loninappleton said:
OK, there's so many variables that affect the lower mids that the tone of each will probably always be different even once you get the stuffing the same, but 'losing' a clarinet implies an incredibly over damped condition that's 'sucking the life' out of the driver which egg crate foam and lossy cab materials are wont to do, though one would think the foam's far enough away if just lining the bottom of a BIB, but only one to know for sure.
Again though, until you reduce all the variables as much as practical there's no way to come to any useful conclusions.
GM
loninappleton said:
At one time you were running the MLTL with no stuffing or lining, making for a very 'live' (distorted) sounding system, i.e. lots of lower mids emphasis that resonates up through the mids into the HF, so for sure it's going to sound more 'forward', etc., than a damped BIB even if lightly damped. Factor in the BIB's wider baffle and its 'sound-staging' is so diminished in comparison and combined with such different tuning alignments there's no telling how you're perceiving the overall presentation, ergo no hope IMO of coming to any useful conclusions to help tweak the BIB with this set-up.
GM
Greets!
The latter.
While I'm sure there's some fancy math to predict it all to a fare-thee-well, I'm forced to visualize how acoustics work (or think they do at typical cab BW frequencies anyway), so prefer to view things at room size, ergo as a short dead end hallway to a large enclosed mall with the back of a wall size driver protruding from the closed end wall.
The mall's acoustically large Vb, closed pipe properties presents a varying acoustic impedance to the driver, so modulates/controls it as much as the driver allows it to. The walls shroud the driver, creating differing horn profiles to the driver's basket and diaphragm with complex reflections up high and localized compression loading with decreasing frequency in the BW below them just like in a horn's throat.
Adding a step halfway down the wall's length sets up a completely new set of complex reflections along with altering the originals to comb filter into higher peaks/nulls, though it does reduce 'throat' pressure.
If we chamfer the walls so that throat pressure is reduced to only a fraction of the cab's and has a 'fast' enough expansion to allow any reflections to rapidly decay away, they can't be modulated or reflected back through the driver by 'mall' pressure.
Where all this becomes a perceived tonal difference depends on many variables such as diaphragm construction, size, suspension and cab compliance, etc., but FWIW my design philosophy is that 'God' is in the details, so while a single one may not be audible they do add up, then considering the negligible extra effort involved there's no good reason not to chamfer IMO when the driver's a wide BW one and the diaphragm can 'feel' the baffle's side wall.
As always though, YMMV.
GM
The latter.
While I'm sure there's some fancy math to predict it all to a fare-thee-well, I'm forced to visualize how acoustics work (or think they do at typical cab BW frequencies anyway), so prefer to view things at room size, ergo as a short dead end hallway to a large enclosed mall with the back of a wall size driver protruding from the closed end wall.
The mall's acoustically large Vb, closed pipe properties presents a varying acoustic impedance to the driver, so modulates/controls it as much as the driver allows it to. The walls shroud the driver, creating differing horn profiles to the driver's basket and diaphragm with complex reflections up high and localized compression loading with decreasing frequency in the BW below them just like in a horn's throat.
Adding a step halfway down the wall's length sets up a completely new set of complex reflections along with altering the originals to comb filter into higher peaks/nulls, though it does reduce 'throat' pressure.
If we chamfer the walls so that throat pressure is reduced to only a fraction of the cab's and has a 'fast' enough expansion to allow any reflections to rapidly decay away, they can't be modulated or reflected back through the driver by 'mall' pressure.
Where all this becomes a perceived tonal difference depends on many variables such as diaphragm construction, size, suspension and cab compliance, etc., but FWIW my design philosophy is that 'God' is in the details, so while a single one may not be audible they do add up, then considering the negligible extra effort involved there's no good reason not to chamfer IMO when the driver's a wide BW one and the diaphragm can 'feel' the baffle's side wall.
As always though, YMMV.
GM
Whelp, I have now done the last operation I can think of:
swap drivers.
The weak side remained the same.
But here is something strange or maybe a cause:
I was playing tones (and I have to guess at this-- about 60 hz in the
audible range.
The weak side driver is getting a lot more excursion (vibrating like anything) while the strong side is much more controlled as to excursion.
I can see it and I can feel it to the touch.
I've swapped everything back and forth. There doesn't seem much else to do except swap again and see if the excursion difference remains.
My wire is balanced-- not thin wire one side, standard the other. Both are a standard wire.
By now this is OT in the BIB thread. I'll just have to EQ it as I've been doing.
swap drivers.
The weak side remained the same.
But here is something strange or maybe a cause:
I was playing tones (and I have to guess at this-- about 60 hz in the
audible range.
The weak side driver is getting a lot more excursion (vibrating like anything) while the strong side is much more controlled as to excursion.
I can see it and I can feel it to the touch.
I've swapped everything back and forth. There doesn't seem much else to do except swap again and see if the excursion difference remains.
My wire is balanced-- not thin wire one side, standard the other. Both are a standard wire.
