings, then without a high pass, the odds are that the drivers will sooner than later be damaged and/or let their smoke out when they're called upon to reproduce any signal below ~0.8x Fs, which considering this driver's high Fs it would be while playing music from most any source recorded after stereo LPs came along in the late '50s.
Note that I've no personal experience with this driver and being designed for prosound apps I may be being overcautious, but better safe than sorry IMO.
Then there's amplitude modulation distortion [AMD] to consider that occurs when drivers used in a wide BW app are driven much beyond a few mm. Some folks can listen to, even enjoy, mass quantities of it, but in making recommendations I feel I should assume a worst case scenario, which is they are like me and find it intolerable for critical listening.
GM
Note that I've no personal experience with this driver and being designed for prosound apps I may be being overcautious, but better safe than sorry IMO.
Then there's amplitude modulation distortion [AMD] to consider that occurs when drivers used in a wide BW app are driven much beyond a few mm. Some folks can listen to, even enjoy, mass quantities of it, but in making recommendations I feel I should assume a worst case scenario, which is they are like me and find it intolerable for critical listening.
GM
GM,
It is obvious you are knowledable in this area so I appreciate your opinions regardless of your experience with this particular driver. And yes, this being for my son means that it will get "cranked up" on a regular basis, so thanks for the warning.
It is becoming apparrent to me that I will likely need to go to a large and simple BR for this driver. That will allow me to build the box in ratios that can live in the space and still allow for some bass reproduction. I am considering a 5 cuft ported enclosure. What is the best freeware cabinet program available for me to calculate the port with, WinISD?
Thanks again for your thoughful responses.
Best,
Ed
I have noted that when changing FS to a lower value the box gets taller and more narrow. I initially set the FS to the drivers spec. When we lower FS are we actually changing the output of the speaker for a given driver? What is the tradeoff, lower power handling, lower SPL (edit, I believe you answered this in the post above, anything lower that .8 of the drivers FS will burn up the driver at lower frequencies, thanks.)? The SM number changes as well, from your previous post you recommend not letting the SM go less than .7 of the drivers calculated value, so I will use that as a stopping point, but it is nice to be able to modify the size of the cabinets w&d by increasing the height. I am sure there is a practical point that this can be done with regard to the ceiling height, can anyone tell me what that may be?
Thanks,
Ed
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Well, it's getting tuned lower than the full octave below Fs of the default tuning, so with the same net Vb it will have a more extended LF, but with a faster roll off and a different harmonic structure that may/may not be beneficial once the room’s impact is factored in. Short of some serious room measurements though, there’s only one way to know for sure.
Correct, BIB tuning dictates an acoustically large net Vb to ensure a reasonable amount of power handling when corner loaded, so reducing it much might reduce it too much IF the room’s gain structure doesn’t add enough low end gain BW to offset it.
Well, I said it’s likely if played at high power without a high pass filter.
T.C.’s original BIB is ~70” tall and works fine with 8 ft ceilings, so at a glance it seems reasonable that it should be at least this tall plus it puts the driver at a good height for most apps.
GM
Correct, BIB tuning dictates an acoustically large net Vb to ensure a reasonable amount of power handling when corner loaded, so reducing it much might reduce it too much IF the room’s gain structure doesn’t add enough low end gain BW to offset it.
Well, I said it’s likely if played at high power without a high pass filter.
T.C.’s original BIB is ~70” tall and works fine with 8 ft ceilings, so at a glance it seems reasonable that it should be at least this tall plus it puts the driver at a good height for most apps.
GM
triadtron playing on my big BIB - YouTube
I made a short video of a Triadtron-amp playing on one of my BIBs. Its a 1,3 watt single end hexfet amp from Tube CAD Journal. No global feedback and only two IRF9530s (i had them laying around).
The microphone in my camera is not good. I dropped my camera in a lake once...
I think one can hear that it has potential anyways. Both the BIBs and my small amp.
Johannes.
