iBIBk developement thread.

Hi G!
Good idea, otherwise posts will drown in the original thread.
I've posted some questions before and move it here.

Dave, Greg, Martin, Scott or who ever has experience of K-sluts ;)
If there are benefits with an outside k-slot, what about inner baffle?

I still have not started with my Sonido BIB's, so should it be same area with a slot as a normal BIB fold? Tough question maybe. The answer, I suspect, will be "BUILD AND LISTEN"

Cheers
 
I think it's more "Build, listen, tweak, listen, tweak listen.....". I like the building and listening part, but quickly get bored with the tweaking and finishing part mainly because my quest is for that unachievable perfection, not optimizing to the lowest compromise.

I'm only posting to this thread because I built the iBIBk for my 127's. I do plan to tweak and measure them, but I've never measured anything before, so I'm waiting for my active XO software provider to launch measuring software that will directly tie in to the XO program instead of learning another program in the meantime.
 
Hi John!
I think it's more "Build, listen, tweak, listen, tweak listen.....".

No doubt about it, the damping I have now, in my BIB's, was "finalized" after, roughly 15 different damping strategies/material. Maybe not so much but I've learned to stop tweaking. When I'm can play most of my records without getting headache or being annoyed by resonances etc..... it's good.

There's simply not possible to have all of it when it comes to music reproduction at home.
Hmm, wait a minute..... of course when perfection in sound is needed, I use my Ibanez 6-string.
Note that I wrote sound, not the skill:rolleyes:

Cheers
 
peterbrorsson said:
Hmm.. started to ramble in the previous post.

John, I forgot to ask if the iBIBk you've built, is outer baffle slot
or inner?

Regards
Peter

My K-slot is at the bottom of the rear panel, though I'm sure on the side would be fine. On both side might be worth experimenting with, since I have a feeling with the terminus so close to the floor that more "breathing" area may be warranted.
 
My K-slot is at the bottom of the rear panel, though I'm sure on the side would be fine.

Yepp, I knew as soon I posted it would be misunderstood. My fault not being clear.
I was thinking of to have the K-slot on the divider inside the box. (the bend)

Regarding the slot on the sides, I'm not sure it will work. With my poor understanding, it's better loaded if it's backwards firing. Shure some more knowledge is around this forum who can clearify that.

Cheers
 
frugal-phile™
Joined 2001
Paid Member
peterbrorsson said:
Regarding the slot on the sides, I'm not sure it will work. With my poor understanding, it's better loaded if it's backwards firing. Shure some more knowledge is around this forum who can clearify that.

At the wavelengths of interest, 2 half-slots on the sides should not seem all that different from one on the back... being able to push it back against the wall will give the terminus maximum help.

dave
 
I've been reading and re reading all that I can find on the Karlson Coupler. It seem to me that it may well work better on a BIB type enclosure than the essentially bandpass type enclosure that he fitted it to. He also designed and patented a type of horn coupler in about 1980 but I have no references as to how this worked.

If the theory is to do with resonances in a tube then the BIB is a tapered tube and is closer in design to the theory. It might work best if the closed part of the bib was used a compression chamber and the speaker was mounted as far down as it would just fit. More like a front loaded horn. The slot could be to the front then with the open end exiting at floor level. Does this make sense. If I had a job I would try it out. there was one version made that is more like a folded TL terminated with a Karlosn slot but again not much about how effective it was.
jamikl
 
Yes, it makes perfect sense. The trick with Karlsons always appears to be in the tuning as it's currently very tricky to get the slot tuned to the correct frequency. But from the graphs etc I've seen, they potentially offer some real benefts. They've had an unjustifiably poor reputation & I'm all in favour of exploring them more fully.

In some ways the BIB already does work on a compression basis -it's a TQWT, and those are in many ways a branch of horn design with linear taper and of particular relevence to this case: end loaded. They're also So=0 for maximum possible pipe-gain. In most the driver is as high up as possible -for some, it's actually higher & needs a spacer (suprabaffle or similar) for the magnet to clear the internal baffle. So it lends itself to playing in this way.
 
jamikl said:
If the theory is to do with resonances in a tube then the BIB is a tapered tube and is closer in design to the theory. It might work best if the closed part of the bib was used a compression chamber and the speaker was mounted as far down as it would just fit. More like a front loaded horn.

The compression chamber is an interesting idea. I've thought about it and I know Scott has too. It would be really interesting to hear two otherwise identical BIB's, one with a CC and one without, to see (hear) what might be gained or lost in terms of sound quality.

