Samuel Jayaraj said:
You're welcome!
Sorry, I didn't read the whole thread, just responded to your post based on a little theory and a fair amount of experience with various types of floor loaded systems. Without full details of the TL, can't comment on the big performance disparity beyond the fact that the BIB with the same driver should drown it out down low.
Right, you only get the full benefit of a BIB by corner loading it, ditto a floor loaded one.
Sorry, didn't review your work, I just happened across this while searching for something else and tossed in my $0.2 worth.
I have my friends iBIB mostly done, I still need to make a supraBaffle and stain it. I put my fe126 drivers in last night and after adding quite a bit of stuffing above the driver they sounded really good. They started with a little but I had to add more about three times.
At first they sounded thin and in great need of some warmth. Guitars would dissapear behind the rest of the music and it lacked overall "oomph". They did not have much stuffing at first because my only experience is with the Harvey's and they did not need much and my friends Abbeys do not need any.
Once I got the stuffing correct everything came together and I am now really happy with them. They get every last bit of bottom end from my drivers and image ok though I think I can get it better adjusting how much they are toed in or out.
They are just flat on the bottom like a regular BIB and I need to take them to his place to see what needs done to adjust the sound since I have corners and he does not so I do not want to tune it to my place when his is different.
I will have pictures and more detailed impressions after I get them all the way finished and tweak the sound a bit.
At first they sounded thin and in great need of some warmth. Guitars would dissapear behind the rest of the music and it lacked overall "oomph". They did not have much stuffing at first because my only experience is with the Harvey's and they did not need much and my friends Abbeys do not need any.
Once I got the stuffing correct everything came together and I am now really happy with them. They get every last bit of bottom end from my drivers and image ok though I think I can get it better adjusting how much they are toed in or out.
They are just flat on the bottom like a regular BIB and I need to take them to his place to see what needs done to adjust the sound since I have corners and he does not so I do not want to tune it to my place when his is different.
I will have pictures and more detailed impressions after I get them all the way finished and tweak the sound a bit.
Scott, the Quarter Wave Loaded Loudspeaker System by John Dix appeared in Everyday Practical Electronics/ETI of October 1999.
Thanks for clarifying that the side slots+K slots = Sm. I thought that the slot cut-outs equal Sm and that the K-slots are an extra.
GM, you are one of the greatest contributors to the BIB idea on this fourm and your comments are welcome.
The data I supplied are those of the manufacturer and not actually measured by me. They could be a bit optimistic but the performance of the driver is among the best I have ever heard for drivers in that class. I have another 15 drivers, so swapping a few in and out to check for average performance should not be a problem.
I have figured that perhaps I need some stuffing from behind the driver up to the sealed end of the of the cab.
The real issue could be Baffle Step.
I used this http://www.sound.westhost.com/bafflestep.htm as a guide and rigged up a compensation circuit. I used VR1 set to about 3.5k, R1=10k and C1=68nF (the values could be way off to what is actually needed) but what I am hearing now is pretty good.
So my questions are:
1. What would be the Baffle Step frequency for a baffle measuring 17"x14" for a 6.50" driver?
2. How about sealing the bottom completely with anoter panel and cutting out two k-slots, one on either side, to equal Sm? Won't this sound better than under damped slots + k Slots?
Thanks for all the help and hope this discussion is helping other potential builders and pushing our understanding of BIBs and k slots.
Thanks for clarifying that the side slots+K slots = Sm. I thought that the slot cut-outs equal Sm and that the K-slots are an extra.
GM, you are one of the greatest contributors to the BIB idea on this fourm and your comments are welcome.
The data I supplied are those of the manufacturer and not actually measured by me. They could be a bit optimistic but the performance of the driver is among the best I have ever heard for drivers in that class. I have another 15 drivers, so swapping a few in and out to check for average performance should not be a problem.
I have figured that perhaps I need some stuffing from behind the driver up to the sealed end of the of the cab.
The real issue could be Baffle Step.
I used this http://www.sound.westhost.com/bafflestep.htm as a guide and rigged up a compensation circuit. I used VR1 set to about 3.5k, R1=10k and C1=68nF (the values could be way off to what is actually needed) but what I am hearing now is pretty good.
So my questions are:
1. What would be the Baffle Step frequency for a baffle measuring 17"x14" for a 6.50" driver?
2. How about sealing the bottom completely with anoter panel and cutting out two k-slots, one on either side, to equal Sm? Won't this sound better than under damped slots + k Slots?
Thanks for all the help and hope this discussion is helping other potential builders and pushing our understanding of BIBs and k slots.
Well I simmed my BSC circuit in Electronics Work Bench. It appears to attenuate signals by 2.5db from about 1kHz upwards, the attenuation falling off gradually from that point on till about 75Hz below which there is no attenuation. This circuit introduced in the signal path just before the power amp also introduces a max. of about 8.5 degrees Phase shift at a central frequency of 200Hz.
Samuel Jayaraj said:
That is what i did in the proposed/thot experiment iBIBk. Part of the idea thou was that given floor load it would be easy to adhust when it actually came to tuning a real world build.