I made a short video of a Triadtron-amp playing on one of my BIBs. Its a 1,3 watt single end hexfet amp from Tube CAD Journal. No global feedback and only two IRF9530s (i had them laying around).
The microphone in my camera is not good. I dropped my camera in a lake once...
I think one can hear that it has potential anyways. Both the BIBs and my small amp.
Johannes.
Yes, this is my B&C 10PS26.
I like the lowish Qms of the B&C driver. It makes it much easier to drive them from a high impedance source without having to "fight" the usual very peaky bass-resonace that higher-Qms-drivers have.
Ipads doesnt do flash?! I have no problem seeing it on my Samsung Galaxy smartphone or my Ubuntu-laptop.
Johannes.
I like the lowish Qms of the B&C driver. It makes it much easier to drive them from a high impedance source without having to "fight" the usual very peaky bass-resonace that higher-Qms-drivers have.
Ipads doesnt do flash?! I have no problem seeing it on my Samsung Galaxy smartphone or my Ubuntu-laptop.
Johannes.
I liked it. Sounds quite nice, even through crappy camera mic. Do you like them enough for a keeper? It looks like a sort of F.A.S.T. concept, bass in BIB and the smallish fullrange doing the top. On another thread there was an idea to build a Frugal horn 3 with some bass helpers. When I saw your video, I though it could be a good combination...
What characteristics make a driver successful in a BIB?
With beginner's luck, I made some BIB's with 2" TBs for my computer. They sound great! So, in my naivete and armed with the BIB calculator, I started trying the design with others and was really disappointed. Still keeping things in a small scale, I have some surplus Vifa 3" drivers (TC9FD18-08) that I want to use.
Fs = 125 Hz
Vas = 1.241L
Qts = .89
The main difference with the successes and the failures is that the Qts on the failures was higher .
Is there other data that I'm missing that would render the design and the calculator ineffective?
With beginner's luck, I made some BIB's with 2" TBs for my computer. They sound great! So, in my naivete and armed with the BIB calculator, I started trying the design with others and was really disappointed. Still keeping things in a small scale, I have some surplus Vifa 3" drivers (TC9FD18-08) that I want to use.
Fs = 125 Hz
Vas = 1.241L
Qts = .89
The main difference with the successes and the failures is that the Qts on the failures was higher .
Is there other data that I'm missing that would render the design and the calculator ineffective?
Problems I had with BiB and the 8 inch driver I'm playing with now, was the volume of the enclosure was always way to big for it, so it was full of holes. Messing around with hornresp to give a volume that gave a reasonable response ended up in the enclosure being too narrow/shallow to fit the mounting depth of the driver without a throat adapter set up. So perhaps it favours drivers that like nice big enclosures?
Did you build all these, or just run sims? If built, where in room were they located? Remember, these are designed for some empirically arrived at internal damping, corner loading and at least ~75% of ceiling height in folded length, so the further away from the ideal, the more dips in the response and rolled off the bass.
As a general rule though, a higher Qts up to around 1.0 is desirable if it doesn't make the cab too large for the available space. FWIW, all the corner pipe horns [not BIBs per se] I did had high Qts drivers all the way up to a whopping ~2.45 Qts. Above about a 1.4 Qts, the pipe horn is a good choice to acoustically damp it down.
Nothing other than maybe increasing Qts on very low Qts drivers, then adding a bit of EQ to 'fill it up' or designing to a lower Fs to make it tall enough or in the case of low Fs drivers, increasing Fs to limit it to two folds.
GM
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Thanks GM
I do not have the software or the know-how to run sims. If I understand what you are saying, I should chuck the idea of a scaled down BIB. Especially if the ceiling height is an integral part of the overall design.
However, I just measured and the ceiling is close to the right height with the speakers sitting up on the computer table. Hmmmm.
JHutka
I do not have the software or the know-how to run sims. If I understand what you are saying, I should chuck the idea of a scaled down BIB. Especially if the ceiling height is an integral part of the overall design.
However, I just measured and the ceiling is close to the right height with the speakers sitting up on the computer table. Hmmmm.
JHutka