By now this is OT in the BIB thread. I'll just have to EQ it as I've been doing.
snafu
I owe you an answer on this. I screwed up: had the balance control out of whack.
What I should have done is take them out and do the inspection method by sight and touch.
Back to normal with the BIB and MLTL. BIB with single
baffle.
I think the double baffle with stepped cutouts is doomed.
Also I have removed all the goop ont hye drivers as well as
the cloth bonnet. they are running lean and natural.
Next venture will be to complete a mate for the MLTL to see if that
improves soundstage. Of note I have had to of the MLTL but too much fiddling meant I had to make new pieces to put the port back where it should be-- bottom and extended.
I have had bibs in pairs and mismatched with the Harvey as well
and in both cases, those narrow cabinets have failed to produce anything like the soundstange on smaller MLTL style cabinets.
As mentioned this may be because my listening position is always pretty close.
GM said:
I owe you an answer on this. I screwed up: had the balance control out of whack.
What I should have done is take them out and do the inspection method by sight and touch.
Back to normal with the BIB and MLTL. BIB with single
baffle.
I think the double baffle with stepped cutouts is doomed.
Also I have removed all the goop ont hye drivers as well as
the cloth bonnet. they are running lean and natural.
Next venture will be to complete a mate for the MLTL to see if that
improves soundstage. Of note I have had to of the MLTL but too much fiddling meant I had to make new pieces to put the port back where it should be-- bottom and extended.
I have had bibs in pairs and mismatched with the Harvey as well
and in both cases, those narrow cabinets have failed to produce anything like the soundstange on smaller MLTL style cabinets.
As mentioned this may be because my listening position is always pretty close.
Jordan BIB... birch ply with MDF center board?
Hello everyone,
I am in the process of planning out my cabs. I bought the drivers on the Independence Day sale and now it's time to look at the details.
In order to reduce costs of buying another sheet of birch ply,and waste, what would the affects be of using MDF for the middle/angled board as opposed to the 18mm Birch ply I will be using for the rest of the cab? Has anyone done this or does anyone have any strong opinions?
Thanks!
Hello everyone,
I am in the process of planning out my cabs. I bought the drivers on the Independence Day sale and now it's time to look at the details.
In order to reduce costs of buying another sheet of birch ply,and waste, what would the affects be of using MDF for the middle/angled board as opposed to the 18mm Birch ply I will be using for the rest of the cab? Has anyone done this or does anyone have any strong opinions?
Thanks!
Greets!
Typing 'mdf' in the 'search this thread' window at the bottom of the page quickly returned this post: http://www.diyaudio.com/forums/showthread.php?s=&postid=1342184&highlight=#post1342184
GM
Typing 'mdf' in the 'search this thread' window at the bottom of the page quickly returned this post: http://www.diyaudio.com/forums/showthread.php?s=&postid=1342184&highlight=#post1342184
GM
Posted on BBBIB, but it's BIB toooo...
10" Eminence Coax Post #271 BBBIB
How does this look?
Would someone sim this please, I lack the expertise to.
Thinking of using the Eminence APT-50 supertweeter, or possibly the Selenium D210 Ti.
here's the info obtained from the " BIB Calculator "
Eminence 10CX
Fs 49
Vas 2.3
Qts 0.39
Line length 137.393
Folded Height 68.697
Vb 14.177
Sm 356.613
Depth(internal) 22.457
Width(internal) 15.880
Z driver 29.814
ABC 11.229
Would probably pad the top of the low freq. driver with the crossover, and put an L pad on the tweeter, to match levels. XO at about 5K?
BTW this would be for HT use, anyone want to hazard a guess how low it will go? ( do you think I would still need a sub? )
This is a mental excercise at this point only, but I think I can slip this past the " approval committee " ( that's WAF to those who know ). Especially if I can " tart it up" to look vaguely " Mission Style" to match other furnishings.
Whaddya Tink?
John
10" Eminence Coax Post #271 BBBIB
How does this look?
Would someone sim this please, I lack the expertise to.
Thinking of using the Eminence APT-50 supertweeter, or possibly the Selenium D210 Ti.
here's the info obtained from the " BIB Calculator "
Eminence 10CX
Fs 49
Vas 2.3
Qts 0.39
Line length 137.393
Folded Height 68.697
Vb 14.177
Sm 356.613
Depth(internal) 22.457
Width(internal) 15.880
Z driver 29.814
ABC 11.229
Would probably pad the top of the low freq. driver with the crossover, and put an L pad on the tweeter, to match levels. XO at about 5K?
BTW this would be for HT use, anyone want to hazard a guess how low it will go? ( do you think I would still need a sub? )
This is a mental excercise at this point only, but I think I can slip this past the " approval committee " ( that's WAF to those who know ). Especially if I can " tart it up" to look vaguely " Mission Style" to match other furnishings.
Whaddya Tink?
John
Bigger is better right? When it's not costly and actually preferable to go bigger, how big is too big?