The height from the floor and the size/configuration of the k-slot are very much a variable to be adjusted.
dave
The driver width doesn't affect baffle-step. Assuming that's a 14in wide baffle, then 4560 / 14 = 325.75Hz -3db step point. You shoudn't need a circuit though as you've got horn-gain correcting for that -assuming the manufacturers claims are accurate, which they often are not. Lowther for example claim a 36Hz Fs for their DX series drivers. Martin measured his at ~60Hz -a consistant result across lots of pairs, so it's not as if those particular units were sub-standard.
I don't know the QW cabinet design -in fact, I haven't heard of Everyday Practical Electronics either, so I can't really comment on that. Any chance of a scan of the design? I'm just wondering if it had a boosted LF region, so the BIB, unlikely as it sounds, in conjunction with possibly inaccurate parameters, appears weak in comparison. That's just a guess though. Weak bass is the last thing these cabinets should have!
Try blanking off one of the openings temporarily and see how that affects the sound. Also -what are they standing on? Something we ran into with the Metronomes only a few days back. Solid floor, or a carpet? If it's the latter, stick something solid under them as a plinth, and again, see what happens.
Best
Scott
I don't know the QW cabinet design -in fact, I haven't heard of Everyday Practical Electronics either, so I can't really comment on that. Any chance of a scan of the design? I'm just wondering if it had a boosted LF region, so the BIB, unlikely as it sounds, in conjunction with possibly inaccurate parameters, appears weak in comparison. That's just a guess though. Weak bass is the last thing these cabinets should have!
Try blanking off one of the openings temporarily and see how that affects the sound. Also -what are they standing on? Something we ran into with the Metronomes only a few days back. Solid floor, or a carpet? If it's the latter, stick something solid under them as a plinth, and again, see what happens.
Best
Scott
Thanks Dave, I now see that your proposed idea had flexibility built into it. I am however, reluctant to cut the k-slot right away because I want to be sure that the normal BIB works with my cabs when I rotate them around by 180 degrees. Once they work well as BIBs are supposed to, then I'll revert back to iBIBk.
Scott, I'll try to make a scan of the QWL design and post it to you. You may be able to better judge whether they have any LF gain.
But what I am saying is that objectively speaking, my cabs lack bass. I will try more stuffing. I will change drivers. Finally, I will try the same cab with my Fostex 168Sigma drivers which are in the same cartons they arrived in from Madisound. I know the dims are not correct for the Fostex, but I will atleast get an idea of how much the driver is contributing to the lean bass I am hearing.
I'll keep you all informed. Thanks again.
Scott, I'll try to make a scan of the QWL design and post it to you. You may be able to better judge whether they have any LF gain.
But what I am saying is that objectively speaking, my cabs lack bass. I will try more stuffing. I will change drivers. Finally, I will try the same cab with my Fostex 168Sigma drivers which are in the same cartons they arrived in from Madisound. I know the dims are not correct for the Fostex, but I will atleast get an idea of how much the driver is contributing to the lean bass I am hearing.
I'll keep you all informed. Thanks again.
Cabinet feet
I'm following planet10's plans rather closely. I'm trying to work out how to make the feet on the cabinet. I think it's important that the height from the floor is adjustable, as I'm reading a lot of people say the Sm from the height area and the Karlson slot area are rather experimental according to the room. It looks like a few pieces of wood are placed on the sides to space the feet out a bit. Is this so that the feet are clearly out of the vent on the bottom or just for stability reasons?
Does anyone have any other pictures of their iBiBk cabinets? I'm pretty impresed with the few I've seen in this thread so far. I'll have some pictures of mine once I finish.
I've got all the panels cut out. I have to carefully consider how I'm going to make the suprabaffles, the Karlson slot shape and actual physical cut, the feet, if I want to mitre the baffle joint, round the top of the baffle, any bracing, and finally, the cabinet feet. Phew!
I'm following planet10's plans rather closely. I'm trying to work out how to make the feet on the cabinet. I think it's important that the height from the floor is adjustable, as I'm reading a lot of people say the Sm from the height area and the Karlson slot area are rather experimental according to the room. It looks like a few pieces of wood are placed on the sides to space the feet out a bit. Is this so that the feet are clearly out of the vent on the bottom or just for stability reasons?
Does anyone have any other pictures of their iBiBk cabinets? I'm pretty impresed with the few I've seen in this thread so far. I'll have some pictures of mine once I finish.
I've got all the panels cut out. I have to carefully consider how I'm going to make the suprabaffles, the Karlson slot shape and actual physical cut, the feet, if I want to mitre the baffle joint, round the top of the baffle, any bracing, and finally, the cabinet feet. Phew!
Anybody using a radius on the edges of the Karlson slot? Should the outer and inner sides be radiused to "round out" the opening?