It does make sense that with the CC acting as a low-pass filter you might be able to push the driver location towards the closed end of the pipe to maximize excitation of the quarter-wave mode without exciting higher resonances. My gut tells me that there might still be an optimum location though, depending on the size of the CC and the throat.

I suppose this is all a little off topic in the K-slot thread. Sorry. :xeye: So... as for where to put the slots, that seems to be a question answered by cut and try, doesn't it? It seems that BL designs like this can sound very good with the mouth in the back. It makes sense that they would be less dependent on location as far as the bass is concerned, which offers more leeway in placing the enclosure for the best presentation of the bulk of the sound coming directly from the front of the driver.

-- Dave
 
Dave, thanks a lot!

Maybe it's better to have them at the sides. Considering one has the distance, back to wall, about 5 cm. It does not make much difference regarding terminus area if it's on the back? More "breathing" would be the result if sides were opened?
Or the advantage with slots is to have an irregular pipe?



Hmm, problem would be aestethics with open sides. WAF rules!

Regards Peter
 
peterbrorsson said:
Maybe it's better to have them at the sides. Considering one has the distance, back to wall, about 5 cm.

That seems too close to the wall with the slot in the back, but what do I know? Let's not forget that Dave's design has the entire enclosure off the floor a little bit. That's bound to change things, and might make a big difference in the over all sound quality. Would have to try it, but it might be a really important feature of this design.


Or the advantage with slots is to have an irregular pipe?

That's my take on the K-slot; the length of the pipe is less well defined. The result is that the Q of the resonances are reduced thereby reducing the ripples in the frequency response. I really want to talk myself into believing that it affects the higher resonances more than the lowest quarter-wave mode that we want to keep, but I haven't come to a firm conclusion on that.

Presumably, the slot(s), a CC (if there were one), and the location of the driver along the pipe all work towards the same goal of reducing ripples. But that's all just theory at this point, and not necessarily good theory when you consider the source (me!)

-- Dave
 
Hi DaveC

That's my take on the K-slot; the length of the pipe is less well defined. The result is that the Q of the resonances are reduced thereby reducing the ripples in the frequency response. I really want to talk myself into believing that it affects the higher resonances more than the lowest quarter-wave mode that we want to keep, but I haven't come to a firm conclusion on that.

That's what my common sense and logic (if that counts) tell me.
For matters sake, I'm totally uneducated for the theory behind all this. BUT sometimes I have a feeling that the small differences in simulations are not detectable, or more terrible, it sounds better!

Hang me for this, if you like but IMHO the room induce more problem than the loudspeakers if loudspeakers are "reasonable" designed. With this I mean loudspeakers designed for a room and not an acoustical dead room. There was a Swedish loudspeaker designer called Stig Carlsson that had this approach and according to me they sound real good. Some people love them, some not. Off topic maybe but...

Regards Peter
 
I try to work with commonsense or intuition too Peter. It does seem that if the BIB was built as I suggest and used for base only with an 8 or 10 inch speaker and the then crossed quite low to a full range then a lot of the uneven response might disappear as the cone would not be interacting with the mouth as all radiation would be from the slot. Does this make sense? For smaller rooms even a 6.5 speaker should provide adequate bass. A small fostex could then be mounted on a supra baffle to handle everything above whatever crossover point was decided on. Not quite full range I know.
jamikl
 
While there is no "k" in this iBIBk, here's another variation, based on something I saw somewhere. I simply calculated the Sm of the bottom (without the k slot) and translated it into two triangles on each side. What would this do for the sound? It looks nice, and maybe it would sound nice in a corner?

My apologies if this is irrelevant to the discussion.
 

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frugal-phile™
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tburman said:
While there is no "k" in this iBIBk, here's another variation, based on something I saw somewhere. I simply calculated the Sm of the bottom (without the k slot) and translated it into two triangles on each side. What would this do for the sound? It looks nice, and maybe it would sound nice in a corner?

If you set the right variable in a k-slot forumla (ie the coefficients on any 2nd or higher order variables) you should be able to get a triangle, so this would be the simliest of k-slots.

Since you have a bottom on the box, the triangles will ned to be bigger (and no need for feet -- even an argument that they are counterproductive). The net effect of those 2 changes would be to push the range of its effect up in frequency. Could easily be countered -- if necessary -- by lengthening the pipe.

dave