According to the xl calculator and zillaspeak.com, the 108e sig bib is very small.
108e sigma bib
length - 88 inches
zdriver - 17.5 inches
sm - 33 inches
This small size is a problem since it wouldn't take much more than a strong breeze to knock them over. Sure, you could make a large base, but I wondered how big the actual enclosure could be.
I modelled the recommended 108 bib as a simple end loaded pipe horn in hornresp, which is obviously not perfect since the bib is not end loaded, but it's enough to get a rough idea. Watching the excursion VERY carefully, I started making the line fatter (larger sm) and longer.
I'm not noticing diminishing returns the bib gets larger than the one recommended for the 126e.
126e bib
length - 97 inches
zdriver - 19.5 inches
sm - 63 inches (the larger more bass version)
In other words, it looks like by making a 108 bib dramatically larger (the size of the 126 bib) results in a significantly lower tuning with ~ the same excursion as the 108 bib.
So how big is too big?
According to the xl calculator and zillaspeak.com, the 108e sig bib is very small.
108e sigma bib
length - 88 inches
zdriver - 17.5 inches
sm - 33 inches
This small size is a problem since it wouldn't take much more than a strong breeze to knock them over. Sure, you could make a large base, but I wondered how big the actual enclosure could be.
I modelled the recommended 108 bib as a simple end loaded pipe horn in hornresp, which is obviously not perfect since the bib is not end loaded, but it's enough to get a rough idea. Watching the excursion VERY carefully, I started making the line fatter (larger sm) and longer.
I'm not noticing diminishing returns the bib gets larger than the one recommended for the 126e.
126e bib
length - 97 inches
zdriver - 19.5 inches
sm - 63 inches (the larger more bass version)
In other words, it looks like by making a 108 bib dramatically larger (the size of the 126 bib) results in a significantly lower tuning with ~ the same excursion as the 108 bib.
So how big is too big?
When you end load a horn the 'sky' is pretty much the limit, but the downside if you have the $$$/space to build such a behemoth its acoustic mass lowers Fs with increasing size it's also over-damping a 'FR' driver's mass controlled BW, so once it reaches a certain mass (horn Vb) you have little/no ~flat BW output above the horn's HF mass corner (same as the driver's originally) and far enough down in output to be of no real use.
For example, here's one I did awhile back to prove several points, though now that Hornresp can combine a pistonic response to it will serve well enough for this one also. Note that it wouldn't let me input a long/large enough horn, so even with corner loading it's not as smooth/flat as what theory predicts (set Ang = 0.0 for infinite to see how 'perfect' the math makes all its plots).
GM
For example, here's one I did awhile back to prove several points, though now that Hornresp can combine a pistonic response to it will serve well enough for this one also. Note that it wouldn't let me input a long/large enough horn, so even with corner loading it's not as smooth/flat as what theory predicts (set Ang = 0.0 for infinite to see how 'perfect' the math makes all its plots).
GM
Attachments
Haven't worked them out, but if you're seeing good results in Hornresp, give it a go and let us know how it turns out since long term mine/Scot's goal is to eventually work up compression loaded BIBs if practical once the original was a done deal, which it is IMO now that there's a simple math routine to design them.
GM
GM
I remember talk of compression loaded bibs long long ago, and IIRC Ron said he was going to get in on that game too, but it's been so long now that I thought this plan was abandoned.
If these new bibs are in the works anytime soon I might just wait for them, since the addition of a cc can't do anything but good. I'm thinking much higher power handling and likely smoother response. But I wouldn't dare trying to work it out on my own.
If these new bibs are in the works anytime soon I might just wait for them, since the addition of a cc can't do anything but good. I'm thinking much higher power handling and likely smoother response. But I wouldn't dare trying to work it out on my own.
Well I hope it's pleasant business that will be keeping you busy and offline.
Anyway, some quick fiddling with adding a cc and just making the bib into an end loaded conical pipe/horn with a cc shows I have no idea what I'm doing but from what I can tell it would be about 6 db too bass heavy and completely swamp the FR output and uses 50% more excursion in the process.
Rather than try to figure it out I'll likely revert back to the original oversized bib plan.
Anyway, some quick fiddling with adding a cc and just making the bib into an end loaded conical pipe/horn with a cc shows I have no idea what I'm doing but from what I can tell it would be about 6 db too bass heavy and completely swamp the FR output and uses 50% more excursion in the process.
Rather than try to figure it out I'll likely revert back to the original oversized bib plan.
Yowie! I'm to sorry hear that. But also, if this is related to vision or hand dexterity, you don't necessarily have to do without computing. There are lots of options, especially on Linux which is free and almost infinitely customizable. Windows' options are not bad either.
Many sites are becoming Section 508-compliant so that they can be accessed via "alternative" browsers (e.g., ones that read the page content, or respond to alternative input devices).
I would happily research and report back on the Linux options. I'm at: rbond at csf dot edu