I don't remember seeing any Karlsons like that. But I don't see why not, so long as you make sure you don't deviate from the slot profile. Then again, as it's a SWAG anyway, probably be wirth trying.
here's someone's 115BK sized KHYBOE (~27x15x20.5) loaded with Altec which appear to have some roundover (my 115BK have it too but looks more like rasped)
http://img214.imageshack.us/img214/8149/superk6lv.jpg
that waveguide sounds better to me than a DDS pro-90
http://img214.imageshack.us/img214/8149/superk6lv.jpg
that waveguide sounds better to me than a DDS pro-90
freddi said:
A thousand retorts spring to mind, each one wittier than the last. I'll refrain from voicing any of them though, which surely shows a striking degree of magnanimity in a person who rarely thinks of any comeback until the next day... 😀
Sorry, couldn't resist. 😉 In point of fact, I'm not at all surprised. Karlsons have a mediocre reputation which is undeserved IMO -they can be extremely effective indeed. The couple of pairs that I've heard (all K15s) impressed me greatly. I've heard smoother enclosures (I've heard rougher ones too) but their dynamic speed & punch below ~600Hz in particular was excellent & overall their ballance of characteristics leaned toward those which I enjoy. Yet another British invention that foundered through lack of investment. The UK had some of the greatest engineers in the world until the 1970s, most of them wearing brown coats & working with slide-rules in a leaking shed because their contemporary Governments wouldn't give them the time of day, let alone any money to develop their ideas properly. Either that, or when said latest invention / development was completed (naturally without any State assistance or even encouragement to help attract private investors) then they would present the aforementioned to a rival nation, gratis, for who-knows what reason, without ever checking to find out a) if the owner / inventor minded, and b) if it was a terribly good idea. Look at what happened with the Rolls Royce Nene. Ever wondered why the MiG 15 was so good? Yes, it was because it had a British engine, directly copied from the examples sent to the Soviet Union in what I can only describe as a moment of insanity on the part of our illustrious leaders.
And they wonder why Britian's in the state it's in today. 🙄
Hi guys,
I'm presently (read finally...) building a iBIBk for the FE103 (the wood has been cut ) but I can' figure out how to size the K slot.
My area is 48 in2, the driver is positionned at about 36 '' from the floor. I will put the K slot in the back of the enclosure next to the wall. The internal width is 6'' and the depth is 8''
According to a few software (FE127e from Planet 10) is order to use the width of 6'' the height of the slot would need to be 20''. Does this seems correct ?
Any help on sizing this K slot would help.
p.s. I usually post on the FR forum as Isophon, this is my first post here 🙂
TIA,
Eric
I'm presently (read finally...) building a iBIBk for the FE103 (the wood has been cut ) but I can' figure out how to size the K slot.
My area is 48 in2, the driver is positionned at about 36 '' from the floor. I will put the K slot in the back of the enclosure next to the wall. The internal width is 6'' and the depth is 8''
According to a few software (FE127e from Planet 10) is order to use the width of 6'' the height of the slot would need to be 20''. Does this seems correct ?
Any help on sizing this K slot would help.
p.s. I usually post on the FR forum as Isophon, this is my first post here 🙂
TIA,
Eric
Eric,
The exact formulation of the Karlson slot is still open to experimentation... I'd sit down with the excel calculator and play unil i had something that "looked" right.
dave
The exact formulation of the Karlson slot is still open to experimentation... I'd sit down with the excel calculator and play unil i had something that "looked" right.
dave
Hi Dave,
I modified the Excel spreadsheet you gave as a attactment of the iBIBk for the FE127e ( thanks) and now I really think I've got something good. The exponential curves compare in numbers to other Karlson I have seen on the web. I have removed a few colomn but kept the essential. I also added an extra colomn that shows the CSA with respect to the lenght of the slot. I finally came up with a slot of 17'' long by 6.5'' wide in order to get an slot area of 48in2.
Last night I cut the K-slot and today the wholes for the wiring cup and driver.
I also used the program called EDGE and found out that the BSC required would be L:4.3mH and R:6-8 ohm.
I will keep you posted.
Regards,
Eric
I modified the Excel spreadsheet you gave as a attactment of the iBIBk for the FE127e ( thanks) and now I really think I've got something good. The exponential curves compare in numbers to other Karlson I have seen on the web. I have removed a few colomn but kept the essential. I also added an extra colomn that shows the CSA with respect to the lenght of the slot. I finally came up with a slot of 17'' long by 6.5'' wide in order to get an slot area of 48in2.
Last night I cut the K-slot and today the wholes for the wiring cup and driver.
I also used the program called EDGE and found out that the BSC required would be L:4.3mH and R:6-8 ohm.
I will keep you posted.
Regards,
Eric
I'm thinking of adding K-slots to my BIBs to lower their gain a bit in the bass. If it smooths the bass out a bit, I'll consider it an added benefit. I'm actually still thinking of inverting them too. It may be sleep deprivation, but I'm having a hard time figuring out how to calculate the K-slot dimensions. The spreadsheets I downloaded seem to require one to know the target length and width from the get go. How does one arrive at those numbers?
pj
pj